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  • 101.
    Wang, Jia-Xing
    et al.
    Dongguan Univ Technol, 1 Daxue Rd, Dongguan 523808, Peoples R China..
    Li, Xin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Li, Chen
    Dongguan Univ Technol, 1 Daxue Rd, Dongguan 523808, Peoples R China..
    Constructing photochromic diarylethene with NIR-absorption beyond 800 nm2021In: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 189, article id 109273Article in journal (Refereed)
    Abstract [en]

    Near-infrared (NIR) absorbing dyes have received increasing attention due to their ability of NIR radiation absorption and efficient light-to-heat conversion. NIR absorbing photochromic diarylethene (DAE) materials, which could modulate NIR absorption upon light stimulation, provide a convenient route to fabricate smart NIR absorbers. In this study, we constructed a new NIR absorbing photochromic DAE system, of which NIR absorption stems from closed isomer bearing triarylamine (TAA) radical (TDEc-ox). Upon 365/440 nm light irradiation, the open isomer TDEo undergoes photo-oxidation and cyclization to yield TDEc-ox, which exhibited NIR absorption at 928 nm in chloroform. TDEc-ox possesses a photo-inactive feature facilitating non-destructive readout of NIR absorption and high stability (lifetime time ? 3 days). Contrary to TDEo, the closed isomer TDEc cannot be directly photo-oxidized to give TDEc-ox. This discrepancy makes TDEc a ?photogenerated TAA radical reservoir?: after cycles of photoisomerization, a controllable accumulation of NIR absorbing TDEc-ox can be achieved.

  • 102. Wang, Q.
    et al.
    Zhang, Q.
    Zhang, Q. -W
    Li, Xin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Zhao, C. -X
    Xu, T. -Y
    Qu, D. -H
    Tian, H.
    Color-tunable single-fluorophore supramolecular system with assembly-encoded emission2020In: Nature Communications, E-ISSN 2041-1723, Vol. 11, no 1, article id 158Article in journal (Refereed)
    Abstract [en]

    Regulating the fluorescent properties of organic small molecules in a controlled and dynamic manner has been a fundamental research goal. Although several strategies have been exploited, realizing multi-color molecular emission from a single fluorophore remains challenging. Herein, we demonstrate an emissive system by combining pyrene fluorophore and acylhydrazone units, which can generate multi-color switchable fluorescent emissions at different assembled states. Two kinds of supramolecular tools, amphiphilic self-assembly and γ-cyclodextrin mediated host-guest recognition, are used to manipulate the intermolecular aromatic stacking distances, resulting in the tunable fluorescent emission ranging from blue to yellow, including a pure white-light emission. Moreover, an external chemical signal, amylase, is introduced to control the assembly states of the system on a time scale, generating a distinct dynamic emission system. The dynamic properties of this multi-color fluorescent system can be also enabled in a hydrogel network, exhibiting a promising potential for intelligent fluorescent materials.

  • 103. Wang, Shangshang
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhao, Wandong
    Chen, Xuanying
    Zhang, Junji
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zou, Qi
    Zhu, Liangliang
    Chen, Wenbo
    Cu2+-Selectivity gated photochromism in Schiff-modified diarylethenes with a star-shaped structure2017In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 5, no 2, p. 282-289Article in journal (Refereed)
    Abstract [en]

    A great deal of effort has been devoted to developing gated photochromic systems due to their advantages in the smart materials and opto-electronic fields, whereas the gating function through certain ions has rarely been addressed. Since the photochromic materials gated by ions can be readily further processed into a multi-functional molecular switch and probe, we herein designed and conveniently synthesized a star-shaped Schiff-based diarylethene derivative showing typical photochromic properties in solution. This compound possesses two response channels (colorimetric and fluorogenic) to Cu2+ ions with photoswitching characteristics, making it a viable photochromic probe. It is noteworthy that its photochromic reactivity can be locked when Cu2+ ions are introduced into the solution. Moreover, the photoinactive and photoactive states can be interchanged reversibly by binding Cu2+ ions and unbinding Cu2+ ions using EDTA, which shows promise for application in multi-controlled molecular switches and smart materials. The mechanism of the photochromic properties locked by Cu2+ ions is reasonably proposed by theoretical simulations. These results could be valuable for the further development of molecular switching systems with multiple stimuli responses.

  • 104. Wang, Yueqiang
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Liu, Bo
    Wu, Wenjun
    Zhu, Weihong
    Xie, Yongshu
    Porphyrins bearing long alkoxyl chains and carbazole for dye-sensitized solar cells: tuning cell performance through an ethynylene bridge2013In: RSC Advances, E-ISSN 2046-2069, Vol. 3, no 34, p. 14780-14790Article in journal (Refereed)
    Abstract [en]

    Two novel porphyrin dyes (Q1 and Q2) bearing alkoxyl chains with a carbazole moiety as the electron donor have been synthesized and utilized as sensitizers for dye-sensitized solar cells (DSSCs). Compared with Q2, the molecule of Q1 has an additional ethynylene bridge between the carbazole moiety and the porphyrin framework. Photophysical and electrochemical properties of the two dyes were investigated by UV-vis, fluorescence spectroscopy and cyclic voltammetry. DFT calculations indicated that Q2 has a more twisted non-planar conformation associated with a smaller p conjugation size because of the absence of ethynylene bridge, which resulted in its better solubility and larger amount of adsorption on TiO2. Compared with Q1, Q2 showed better photovoltaic performance, with a short-circuit photocurrent density (J(sc)) of 11.3 mA cm(-2), an open-circuit photovoltage (V-oc) of 0.68 V, and a fill factor (ff) of 0.71, corresponding to an overall conversion efficiency of 5.51% under standard global AM 1.5 solar light conditions. The additional ethynylene bridge in Q1 extends the absorption bands to a longer wavelength region with the absorption threshold of 743 nm on the TiO2 film compared with that of 681 nm for Q2, but the cell efficiency is decreased to 2.22%, which may be ascribed to the worse solubility and stronger aggregation tendency resulting from the better molecule planarity. These results indicate that the extension of the absorption bands to a longer wavelength region by the introduction of an additional ethynylene bridge may result in worse solubility and more severe aggregation, and thus decrease the cell efficiency. For the design of efficient DSSC sensitizers, these contradictory effects must be fully considered and well balanced.

  • 105. Wang, Yueqiang
    et al.
    Xu, Lu
    Wei, Xiaodong
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Wu, Wenjun
    Xie, Yongshu
    2-Diphenylaminothiophene as the donor of porphyrin sensitizers for dye-sensitized solar cells2014In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 38, no 7, p. 3227-3235Article in journal (Refereed)
    Abstract [en]

    Four novel D-pi-A porphyrin dyes (YQ1 YQ4) with 2-diphenylaminothiophene attached at the mesoposition as the electron donor have been synthesized and used as the sensitizers for dye sensitized solar cells (DSSCs). 4-Ethynylbenzoic acid and 2-cyanoacrylic acid were incorporated as the anchoring moieties in YQ1, and YQ2 YQ4, respectively. Due to the extended conjugation size, the absorption spectra of YQ2 YQ4 showed Soret band maxima in the range of 447-468 nm, which is red shifted as compared to that of 446 nm for Y01. Furthermore, in comparison with most reported porphyrin dyes with similar structures, YQ1-YQ4 demonstrate obviously red-shifted absorption maxima and broadened Soret bands, indicating that these porphyrin dyes may be developed as promising DSSC sensitizers. The electrochemical studies and DFT calculations indicated that all the four dyes were capable of serving as DSSC sensitizers. Thus, DSSCs were fabricated based on these dyes. The cells based on YQ4 showed the power conversion efficiency of 5.00%, which is higher than those of 4.23% and 4.38% for YQ2 and YQ3, respectively. This observation may be attributed to the suppression of the dye aggregation by the hexyl group attached to the thienyl ring of YQ4. On the other hand, YQ2 YQ4 demonstrated lower efficiencies compared with Y01, which may be ascribed to the floppy structures of the cyanoacrylic acid-based porphyrins that provide free space for charge recombination. As a result, the DSSCs based on Y01 exhibited the highest efficiency of 6.01%. This work demonstrates that the introduction of 2-diphenylaminothiophene into a porphyrin framework can obviously red-shift and broaden the absorption bands of the porphyrin dyes, resulting in high solar cell efficiencies. Hence, the introduction of 2-diphenylaminothiophene as the electron donor may be promising for the design of efficient porphyrin-based DSSC sensitizers.

  • 106. Wei, Pingchun
    et al.
    Zhang, Kai
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Meng, Deying
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ou, Zhongping
    Ng, Seikweng
    Furuta, Hiroyuki
    Xie, Yongshu
    Neo-Fused Hexaphyrin: A Molecular Puzzle Containing an N-Linked Pentaphyrin2014In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 53, no 51, p. 14069-14073Article in journal (Refereed)
    Abstract [en]

    The first neo-confused hexaphyrin(1.1.1.1.1.0) was synthesized by oxidative ring closure of a hexapyrrane bearing two terminal "confused" pyrroles. The new compound displays a folded conformation with a short interpyrrolic C center dot center dot center dot N distance of 3.102 angstrom, and thus it readily underwent ring fusion to afford a neo-fused hexaphyrin with an unprecedented 5,5,5,7-tetracyclic ring structure. Furthermore, coordination of Cu-II triggered a ring opening/contracting reaction to afford a Cu-II complex of an N-linked pentaphyrin derivative. The roles of reactive N-C bonds in the porphyrinoid macrocycles were demonstrated.

  • 107. Wei, Tiantian
    et al.
    Sun, Xi
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Xie, Yongshu
    Systematic Investigations on the Roles of the Electron Acceptor and Neighboring Ethynylene Moiety in Porphyrins for Dye-Sensitized Solar Cells2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 39, p. 21956-21965Article in journal (Refereed)
    Abstract [en]

    Cyanoacrylic and carboxyl groups have been developed as the most extensively used electron acceptor and anchoring group for the design of sensitizers for dye-sensitized solar cells. In terms of the photoelectric conversion efficiency, each of them has been demonstrated to be superior to the other one in certain cases. Herein, to further understand the effect of these two groups on cell efficiencies, a series of porphyrin sensitizers were designed and synthesized, with the acceptors systematically varied, and the effect of the neighboring ethynylene unit was also investigated. Compared with the sensitizer XW5 which contains a carboxyphenyl anchoring moiety directly linked to the meso-position of the porphyrin framework, the separate introduction of a strongly electron-withdrawing cyanoacrylic acid as the anchoring group or the insertion of an ethynylene unit can achieve broadened light absorption and IPCE response, resulting in higher J(sc) and higher efficiency. Thus, compared with the efficiency of 4.77% for XW5, dyes XW1 and XW6 exhibit higher efficiencies of 7.09% and 5.92%, respectively. Simultaneous introduction of the cyanoacrylic acid and the ethynylene units into XW7 can further broaden light absorption and thus further improve the J(sc). However, XW7 exhibits the lowest V-oc value, which is not only related to the floppy structure of the cyanoacrylic group but also related to the aggravated dye aggregation effect due to the extended framework. As a result, XW7 exhibits a relatively low efficiency of 5.75%. These results indicate that the combination of the ethynylene and cyanoacrylic groups is an unsuccessful approach. To address this problem, a cyano substituent was introduced to XW8 at the ortho position of the carboxyl group in the carboxyphenyl acceptor. Thus, XW8 exhibits the highest efficiency of 7.59% among these dyes. Further cosensitization of XW8 with XS3 dramatically improved the efficiency to 9.31%.

  • 108.
    Wu, H.
    et al.
    State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, China.
    Hang, C.
    State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, China.
    Li, Xin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Yin, L.
    State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, China.
    Zhu, M.
    State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, China.
    Zhang, J.
    State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, China.
    Zhou, Y.
    State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, China.
    Ågren, Hans
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Zhang, Q.
    State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, China.
    Zhu, L.
    State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, 200433, China.
    Correction: Molecular stacking dependent phosphorescence-fluorescence dual emission in a single luminophore for self-recoverable mechanoconversion of multicolor luminescence (Chemical Communications (2016) DOI: 10.1039/C6CC04901J)2016In: Chemical Communications, ISSN 1359-7345, Vol. 52, no 100, p. 14500-14501Article in journal (Refereed)
  • 109. Wu, H.
    et al.
    Hang, C.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Yin, L.
    Zhu, M.
    Zhang, J.
    Zhou, Y.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhang, Q.
    Zhu, L.
    Molecular stacking dependent phosphorescence-fluorescence dual emission in a single luminophore for self-recoverable mechanoconversion of multicolor luminescence2017In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 53, no 18, p. 2661-2664Article in journal (Refereed)
    Abstract [en]

    A self-recoverable mechanoconversion of multicolor luminescence was observed by crystallization-induced self-assembly. Such a self-assembly led to the formation of nanorods with different molecular stacking modes, thus making the phosphorescence/fluorescence proportion alterable. Therefore, multicolor luminescence of the single luminophore can be achieved by a straightforward reversible mechanical stimulus.

  • 110. Wu, H.
    et al.
    Zhou, Y.
    Yin, L.
    Hang, C.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Yi, T.
    Zhang, Q.
    Zhu, L.
    Helical self-assembly-induced singlet-triplet emissive switching in a mechanically sensitive system2017In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 2, p. 785-791Article in journal (Refereed)
    Abstract [en]

    In nanoscience, chirality has shown a significant ability to tune materials' electronic properties, whereas imposing macrochirality into the regulation of singlet-triplet features of organic optoelectronics remains a challenging research topic. Since the tuning for singlet and triplet excited-state properties in a single π-functional molecule connects to its multicolor luminescent application and potential improvement of internal quantum efficiency, we here report that supramolecular chirality can be employed to toggle the singlet and triplet emissions in a welldesigned asterisk-shaped molecule. Employing a hexathiobenzene-based single luminophore as a prototype and functionalizing it with chiral α-lipoiate side groups, we find that helical nanoarchitectures can accordingly form in mixed DMF/H20 solution. On this basis, switching between fluorescence and phosphorescence of the material can be realized upon helical self-assembly and dissociation. Such a behavior can be attributed to a helical-conformation-dependent manipulation of the intersystem crossing. Furthermore, reversible mechanoluminescence of the corresponding solid sample was also observed to rely on an analogous molecular self-assembly alternation. These results can probably provide new visions for the development of next-generation supramolecular chiral functional materials.

  • 111. Wu, Hongwei
    et al.
    Zhao, Pei
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Chen, Wenbo
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhang, Qing
    Zhu, Liangliang
    Tuning for Visible Fluorescence and Near-Infrared Phosphorescence on a Unimolecular Mechanically Sensitive Platform via Adjustable CH-pi Interaction2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 4, p. 3865-3872Article in journal (Refereed)
    Abstract [en]

    CH-pi interaction-assisted alignment of organic conjugated systems has played an important role to regulate molecular electronic and photophysical properties, whereas harnessing such a smart noncovalent interaction into the tuning of unimolecular complex emissive bands covering a wide spectral region remains a challenging research topic. Since the tuning for visible and near-infrared emissive properties in a single pi-functional platform relates to its multicolor luminescent behaviors and potential superior application in analysis, bioimaging, and sensing, herein, we report a proportional control of the singlet and triplet emissions that cover visible and near-infrared spectral regions, respectively, can be straightforwardly achieved by CH-pi interaction-assisted self-assembly at the unimolecular level. Employing an octathionaphthalene-based single luminophore as a prototype, we find that a strength-adjustable CH-pi interaction-assisted self-assembly can be established in mixed DMF/H2O and in the film state. The hybridization of planar local excited and intramolecular charge transfer transitions occurs on the basis, allowing a competitive inhibition to the intersystem crossing process to generate a complex emission composed of visible fluorescence and near-infrared phosphorescence. Furthermore, reversible mechanochromic and mechanoluminescent conversions of the corresponding solid sample can both be observed to rely on a corresponding self-assembly alternation. These results can probably provide new visions for the development of future intelligent and multifunctional luminescent materials.

  • 112. Wu, Yue
    et al.
    Guo, Zhiqian
    Zhu, Wei-Hong
    Wan, Wei
    Zhang, Junji
    Li, Wenlong
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Tian, He
    Li, Alexander D. Q.
    Photoswitching between black and colourless spectra exhibits resettable spatiotemporal logic2016In: Materials Horizons, ISSN 2051-6347, E-ISSN 2051-6355, Vol. 3, no 2, p. 124-129Article in journal (Refereed)
    Abstract [en]

    Logic is the key to computing. Traditionally, logic devices have been fabricated by the top-down approach, whose dimensions are drastically limited. The ultimate goal is to use molecular tailorability to design logics using the "bottom-up'' approach. Here we report an unprecedented photochromic molecule that undergoes unimolecular logic switching when excited anywhere in the entire UV-visible spectrum, thus a bottom-up, all-photonic, molecular logic gate. Specifically, these molecular photonic logics embedded in the polymer thin films function as the "AND'' or "OR'' gate at different temporal responses. To achieve high information-processing density, moreover, a ternary flip-flap-flop gate is realized in the molecular logic because the fact that this photochromic molecule can be photoswitched anywhere in its UV-vis spectrum enabled three different lasers (532, 473, and 561 nm) as the inputs to deliver the complex logic optical outputs.

  • 113. Wu, Yun
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Effect of dihedral angle of bridge unit on the performance of dye-sensitized solar cell2016In: Chinese Chemical Letters, ISSN 1001-8417, E-ISSN 1878-5964, Vol. 27, no 6, p. 927-932Article in journal (Refereed)
    Abstract [en]

    In this work, we investigated the impact of bridge unit on their photo-physical and photovoltaic performance. Increased planarity of the dyes effectively extended the absorption, but reduces the efficiency. Interestingly we found that dyes with a thiophene conjugate unit showed inferior performance when compared with benzene. Theoretical computation indicates a large dihedral angle in the latter system. EIS analysis evidenced the severe recombination in the thiophene-based dye, showing that good planarity may lead to dye aggregation and decrease the efficiency.

  • 114. Wu, ZhiFang
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Li, Jing
    Hua, JianLi
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Tian, He
    Influence of the Auxiliary Acceptor on the Absorption Response and Photovoltaic Performance of Dye-Sensitized Solar Cells2014In: Chemistry - An Asian Journal, ISSN 1861-4728, E-ISSN 1861-471X, Vol. 9, no 12, p. 3549-3557Article in journal (Refereed)
    Abstract [en]

    Three new dyes with a 2-(1,1-dicyanomethylene)rhodanine (IDR-I, -II, -III) electron acceptor as anchor were synthesized and applied to dye-sensitized solar cells. We varied the bridging molecule to fine tune the electronic and optical properties of the dyes. It was demonstrated that incorporation of auxiliary acceptors effectively increased the molar extinction coefficient and extended the absorption spectra to the near-infrared (NIR) region. Introduction of 2,1,3-benzothiadiazole (BTD) improved the performance by nearly 50%. The best performance of the dye-sensitized solar cells (DSSCs) based on IDR-II reached 8.53% (short-circuit current density (J(sc))=16.73mAcm(-2), open-circuit voltage (V-oc)=0.71V, fill factor (FF)=71.26%) at AM1.5 simulated sunlight. However, substitution of BTD with a group that featured the more strongly electron-withdrawing thiadiazolo[3,4-c]pyridine (PT) had a negative effect on the photovoltaic performance, in which IDR-III-based DSSCs showed the lowest efficiency of 4.02%. We speculate that the stronger auxiliary acceptor acts as an electron trap, which might result in fast combination or hamper the electron transfer from donor to acceptor. This inference was confirmed by electrical impedance analysis and theoretical computations. Theoretical analysis indicates that the LUMO of IDR-III is mainly localized at the central acceptor group owing to its strong electron-withdrawing character, which might in turn trap the electron or hamper the electron transfer from donor to acceptor, thereby finally decreasing the efficiency of electron injection into a TiO2 semiconductor. This result inspired us to select moderated auxiliary acceptors to improve the performance in our further study.

  • 115. Wu, Zhifang
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Li, Jing
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Hua, Jianli
    Tian, He
    Effect of bridging group configuration on photophysical and photovoltaic performance in dye-sensitized solar cells2015In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 27, p. 14325-14333Article in journal (Refereed)
    Abstract [en]

    Three new metal-free organic sensitizers with a D-A-p-A configuration based on a triarylamine donor, 2,1,3-benzothiadiazole (BTD) and different pi units have been synthesized. Because a long alkyl side chain has been attached to the thiophene adjacent to BDT, HECA achieves the best performance. Under standard global AM 1.5 solar light conditions, the HECA based-device gives the best conversion efficiency of 9.13% with a J(sc) of 16.14 mA cm(-2), a V-oc of 0.72 V and a FF of 0.77. Although EDCA displays superior optical properties, it does not give the desired results. The device based on EDCA achieves efficiency of 7.37% with a J(sc) of 15.56 mA cm(-2), a V-oc of 0.67 V and a FF of 0.70. EIS analysis confirms the existence of fast recombination in the EDCA system. Further computational analysis indicates that the coplanarity and the very strong affinity to iodine molecules of EDCA may be the origin of the low performance.

  • 116. Wu, Zhifang
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Hua, Jianli
    Tian, He
    Pyrimidine-2-carboxylic Acid as an Electron-Accepting and Anchoring Group for Dye-Sensitized Solar Cells2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 48, p. 26355-26359Article in journal (Refereed)
    Abstract [en]

    We report a new dye (INPA) adopting pyrimidine-2-carboxylic acid as an electron-accepting and anchoring group to be used in dye-sensitized solar cells. IR spectral analysis indicates that the anchoring group may form two coordination bonds with TiO2 and so facilitate the interaction between the anchoring group and TiO2. The INPA-based cell exhibits an overall conversion efficiency of 5.45%, which is considerably higher than that obtained with cyanoacrylic acid commonly used as the electron acceptor.

  • 117. Xie, Yongshu
    et al.
    Wei, Pingchun
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Hong, Tao
    Zhang, Kai
    Furuta, Hiroyuki
    Macrocycle Contraction and Expansion of a Dihydrosapphyrin Isomer2013In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, no 51, p. 19119-19122Article in journal (Refereed)
    Abstract [en]

    Cyclization of a pentapyrrane with two terminal beta-linked pyrroles afforded a dihydrosapphyrin isomer (1) with the pyrroles linked in a unique beta,alpha-alpha,beta mode, which was rather reactive, and thus it readily underwent a ring-contracted rearrangement to a pyrrolyl norrole (2), and succeeding ring expansion to a terpyrrole-containing isosmaragdyrin analogue (4). 1, 2, and 4 contain the internal ring pathways with a minimum of 17, 15, and 16 atoms, respectively. 1, 2, and 4 are almost nonfluorescent, whereas the complex of 2 with Zn2+ shows a distinct NIR emission peak at 741 nm. The unprecedented pyrrole transformation chemistry by confusion approach is illustrated.

  • 118. Yan, H.
    et al.
    Zhu, L.
    Li, X.
    Kwok, A.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhao, Y.
    Photothermal-responsive [2]rotaxanes2013In: RSC Advances, ISSN 2046-2069, Vol. 3, no 7, p. 2341-2350Article in journal (Refereed)
    Abstract [en]

    Three photothermal-responsive α-cyclodextrin-based [2]rotaxanes were prepared via the copper(i)-catalyzed azide-alkyne cycloaddition, in which the α-cyclodextrin ring was threaded onto the azobenzene dumbbell component. The difference between the three [2]rotaxanes are the length of the ethylene glycol repeating chains connected between the azobenzene and triazole units in the dumbbell components. The α-cyclodextrin rings in the [2]rotaxanes can be reversibly switched between the azobenzene unit and triazole/ethylene glycol unit driven by the trans-cis isomerization of the azobenzene unit. The trans-to-cis isomerization of the azobenzene unit under UV light irradiation (365 nm) leads the α-cyclodextrin ring moving to the triazole/ethylene glycol unit, while the cis-to-trans isomerization of the azobenzene unit under either visible light irradiation or heating enables the α-cyclodextrin ring shuttling back to the azobenzene station. The different ethylene glycol repeating chains in the [2]rotaxanes can affect (1) the isomerization rates of the azobenzene units, i.e. the longer the chain, the faster the isomerization rate, and (2) fluorescent quantum yields of the [2]rotaxanes, i.e. the longer the chain, the lower the fluorescent quantum yield. In addition, the quantum yields of the [2]rotaxanes were enhanced by UV light irradiation and decreased back upon visible light irradiation or heating at 65 °C. The current research provides a fundamental understanding of the working mechanism for photothermal-responsive [2]rotaxanes.

  • 119. Yang, Guosheng
    et al.
    Tang, Yunyu
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Xie, Yongshu
    Efficient Solar Cells Based on Porphyrin Dyes with Flexible Chains Attached to the Auxiliary Benzothiadiazole Acceptor: Suppression of Dye Aggregation and the Effect of Distortion2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 42, p. 36875-36885Article in journal (Refereed)
    Abstract [en]

    Donor-pi-acceptor-type porphyrin dyes have been widely used for the fabrication of efficient dye-sensitized solar cells (DSSCs) owing to their strong absorption in the visible region and the ease of modifying their chemical structures and photovoltaic behavior. On the basis of our previously reported efficient porphyrin dye XW11, which contains a phenothiazine-based electron donor, a pi-extending ethynylene unit, and an auxiliary benzothiadiazole acceptor, we herein report the syntheses of novel porphyrin dyes XW26- XW28 by introducing one or two alkyl/alkoxy chains into the auxiliary acceptor. The introduced chains can effectively suppress dye aggregation. As a result, XW26 XW28 show excellent photovoltages of 700, 701, and 711 mV, respectively, obviously higher than 645 mV obtained for XW11. Nevertheless, the optimized structures of XW26 and XW27 exhibit severe distortion, showing large dihedral angles of 57.2(circle) and 44.0(circle), respectively, between the benzothiadiazole and benzoic acid units, resulting from the steric hindrance between the benzoic acid unit and the neighboring alkyl/alkoxy chain on the benzothiadiazole unit, and thus blue-shifted absorption, decreased photocurrents. and low efficiencies of 5.19% and 6.42% were observed for XW26 and XW27, respectively. Interestingly, XW26 exhibits a more blue -shifted absorption spectrum relative to XW27, indicating that the steric hindrance of the alkyl/alkoxy chains has a more pronounced effect than the electronic effect. Different from XW26 and XW27, XW28 contains only one alkyl chain neighboring the ethynylene unit, which does not induce obvious steric hindrance with the benzoic acid unit, and thus distortion of the molecule is not seriously aggravated compared with XW11. Hence, its absorption spectrum and photocurrent are similar to those of XW11. As a result, a higher efficiency of 9.12% was achieved for XW28 because of its suppressed dye aggregation and higher photovoltage. It is worth noting that a high efficiency of 10.14% was successfully achieved for XW28 upon coadsorption with CD CA, which is also higher than the corresponding efficiency obtained for XW11. These results provide a novel approach for developing efficient porphyrin dyes by introducing chains into the suitable position of the auxiliary benzothiadiazolyl moiety to suppress dye aggregation, without seriously aggravating distortion of the dye molecules.

  • 120. Yang, Lin
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Qu, Yi
    Qu, Weisong
    Zhang, Xiao
    Hang, Yandi
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Hua, Jianli
    Red turn-on fluorescent phenazine-cyanine chemodosimeters for cyanide anion in aqueous solution and its application for cell imaging2014In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 203, p. 833-847Article in journal (Refereed)
    Abstract [en]

    Two chemodosimeters PDMI and PMI for cyanide detection were designed and synthesized based onphenazinecyanine dyes with N-methyl indolium group as receptor unit. According to the specific reactivity of indolium C-N+ bond against cyanide anion, both of them featured high sensitivity with detectionlimit of 1.4 mu M and 200 nM, respectively, and high selectivity against other anions. The quenching effecton phenazine-cyanine fluorophore by strong intramolecular charge transfer (ICT) from phenazine donorto indolium receptor made both PDMI and PMI non-emissive at the original state. After addition ofcyanide, the ICT effect decreased and vanished leading to dramatic " off-on" fluorescence enhancement. PDMI which proceeded bilateral electrophilic reaction toward cyanide anion provided an emission signal at 580 nm in HEPES buffer with naked-eye detectable color change. Probe PMI utilized an unreactiveformyl group instead of one reactive N-methyl indolium group as the electron-withdrawing component. Due to the unilateral recognition process for cyanide the ICT orientation of PMI was redirectedthus exhibited fluorescence enhancement with maximum emission at 630 nm. Meanwhile, PMI wasapplied for monitoring intracellular cyanide in Hela cells and proved to achieve "off-on" fluorescentsignal confirmed by confocal laser scanning microscopic imaging.

  • 121. Yang, Lin
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Yang, Jiabao
    Qu, Yi
    Hua, Jianli
    Colorimetric and Ratiometric Near-Infrared Fluorescent Cyanide Chemodosimeter Based on Phenazine Derivatives2013In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 5, no 4, p. 1317-1326Article in journal (Refereed)
    Abstract [en]

    Two new near-infrared chemodosimeters for cyanide anion based on 5,10-dihexyl-5,10-dihydrophenazine were designed and synthesized. With dicyano-vinyl groups as the recognition site and electron-withdrawing groups on both sides, probe 1 exhibited an intramolecular charge transfer (ICT) absorption band at 545 nm and emission band at 730 nm, respectively, and thus showed an ICT block process and realized an 'on-off" response after bilateral reaction with cyanide anions in CH3CN. Probe 2 utilized an unreactive formyl group instead of one of the two reactive dicyano-vinyl groups as the electron-withdrawing component. Due to the unilateral recognition process the ICT of probe 2 was redirected and lead to a remarkably colorimetric and ratiometric near-infrared (NIR) fluorescent response for cyanine. Both probes provided high sensitivity and selectivity with apparent response signals which can be observed by naked eyes, even in the copresence of various other interference anions. Optical spectroscopic techniques, NMR titration measurements, and density functional theory calculations were conducted to rationalize the sensing mechanisms of these two probes.

  • 122.
    Yang, Shun
    et al.
    East China Univ Sci & Technol, Frontiers Sci Ctr Materiobiol & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr, Key Lab Adv Mat,Inst Fine Chem,Sch Chem & Mol Eng, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Frontiers Sci Ctr Materiobiol & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr,Inst, Joint Int Res Lab Precis Chem & Mol Engn,Sch Chem, Shanghai 200237, Peoples R China..
    Zhao, Cai-Xin
    East China Univ Sci & Technol, Frontiers Sci Ctr Materiobiol & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr, Key Lab Adv Mat,Inst Fine Chem,Sch Chem & Mol Eng, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Frontiers Sci Ctr Materiobiol & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr,Inst, Joint Int Res Lab Precis Chem & Mol Engn,Sch Chem, Shanghai 200237, Peoples R China..
    Crespi, Stefano
    Univ Groningen, Fac Sci & Engn, Stratingh Inst Chem, Nijenborgh 4, NL-9747 AG Groningen, Netherlands..
    Li, Xin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Zhang, Qi
    East China Univ Sci & Technol, Frontiers Sci Ctr Materiobiol & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr, Key Lab Adv Mat,Inst Fine Chem,Sch Chem & Mol Eng, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Frontiers Sci Ctr Materiobiol & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr,Inst, Joint Int Res Lab Precis Chem & Mol Engn,Sch Chem, Shanghai 200237, Peoples R China..
    Zhang, Zhi-Yun
    East China Univ Sci & Technol, Frontiers Sci Ctr Materiobiol & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr, Key Lab Adv Mat,Inst Fine Chem,Sch Chem & Mol Eng, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Frontiers Sci Ctr Materiobiol & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr,Inst, Joint Int Res Lab Precis Chem & Mol Engn,Sch Chem, Shanghai 200237, Peoples R China..
    Mei, Ju
    East China Univ Sci & Technol, Frontiers Sci Ctr Materiobiol & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr, Key Lab Adv Mat,Inst Fine Chem,Sch Chem & Mol Eng, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Frontiers Sci Ctr Materiobiol & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr,Inst, Joint Int Res Lab Precis Chem & Mol Engn,Sch Chem, Shanghai 200237, Peoples R China..
    Tian, He
    East China Univ Sci & Technol, Frontiers Sci Ctr Materiobiol & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr, Key Lab Adv Mat,Inst Fine Chem,Sch Chem & Mol Eng, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Frontiers Sci Ctr Materiobiol & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr,Inst, Joint Int Res Lab Precis Chem & Mol Engn,Sch Chem, Shanghai 200237, Peoples R China..
    Qu, Da-Hui
    East China Univ Sci & Technol, Frontiers Sci Ctr Materiobiol & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr, Key Lab Adv Mat,Inst Fine Chem,Sch Chem & Mol Eng, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Frontiers Sci Ctr Materiobiol & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr,Inst, Joint Int Res Lab Precis Chem & Mol Engn,Sch Chem, Shanghai 200237, Peoples R China..
    Reversibly modulating a conformation-adaptive fluorophore in [2]catenane2021In: Chem, ISSN 2451-9308, E-ISSN 2451-9294, Vol. 7, no 6, p. 1544-1556Article in journal (Refereed)
    Abstract [en]

    Tuning molecular emission by chemicalmeans has long been a fundamental topic, because the emerging methodologies and mechanisms of this topic usually bring a lot of opportunities in many multi-disciplinary applications. Here, we demonstrate the reversible switching of a conformation-adaptive fluorophore, 9,14-diphenyl-9,14-dihydrodibenzo[ a,c]phenazine (DPAC), by incorporating this fluorescent unit into a mechanically interlocked [2]catenane. Taking advantage of the mechanical bond of [2]catenane, the conformational freedom of the DPAC-macrocycle can be modulated by the co-conformational state of the [2]catenane, thus enabling the reversible switching of the fluorescent properties of DPAC. Owing to the mechanically interlocked structure, this fluorescent molecular system can be switched in a dual-mode (wavelength or intensity), visually recognizable, and highly reversible manner. This work provides a distinctmechanism of switchingmolecular emission by modulating conformation-adaptive fluorescent systems in mechanically interlocked structures.

  • 123. Zhang, Hui
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhang, Duo
    Zhang, Liang
    Kapilashrami, Mukes
    Sun, Tao
    Glans, Per-Anders
    Zhu, Junfa
    Zhong, Jun
    Hu, Zheng
    Guo, Jinghua
    Sun, Xuhui
    Comprehensive electronic structure characterization of pristine and nitrogen/phosphorus doped carbon nanocages2016In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 103, p. 480-487Article in journal (Refereed)
    Abstract [en]

    The electronic structures of carbon nanocages (CNCs) and nitrogen/phosphorus doped carbon nanocages (N-CNCs/P-CNCs) have been studied by X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES) and resonant X-ray emission spectroscopy (RXES). The doping configurations for N/P dopants are identified from the experiments. The results have shown that there are three major doping configurations for nitrogen but only one doping configuration for phosphorus. The nitrogen doping reveals the complex coexistence of graphite-like, pyridine-like and pyrrole-like configurations that are proved by density functional theory (DFT) simulations, while the phosphorus doping presents only the "graphite-like" configuration. The different configuration profiles result in less atomic structure ordering of N-CNCs than that of P-CNCs. XAS spectra obtained from both surface and bulk sensitive detection suggest different chemical environments between the interior and shell for all types of nanocages. The electronic structure modifications show significant difference between nitrogen and phosphorus doping from the DOS calculations. (C) 2016 Elsevier Ltd. All rights reserved.

  • 124. Zhang, Kai
    et al.
    Wei, Pingchun
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Xie, Yongshu
    Oxidative Ring Closure and Metal Triggered Ring Opening: Syntheses of Macrocyclic and Linear Hexapyrroles2014In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 16, no 24, p. 6354-6357Article in journal (Refereed)
    Abstract [en]

    A C6F5-substituted hexapyrrane (1) was synthesized in one step. Oxidative cyclization of 1 with DDQ afforded a phlorindipyrrin conjugate (2), and subsequent FeCl3-assisted oxidative cleavage of 2 afforded a terminally di-a-methoxy substituted hexapyrrin (3). On the other hand, oxidation of 1 with FeCl3 afforded 3, a hexapyrrinone Fe3+ complex (4), and a hexaphyrin (1,1,1,1,1,0) (5). These results indicate that the oxidation of hexapyrranes may be developed as an effective approach for the syntheses of novel linear and macrocyclic hexapyrroles.

  • 125.
    Zhang, Qi
    et al.
    East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Key Lab Adv Mat, 130 Meilong Rd, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Joint Int Res Lab Precis Chem & Mol Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China..
    Rao, Si-Jia
    East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Key Lab Adv Mat, 130 Meilong Rd, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Joint Int Res Lab Precis Chem & Mol Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China..
    Xie, Tao
    East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Key Lab Adv Mat, 130 Meilong Rd, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Joint Int Res Lab Precis Chem & Mol Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China..
    Li, Xin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Xu, Tian-Yi
    East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Key Lab Adv Mat, 130 Meilong Rd, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Joint Int Res Lab Precis Chem & Mol Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China..
    Li, Da-Wei
    East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Key Lab Adv Mat, 130 Meilong Rd, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Joint Int Res Lab Precis Chem & Mol Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China..
    Qu, Da-Hui
    East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Key Lab Adv Mat, 130 Meilong Rd, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Joint Int Res Lab Precis Chem & Mol Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China..
    Long, Yi-Tao
    East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Key Lab Adv Mat, 130 Meilong Rd, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Joint Int Res Lab Precis Chem & Mol Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China..
    Tian, He
    East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Key Lab Adv Mat, 130 Meilong Rd, Shanghai 200237, Peoples R China.;East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Joint Int Res Lab Precis Chem & Mol Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China..
    Muscle-like Artificial Molecular Actuators for Nanoparticles2018In: Chem, ISSN 2451-9308, E-ISSN 2451-9294, Vol. 4, no 11, p. 2670-2684Article in journal (Refereed)
    Abstract [en]

    Muscle tissue performs crucial contraction/extension motions that generate mechanical force and work by consuming chemical energy. Inspired by this naturally created biomolecular machine, artificial molecular muscles are designed and synthesized to undertake linear actuation functions. However, most of these muscle-like actuators are performed at large ensembles, while to realize the nanoscale actuation at the single-to few-molecule level remains challenging. Herein, we developed an artificial muscle-like molecular actuator that can reversibly control the proximity of the attached nano-objects, gold nanoparticles, within the single-molecule length level by its stimuli-responsive muscle-like linear contraction/extension motion. The molecular actuation motion is accompanied by an optical signal output resulting from the plasmonic resonance properties of gold nanoparticles. Meanwhile, the thermal noise of the muscle-like molecular actuator can be overcome by integrating the optical signal over a sufficiently long period.

  • 126. Zhang, Qi-Wei
    et al.
    Li, Dengfeng
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    White, Paul B.
    Mecinovic, Jasmin
    Ma, Xiang
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Nolte, Roeland J. M.
    Tian, He
    Multicolor Photoluminescence Including White-Light Emission by a Single Host-Guest Complex2016In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 41, p. 13541-13550Article in journal (Refereed)
    Abstract [en]

    Achieving multicolor photoluminescence, 'especially white-light emission, under mild conditions based on a single "fluorescent compound-is a great challenge. Herein, we report a novel colorful-emission host guest complex BPCY, which is composed of a two-arm fluorescent guest molecule (BPC) and gamma-cyclodextrin (gamma-CD) as the host-molecule. BPC bears a unique asymmetrical donor acceptor donor (D-1-A(+)similar to D-2)-type structure, where D-1, A(+), and D-2 stand for the binaphthol electron donor, pyridinium electron acceptor, and coumarin electron donor, respectively. The luminescence property of BPC shows dual-sensitivity, i.e., toward the excitation wavelength and the cyclodextrin host molecule. Under certain conditions, the complex shows three different emission wavelengths, allowing the realization of multicolor photoluminescence, including red (R), green (G), and blue (B) as well as various intermediate colors by orthogonally modulating these two stimuli. In this way, nearly pure white-light emission with CIE coordinates (0.33, 0.34) could be generated. A combination of structural, spectroscopic, and computational simulation studies revealed the occurrence of synergetic mechanistic processes for the stimuli-responsive multicolor luminescence of the BPCY complex, namely, host-enhanced intramolecular charge-transfer (ICT) and host-induced restriction of intramolecular rotation (RIR). This new supramolecular complex with superior multicolor emission abilities may find wide applications in the fields of information processing and display media. Furthermore, the molecular design rationale presented here may provide a new design strategy for the development of high performance optical materials using a single supramolecular platform.

  • 127. Zhang, W.
    et al.
    Wu, Y.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Li, E.
    Song, X.
    Jiang, H.
    Shen, C.
    Zhang, H.
    Tian, H.
    Zhu, W. -H
    Molecular engineering and sequential cosensitization for preventing the “trade-off” effect with photovoltaic enhancement2017In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 8, no 3, p. 2115-2124Article in journal (Refereed)
    Abstract [en]

    In dye-sensitized solar cells (DSSCs), it is essential to use rational molecular design to obtain promising photosensitizers with well-matched energy levels and narrow optical band gaps. However, the “trade-off” effect between the photocurrent and photovoltage is still a challenge. Here we report four benzoxidazole based D-A-π-A metal-free organic dyes (WS-66, WS-67, WS-68 and WS-69) with different combinations of π-spacer units and anchoring-acceptor groups. Either extending the π-spacer or enhancing the electron acceptor can efficiently modulate the molecular energy levels, leading to a red-shift in the absorption spectra. The optimal dye, WS-69, containing a cyclopentadithiophene (CPDT) spacer and cyanoacetic acid acceptor, shows the narrowest energy band gap, which displays a very high photocurrent density of 19.39 mA cm−2, but suffers from a relatively low photovoltage of 696 mV, along with the so-called deleterious “trade-off” effect. A cosensitization strategy is further adopted for enhancing the device performance. Optimization of the dye loading sequence is found to be capable of simultaneously improving the photocurrent and photovoltage, and distinctly preventing the “trade-off” effect. The superior cosensitized cell exhibits an excellent power-conversion efficiency (PCE) of 10.09% under one-sun irradiation, and 11.12% under 0.3 sun irradiation, which constitutes a great achievement in that the efficiency of a pure metal-free organic dye with iodine electrolyte can exceed 11% even under relatively weak light irradiation. In contrast with the previous cosensitization strategy which mostly focused on compensation of light-harvesting, we propose a novel cosensitization architecture, in which the large molecular-sized, high photocurrent dye WS-69 takes charge of broadening the light-harvesting region to generate a high short-circuit current (JSC) while the small molecular-sized, high photovoltage dye WS-5 is responsible for retarding charge recombination to generate a high open-circuit voltage (VOC). In addition, adsorption amount and photo-stability studies suggest that the cyano group in the anchoring acceptor is important for the stability since it is beneficial towards decreasing the LUMO levels and enhancing the binding of dyes onto TiO2 nanocrystals.

  • 128. Zhang, X.
    et al.
    Chen, L.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Mao, J.
    Wu, W.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Hua, J.
    Photovoltaic properties of bis(octyloxy)benzo-[c][1,2,5]thiadiazole sensitizers based on an N,N-diphenylthiophen-2-amine donor2014In: Journal of Materials Chemistry C, ISSN 2050-7526, Vol. 2, no 20, p. 4063-4072Article in journal (Refereed)
    Abstract [en]

    Three D-A-π-A sensitizers (DOBT-IV to DOBT-VI) with N,N- diphenylthiophen-2-amine as the donor and bis(octyloxy)benzo-[c][1,2,5] thiadiazole (DOBT) as the auxiliary acceptor have been designed and synthesized. Their applications to dye-sensitized solar cells with I-/I 3 - and Co(ii)/(iii) electrolytes were measured and characterized. Via fine tuning of the π-bridge, the highest photoelectric conversion efficiency of 7.16% was obtained with Jsc = 16.88 mA cm-2, Voc = 0.662 V and FF = 64.03% for the DOBT-V based dye-sensitized solar cells using the I-/I3 - electrolyte under standard global AM1.5 solar conditions. A photoelectric conversion efficiency of 6.14% was obtained with Jsc = 11.35 mA cm-2, Voc = 0.760 V and FF = 71.16% with the Co(ii)/(iii) electrolyte under standard global AM1.5 solar conditions. The optical and electrochemical properties and the photovoltaic performance were evaluated and investigated using density functional theory calculations, a behavior study of the four performance parameters with dependence of the incident light intensity, electrochemical impedance spectroscopy and intensity-modulated photo-voltage spectrometry.

  • 129. Zhang, Xiaoyu
    et al.
    Guo, Fuling
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    He, Jinxiang
    Wu, Wenjun
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Hua, Jianli
    Effect of thiophene in bithiazole-bridged sensitizers on the performance of dye-sensitized solar cells2014In: Nano, ISSN 1793-2920, Vol. 9, no 5, p. 1440009-Article in journal (Refereed)
    Abstract [en]

    In this paper, we have designed and synthesized four bithiazole-bridged sensitizers (BT-T2, TBT-T2, BT-T3 and TBT-T3) with triphenylamine and indoline as the donor segment and applied them to dye-sensitized solar cells (DSSCs). For triphenylamine-based sensitizers as BT-T2 and TBT-T2, adding one thiophene unit between triphenylamine donor and bithiazole moiety not only led to bathochromic shift of the maximum absorption and increase of molar extinction coefficient, but also enhanced the photovoltaic conversion efficiency from 7.12% of BT-T2 to 7.51% of TBT-T2. But for indoline-based sensitizers as BT-T3 and TBT-T3, adding one thiophene unit between indoline donor and bithiazole moiety resulted in hypochromatic shift instead of bathochromic shift. We employed the density functional theory (DFT) calculations to further investigate the influence of the thiophene unit on their optical and electronic properties and photovoltaic performance of corresponding DSSC devices. Given the results, a reasonable explanation is the introduction of thiophene unit suppressed the intramolecular charge transfer and charge separation in the conjugation system of indoline-based sensitizer, which led to the hypochromatic shift of the maximum absorption wavelength and finally the low J(sc). Since the J(sc) dropped sharply from 15.26mAcm(-2) to 4.52mAcm(-2), the photovoltaic conversion efficiency decreased dramatically from 7.86% to 1.93%.

  • 130. Zhang, Xiaoyu
    et al.
    Mao, Jiangyi
    Wang, Dan
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Yang, Jiabao
    Shen, Zhongjin
    Wu, Wenjun
    Li, Jing
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Hua, Jianli
    Comparative Study on Pyrido[3,4-b]pyrazine-Based Sensitizers by Tuning Bulky Donors for Dye-Sensitized Solar Cells2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 4, p. 2760-2771Article in journal (Refereed)
    Abstract [en]

    Dye-sensitized solar cells (DSSCs) with cobalt electrolytes have gained increasing attention. In this Research Article, two new pyrido[3,4-b]pyrazine-based sensitizers with different cores of bulky donors (indoline for DT-1 and triphenylamine for DT-2) were designed and synthesized for a comparative study of their photophysical and electrochemical properties and device performance and were also analyzed through density functional theory calculations. The results of density function theory calculations reveal the limited electronic communication between the biphenyl branch at the cis-position of N-phenylindoline and the indoline core, which could act as an insulating blocking group and inhibit the dye aggregation and charge recombination at the interface of TiO2/dye/electrolyte. As expected, DSSCs based on DT-1 with cobalt redox electrolyte gained a higher photoelectric conversion efficiency of 8.57% under standard AM 1.5 G simulated sunlight, with J(sc) = 16.08 mA cm(-2), V-oc = 802 mV, and FF = 0.66. Both electrochemical impedance spectroscopy (EIS) and intensity-modulated photovoltage spectroscopy (IMVS) suggest that charge recombination in DSSCs based on DT-1 is much less than that in their counterparts of DT-2, owing to the bigger donor size and the insulating blocking branch in the donor of DT-1.

  • 131. Zhiyun, Zhang
    et al.
    Jinlong, Han
    Li, Xin
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, Centre for High Performance Computing, PDC.
    Shengyun, Cai
    Jianhua, Su
    Novel Organic Dyes Based on Bulky Tri(triphenylamine)-Substituted Styrene for Dye-Sensitized Solar Cells2012In: Chinese journal of chemistry, ISSN 1001-604X, E-ISSN 1614-7065, Vol. 30, no 12, p. 2779-2785Article in journal (Refereed)
    Abstract [en]

    Three novel donor-p-acceptor (D-p-A) metal-free organic dyes (TB, TS and TF) based on tri(triphenylamine)-substituted styrene as donor with various conjugated linkers (benzene, thiophene and furan) were synthesized, characterized and used for the application of dye-sensitized solar cells (DSSCs). Under the same condition, The photo-to-electrical conversion efficiency of the DSSCs sensitized with TB, TS and TF reach 1.84%, 4.10% and 4.52%, respectively, which are lower than that sensitized with R1 (5.02%) with one triphenylamine unit. The results suggest that these bulky donor-based sensitizers are unfavorable to DSSCs.

  • 132. Zhou, Haitao
    et al.
    Huang, Wei
    Ding, Li
    Cai, Shengyun
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Li, Bo
    Su, Jianhua
    New cyano-substituted organic dyes containing different electrophilic groups: aggregation-induced emission and large two-photon absorption cross section2014In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 70, no 39, p. 7050-7056Article in journal (Refereed)
    Abstract [en]

    Three aggregation-induced emission active dyes (3a-c) were synthesized and their one- and two-photon absorption properties have been investigated. They were all found to be weakly fluorescent in THF solution, while they exhibited dramatic fluorescence enhancement in water/THF mixtures. The solid fluorescence of 3a-c was recorded and their fluorescence quantum efficiency (Phi(F)) values were determined to be 8.0%, 8.1%, and 16.4%, respectively. Moreover, the two-photon absorption (2PA) cross-sections (sigma) of 3a-c were measured and 3a showed the highest value of 702 GM. The excellent aggregation-induced emission and 2PA properties provide a promising alternative for biophotonic materials.

  • 133. Zhou, Ying
    et al.
    Li, Xing
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Chen, Jue
    Yu, Fengtao
    Hua, Jianli
    The Effect of Pyridyl Nitrogen Atom Position in Pyrido-[3,4-b]pyrazines in Donor-Acceptor-pi-Acceptor Dyes on Absorption, Energy Levels, and Photovoltaic Performances of Dye-Sensitized Solar Cells2016In: ASIAN JOURNAL OF ORGANIC CHEMISTRY, ISSN 2193-5807, Vol. 5, no 2, p. 293-300Article in journal (Refereed)
    Abstract [en]

    A donor-acceptor-pi-acceptor (D-A-pi-A)-type organic dye (DTN-1) incorporating a pyrido[3,4-b]pyrazine (PP) unit with the pyridyl N atom adjacent to the anchoring group has been synthesized for use in dye-sensitized solar cells (DSSCs). The maximum absorption wavelength of DTN-1 was clearly red-shifted compared with dye DT-1, based on PP unit with the pyridyl N atom adjacent to the donor group. However, this change of structure has a negative effect on photovoltaic performances, and devices made with DTN-1 only reached a power conversion efficiency of 6.10% under AM1.5G irradiation compared with 8.57% achieved by DT-1. Density functional theory calculations suggest that DTN-1 has a smaller oscillator strength, which is connected to its relatively low light-harvesting efficiency. In addition, the results of electrochemical impedance spectroscopy (EIS) reveal that charge recombination in DSSCs based on DTN-1 is more than that in the counterpart DT-1, thus leading to a lower open-circuit voltage (V-oc).

  • 134. Zhou, Yunyun
    et al.
    Zhuang, Yaping
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Yu, Lin
    Ding, Jiandong
    Zhu, Liangliang
    Selective Dual-Channel Imaging on Cyanostyryl-Modified Azulene Systems with Unimolecularly Tunable Visible-Near Infrared Luminescence2017In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, no 32, p. 7642-7647Article in journal (Refereed)
    Abstract [en]

    Although organic light-emitting molecules have received a growing attention and applicability in modern bioimaging science, the design and control of complex photoluminescent properties in unimolecularly selective imaging remains a challenging topic. Considering that tunable multipathway imaging can be advantagedly connected with treatment processes in therapy, the integration of an azulene and a cyanostyryl moiety into one skeleton is carried out for the generation of in situ stimuli-responsive luminescent materials, with the aim to achieve tunable and effective emissions in distinct channels through smart molecular design on a single-molecular platform. This strategy takes advantage of 1) the Z/E isomerization of the cyanostyryl unit that can vary the push-pull effect of the substitution on azulene, accompanied by altering absorption and emission of individual excited states, and 2) an optimized excited-state regulation for opening a near infrared emissive channel and making up for a controllable dual-pathway luminescent system together with the utilization of visible emission. As exemplified by a demonstration of manipulating the luminescence at the cell level, the materials exhibit a superior application potential for unimolecularly selective imaging, labeling and probing events.

  • 135. Zhu, Haibo
    et al.
    Li, Wenqin
    Wu, Yongzhen
    Liu, Bo
    Zhu, Shiqin
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhu, Weihong
    Insight into Benzothiadiazole Acceptor in D-A-pi-A Configuration on Photovoltaic Performances of Dye-Sensitized Solar Cells2014In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 2, no 4, p. 1026-1034Article in journal (Refereed)
    Abstract [en]

    The option of conjugated pi-linkers is critical for molecular engineering toward the energy-level strategy of donor-pi-acceptor (D-pi-A) sensitizers. There is always a balance in the optimization of a it-linker. The pi-conjugation should be enlarged to expand the light-harvesting capability of sensitizers for an increase in photocurrent; however, the oversized it-linker also would affect seriously the photovoltage and photostability. Two sensitizers, WS-22 and WS-23, are constructed without or with benzothiadiazole (BTD) in a molecular skeleton, aiming to gain insight into the effect of an auxiliary acceptor in D-A-pi-A sensitizers on the photophysical and photovoltaic performances, especially focusing on the exploitation of the short circuit current density (J(sc)) and open circuit voltage (V-oc). Compared with the typical D-pi-A sensitizer WS-22, the incorporation of an auxiliary acceptor of BTD in WS-23 can improve the light-harvesting ability both in red-shifting the absorption peaks and the increment of absorption coefficient. The predominant increase by 15.6% in light-harvesting efficiency (LHE) of WS-23 results in a relatively higher J(sc) from 13.77 (WS-22) to 16.91 mA cm(-2) (WS-23). Moreover, the improvement of the V-oc in WS-23 is originated by a synergy contribution of the uplifting of E-CB and inhibition of charge recombination. The stepped light-induced transient (SLIT) measurements indicate that the introduction of BTD can negatively shift the conduction band of the TiO2 film. For WS-23, the higher molecular dipole moment can bring forth a more effective charge separation between donor and acceptor units, also resulting in an increase in V-oc. The incorporated BTD unit can increase V-oc by 57 mV, arising from the CB edge shift of TiO2 (accounting for 40%, 23 mV) and the retarding charge recombination (accounting for 60%, 34 mV). As a consequence, WS-23 realizes an optimizing photovoltaic efficiency (eta = 8.15%), with an improvement of 36.5% with respect to WS-22.

  • 136. Zhu, L.
    et al.
    Ang, C. Y.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Nguyen, K. T.
    Tan, S. Y.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhao, Y.
    Luminescent color conversion on cyanostilbene-functionalized quantum dots via in-situ photo-tuning2012In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 24, no 29, p. 4020-4024Article in journal (Refereed)
    Abstract [en]

    Photo-responsive CdSe quantum dots functionalized with the cyanostilbene unit are synthesized. The as-prepared quantum dot hybrid reveals a photo-tunable dual fluorescent characteristic. White light emission can be generated in situ from the hybrid through photoirradiation to adjust the relative intensities of the two complementary emissions. Luminescent color conversion through yellow, white, and blue can be realized by varying the photoirradiation time.

  • 137. Zhu, Liang-Liang
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Ji, Feng-Yuan
    Ma, Xiang
    Wang, Qiao-Chun
    Tian, He
    Photolockable Ratiometric Viscosity Sensitivity of Cyclodextrin Polypseudorotaxane with Light-Active Rotor Graft2009In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 25, no 6, p. 3482-3486Article in journal (Refereed)
    Abstract [en]

    A prototype, based on light-active fluorescent rotor grafted to beta-cyclodextrin, shows a good solvent viscosity-sensitive behavior due to the environment-dependent nonradiative decay. With the reversible photoisomerization of the cyanostilbene unit, the viscosity sensitivity of the molecular rotor could be locked and activated, and the two switchable states can be distinguished by fluorescent signals. This cyclodextrin derivative was threaded to form a novel polypseudorotaxane. Such supramolecular assembly displays a lockable ratiometric fluorescent viscosity sensitivity with two emission channels: one aroused by fluorophore's intramolecular excimer without influenced by viscosity is used to gauge the concentration of the compound, while the other corresponding to the monomer's rotor fluorescence acts as a viscosity-sensitive signal and it can be shut off by UV irradiation.

  • 138. Zhu, Liangliang
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Sanders, Samuel N.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Unimolecular Photopolymerization of High-Emissive Materials on Cylindrical Self-Assemblies2015In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 48, no 15, p. 5099-5105Article in journal (Refereed)
    Abstract [en]

    We report a novel self-assembly pathway from a bis(imidazolyl) diphenyl-diacetylene (DPDA) compound as a realization of self-templated photopolymerization with high polymerization degrees. The work takes advantage of a cylindrical self-assembly that strengthens the preorganization of the diphenyl-diacetylene moiety at the single molecular level. On this basis, photopolymerization of DPDA can be conducted smoothly to form high-molecular-weight polydiphenyl diacetylene. Such a cylindrical self-assembly is highly dependent on molecular structure, and control studies show that only oligomers can be formed on random self-assemblies from a monoimidazolyl or nonimidazolyl diphenyl-diacetylene compound. Moreover, the cylindrical self-assembly based systems bear aggregation-induced emission enhancement characteristics and are solution processable. The leading thin-film could afford a selectively tunable function in luminescent micropatterns.

  • 139. Zhu, Liangliang
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Wu, Shaojue
    Nguyen, Kim Truc
    Yan, Hong
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhao, Yanli
    Chirality Control for in Situ Preparation of Gold Nanoparticle Superstructures Directed by a Coordinatable Organogelator2013In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, no 24, p. 9174-9180Article in journal (Refereed)
    Abstract [en]

    Imposing chirality into nanoscale superstructures is a major step forward toward systematic understanding and utilization of nanomaterials. In an attempt to achieve tunable chirality during in situ preparation of hybrid nanomaterials, we here report a novel unimolecular strategy of employing a coordinatable organogelator for the realization of chirality control in the formation of gold nanoparticle superstructures. The work takes advantage of thermally reversible sol-gel transition of the chiral dispersion as template, which causes different micelle properties that can influence the coordination ability between the organogelator and Au(III) ions. Followed by a reduction reaction, gold nanoparticle superstructures with P-helicity were prepared from the sol form of the template through a coordination-induced chiral inversion, whereas those with M-helicity were obtained from the gel form with chiral holding. Such superstructures are solvent-stable and the chirality difference between them could be observed in many solvent environments.

  • 140. Zhu, Liangliang
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhang, Quan
    Ma, Xing
    Li, Menghuan
    Zhang, Huacheng
    Luo, Zhong
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhao, Yanli
    Unimolecular Photoconversion of Multicolor Luminescence on Hierarchical Self-Assemblies2013In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, no 13, p. 5175-5182Article in journal (Refereed)
    Abstract [en]

    Facile tuning of photophysical properties is highly desirable for boosting the performance and versatility of photoluminescent materials. In an attempt to overcome the challenge of achieving the photoswitching of multicolor luminescence on unimolecular platforms, we here report a novel hierarchical self-assembly of a cyanostilbene-naphthalimide dyad as the realization of phototunable luminescence at the unimolecular level. The work takes advantage of the photoisomerization of the cyanostilbene moiety from the Z form to its E form, which causes a morphological disorder in the molecular self-assembly and gives rise to a dual fluorescent characteristic accompanied by a progressive luminescent color conversion from yellow to green and finally to blue. Such systems with convertible multicolor luminescence might exhibit application potentials for unimolecular selective imaging and labeling, as exemplified by the cell imaging studies presented in this work.

  • 141. Zhu, Liangliang
    et al.
    Tran, Helen
    Beyer, Frederick L.
    Walck, Scott D.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Killops, Kato L.
    Campos, Luis M.
    Engineering Topochemical Polymerizations Using Block Copolymer Templates2014In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, no 38, p. 13381-13387Article in journal (Refereed)
    Abstract [en]

    With the aim to achieve rapid and efficient topochemical polymerizations in the solid state, via solution-based processing of thin films, we report the integration of a diphenyldiacetylene monomer and a poly(styrene-b-acrylic acid) block copolymer template for the generation of supramolecular architectural photopolymerizable materials. This strategy takes advantage of non-covalent interactions to template a topochemical photopolymerization that yields a polydiphenyldiacetylene (PDPDA) derivative. In thin films, it was found that hierarchical self-assembly of the diacetylene monomers by microphase segregation of the block copolymer template enhances the topochemical photopolymerization, which is complete within a 20 s exposure to UV light. Moreover, UV-active cross-linkable groups were incorporated within the block copolymer template to create micropattems of PDPDA by photolithography, in the same step as the polymerization reaction. The materials design and processing may find potential uses in the microfabrication of sensors and other important areas that benefit from solution-based processing of flexible conjugated materials.

  • 142.
    Zhu, Ning
    et al.
    E China Univ Sci & Technol, Key Lab Adv Mat, Shanghai 200237, Peoples R China.;E China Univ Sci & Technol, Inst Fine Chem, Shanghai 200237, Peoples R China..
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Wang, Yuan
    Chinese Acad Sci, Key Lab Photochem Convers & Optoelect Mat, Tech Inst Phys & Chem, Beijing 100190, Peoples R China..
    Ma, Xiang
    E China Univ Sci & Technol, Key Lab Adv Mat, Shanghai 200237, Peoples R China.;E China Univ Sci & Technol, Inst Fine Chem, Shanghai 200237, Peoples R China..
    Photo-responsive chiral cyclic molecular switches based on stiff stilbene2016In: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 125, p. 259-265Article in journal (Refereed)
    Abstract [en]

    Two novel photo-responsive chiral cyclic molecular switches constituted of stiff stilbene and binaphthyl moieties connected through alkyl chains of different length were fabricated. The cyclization synthetic strategy employed herein made it convenient to obtain the pure Z isomers rather than Z/E isomer mixtures. The detailed photo-switching behaviors of target compounds were studied by the UV-Vis absorption and circular dichroism spectra in dichloromethane. The twist angles of the binaphthyl of the switches were able to be reversibly modulated by Z/E isomerization of stiff stilbene unit under alternative UV light stimuli and influenced by the length of alkyl chain to some extent.

  • 143. Zou, Qi
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Xu, Qunjie
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhao, Wandong
    Qu, Yi
    A near-infrared "on-off" fluorescent and colourimetric cyanide chemodosimeter based on phenothiazine with applications in living cell imaging2014In: RSC Advances, E-ISSN 2046-2069, Vol. 4, no 104, p. 59809-59816Article in journal (Refereed)
    Abstract [en]

    A great deal of effort has been devoted to developing easy-to-use near-infrared probes for detecting analytes due to their advantages in the field of biosensing. Herein, a near-infrared "on-off" fluorescent chemodosimeter PTZ based on dicyano-vinyl-functionalised phenothiazine was designed and synthesised. The PTZ compound was shown to efficiently recognise cyanide ions in aqueous media by virtue of the special nucleophilicity of cyanide ions, which affects the intramolecular charge transfer efficiency in the molecule. Furthermore, it was found that it exhibited a rapid colourimetric and quenchable near-infrared (NIR) fluorescent response to cyanide ions with a detection limit as low as 67 nM, and that other anions showed almost no interference even at high concentrations. Optical spectroscopic measurements, H-1 NMR and mass spectrometry titrations, and theoretical simulations were carried out to elucidate the sensing mechanism of compound PTZ. Moreover, potential applications of this compound for biosensing have been exemplified by the successful fluorescent microscopic imaging for the detection of cyanide ions in HeLa cells.

  • 144. Zou, Qi
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhou, Ji
    Bai, Kangkang
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Synthesis and photochromism of a spirooxazine derivative featuring a carbazole moiety: Fast thermal bleaching and excellent fatigue resistance2014In: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 107, p. 174-181Article in journal (Refereed)
    Abstract [en]

    A novel photochromic spirooxazine derivative bearing a carbazole moiety (SOC) was synthesized and studied in solution under flash photolysis conditions. It is found to exhibit excellent characteristics like high photochromic response, large steady-state optical density, fast thermal bleaching rate and good fatigue-resistance. The effect of different solvents on the photochromic properties of the compound was evaluated, revealing that the photochromic properties can be modulated by different solvents based on the corresponding polarity. The mechanism and kinetics of the thermal fading process of compound SOC were additionally investigated by theoretical simulations, where the isomerization pathway from the trans-trans-cis conformation was found to be several times faster than that from the cis-trans-cis conformation. This type of fast-bleaching and fatigue-resistent photochromic compounds is expected to pave an exciting avenue in future development of high-performance photochromic materials.

  • 145. Zou, Qi
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Configurable photochromism of an unsymmetrical dithienylethene derivative by Cu2+ ions or water2014In: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 111, p. 1-7Article in journal (Refereed)
    Abstract [en]

    We describe a gated photochromic behavior of an unsymmetrical dithienylethene derivative, which is intrinsically inert to photoisomerization in organic solvents and which is activated by addition of Cu2+ ions or water. The mechanism behind the gated photochromic property is interpreted by theoretical simulations, suggesting that the energy levels of frontier molecular orbitals are altered by the interaction of the Schiff base moiety with Cu2+ ions or water molecules. Potential applications of such gated photochromic materials have been exemplified not only by the reversible interchange between the photoactive and photoinactive states triggered by Cu2+ ions and EDTA, but also by the construction of a keypad with sequence-dependent input signals at the molecular level.

123 101 - 145 of 145
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