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  • 1.
    Baryshnikov, Gleb V.
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Bogdan Khmelnitsky National University, Ukraine; Tomsk State University, Russian Federation.
    Valiev, Rashid R.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Tomsk State University, Russian Federation; Tomsk Polytechnic University, Russian Federation.
    Minaev, Boris F.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Bogdan Khmelnitsky National University, Ukraine; Tomsk State University, Russian Federation.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    A computational study of aromaticity and photophysical properties of unsymmetrical azatrioxa[8]circulenes2017In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 41, no 7, p. 2717-2723Article in journal (Refereed)
    Abstract [en]

    Owing to their potential use in organic light-emitting diodes and field-effect transistors we present a theoretical study of a series of unsymmetrical azatrioxa[8]circulenes in order to explain the impact of outer substituents and benzoannelation on photophysical constants and aromaticity of these compounds in terms of spin-orbit coupling perturbation and magnetically-induced ring currents. It is argued that the S1-Tn inter-system crossing processes constitute the main deactivation pathways for the fluorescence quenching, something that is supported by a good agreement obtained with experimental data on fluorescence quantum yields. The concept of the gauge-including magnetically induced currents has been applied in order to estimate the role of substituents and benzoannelated fragments on the aromaticity and particularly on the overall balance between the diatropic “aromatic” and paratropic “antiaromatic” current strengths. While a variation of the substituents in the outer perimeter of the studied circulenes does not provide a clear effect on their aromaticity, it is demonstrated that an additional benzoannelation (π-extension) of the azatrioxa[8]circulene macrocycle induces a significant aromaticity enhancement.

  • 2.
    Baryshnikov, Gleb V.
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Valiev, Rashid R.
    Minaev, Boris F.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Substituent-sensitive fluorescence of sequentially N-alkylated tetrabenzotetraaza[8]circulenes2017In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 41, no 15, p. 7621-7625Article in journal (Refereed)
    Abstract [en]

    We explore the use of substituent-sensitive balance between fluorescence and non-radiative decay as a tool for optical tuning of promising materials for organic light emitting diode applications. A series of N-butylated tetrabenzotetraaza[8]circulenes is studied computationally in order to explain the gradual decrease of fluorescence intensity with the increase of the substituent number. The inter-system crossing probability is found to increase upon the gradual substitution of the circulene macrocycle as a result of the decrease of the S-1-T-1 energy gap due to the deformation of the tetrabenzotetraaza[8] circulenes and therefore the distortion of the pi-conjugation within the macrocycles. In contrast, the S-1-T-1 spin-orbit coupling matrix elements are quite insensitive to the number of outer substituents. As a result, the fluorescence-responsible pi pi(star) transition becomes less intense and the fluorescence rate constant decreases.

  • 3. Bernhardt, Paul V.
    et al.
    Boschloo, Gerrit K.
    Bozoglian, Fernando
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Martinez, Manuel
    Sienrad, Beatriz
    Tailoring mixed-valence Co-III/Fe-II complexes for their potential use as sensitizers in dye sensitized solar cells2008In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 32, no 4, p. 705-711Article in journal (Refereed)
    Abstract [en]

    Dinuclear class II Co-III/Fe-II mixed-valence complexes of type [LnCo (III)(mu-NC) Fe-II(CN)(3)L-2](m-) (where L-n represents a pentadentate macrocycle and L-2 a bpy ligand or two cyanides) have electronic properties that make them possible sensitizers in DSSC ( dye sensitized solar cells). For this purpose the new complex Na-2[{trans-L14COOCo III( m-NC)} Fe II( CN) 5] has been prepared and characterized by the usual methods and its sensitizer properties compared with those of the already known [{trans-L14COOCo (III)(mu-NC)}Fe-II(CN)(5)](2-)(CN)(3)(bipy)(eq,ax)](ClO4). The complex [{trans-L14COOCo (III)(mu-NC)}Fe-II(CN)(5)](2-) has been designed for the actuation of an electron injection from the cobalt centre on MMCT, while the [{trans-L14COOCo (III)(mu-NC)}Fe-II(CN)(3)(bipy)](+) structure can produce a tuned injection from the iron centre via an MLCT electronic state, as described for similar systems. The characterization on solid oxide semiconductor supports has been carried out for these two complexes and the results have been compared with the behaviour observed in aqueous solution and in solvents of varying polarities. Their use in DSSC has been checked and, while a sensitizer response is observed for [{trans-L14COOCo (III)(mu-NC)}Fe-II(CN)(5)](2-), complex [{trans-L14COOCoIII(mu-NC)}Fe-II(CN)(3)(bipy)(eq,ax)](+) does not produce any electrical current on illumination. The low efficiency of the built DSSC can be easily related both with the very low value of the extinction coefficient of the MMCT band responsible for the electron injection, and with the small driving force for the reduction of the complex with the standard I-2/I-3 (-) system used after electron injection.

  • 4. Bondarchuk, Sergey V.
    et al.
    Minaev, Boris F.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Bogdan Khmelnitsky Cherkasy National University, Ukraine.
    Two isomeric solid carbon nitrides with 1:1 stoichiometry which exhibit strong mechanical anisotropy2017In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 41, no 21, p. 13140-13148Article in journal (Refereed)
    Abstract [en]

    Two isomeric layered carbon nitride phases in a trigonal crystal system with 1:1 stoichiometry, NCCN and NCNC (space group P3m1), are studied using first principles calculations and quantum theory of atoms in molecules (QTAIM) analysis, where the latter phase is predicted for the first time. Comprehensive characterization of these materials is performed to determine their thermodynamic, elastic and spectral (vibrational, UV-vis and NMR) properties. High-throughput scheme for band structure calculations along with the accurate hybrid functional HSE06 provide the indirect band gaps of 3.142 eV (NCNC) and 5.021 eV (NCCN). Phonon dispersion calculations prove that the studied materials are dynamically stable at ambient pressure. The NCCN phase demonstrates a poor spectral pattern on infrared (IR) intensities and Raman activities, whereas the NCNC polymorph is expected to be effectively detectable by both spectral techniques. The UV-vis spectra of the studied phases display absorption bands between ca. 50-150 nm, which indicates that these isomers are transparent to visible light. Elastic constant calculations indicate strong anisotropy of their Young's moduli. In the [1 0 0] equivalent to [0 1 0] plane directions the modulus values are 914.6 GPa (NCNC) and 865.1 GPa (NCCN). In the [0 0 1] direction, which is perpendicular to the layer plane, the Young's moduli are much smaller and equal to 73.3 GPa and 58.4 GPa for NCNC and NCCN, respectively. The exfoliation energies are expected to be about 3 (NCNC) and 2 (NCCN) times higher than those of graphite.

  • 5. Bouit, Pierre-Antoine
    et al.
    Westlund, Robert
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Feneyrou, Patrick
    Maury, Olivier
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Andraud, Chantal
    Dendron-decorated cyanine dyes for optical limiting applications in the range of telecommunication wavelengths2009In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 33, no 5, p. 964-968Article in journal (Refereed)
    Abstract [en]

    Cyanine dyes decorated with 2,2-bis(methylol) propionic acid (bis-MPA) based dendrons up to third generation were synthesized. Dendrons were attached to the chromophore using a "click chemistry'' reaction. Photophysical characterizations of these dyes show intense absorption and emission in the near-infrared (NIR), while nonlinear transmission experiments of the dendron-decorated chromophores indicate that properties in the IR of the parent dyes are conserved. This synthetic approach is a crucial preliminary step towards the preparation of solid functional materials for optical limiting (OL) applications in the IR.

  • 6. Deksnys, T.
    et al.
    Simokaitiene, J.
    Keruckas, J.
    Volyniuk, D.
    Bezvikonnyi, O.
    Cherpak, V.
    Stakhira, P.
    Ivaniuk, K.
    Helzhynskyy, I.
    Baryshnikov, Glib
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Minaev, B.
    Grazulevicius, J. V.
    Synthesis and characterisation of a carbazole-based bipolar exciplex-forming compound for efficient and color-tunable OLEDs2017In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 41, no 2, p. 559-568Article in journal (Refereed)
    Abstract [en]

    A new ambipolar fluorophore, 3,6-di(4,4′-dimethoxydiphenylaminyl)-9-(1-naphthyl)carbazole, was synthesized and its physical properties were studied by differential scanning calorimetry, thermogravimetric analysis, UV-vis absorption, luminescence and photoelectron emission spectroscopy, cyclic voltammetry and a time of flight method. The latter technique indicates that the compound demonstrates bipolar semiconducting properties. Using the synthesized compound as an emissive material, a single-layer OLED with an electroluminescence spectrum containing a voltage-dependent electroplex emission band in the region of 550-650 nm was fabricated. Another OLED was fabricated with an additional electron transporting bathophenanthroline layer that forms a direct interface with the layer of 3,6-di(4,4′-dimethoxydiphenylaminyl)-9-(1-naphthyl)carbazole. A strong exciplex-type band in the electroluminescence spectrum of this OLED with an emission maximum at ca. 540 nm was observed. The electroluminescence spectra of both devices were found to be clearly dependent on the applied bias. This effect can be useful for the development of efficient and colour-tunable OLEDs.

  • 7.
    Dinér, Peter
    et al.
    University of Gothenburg.
    Andersson, T.
    Kjellén, J.
    Elbing, K.
    Hohmann, S.
    Grotli, M.
    Short cut to 1,2,3-triazole-based p38 MAP kinase inhibitors via [3+2]-cycloaddition chemistry2009In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 331010-1016, no 5, p. 1010-1016Article in journal (Refereed)
  • 8.
    Fagerland, Jenny
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pappalardo, Daniela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. University of Sannio, Italy.
    Modulating the thermal properties of poly(hydroxybutyrate) by the copolymerization of rac-beta-butyrolactone with lactide2016In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 40, no 9, p. 7671-7679Article in journal (Refereed)
    Abstract [en]

    Biobased poly(hydroxybutyrate) is produced by microorganisms under controlled conditions. It is a linear, high molecular weight, fully isotactic and highly crystalline polymer. However, it has poor mechanical and thermal properties. We have modulated the thermal properties of this material by ring-opening co-polymerization of rac-beta-butyrolactone (BL) with lactide (LA) in the presence of salan-based yttrium and aluminum catalysts. The prepared poly(hydroxybutyrate-co-lactide) copolymers were characterized by proton and carbon nuclear magnetic resonance (H-1 and C-13 NMR), size exclusion chromatography (SEC) and differential scanning calorimetry (DSC) analyses. The salan-yttrium compound was a more effective catalyst compared to the aluminum compound, affording high molecular weight copolymers with higher monomer conversion and a monomodal distribution of the molecular weights. The kinetic experiments showed a higher rate of polymerization for the LA with respect to the BL. The copolymers were amorphous and DSC showed unique transition temperatures for all of the samples. The formation of a gradient copolymer is proposed.

  • 9.
    Karaush, Nataliya N.
    et al.
    Bogdan Khmelnitsky Natl Univ, Dept Chem & Nanomat Sci, UA-18031 Cherkassy, Ukraine..
    Baryshnikov, Gleb V.
    Bogdan Khmelnitsky Natl Univ, Dept Chem & Nanomat Sci, UA-18031 Cherkassy, Ukraine.
    Ågren, Hans
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology. Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden..
    Minaev, Boris F.
    Bogdan Khmelnitsky Natl Univ, Dept Chem & Nanomat Sci, UA-18031 Cherkassy, Ukraine..
    A theoretical study of new representatives of closed- and open-circle benzofuran and benzocyclopentadienone oligomers2018In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 42, no 14, p. 11493-11505Article in journal (Refereed)
    Abstract [en]

    Owing to their potential use as materials for strong optical rotation, circular dichroism and circularly polarized luminescence, the structure and energetic stability of novel closed- and open-circle benzofuran and benzocyclopentadienone oligomers have been studied computationally using the DFT method. It is found that an extension of the macrocycle size (n = 10-30) for the closed-circle species leads to a gradual transformation of their structure from saddle- to helical- and then to a wing-like shape. At the same time, the smaller closed-circle representatives with n = 4 and 6 exhibit a bowl-shaped structure due to the high energy strain of their molecular structures. Application of the NICS (nucleus-independent chemical shift) criterion to the here studied open-circle benzofuran and benzocyclopentadienone species with planar linear, planar fan-shape and helical molecular topology indicates that for the planar benzofuran series the inner benzene ring is more aromatic than the outer hexagons, while the aromaticity of the outer and inner furan rings is insensitive to the molecular size variations. The replacement of the aromatic furan rings by antiaromatic cyclopentadienone fragments for the planar linear species leads to a decrease of aromaticity of the benzene rings from the edge to the center of the benzocyclopentadienone chain. On the other hand, for the planar fan-shape benzocyclopentadienone series a zigzag trend in the NICS values is observed for the benzene rings. Loss of planarity only slightly affects the aromaticity of the helical open-circle benzofuran and benzocyclopentadienone oligomers. We propose that an increase of the NICS indices for the outer and inner rings of the macromolecular helical species is due to the magnetic couplings between the superimposed benzene and furan/cyclopentadienone rings.

  • 10.
    Li, Ende
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zhou, Hui
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Östlund, Victor
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hertzberg, Robin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Regio- and stereoselective synthesis of conjugated trienes from silaborated 1,3-enynes2016In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 40, no 7, p. 6340-6346Article in journal (Refereed)
    Abstract [en]

    Products obtained from palladium-catalyzed regioselective cis-addition of (chlorodimethylsilyl)pinacolborane to the alkyne bond of 1,4-disubstituted 1,3-enynes were subjected to Suzuki-Miyaura coupling with alkenyl iodides. Hiyama coupling of the resulting silanol-functionalized trienes provided tetrasubstituted conjugated trienes with different substitution patterns, whereas protiodesilylation with fluoride gave trisubstituted trienes. The methodology presented gives access to conjugated trienes with control of regio- and stereochemistry.

  • 11. Ma, C. B.
    et al.
    Chen, C. N.
    Liu, Q. T.
    Liao, D. H.
    Li, L.
    Sun, Licheng C.
    Structural transformation mediated by o-, m-, and p-phthalates from two to three dimensions for manganese/phthalate/4,4 '-bpy complexes (4,4 '-bpy=4,4 '-bipyridine)2003In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 27, no 5, p. 890-894Article in journal (Refereed)
    Abstract [en]

    Three isomers of o-, m-, and p-phthalate are used to link together Mn centres, resulting in [Mn(phth)(H2O)(x)](n) moieties ( phth = phthalate dianion) with single-chain, double-chain and sheet structures, respectively, which predetermine the extended structures derived from the crosslinkage of 4,4'-bipyridine, and show the influence of isomerism of the phthalate on topological changes of the final polymers from two dimensional (2D) single-layer, double-layer to 3D network architectures. These structural changes in topology are correlated with the differences in the magnetic and optical properties of the polymers.

  • 12. Moores, Audrey
    et al.
    Poyatos, Macarena
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry.
    Crabtree, Robert H.
    Catalysed low temperature H-2 release from nitrogen heterocycles2006In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 30, no 11, p. 1675-1678Article in journal (Refereed)
    Abstract [en]

    In an experimental and computational study, nitrogen- and oxygen-containing heterocycles were compared with carbocycles as liquid substrates for hydrogen release with heterogeneous catalysts. Heteroatom substitution, particularly by nitrogen, favours low temperature H-2 release; indoline was fully dehydrogenated in less than 30 min with Pd/C at 110 degrees C.

  • 13. 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.

  • 14. Xie, Hujun
    et al.
    Wang, Lihong
    Li, Yang
    Kuang, Jian
    Wu, Zunyi
    Fan, Ting
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Leic, Qunfang
    Fang, Wenjun
    N-Insertion reaction mechanisms of phenyl azides with a hafnium hydride complex: a quantum chemistry calculation2017In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 41, no 12, p. 5007-5011Article in journal (Refereed)
    Abstract [en]

    Density functional theory (DFT) calculations were performed to investigate the detailed mechanisms for the N-insertion reaction of phenyl azides with a hafnium hydride complex. This reaction involves an intermolecular hydride transfer from the hafnium center of complex 1 (Cp2HfH2)-Hf-star to the terminal nitrogen atom of a phenyl azide. Subsequently, a 1,3 hydrogen shift from the N1 atom to the N3 atom takes place, accompanied by cleavage of the N2-N3 bond to provide amido complex 3 (Cp2HfH)-Hf-star(NHPh) and dinitrogen. A further reaction is related to the intermolecular hydride transfer from the hafnium center to the N1' atom of a second phenyl azide, followed by the formation of the final product, bis(amido) complex 9 (Cp2HfH)-Hf-star(NHPh)(2) via the liberation of the second dinitrogen, which is the rate-determining step with an overall barrier of 29.8 kcal mol(-1). Frontier molecular orbital theory analysis shows that phenyl azides are activated by nucleophilic attack by the hydride ligand, which is consistent with our previous studies of N2O activation by other transition-metal hydride complexes.

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