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  • 51. Bednarska, Joanna
    et al.
    Zalesny, Robert
    Wielgus, Malgorzata
    Jedrzejewska, Beata
    Puttreddy, Rakesh
    Rissanen, Kari
    Bartkowiak, Wojciech
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Osmialowski, Borys
    Two-photon absorption of BF2-carrying compounds: insights from theory and experiment2017In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 8, p. 5705-5708Article in journal (Refereed)
    Abstract [en]

    This communication presents a structure-property study of a few novel pyridine-based difluoroborate compounds with a N-BF2-O core, which exhibit outstanding fluorescence properties. To exploit their potential for two-photon bioimaging, relationships between the two-photon action cross section and systematic structural modifications have been investigated and unravelled.

  • 52. Belyanin, Maxim L.
    et al.
    Stepanova, Elena V.
    Valiev, Rashid R.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. National Research Tomsk Polytechnic University, Russian Federation.
    Filimonov, Victor D.
    Usov, Vladimir Y.
    Borodin, Oleg Y.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Design, synthesis and evaluation of a new Mn - Contrast agent for MR imaging of myocardium based on the DTPA-phenylpentadecanoic acid complex2016In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 665, p. 111-116Article in journal (Refereed)
    Abstract [en]

    In the present paper we describe the first synthesis and evaluation of a novel Mn (II) complex (DTPA-PPDA Mn (II)) which contains a C-15 fatty acid moiety that has high affinity to the heart muscle. The complexation energy of DTPA-PPDA Mn (II) evaluated by quantum chemistry methodology indicates that it essentially exceeds the corresponding value for the known DTPA Mn (II) complex. Molecular docking revealed that the affinity of the designed complex to the heart-type transport protein H-FABP well exceeds that of lauric acid. Phantom experiments in low-field MRI the designed contrast agent provides MR imaging comparable to gadopentetic acid.

  • 53.
    Bennett, Kochise
    et al.
    Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA.;Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA..
    Zhang, Yu
    Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA..
    Kowalewski, Markus
    Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA..
    Hua, Weijie
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA.;KTH Royal Inst Technol, Sch Biotechnol, Dept Theoret Chem & Biol, S-10691 Stockholm, Sweden..
    Mukamel, Shaul
    Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA.;Univ Calif Irvine, Dept Phys & Astron, Irvine, CA 92697 USA.;Freiburg Inst Adv Studies FRIAS, Freiburg, Germany..
    Multidimensional resonant nonlinear spectroscopy with coherent broadband x-ray pulses2016In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T169, article id 014002Article in journal (Refereed)
    Abstract [en]

    New x-ray free electron laser (XFEL) and high harmonic generation (HHG) light sources are capable of generating short and intense pulses that make x-ray nonlinear spectroscopy possible. Multidimensional spectroscopic techniques, which have long been used in the nuclear magnetic resonance, infrared, and optical regimes to probe the electronic structure and nuclear dynamics of molecules by sequences of short pulses with variable delays, can thus be extended to the attosecond x-ray regime. This opens up the possibility of probing core-electronic structure and couplings, the real-time tracking of impulsively created valence-electronic wavepackets and electronic coherences, and monitoring ultrafast processes such as nonadiabatic electron-nuclear dynamics near conical-intersection crossings. We survey various possible types of multidimensional x-ray spectroscopy techniques and demonstrate the novel information they can provide about molecules.

  • 54.
    Biler, Michal
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Biedermann, David
    Valentova, Katerina
    Kren, Vladimir
    Kubala, Martin
    Quercetin and its analogues: optical and acido-basic properties2017In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 39, p. 26870-26879Article in journal (Refereed)
    Abstract [en]

    This study is focused on eight structurally analogous natural flavonoids that exhibit a wide range of biological activities, which are of interest in pharmacy, cosmetics and the food industry. Using both experimental and theoretical approaches, we relate their fundamental physico-chemical properties to the structural motifs, with particular focus on UV/Vis absorption properties and pH dependence. We highlight the role of the C2-C3 double bond, whose presence or absence is responsible for the switch between absorption bands in the UVB and UVA regions, which is rationalized by strong modification of the involved molecular orbitals. After deprotonation in an alkaline environment, a typical switch in intensity at the maximum absorption wavelength (lambda(max)) is observed enabling the calculation of pK(a) values for compounds with a C2-C3 single bond, whereas a bathochromic shift of lambda(max) vs. pH is observed for the C2-C3 double bond containing compounds. These behaviors are also rationalized and understood by MO analysis. Interestingly, high pH (above 11 for ampelopsin and above 9 for myricetin) induces the formation of a long-wavelength peak arising from double and/or triple deprotonation. Substitution at position C3 by the OH group has almost no effect on lambda(max) for taxifolin and eriodictyol, whereas the effect is larger for quercetin and luteolin. An additional sugar moiety at C3 has a stabilizing effect and induces only minor changes in spectral behavior.

  • 55. Bondarchuk, S. V.
    et al.
    Minaev, Boris F.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Two-dimensional honeycomb (A7) and zigzag sheet (ZS) type nitrogen monolayers. A first principles study of structural, electronic, spectral, and mechanical properties2017In: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 133, p. 122-129Article in journal (Refereed)
    Abstract [en]

    Two single-bonded 2D nitrogen allotropes of the honeycomb (A7) and zigzag sheet (ZS) topology have been calculated using density functional theory (DFT). The optical (vibrational, absorption, nuclear magnetic resonance), thermodynamic and elastic properties of the A7 and ZS sheets have been calculated for the first time. The band structure calculation have revealed a semiconducting nature of the ZS sheet with a direct gap of 1.246 eV, while the A7 monolayer behaves as an insulator with an indirect gap of 3.842 eV. Phonon dispersion calculations have justified these structures as vibrationally stable 2D materials. The IR spectroscopy completely failed in the characterization of the studied materials, while the Raman spectroscopy can be effectively applied for the experimental spectral identification. The absorption spectra demonstrate complete opacity of the A7 and ZS monolayers to the UV irradiation only above ca. 9 and 6 eV, respectively. Thus, the studied materials are expected to be transparent to the visible light. The electron arrangement of the nitrogen nuclei in the studied polynitrogen sheets is denser compared to the N2 molecule which follows from the calculation of the values of magnetic shielding tensors. The elastic constants reveal a robust mechanical stability of the studied 2D nitrogen allotropes. The Young moduli values are only twice as lower than that of the graphene molecule.

  • 56. Bondarchuk, S. V.
    et al.
    Minaev, Boris
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Fesak, A. Y.
    Theoretical study of the triplet state aryl cations recombination: A possible route to unusually stable doubly charged biphenyl cations2013In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 113, no 24, p. 2580-2588Article in journal (Refereed)
    Abstract [en]

    The self-recombination reactions of 4-aminophenyl cations and parent phenyl cations, each in ground triplet states, are studied within the framework of density functional theory. Only the total zero spin (singlet state) is chosen, as the quintet and triplet counterparts are nonreactive in these systems. The recombination products are the benzidine and biphenyl doubly charged cations. These species are unexpectedly stable. The transition state of the 4-aminophenyl cations reaction is located at the distance of about 4.0 Å between the ipso-carbon atoms. The activation barrier is predominantly formed by electrostatic repulsion between two cations and is estimated to be 27.6 kcal mol-1 [B3LYP/6-311+G(d,p)]. Similar results are obtained for the phenyl cations recombination. The general importance of the participation of other aryl cations in analogous organic reactions is discussed. © 2013 Wiley Periodicals, Inc. The chemical reactivity of diamagnetic molecules is largely determined by the properties of their triplet excited states rather than their closed-shell ground singlet state. As an example of this type of "spin-catalysis," the self-recombination reaction of the triplet state 4-aminophenyl cations leads to the formation of the benzidine dication. The corresponding transition state is "reactant-like" and located at the CipsoCipso interatomic distance of 4.0 Å.

  • 57. Bondarchuk, Sergey V.
    et al.
    Minaev, Boris F.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Bogdan Khmelnitsky Cherkasy Natl Univ, Ukraine.
    DFT design of polyguanidine - a unique two-dimensional material with high-energy density2017In: Molecular Physics, ISSN 0026-8976, E-ISSN 1362-3028, Vol. 115, no 19, p. 2423-2430Article in journal (Refereed)
    Abstract [en]

    We report herein a theoretical prediction and characterisation of a new two-dimensional (2D) material based on energetic polyguanidine. The structure represents a hexagonal type lattice of the P6/m space group. The material is dynamically and mechanically stable. Highly accurate band structure calculation with hybrid functional HSE06 reveals a tiny direct band gap being equal to 0.181 eV. We provide an additional spectral characterisation of the 2D polyguanidine substance including UV-vis, nuclear magnetic resonance and nuclear quadrupolar resonance parameters. The electron transport properties of a 26.6 angstrom wide polyguanidine ribbon are calculated in terms of tight-binding density functional theory approach. The predicted 2D material is also analysed by means of Quantum Theory of Atoms in Molecules and the aromatic character of the formed rings is estimated using nucleus-independent chemical shifts quantities.

  • 58. Bondarchuk, Sergey V.
    et al.
    Minaev, Boris F.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Super high-energy density single-bonded trigonal nitrogen allotrope-a chemical twin of the cubic gauche form of nitrogen2017In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 9, p. 6698-6706Article in journal (Refereed)
    Abstract [en]

    A new ambient- pressure metastable single- bonded 3D nitrogen allotrope (TrigN) of trigonal symmetry (space group R(-)3) was calculated using density functional theory (DFT). A comprehensive characterization of this material, comprising thermodynamic, elastic, and spectral (vibrational, UV-vis absorption, and nuclear magnetic resonance) properties, was performed. Using high-throughput band structure calculation, the TrigN phase was characterized as an insulator with an indirect band gap of 2.977 eV. Phonon dispersion calculations justified that this structure is vibrationally stable at ambient pressure. The calculated Raman activities at the Gamma-point demonstrated a rich pattern, whereas no relatively intense transitions were observed in its IR absorption spectrum. The TrigN material is almost transparent to visible light as well as to ultraviolet A and B. The main absorption peaks appeared within the range of 50-200 nm. The electron arrangement of the nitrogen nuclei in the studied nitrogen allotrope is much denser compared to that of the molecular nitrogen, which is in agreement with the calculated magnetic shielding tensor values. Robust mechanical stability is revealed from the elastic constants calculation. Due to strong anisotropy, the values of the Young's moduli vary from 281 to 786 GPa. A huge amount of internal energy is enclosed in the TrigN material. Upon decomposition to molecular nitrogen, the energy release is expected to be 11.01 kJ g(-1) compared to the value of 10.22 kJ g(-1) for the cubic gauche form of nitrogen. The TrigN allotrope possesses unique detonation characteristics with a detonation pressure of 146.06 GPa and velocity of 15.86 km s(-1).

  • 59.
    Bondarchuk, Sergey V.
    et al.
    Bogdan Khmelnitsky Cherkasy National University, Ukraine.
    Minaev, Boris F.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Bogdan Khmelnitsky Cherkasy National University, Ukraine .
    Theoretical Study of Relationships between Structural, Optical, Energetic, and Magnetic Properties and Reactivity Parameters of Benzidine and Its Oxidized Forms2014In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 118, no 38, p. 8872-8882Article in journal (Refereed)
    Abstract [en]

    Structural, topological, optical, energetic, and magnetic properties and reactivity parameters of benzidine, its radical cation, and its dication as well as molecular complexes of the benzicline dication with the F-, Cl-, Br-, I-, NO3-, HSO4-, and H2PO4- anions were calculated at the B3LYP/6-311++G(2d,2p) level of theory in the CH2Cl2 medium. The CAM-B3LYP functional (as the most reliable one) and the 6-311++G(3df,3pd) basis set were used for the UV-vis absorption spectra prediction. The obtained spectral results are in a good agreement with available experimental data. A number of the calculated global and local molecular properties, including several recently developed ones, (in general, more than 20 parameters), namely, lambda(max), the bond lengths and orders (l and L-A,L-B), adiabatic ionization energy (IEad), global electrophilicity index (omega), condensed electrophilic Fukui functions (f(+)) and dual descriptor (Delta f(A)), van der Waals molecular volume, nuclear independent chemical shifts (NICS) and QTAIM topological parameters were estimated in the critical points of the C(1)-C(1'), C(2)-C(3), and C(4)-N bonds as well as at the ring critical point. These quantities were found to be in a strong linear dependence (R-2 > 0.99 in most cases) with the number of detached electrons (N-el) from the benzidine molecule up to formation of the dication (N-el = 2). On one hand, a position of the long-wave absorption band (lambda(CT)) corresponding to the anion-to-cation charge transfer in the neutral complexes of the benzidine dication with anions, correlates with the Mulliken electronegativity of the anion (R-2 = 0.8646) and its adiabatic ionization energy (R-2 = 0.8054). On the other hand, the correlations with the anion charge in the complexes and the anion isotropic polarizability are rather poor (R-2 = 0.6392 and 0.3470, respectively). On the ground of the obtained strong relationships, one may recommend the calculated molecular properties as potentially preferable descriptors for the benzidine-based compounds in terms of the QSAR methodology.

  • 60.
    Bondarchuk, Sergey V.
    et al.
    Bogdan Khmelnitsky Cherkasy National University, Ukraine.
    Minaev, Boris F.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Bogdan Khmelnitsky Cherkasy National University, Ukraine.
    Thermally accessible triplet state of pi-nucleophiles does exist. Evidence from first principles study of ethylene interaction with copper species2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 15, p. 11558-11569Article in journal (Refereed)
    Abstract [en]

    Three different models of ethylene interaction with copper species, namely, the Cu(100) surface, odd-numbered copper clusters C2H4/Cu-n (where n = 3, 7, 11, 15, 17, 19, 21, 25 and 27) and atomic copper C2H4/Cu were studied theoretically. It was found that the ethylene molecule possesses three different types of bonding depending on the presence of the unpaired spin on the reacting copper atom. These bonding structures demonstrate different types of band gap (bulk) or SOMO-LUMO gaps (cluster/atom), where SOMO stands for the singly occupied and LUMO means the lowest unoccupied molecular orbitals of the copper species. The obtained results are in good agreement with the previous experimental and computational results on the structural, spectral and energetic properties of the studied species. The bulk copper and sub-nanosized clusters (n > 7) build up the mono-pi-bonded ground state complexes with ethylene where the latter species possesses the C-2v symmetry. The single-atom complex C2H4/Cu forms the CS-symmetrical ground state (X) over tilde (2)A' and the excited B-2(2) and B-4 state complexes of the C-2v and C-2 symmetry, respectively. The (X) over tilde (2)A' state complex is mono-sigma-bonded and involves the singlet ethylene moiety. The more tightly bound excited B-2(2) complex has the di-sigma-bonded structure and corresponds to the triplet ethylene. The adiabatic energy difference between the B-2(2) and (X) over tilde (2)A' states is equal to 10.8 kcal mol(-1) and can be ascribed to the singlet-triplet splitting of the ethylene moiety interacting with copper. The QTAIM analysis supports the coordination type of the Cu-C bonds in all the studied complexes. Formation of the C2H4/Cu(100), C2H4/Cu-n and C2H4/Cu species is in accord with the well-known Dewar-Chatt-Duncanson model, in such a way that the opposing sigma-donation step yields the ground state complex ((X) over tilde (2)A'), while the subsequent more expensive supporting pi*-back donation step provides the excited B-2(2) state complex. In the present paper we have developed a computational procedure to optimize the latter complex.

  • 61. 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.

  • 62. Bondarchuk, Sergey V.
    et al.
    Smalius, Victor V.
    Minaev, Boris F.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Bogdan Khmelnitsky Cherkasy National University, Ukraine .
    A combined experimental and density functional study of 1-(arylsulfonyl)-2-R-4-chloro-2-butenes reactivity towards the allylic chlorine2015In: Journal of Physical Organic Chemistry, ISSN 0894-3230, E-ISSN 1099-1395, Vol. 28, no 6, p. 403-413Article in journal (Refereed)
    Abstract [en]

    Nucleophilic substitution and dehydrochlorination reactions of a number of the ring-substituted 1-(arylsulfonyl)-2-R-4-chloro-2-butenes are studied both experimentally and theoretically. The developed synthetic procedures are characterized by a general rapidity, cheapness, and simplicity providing moderate to high yields of 1-arylsulfonyl 1,3-butadienes (48-95%), 1-(arylsulfonyl)-2-R-4-(N,N-dialkylamino)-2-butenes (31-53%), 1-(arylsulfonyl)-2-R-2-buten-4-ols (37-61%), and bis[4-(arylsulfonyl)-3-R-but-2-enyl]sulfides (40-70%). The density functional theory B3LYP/6-311++G(2d,2p) calculations of the intermediate allylic cations in acetone revealed their high stability occurring from a resonance stabilization and hyperconjugation by the SO2Ar group. The reactivity parameters estimated at the bond critical points of the diene/allylic moiety display a high correlation (R-2>0.97) with the Hammett (sigma(p)) constants. 1-Arylsulfonyl 1,3-butadienes are characterized by a partly broken conjugated system, which follows from analysis of the two-centered delocalization () and localization () index values. The highest occupied molecular orbital energies of 1-arylsulfonyl 1,3-butadienes are lower than those of 1,3-butadiene explaining their low reactivity towards the Diels-Alder condensation.

  • 63.
    Bondesson, Laban
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Royal Inst Technol, Dept Theoret Chem, SE-10691 Stockholm, Sweden..
    Rudberg, Elias
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Royal Inst Technol, Dept Theoret Chem, SE-10691 Stockholm, Sweden..
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Royal Inst Technol, Dept Theoret Chem, SE-10691 Stockholm, Sweden..
    Salek, Pawel
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Royal Inst Technol, Dept Theoret Chem, SE-10691 Stockholm, Sweden..
    Erratum to: Basis set dependence of solute-solvent interaction energy of benzene in waterA HF/DFT study (vol 29, pg 1725, 2008)2012In: Journal of Computational Chemistry, ISSN 0192-8651, E-ISSN 1096-987X, Vol. 33, no 3, p. 354-354Article in journal (Refereed)
  • 64. Bora, D. K.
    et al.
    Cheng, X.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Lawrence Berkeley National Laboratory, United States; University of Science and Technology of China, China.
    Kapilashrami, M.
    Glans, P. A.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. University of Science and Technology of China, China.
    Guo, J. -H
    Influence of crystal structure, ligand environment and morphology on Co L-edge XAS spectral characteristics in cobalt compounds2015In: Journal of Synchrotron Radiation, ISSN 0909-0495, E-ISSN 1600-5775, Vol. 22, p. 1450-1458Article in journal (Refereed)
    Abstract [en]

    The electronic structure of a material plays an important role in its functionality for different applications which can be probed using synchrotron-based spectroscopy techniques. Here, various cobalt-based compounds, differing in crystal structure, ligands surrounding the central metal ion and morphology, have been studied by soft X-ray absorption spectroscopy (XAS) at the Co L-edge in order to measure the effect of these parameters on the electronic structure. A careful qualitative analysis of the spectral branching ratio and relative intensities of the L 3 and L 2 peaks provide useful insight into the electronic properties of compounds such as CoO/Co(OH)2, CoCl2.6H2O/CoF2.4H2O, CoCl2/CoF2, Co3O4 (bulk/nano/micro). For further detailed analysis of the XAS spectra, quantitative analysis has been performed by fitting the spectral profile with simulated spectra for a number of cobalt compounds using crystal field atomic multiplet calculations.

  • 65. Bouchet, Aude
    et al.
    Brotin, Thierry
    Linares, Mathieu
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Cavagnat, Dominique
    Buffeteaeu, Thierry
    Enantioselective Complexation of Chiral Propylene Oxide by an Enantiopure Water-Soluble Cryptophane2011In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 76, no 10, p. 4178-4181Article in journal (Refereed)
    Abstract [en]

    ECD and NMR experiments show that the complexation of propylene oxide (PrO) within the cavity of an enantiopure water-soluble cryptophane 1 in NaOH solution is enantioselective and that the (R)-PrO@PP-1 diastereomer is more stable than the (S)-PrO@PP-1 diastereomer with a free energy difference of 1.7 kJ/mol. This result has been confirmed to by molecular dynamics (MD) and ab initio calculations. The enantioselectivity is preserved in LiOH and KOH solutions even though the binding constants decrease, whereas PrO is not complexed in CsOH solution.

  • 66. Brena, Barbara
    et al.
    Siegbahn, Per E. M.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Modeling Near-Edge Fine Structure X-ray Spectra of the Manganese Catalytic Site for Water Oxidation in Photosystem II2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 41, p. 17157-17167Article in journal (Refereed)
    Abstract [en]

    The Mn Is near-edge absorption fine structure (NEXAFS) has been computed by means of transition-state gradient-corrected density functional theory (DFT) on four Mn4Ca clusters modeling the successive S-0 to S-3 steps of the oxygen-evolving complex (OEC) in photosystem II (PSII). The model clusters were obtained from a previous theoretical study where they were determined by energy minimization. They are composed of Mn(III) and Mn(IV) atoms, progressing from Mn(III)(3)Mn(IV) for S-0 to Mn(III)(2)Mn(IV)(2) for S-1 to Mn(III)Mn(IV)(3) for S-2 to Mn(IV)(4) for S-3, implying an Mn-centered oxidation during each step of the photosynthetic oxygen evolution. The DFT simulations of the Mn Is absorption edge reproduce the experimentally measured curves quite well. By the half-height method, the theoretical IPEs are shifted by 0.93 eV for the S-0 -> S-1 transition, by 1.43 eV for the S-1 -> S-2 transition, and by 0.63 eV for the S-2 -> S-3 transition. The inflection point energy (IPE) shifts depend strongly on the method used to determine them, and the most interesting result is that the present clusters reproduce the shift in the S-2 -> S-3 transition obtained by both the half-height and second-derivative methods, thus giving strong support to the previously suggested structures and assignments.

  • 67. Brotin, Thierry
    et al.
    Montserret, Roland
    Bouchet, Aude
    Cavagnat, Dominique
    Linares, Mathieu
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Buffeteau, Thierry
    High Affinity of Water-Soluble Cryptophanes for Cesium Cations2012In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 77, no 2, p. 1198-1201Article in journal (Refereed)
    Abstract [en]

    Exceptionally high affinity for cesium cations was achieved in aqueous solution using two enantiopure cryptophanes. Complexation of cesium was evidenced by Cs-133 NMR spectroscopy and by electronic circular dichroism (ECD). Binding constants as high as 6 X 10(9) M-1 have been measured by isothermal titration calorimetry (ITC). Very strong complexation of rubidium cations (K similar to 10(6) M-1) has also been measured. Chiral hosts allowed the detection of the two cations at low concentrations (mu M) using ECD.

  • 68. Brown, Christian
    et al.
    Szpryngiel, Scarlett
    Guanglin, Kuang
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Srivastava, Vaibhav
    Ye, Weihua
    McKee, Lauren S.
    Tu, Yaoquan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Maler, Lena
    Bulone, Vincent
    Structural and functional characterization of the microtubule interacting and trafficking domains of two oomycete chitin synthases2016In: The FEBS Journal, ISSN 1742-464X, E-ISSN 1742-4658, Vol. 283, no 16, p. 3072-3088Article in journal (Refereed)
    Abstract [en]

    Chitin synthases (Chs) are responsible for the synthesis of chitin, a key structural cell wall polysaccharide in many organisms. They are essential for growth in certain oomycete species, some of which are pathogenic to diverse higher organisms. Recently, a microtubule interacting and trafficking (MIT) domain, which is not found in any fungal Chs, has been identified in some oomycete Chs proteins. Based on experimental data relating to the binding specificity of other eukaryotic MIT domains, there was speculation that this domain may be involved in the intracellular trafficking of Chs proteins. However, there is currently no evidence for this or any other function for the MIT domain in these enzymes. To attempt to elucidate their function, MIT domains from two Chs enzymes from the oomycete Saprolegnia monoica were cloned, expressed, and characterized. Both were shown to interact strongly with the plasma membrane component, phosphatidic acid, and to have additional putative interactions with proteins thought to be involved in protein transport and localization. Aiding our understanding of these data, the structure of the first MIT domain from a carbohydrate-active enzyme (MIT1) was solved by NMR, and a model structure of a second MIT domain (MIT2) was built by homology modeling. Our results suggest a potential function for these MIT domains in the intracellular transport and/or regulation of Chs enzymes in the oomycetes. DatabaseStructural data are available in the Biological Magnetic Resonance Bank (BMRB) database under the accession number 19987 and the PDB database under the accession number .

  • 69.
    Brumboiu, Iulia Emilia
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Prokopiou, G.
    Kronik, L.
    Brena, B.
    Valence electronic structure of cobalt phthalocyanine from an optimally tuned range-separated hybrid functional2017In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 147, no 4, article id 044301Article in journal (Refereed)
    Abstract [en]

    We analyse the valence electronic structure of cobalt phthalocyanine (CoPc) by means of optimally tuning a range-separated hybrid functional. The tuning is performed by modifying both the amount of short-range exact exchange (α) included in the hybrid functional and the range-separation parameter (γ), with two strategies employed for finding the optimal γ for each α. The influence of these two parameters on the structural, electronic, and magnetic properties of CoPc is thoroughly investigated. The electronic structure is found to be very sensitive to the amount and range in which the exact exchange is included. The electronic structure obtained using the optimal parameters is compared to gas-phase photo-electron data and GW calculations, with the unoccupied states additionally compared with inverse photo-electron spectroscopy measurements. The calculated spectrum with tuned γ, determined for the optimal value of α = 0.1, yields a very good agreement with both experimental results and with GW calculations that well-reproduce the experimental data.

  • 70. Bu, L.
    et al.
    Chen, J.
    Wei, X.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Xie, Y.
    An AIE and ICT based NIR florescent probe for cysteine and homocysteine2017In: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 136, p. 724-731Article in journal (Refereed)
    Abstract [en]

    A combination of aggregation-induced emission and intramolecular charge transfer was achieved by using a triphenylamine analogue and a dicyanovinyl moiety as the electron donating and accepting units, respectively. Hence, we designed and synthesized a probe with a D-π-A framework as a near-infrared fluorescence turn-on probe for biothiols (cysteine and homocysteine). Owing to the remarkable intramolecular charge transfer effect as well as intramolecular rotations associated with the donor moiety, the probe exhibits extremely weak fluorescence, which becomes a good starting point for developing fluorescence “turn-on” probes. Upon reaction with cysteine or homocysteine utilizing the dicyanovinyl moiety, the intramolecular charge transfer character was weakened, and the reacting products were observed to aggregate in aqueous solutions, resulting in the aggregation-induced emission effect with red fluorescence at 651 and 656 nm, respectively. Hence, the probe could be used as a fluorescence “turn-on” sensor for cysteine and homocysteine, with the sensing time of less than 4 min and the detection limits of 8.4 μM and 5.7 μM towards cysteine and homocysteine, respectively. The probe could distinguish cysteine and homocysteine from glutathione. The sensing mechanism was systematically investigated by employing high resolution mass spectrometry, 1H NMR and density functional theory calculations as well as checking the solvent viscosity dependent fluorescence, and thus the nucleophilic addition products, the intramolecular charge transfer character, and the aggregation-induced emission behaviour were clearly elucidated. It is noteworthy that the low cytotoxicity, the intrinsic aggregation-induced emission nature and near-infrared emissions enable the application of the probe in living cell imaging. © 2016 Elsevier Ltd

  • 71.
    C. Couto, Rafael
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Vaz da Cruz, Vinícius
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ertan, Emelie
    Eckert, Sebastian
    Fondell, Mattis
    Dantz, Marcus
    Kennedy, Brian
    Schmitt, Thorsten
    Pietzsch, Annette
    F. Guimarães, Freddy
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Gel’mukhanov, Faris
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Odelius, Michael
    Kimberg, Victor
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Föhlisch, Alexander
    Selective gating to vibrational modes through resonant X-ray scattering2017In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, p. 14165-1-14165-7Article in journal (Refereed)
    Abstract [en]

    The dynamics of fragmentation and vibration of molecular systems with a large number of coupled degrees of freedom are key aspects for understanding chemical reactivity and properties. Here we present a resonant inelastic X-ray scattering (RIXS) study to show how it is possible to break down such a complex multidimensional problem into elementary components. Local multimode nuclear wave packets created by X-ray excitation to different core-excited potential energy surfaces (PESs) will act as spatial gates to selectively probe the particular ground-state vibrational modes and, hence, the PES along these modes. We demonstrate this principle by combining ultra-high resolution RIXS measurements for gas-phase water with state-of-the-art simulations.

  • 72. Cai, Shengyun
    et al.
    Hu, Xiaohao
    Tian, Guojian
    Zhou, Haitao
    Chen, Wei
    Huang, Jinhai
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Su, Jianhua
    Photo-stable substituted dihydroindolo[2,3-b]carbazole-based organic dyes: tuning the photovoltaic properties by optimizing the pi structure for panchromatic DSSCs2014In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 70, no 43, p. 8122-8128Article in journal (Refereed)
    Abstract [en]

    Three dihydroindolo[2,3-b]carbazole (DDC) donor based organic dyes (DDC6-DDC8) with long conjugated systems were successfully synthesized and characterized by optical, electrochemical, computational analysis, and photovoltaic methods. It was found that the elongated pi system as well as the high molar extinction coefficients (4.2-5.3 M-1 cm(-1)) sufficiently reinforced the light harvesting ability with the IPCE response of one dye DDC8 extended to 850 nm, which resulted in large J(sc) of these dyes based devices (high as 16.41 mA cm(-2)). The attached alkyl chains suppress the dark current to some extent, resulting the DDC6 and DDC7 devices in high V-oc, while DDC8 displayed low V-oc, because BTD in DDC8 could attract the iodine ion, which could accelerate the charge recombination. Among the three dyes, DDC7 displayed the best performance with an eta value 6.53% under 4 mu m thick scattering layer (condition 1+1), which was boosted to 7.49% under 8 mu m thick scattering layer (condition 1+2). The photo-stability measurements indicated that all the three dyes are fairly photo-stable.

  • 73. Cao, Hui
    et al.
    Zhang, Qun
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhang, Chaozhi
    Substituent Effect on Hole Mobility of Conjugated Polymers in Photovoltaic Cells2013In: Asian Journal of Chemistry, ISSN 0970-7077, E-ISSN 0975-427X, Vol. 25, no 4, p. 2177-2181Article in journal (Refereed)
    Abstract [en]

    In this work, we have theoretically investigated the substituent effect on hole mobility of the conjugated alternating polymers typically applied in photovoltaic cells. We found that both linear and nonlinear behaviour of binding energy of polarons with respect to their extension size in two series of polymers. The resistances in the process of polaron's jumping between polymer chains are thus different. The experimental relative hole mobility of two kinds of polymers are well explained. Analysis of substituent effect provides insight into obtaining better hole-transport conjugated polymers in future.

  • 74.
    Cao, Xinrui
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    First-Principles Modeling of Selected Heterogeneous Reactions Catalyzed by Noble-Metal Nanoparticles2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Heterogeneous catalysis is an important branch in catalysis, in which the catalyst and reactants are in different physical phases. In this thesis, we have carried out extensive first-principles calculations to explore the selected heterogeneous reactions catalyzed by the noble-metal nanoparticles. The major results of the thesis fall into two categories: (1) the discovery of the scaling relations for predicting the catalytic activity of nanoparticles; (2) the computational characterization of the catalytic activity and mechanism for specific catalytic reactions. For the first category, we have made efforts to develop the scaling relations for binary noble-metal nanoparticles. The obtained results show that the scaling relation not only holds at the nanoscale, but can also be unified with those obtained for the extended surfaces. Our findings shed new light for the efficient screening of nanoparticles with superior catalytic properties. The second part of the thesis summarizes our studies on different catalytic systems. One of the focuses is to study the catalytic properties of the single Pd-doped Cu55 nanoparticle toward H2 dissociation and propane dehydrogenation. The possible reaction mechanisms and effects of the single and multiple Pd doping on the catalytic activity have been extensively examined. Our calculations reveal that single-Pd-doped Cu55 cluster bears good balance between the maximum use of the noble metal and the high activity, and it may serve as a promising single-atom catalyst. We have also systematically studied the reduction process of graphene fluoride catalyzed by the Pt-coated metallic tip under different atmospheres, aiming to provide a feasible strategy for scanning probe lithography to fabricate electronic circuits at the nanoscale on graphene fluoride. It is found that the tip-induced reduction of graphene fluoride with assistance of pure hydrogen atmosphere is facile despite the release of hazard hydride fluoride. The ethylene molecule is predicted to be an excellent acceptor for fluoride abstraction from graphene fluoride, but the corresponding defluorination cycle can not be recycled. Our calculations have finally revealed that under the mixture hydrogen and ethylene atmosphere, the Pt-coated tip can effectively and sequentially reduce graphene fluoride with the release of relatively harmless reduction product, fluoroethane. The proposed cyclic reduction strategy is energetically highly favorable and is ready to be employed in experiments. Our theoretical studies provide yet another convincing example to demonstrate the power of the density functional theory for studying the nano-catalysis. It should also been mentioned that the present calculations are restricted to relatively small-sized clusters due to the limited computational resources. It is highly desirable to further study complicated interfacial systems and to provide a full picture of heterogeneous catalysis with the aid of ab initio molecular dynamics simulations in the future.

  • 75.
    Cao, Xinrui
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Fu, Qiang
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Catalytic activity of Pd-doped Cu nanoparticles for hydrogenation as a single-atom-alloy catalyst2014In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, no 18, p. 8367-8375Article in journal (Refereed)
    Abstract [en]

    The single atom alloy of extended surfaces is known to provide remarkably enhanced catalytic performance toward heterogeneous hydrogenation. Here we demonstrate from first principles calculations that this approach can be extended to nanostructures, such as bimetallic nanoparticles. The catalytic properties of the single-Pd-doped Cu-55 nanoparticles have been systemically examined for H-2 dissociation as well as H atom adsorption and diffusion, following the concept of single atom alloy. It is found that doping a single Pd atom at the edge site of the Cu-55 shell can considerably reduce the activation energy of H-2 dissociation, while the single Pd atom doped at the top site or in the inner layers is much less effective. The H atom adsorption on Cu-55 is slightly stronger than that on the Cu(111) surface; however, a larger nanoparticle that contains 147 atoms could effectively recover the weak binding of the H atoms. We have also investigated the H atom diffusion on the 55-atom nanoparticle and found that spillover of the produced H atoms could be a feasible process due to the low diffusion barriers. Our results have demonstrated that facile H-2 dissociation and weak H atom adsorption could be combined at the nanoscale. Moreover, the effects of doping one more Pd atom on the H-2 dissociation and H atom adsorption have also been investigated. We have found that both the doping Pd atoms in the most stable configuration could independently exhibit their catalytic activity, behaving as two single-atom-alloy catalysts.

  • 76.
    Cao, Xinrui
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ji, Yongfei
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Hu, Wei
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Department of Chemical Physics, University of Science and Technology of ChinaHefei, China.
    Duan, Sai
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Department of Chemical Physics, University of Science and Technology of ChinaHefei, China .
    Feasible Catalytic Strategy for Writing Conductive Nanoribbons on a Single-Layer Graphene Fluoride2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 39, p. 22643-22648Article in journal (Refereed)
    Abstract [en]

    An accessible method for local reduction of graphene fluoride catalyzed by the Pt-coated nanotip with the assistance of a mixture of hydrogen and ethylene atmosphere is proposed and fully explored theoretically. Detailed mechanisms and roles of hydrogen and ethylene molecules in the cyclic reduction is discussed based on extensive first-principles calculations. It is demonstrated that the proposed cyclic reduction strategy is energetically favorable. This new strategy can be effectively applied in scanning probe lithography to fabricate electronic circuits at the nanoscale on graphene fluoride under mild conditions.

  • 77.
    Cao, Xinrui
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ji, Yongfei
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. University of Science and Technology of China, China.
    Dehydrogenation of Propane to Propylene by a Pd/Cu Single-Atom Catalyst: Insight from First-Principles Calculations2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 2, p. 1016-1023Article in journal (Refereed)
    Abstract [en]

    The catalytic properties of the single-Pd-doped Cu55 nanoparticle toward propane dehydrogenation have been systemically investigated by first-principles calculations, and the possible reaction mechanisms and effects of the single and multiple Pd doping on the catalytic activity have been discussed. Calculations reveal that the low-energy catalytic conversion of propane to propylene by the Pd/Cu single-atom catalyst comprises the initial crucial C–H bond breaking at either the methyl or methylene group, the facile diffusion of detached H atoms on the Cu surface, and the subsequent C–H bond dissociation activation of the adsorbed propyl species. The single-Pd-doped Cu55 nanoparticle shows remarkable activity toward C–H bond activation, and the presence of relatively inactive Cu surface is beneficial for the coupling and desorption of detached H atoms and can reduce side reactions such as deep dehydrogenation and C–C bond breaking. The single-Pd-doped Cu55 cluster bears good balance between the maximum use of the noble metal and the activity, and it may serve as a promising single-atom catalyst toward selective dehydrogenation of propane.

  • 78.
    Cao, Xinrui
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Study of the Electronic and Optical Properties of Hybrid Triangular (BN)(x)C-y Foams2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 38, p. 22181-22187Article in journal (Refereed)
    Abstract [en]

    The triangular foam is a newly designed 3D network structure only containing sp(2) bonding. The triangular carbon foam and its boron nitride analogue are predicted to be metallic and semiconducting, respectively (Chem. Commun. 2011, 47 (15), 4406-4408). Here a series of hybrid 3D network models from the BN- and C-doping of both carbon and BN foams have been designed. These newly designed hybrid (BN)(x)C-y foams are predicted to have comparable stability with their undoped crystalline networks, and the conversion between metallic and semiconducting behavior can be achieved by different doping patterns. Furthermore, these hybrid network structures have strong absorption in a wide range of UV region and relatively weak absorption in the visible-light range, and they should be quite promising for the design of electronic and optical devices.

  • 79. Carniato, S.
    et al.
    Selles, P.
    Journel, L.
    Guillemin, R.
    Stolte, W. C.
    El Khoury, L.
    Marin, T.
    Gel'mukhanov, Faris
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Lindle, D. W.
    Simon, M.
    Thomson-resonant interference effects in elastic x-ray scattering near the Cl K edge of HCl2012In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 137, no 9, p. 094311-Article in journal (Refereed)
    Abstract [en]

    We experimentally observed interference effects in elastic x-ray scattering from gas-phase HCl in the vicinity of the Cl Kedge. Comparison to theory identifies these effects as interference effects between non-resonant elastic Thomson scattering and resonant Raman scattering. The results indicate the non-resonant Thomson and resonant Raman contributions are of comparable strength. The measurements also exhibit strong polarization dependence, allowing an easy identification of the resonant and non-resonant contributions.

  • 80. Carravetta, V.
    et al.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Symmetry Breaking and Hole Localization in Multiple Core Electron Ionization2013In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 117, no 31, p. 6798-6802Article in journal (Refereed)
    Abstract [en]

    Motivated by recent opportunitites to study hollow molecules with multiple core holes offered by X-ray free electron lasers, we revisit the core-hole localization and symmetry breaking problem, now studying ionization of more than one core electron. It is shown, using a N-2 molecule with one, two, three, and four core holes, for example, that in a multiconfigurational determination of the core ionization potentials employing a molecular point group with broken inversion symmetry, one particular configuration is sufficient to account for the symmetry breaking relaxation energy in an independent particle approximation in the case of one or three holes, whereas the choice of point group symmetry is unessential for two and four holes. The relaxation energy follows a quadratic dependence on the number of holes in both representations.

  • 81. Carravetta, Vincenzo
    et al.
    Monti, Susanna
    Li, Cui
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Theoretical Simulations of Structure and X-ray Photoelectron Spectra of Glycine and Diglycine Adsorbed on Cu(110)2013In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 29, no 32, p. 10194-10204Article in journal (Refereed)
    Abstract [en]

    The study of adsorption of glycine and glycylglycine (or diglycine) on a copper surface is an important step for the comprehension of mechanisms that determine the stability of biological functionalizers on metal substrates. These two molecules can be considered as prototypes and essential models to investigate, theoretically and experimentally, the adaptability of flexible short peptide chains to a definite interface. In this work, we have improved and updated earlier molecular dynamics simulations by including reactivity of the various species and the comparison of ab initio calculated C, N, and O core photoelectron chemical shifts with the ones found in previous studies. New diglycine-copper bonding is predicted, and the results of the chemical shift analysis are, in all cases, fully compatible with structural information obtained through experimental measurements. Moreover, we have found that the process of proton transfer, which is fundamental in the dynamics of amino acids and peptides, occurs mainly by intermolecular interaction between the first and second layer of the adsorbate.

  • 82. Carrete, Jesus
    et al.
    Mingo, Natalio
    Tian, Guangjun
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Baev, Alexander
    Prasad, Paras N.
    Thermoelectric Properties of Hybrid Organic-Inorganic Superlattices2012In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 20, p. 10881-10886Article in journal (Refereed)
    Abstract [en]

    We theoretically evaluate the thermoelectric transport coefficients of hybrid thiophene/SiGe superlattices and the effect of their chemical tuning via phenyl groups. Owing to the interplay between alloy scattering and phonon transmission at the molecular layers, very low thermal conductivities under 1 W/(m K) and values of ZT more than twice as large as those of bulk SiGe can be attained. These results highlight exciting possibilities of organic-inorganic hybrid systems, as compared to traditional inorganic thermoelectrics.

  • 83.
    Carvalho Couto, Rafael
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Coupled electron-nuclear dynamics in inelastic X-ray scattering2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This Thesis is devoted to theoretical and experimental studies of resonant inelastic X-ray scattering (RIXS) of carbon monoxide and water molecules. Using state-of-the-art ab initio electronic structure calculations and a time-dependent wave packet formalism, we make a complete analysis of the experimental RIXS spectra of the two molecular systems. In the CO RIXS analysis, we are able to reproduce the RIXS experiment with an excellent accuracy. Interference between different RIXS channels corresponding to the scattering via orthogonal molecular orbitals in the core-excited state of CO is described. We show the complete breakdown of the Born-Oppenheimer approximation in the region where forbidden final Rydberg states are mixed with a valence allowed final state. Here we explain the formation of a spectral feature which was attributed to a single state in previous studies. Moreover, through an experimental-theoretical combination, we improve the minimum of the valence E’Π excited state potential, along with the coupling constant between two Rydberg states. We developed a new theoretical approach to describe triatomic molecules through the wave packet propagation formalism to study the water system, which reproduces with high accuracy the vibrational structure of the high-resolution experimental quasi-elastic RIXS spectra. We demonstrate that due to the vibrational mode coupling and anharmonicity of the ground and core-excited potential energy surfaces, different core-excited states in RIXS can be used as gates to probe different vibrational dynamics and to map the ground state potential. Isotopic substitution is investigated by theoretical simulations and important dynamical features are discussed, especially for the dissociative core-excited state, where a so-called “atomic” peak is formed. We show the strong potential of high-resolution RIXS experiments combined with high-level theoretical simulations for advanced studies of highly excited molecular states.

  • 84.
    Chattopadhyaya, Mausumi
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Murugan, N. Arul
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Rinkevicius, Zilvinas
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Origin of the Absorption Band of Bromophenol Blue in Acidic and Basic pH: Insight from a Combined Molecular Dynamics and TD-DFT/MM Study2016In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 120, no 36, p. 7175-7182Article in journal (Refereed)
    Abstract [en]

    We study the linear and nonlinear optical properties of a well-known acid base indicator, bromophenol blue (BPB), in aqueous solution by employing static and integrated approaches. In the static approach, optical properties have been calculated using time-dependent density functional theory (TD-DFT) on the fully relaxed geometries of the neutral and different unprotonated forms of BPB. Moreover, both closed and open forms of BPB were considered. In the integrated approach, the optical properties have been computed over many snapshots extracted from molecular dynamics simulation using a hybrid time-dependent density functional theory/molecular mechanics approach. The static approach suggests closed neutral double right arrow anionic interconversion as the dominant mechanism for the red shift in the absorption spectra of BPB due to a change from acidic to basic pH. It is found by employing an integrated approach that the two interconversions, namely open neutral double right arrow anionic and open neutral double right arrow dianionic, can contribute to the pH- dependent shift in the absorption spectra of BPB. Even though both static and integrated approaches reproduce the pH-dependent red shift in the absorption spectra of BPB, the latter one is suitable to determine both the spectra and spectral broadening. Finally, the computed static first hyperpolarizability for various protonated and deprotonated forms of BPB reveals that this molecule can be used as a nonlinear optical probe for pH sensing in addition to its highly exploited use as an optical probe.

  • 85. Chattopadhyaya, Mausumi
    et al.
    Natarajan Arul, Murgan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Alam, Md. Mehboob
    Chakrabarti, Swapan
    Spatial spin-charge separation in neutral endohedral metallofullerene: A combined restricted open-shell MP2 and Car-Parrinello molecular dynamics study2013In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 557, p. 71-75Article in journal (Refereed)
    Abstract [en]

    We present the first theoretical evidence of the unusual separation of spin and charge degrees of freedom of electron in a neutral endohedral metallofullerene, Sc@C-50. To demystify its origin, we have performed computation at the level of ROMP2 in combination with Car-Parrinello molecular dynamics at 300 K on a series of Sc@C-n. Our inspection reveals that a sharp fall of electron correlation in Sc@C-50 makes the system so sensitive that, to avoid additional Pauli repulsion, Sc leaves the charge component of the solitary 3d electron to C-50 keeping the spin density over its own.

  • 86. Chen, Bin
    et al.
    Ding, Yubin
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhu, Weihong
    Hill, Jonathan P.
    Ariga, Katsuhiko
    Xie, Yongshu
    Steric hindrance-enforced distortion as a general strategy for the design of fluorescence "turn-on" cyanide probes2013In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 49, no 86, p. 10136-10138Article in journal (Refereed)
    Abstract [en]

    For the rational design of fluorescence "turn-on" cyanide probes, a general strategy is developed by introducing a dicyanovinyl group at the sterically demanding position of a large pi framework.

  • 87. Chen, Bin
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Wu, Wenjun
    Zha, Quanzheng
    Xie, Yongshu
    A novel trigeminal zinc porphyrin and corresponding porphyrin monomers for dye-sensitized solar cells2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 21, p. 10439-10449Article in journal (Refereed)
    Abstract [en]

    A novel trigeminal zinc porphyrin sensitizer (T) and two zinc porphyrin monomers (M1 and M2) were successfully designed and synthesized. The spectral, electrochemical, and photovoltaic properties of the porphyrin dyes were investigated. Compared with M1, the molecule of M2 has an additional aliphatic n-hexyloxyl chain at the meso-position of the porphyrin framework, and such a structure is favorable for the formation of a compact hydrophobic layer at the TiO2 surface and the retardation of the diffusion of I-3(-) ions into the nanoporous TiO2 electrode, resulting in more effective suppression of the charge recombination process and a higher V-oc. Meanwhile, M2 has larger IPCE values than those of M1, leading to the higher J(sc) value. Thus, the DSSC devices based on M2 demonstrated a relatively high power conversion efficiency of 5.77%, with the J(sc), V-oc and ff values of 13.93 mA cm(-2), 732 mV, and 0.566, respectively. Even though dye T has the highest molar absorption coefficients and multiple binding moieties, the corresponding power conversion efficiency is 2.30%, which is lower than those for M1 and M2. These observations may be ascribed to the low efficiency of the electron injection process caused by the isolation of the LUMOs from the anchoring carboxyl groups in addition to the lowest adsorption amount.

  • 88. Chen, Bin
    et al.
    Sun, Lu
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Xie, Yong-Shu
    Modulation of photovoltaic behavior of dye-sensitized solar cells by electron donors of porphyrin dyes and cosensitization2015In: Chinese Chemical Letters, ISSN 1001-8417, E-ISSN 1878-5964, Vol. 26, no 7, p. 899-904Article in journal (Refereed)
    Abstract [en]

    Porphyrin dyes have received great attention due to their excellent photovoltaic performance in dye-sensitized solar cells (DSSCs). In this work, dyes XC1-XC3 were synthesized by introducing various numbers of bis(4-methoxyphenyl)amino and p-hexyloxyphenyl groups to porphyrin mesa-positions. The XC1 molecule contains two p-hexyloxyphenyl groups, and its DSSCs showed the power conversion efficiency of 4.81%. For XC2 and XC3, the replacement of p-hexyloxyphenyl with diphenylamino groups can effectively enhance the light harvesting around 500 nm. However, the highest occupied molecular orbitals (HOMOs) were elevated too much, which suppressed the dye regeneration processes, leading to low cell efficiencies of 2.51% and 1.27% for XC2, and XC3, respectively. To further improve the cell performance, an anthracene derivative C1 was used as the cosensitizer for XC1, which increased both the J(sc) and V-oc values, with an improved efficiency of 5.75%.

  • 89. Chen, Bin
    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
    TICT based fluorescence "turn-on" hydrazine probes2014In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 199, p. 93-100Article in journal (Refereed)
    Abstract [en]

    Fluorescence "turn-on" probes PC3 and C3 with weak background emissions were developed for hydrazine sensing. The aldehyde and dicyanovinyl groups were used as the recognition units for PD and C3, respectively. Because of low reactivity of the aldehyde group, the fluorescence of PC3 was enhanced by only ca. 93 folds upon addition of a large amount of 1646 eq. hydrazine. In contrast, 0 exhibited fluorescence enhancement by ca. 239 folds upon addition of only 1.3 eq. hydrazine, and thus it showed high sensitivity towards hydrazine, with the detection limit of 7 ppb. In aqueous systems, it also works well with improved selectivity for hydrazine over CN-. The weak fluorescence of PC3 and 0 can be ascribed to twisted intramolecular charge transfer (TICT) processes by the combination of the bulky diphenylamino and 9-anthryl units, which were well demonstrated by theoretical calculations, viscosity dependent fluorescence, and fluorescence decay behaviour. Addition of hydrazine induced the disappearance of the TICT deactivation pathway, resulting in the observed fluorescence enhancement. It can be concluded that the combination of the bulky diphenylamino and 9-anthryl units is an effective approach for developing fluorescence turn-on hydrazine probes based on the TICT mechanism.

  • 90. Chen, Bin
    et al.
    Yu, Gang
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ding, Yubin
    Wang, Cheng
    Liu, Zhiwei
    Xie, Yongshu
    Full-colour luminescent compounds based on anthracene and 2,2 '-dipyridylamine2013In: Journal of Materials Chemistry C, ISSN 2050-7526, Vol. 1, no 44, p. 7409-7417Article in journal (Refereed)
    Abstract [en]

    Starting from two simple units of anthracene and 2,2'-dipyridylamine, a series of new luminescent compounds 1-8 were designed and synthesized by a combined strategy of changing the connection mode between the two units, extending the conjugation size, and introducing an additional electron donor. Photophysical properties of 1-8 were investigated and discussed on the basis of solvatochromic behaviour, theoretical calculations, crystal structure, and optimized structures. Interestingly, the emission wavelengths of these compounds could be successfully tuned from violet to red both in solutions and the solid-state, and prominent positive solvatochromism was observed for the compounds with a D-p-A framework. Consider compound 7 as an example, it shows peaks at 526 nm and 627 nm in cyclohexane and DMSO, respectively. Meanwhile, the quantum yield was decreased from 0.80 in cyclohexane to 0.12 in DMSO. The introduction of bulky groups was demonstrated to be effective for suppressing the aggregation effect and thus improving the solid state emission quantum yield. These results indicate that the combined structure modulation strategy offers a powerful tool for tuning the emission behaviour. To demonstrate the possibility of practical applications, 2 was employed as the emitting material for the fabrication of deep-blue organic light-emitting diodes (OLEDs), which showed a maximum external quantum efficiency of 2.2%. The CIE coordinates of (0.15, 0.08) are indicative of excellent blue color purity.

  • 91. Chen, G.
    et al.
    Damasco, J.
    Qiu, H.
    Shao, W.
    Ohulchanskyy, T. Y.
    Valiev, Rashid
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Tomsk State University,Tomsk, Russian Federation.
    Wu, X.
    Han, G.
    Wang, Y.
    Yang, C.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Prasad, P. N.
    Energy-Cascaded Upconversion in an Organic Dye-Sensitized Core/Shell Fluoride Nanocrystal2015In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 15, no 11, p. 7400-7407Article in journal (Refereed)
    Abstract [en]

    Lanthanide-doped upconversion nanoparticles hold promises for bioimaging, solar cells, and volumetric displays. However, their emission brightness and excitation wavelength range are limited by the weak and narrowband absorption of lanthanide ions. Here, we introduce a concept of multistep cascade energy transfer, from broadly infrared-harvesting organic dyes to sensitizer ions in the shell of an epitaxially designed core/shell inorganic nanostructure, with a sequential nonradiative energy transfer to upconverting ion pairs in the core. We show that this concept, when implemented in a core-shell architecture with suppressed surface-related luminescence quenching, yields multiphoton (three-, four-, and five-photon) upconversion quantum efficiency as high as 19% (upconversion energy conversion efficiency of 9.3%, upconversion quantum yield of 4.8%), which is about ∼100 times higher than typically reported efficiency of upconversion at 800 nm in lanthanide-based nanostructures, along with a broad spectral range (over 150 nm) of infrared excitation and a large absorption cross-section of 1.47 × 10-14 cm2 per single nanoparticle. These features enable unprecedented three-photon upconversion (visible by naked eye as blue light) of an incoherent infrared light excitation with a power density comparable to that of solar irradiation at the Earth surface, having implications for broad applications of these organic-inorganic core/shell nanostructures with energy-cascaded upconversion.

  • 92. Chen, G.
    et al.
    Ning, Z.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Nanostructured solar cells2016In: Nanomaterials, ISSN 2079-4991, Vol. 6, no 8, article id 145Article in journal (Refereed)
    Abstract [en]

    We are glad to announce the Special Issue “Nanostructured Solar Cells”, published in Nanomaterials. This issue consists of eight articles, two communications, and one review paper, covering major important aspects of nanostructured solar cells of varying types. From fundamental physicochemical investigations to technological advances, and from single junction solar cells (silicon solar cell, dye sensitized solar cell, quantum dots sensitized solar cell, and small molecule organic solar cell) to tandem multi-junction solar cells, all aspects are included and discussed in this issue to advance the use of nanotechnology to improve the performance of solar cells with reduced fabrication costs.

  • 93. Chen, G.
    et al.
    Shao, W.
    Valiev, Rashid R.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ohulchanskyy, T. Y.
    He, G. S.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Prasad, P. N.
    Efficient Broadband Upconversion of Near-Infrared Light in Dye-Sensitized Core/Shell Nanocrystals2016In: Advanced Optical Materials, ISSN 2195-1071Article in journal (Refereed)
  • 94.
    Chen, Guanying
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ohulchanskyy, T. Y.
    Liu, S.
    Law, W. -C
    Wu, F.
    Swihart, M. T.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Prasad, P. N.
    Core/shell NaGdF 4:Nd 3+/NaGdF 4 nanocrystals with efficient near-infrared to near-infrared downconversion photoluminescence for bioimaging applications2012In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 6, no 4, p. 2969-2977Article in journal (Refereed)
    Abstract [en]

    We have synthesized core/shell NaGdF 4:Nd 3+/NaGdF 4 nanocrystals with an average size of 15 nm and exceptionally high photoluminescence (PL) quantum yield. When excited at 740 nm, the nanocrystals manifest spectrally distinguished, near-infrared to near-infrared (NIR-to-NIR) downconversion PL peaked at ∌900, ∌1050, and ∌1300 nm. The absolute quantum yield of NIR-to-NIR PL reached 40% for core-shell nanoparticles dispersed in hexane. Time-resolved PL measurements revealed that this high quantum yield was achieved through suppression of nonradiative recombination originating from surface states and cross relaxations between dopants. NaGdF 4:Nd 3+/NaGdF 4 nanocrystals, synthesized in organic media, were further converted to be water-dispersible by eliminating the capping ligand of oleic acid. NIR-to-NIR PL bioimaging was demonstrated both in vitro and in vivo through visualization of the NIR-to-NIR PL at ∌900 nm under incoherent lamp light excitation. The fact that both excitation and the PL of these nanocrystals are in the biological window of optical transparency, combined with their high quantum efficiency, spectral sharpness, and photostability, makes these nanocrystals extremely promising as optical biomaging probes.

  • 95. Chen, Guanying
    et al.
    Ohulchanskyy, Tymish Y.
    Kachynski, Aliaksandr
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Prasad, Paras N.
    Intense Visible and Near-Infrared Upconversion Photoluminescence in Colloidal LiYF4:Er3+ Nanocrystals under Excitation at 1490 nm2011In: ACS NANO, ISSN 1936-0851, Vol. 5, no 6, p. 4981-4986Article in journal (Refereed)
    Abstract [en]

    We report intense upconversion photoluminescence (PL) In colloidal LiYF4:Er(3+)nanocrystals under excitation with telecom-wavelength at 1490 nm. The intensities of two- and three-photon anti-Stokes upconversion PL bands are higher than or comparable to that of the Stokes emission under excitation with low power density in the range 5-120 W/cm(2). The quantum yield of the uptonversion PL was measured to be as high as similar to 1.2 +/- 0.1%, which is almost 4 times higher than the highest upconversion PL quantum yield reported to date for lanthanide-doped nanocrystals In 100 nm sized hexagonal NaYF4:Yb(3+)20%, Er(3+)2% using excitation at similar to 980 nm. A power dependence study revealed that the intensities of all PL bands have linear dependence on the excitation power density, which was explained by saturation effects in the intermediate energy states.

  • 96.
    Chen, Guanying
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ohulchanskyy, Tymish Y.
    Law, Wing Cheung
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Prasad, Paras N.
    Monodisperse NaYbF4: Tm3+/NaGdF4 core/shell nanocrystals with near-infrared to near-infrared upconversion photoluminescence and magnetic resonance properties2011In: NANOSCALE, ISSN 2040-3364, Vol. 3, no 5, p. 2003-2008Article in journal (Refereed)
    Abstract [en]

    We report core/shell NaYbF4 : Tm3+/NaGdF4 nanocrystals to be used as probes for bimodal near infrared to near infrared (NIR-to-NIR) upconversion photoluminescence (UCPL) and magnetic resonance (MR) imaging. The NaYbF4 : Tm3+ nanocrystals were previously reported to produce the intense NIR-to-NIR UCPL peaked at similar to 800 nm under excitation at similar to 975 nm. We have found that the growth of a NaGdF4 shell on surface of the NaYbF4 : Tm3+ nanocrystals results in the increase in the intensity of UCPL of Tm3+ ions by about 3 times. Unlike biexponential PL decay of NaYbF4 : Tm3+ nanocrystals, the PL decay of NaYbF4 : Tm3+/NaGdF4 core/shell nanocrystals is single exponential and of longer lifetime due to the suppression of surface quenching effects for Tm3+ PL. The growth of a NaGdF4 shell on surface of the NaYbF4 : Tm3+ nanocrystals also provides high MR relaxivity from paramagnetic Gd3+ ions contained in the shell. The T1-weighted MR signal of the (NaYbF4:2% Tm3+)/NaGdF4 nanoparticles was measured to be about 2.6 mM(-1)s(-1). Due to the combined presence of efficient optical and MR imaging capabilities, nanoprobes based on NaYbF4 : Tm3+/NaGdF4 fluoride nanophosphors can be considered as a promising platform for simultaneous bimodal PL and MR bioimaging.

  • 97.
    Chen, Guanying
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Shen, Jie
    Ohulchanskyy, Tymish Y.
    Patel, Nayan J.
    Kutikov, Artem
    Li, Zhipeng
    Song, Jie
    Pandey, Ravindra K.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Prasad, Paras N.
    Han, Gang
    (alpha-NaYbF4:Tm3+)/CaF2 Core/Shell Nanoparticles with Efficient Near-Infrared to Near-Infrared Upconversion for High-Contrast Deep Tissue Bioimaging2012In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 6, no 9, p. 8280-8287Article in journal (Refereed)
    Abstract [en]

    We describe the development of novel and biocompatible core/shell (alpha-NaYbF4:Tm3+)/CaF2 nanoparticles that exhibit highly efficient NIRin-NIROut upconversion (UC) for high contrast and deep bioimaging. When excited at similar to 980 nm, these nanoparticles emit photoluminescence (PL) peaked at similar to 800 nm. The quantum yield of this UC PL under low power density excitation (similar to 0.3 W/cm(2)) is 0.6 +/- 0.1%. This high UC PL efficiency is realized by suppressing surface quenching effects via heteroepitaxial growth of a biocompatible CaF2 shell, which results in a 35-fold increase in the intensity of UC PL from the core. Small-animal whole-body UC PL imaging with exceptional contrast (signal-to-background ratio of 310) is shown using BALB/c mice intravenously injected with aqueously dispersed nanoparticles (700 pmol/kg). High-contrast UC PL imaging of deep tissues is also demonstrated, using a nanoparticle-loaded synthetic fibrous mesh wrapped around rat femoral bone and a cuvette with nanoparticle aqueous dispersion covered with a 3.2 cm thick animal tissue (pork).

  • 98. Chen, Guanying
    et al.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ohulchanskyy, Tymish Y.
    Prasad, Paras N.
    Light upconverting core-shell nanostructures: nanophotonic control for emerging applications2015In: Chemical Society Reviews, ISSN 0306-0012, E-ISSN 1460-4744, Vol. 44, no 6, p. 1680-1713Article in journal (Refereed)
    Abstract [en]

    Light upconverting nanostructures employing lanthanide ions constitute an emerging research field recognized with wide ramifications and impact in many areas ranging from healthcare, to energy and, to security. The core-shell design of these nanostructures allows us to deliberately introduce a hierarchy of electronic energy states, thus providing unprecedented opportunities to manipulate the electronic excitation, energy transfer and upconverted emissions. The core-shell morphology also causes the suppression of quenching mechanisms to produce efficient upconversion emission for biophotonic and photonic applications. Using hierarchical architect, whereby each shell layer can be defined to have a specific feature, the electronic structure as well as the physiochemical structure of the upconverting nanomaterials can be tuned to couple other electronic states on the surface such as excitations of organic dye molecules or localized surface plasmons from metallic nanostructures, or to introduce a broad range of imaging or therapeutic modalities into a single conduct. In this review, we summarize the key aspects of nanophotonic control of the light upconverting nanoparticles through governed design and preparation of hierarchical shells in the core-shell nanostructures, and review their emerging applications in the biomedical field, solar energy conversion, as well as security encoding.

  • 99. Chen, H.
    et al.
    Gao, Y.
    Lu, Z.
    Ye, L.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Center on Molecular Devices, Dalian University of Technology (DUT), Dalian 116024, China.
    Copper Oxide Film In-situ Electrodeposited from Cu(II) Complex as Highly Efficient Catalyst for Water Oxidation2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 230, p. 501-507Article in journal (Refereed)
    Abstract [en]

    Water splitting is deemed as an effective pathway for producing ideal clean energy, such as hydrogen. Here, a copper oxide film (Cu-Tris film) was prepared in-situ from a 0.2 M phosphate buffer solution (pH = 12.0) containing 1.0 mM Cu2+ and 2.0 mM Tris via controlled-potential electrodeposition. The Cu-Tris film showed a significantly low overpotential of 390 mV at a current density of 1.0 mA/cm2 for electrocatalytic water oxidation. Simultaneously, a considerably low Tafel slope of 41 mV/decade was achieved. This Cu-Tris film also exhibited a high and stable current density of ca. 7.5 mA/cm2 at 1.15 V vs. NHE for long-term electrocatalysis (10 h). These results demonstrated the superior performance of the developed Cu-Tris film, which should be attributed to the regulating effect of the five coordinated planar structure of the Cu-Tris complex precursor during the process of electrodeposition.

  • 100. Chen, Long
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ying, Weijiang
    Zhang, Xiaoyu
    Guo, Fuling
    Li, Jing
    Hua, Jianli
    5,6-Bis(octyloxy)benzo[c][1,2,5]thiadiazole-Bridged Dyes for Dye-Sensitized Solar Cells with High Open-Circuit Voltage Performance2013In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 9, p. 1770-1780Article in journal (Refereed)
    Abstract [en]

    Three new metal-free dyes with a 5,6-bis(octyloxy) benzo[c][1,2,5] thiadiazole core (DOBT-I-III) have been designed and synthesized for use as DSSCs. Their absorption properties and electrochemical and photovoltaic performances have been investigated systematically. The DSSCs based on DOBT-I-III show high open-circuit voltages (V-oc) of 829, 818, and 784 mV, respectively. Of the three dyes, DOBT-III, which contains a thiophene-bridging linker, exhibits the best photovoltaic performance: a short-circuit photocurrent density (J(sc)) of 12.74 mA cm(-2) and a fill factor (FF) of 0.73, which corresponds to an overall conversion efficiency of 7.29% under standard global AM 1.5 solar conditions.

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