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Bathochromic Effect

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Magdalena Makarska-bialokoz – 1st expert on this subject based on the ideXlab platform

  • Non-covalent interactions between thio-caffeine derivatives and water-soluble porphyrin in ethanol-water environment.
    Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2017
    Co-Authors: Agnieszka Lipke, Magdalena Makarska-bialokoz, Arleta Sierakowska, Beata Jasiewicz

    Abstract:

    Abstract To determine the binding interactions and ability to form the non-covalent systems, the association process between 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21H,23H-porphine tetra-p-tosylate (H2TTMePP) and a series of five structurally diverse thio-caffeine analogues has been studied in ethanol and ethanol-water solutions, analyzing its absorption and steady-state fluorescence spectra. The porphyrin fluorescence lifetimes in the systems studied were established as well. During the titration with thio-caffeine compounds the slight Bathochromic Effect and considerable hypochromicity of the porphyrin Soret band maximum can be noted. The fluorescence quenching Effect observed for interactions in H2TTMePP – thio-caffeine derivative systems, as well as the order of binding and fluorescence quenching constants (of 105–103 mol− 1) suggest the existence of the mechanism of static quenching due to the formation of non-covalent and non-fluorescent stacking complexes. In all the systems studied the phenomenon of the fractional accessibility of the fluorophore for the quencher was observed as well. Additionally, the specific binding interactions, due to the changes in reaction environment polarity, can be observed. It was found that thio-caffeine compounds can quench the porphyrin fluorescence according to the structure of thio-substituent in caffeine molecule. The obtained results can be potentially useful from scientific, therapeutic or environmental points of view.

  • Spectroscopic evidence of xanthine compounds fluorescence quenching Effect on water-soluble porphyrins
    Journal of Molecular Structure, 2015
    Co-Authors: Magdalena Makarska-bialokoz

    Abstract:

    Abstract The formation of π-stacked complexes between water-soluble porphyrins: 4,4′,4″,4″′-(21 H ,23 H -porphine-5,10,15,20-tetrayl)tetrakis-(benzoic acid) (H 2 TCPP), 5,10,15,20-tetrakis(4-sulfonatophenyl)-21 H ,23 H -porphine (H 2 TPPS 4 ), 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21 H ,23 H -porphine tetra- p -tosylate (H 2 TTMePP), 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21 H ,23 H -porphine tetra- p -tosylate (H 2 TMePyP), the Cu(II) complexes of H 2 TTMePP and H 2 TMePyP, as well as chlorophyll a with xanthine, theophylline (1,3-dimethylxanthine) and theobromine (3,7-dimethylxanthine) has been studied analysing their absorption and steady-state fluorescence spectra in aqueous (or acetone in case of chlorophyll a) solution. During titration by the compounds from xanthine group the Bathochromic Effect in the porphyrin absorption spectra as well as the hypochromicity of the porphyrin Soret maximum can be noticed. The fluorescence quenching Effect observed during interactions in the systems examined suggests the process of static quenching. The association and fluorescence quenching constants are of the order of magnitude of 10 3  − 10 2  mol −1 . The results obtained show that xanthine and its derivatives can quench the fluorescence of the porphyrins according to the number of methyl groups in the molecule of quencher.

  • Spectroscopic study of associated systems formed between water-soluble cationic porphyrins or their copper (II) complexes and nucleic building blocks
    Central European Journal of Chemistry, 2013
    Co-Authors: Magdalena Makarska-bialokoz

    Abstract:

    The association process between two water soluble cationic porphyrins, 5,10,15,20-tetrakis[4-(trimethyl-ammonio)phenyl]-21 H ,23 H -porphine tetra- p -tosylate (H_2TTMePP) and 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21 H ,23 H -porphine tetra- p -tosylate (H_2TMePyP), as well as their Cu (II) complexes, with five series of nucleic agents has been studied using UV-VIS spectroscopy in aqueous solutions. During the titration with nucleic compounds the Bathochromic Effect of porphyrins absorption spectra can be observed as well as the hypochromicity of the Soret maximum. The association constants were calculated using a curve-fitting procedure (K_AC of the order of magnitude of 10^3–10^5 mol^−1). It has been shown that the interactions of H_2TTMePP with nucleic agents are much stronger than interactions of H_2TMePyP, which is most likely related to the kind and the size of the porphyrin substituent groups partaking in the process of stacking. The strength of the observed associated systems increases generally in a series: nucleic base < nucleoside < nucleotide.

Peng Wang – 2nd expert on this subject based on the ideXlab platform

  • the structure property relationship of organic dyes in mesoscopic titania solar cells only one double bond difference
    Energy and Environmental Science, 2011
    Co-Authors: Difei Zhou, Mingfei Xu, Xiaoyan Jing, Peng Wang

    Abstract:

    A photosensitizer plays a crucial role in the conversion of solar light to electricity in dye-sensitized solar cells (DSCs). Thereby an all-sided apprehension on its structure–property relationship should to a large extent expedite rational material design. In this paper, we investigate some general impacts of one double-bond variation upon the optoelectronic features of three pairs of cyanoacrylic acid dyes. One double-bond insertion between a triphenylamine electron donor and π-conjugated heterocycles such as thiophene, 3,4-ethylenedioxythiophene and 4,4-dihexyl-4H-cyclopenta[2,1-b:3,4-b]dithiophene endows a Bathochromic Effect in terms of electronic absorption of a dye-coated titania film, but leads to a relatively lower electron injection yield as indicated by transient emission measurements. Moreover, this style of one more double-bond incorporation brings forth a lower open-circuit photovoltage, owing to the occurrences of a downwards shifted titania conduction band edge and an augmented rate constant of charge recombination at the titania/electrolyte interface as revealed by electrical impedance analyses.

  • The structure–property relationship of organic dyes in mesoscopic titania solar cells: only one double-bond difference
    Energy and Environmental Science, 2011
    Co-Authors: Difei Zhou, Mingfei Xu, Xiaoyan Jing, Peng Wang

    Abstract:

    A photosensitizer plays a crucial role in the conversion of solar light to electricity in dye-sensitized solar cells (DSCs). Thereby an all-sided apprehension on its structure–property relationship should to a large extent expedite rational material design. In this paper, we investigate some general impacts of one double-bond variation upon the optoelectronic features of three pairs of cyanoacrylic acid dyes. One double-bond insertion between a triphenylamine electron donor and π-conjugated heterocycles such as thiophene, 3,4-ethylenedioxythiophene and 4,4-dihexyl-4H-cyclopenta[2,1-b:3,4-b]dithiophene endows a Bathochromic Effect in terms of electronic absorption of a dye-coated titania film, but leads to a relatively lower electron injection yield as indicated by transient emission measurements. Moreover, this style of one more double-bond incorporation brings forth a lower open-circuit photovoltage, owing to the occurrences of a downwards shifted titania conduction band edge and an augmented rate constant of charge recombination at the titania/electrolyte interface as revealed by electrical impedance analyses.

  • Influence of the electrolyte cation in organic dye-sensitized solar cells: lithium versus dimethylimidazolium
    Energy and Environmental Science, 2010
    Co-Authors: Renzhi Li, Difei Zhou, Yinghui Wang, Peng Wang

    Abstract:

    We investigate the influence of electrolyte cations such as lithium and dimethylimidazolium on the spectroscopic and electrical characteristics of dye-sensitized solar cells based on a metal-free chromophore C218. An evident Bathochromic Effect of lithium with respect to dimethylimidazolium is noticed for the C218 dye-coated nanocrystalline titania film via measuring electronic absorption and photocurrent action spectra. In comparison with dimethylimidazolium, the use of lithium as the electrolyte cation evokes a downward shift of the excited-state redox potential of the C218 sensitizer by 120 mV, and that of the conduction band edge of the nanocrystalline TiO2 film by 390 meV. The resultant remarkable variation in the energy alignment at the titania/dye interface brings on dissimilar electron injection yields as revealed by transient emission measurements. Modulating the titania surface states distribution with lithium relative to dimethylimidazolium induces a slightly declining electron diffusion coefficient in the mesoporous titania film. However, the adsorption of lithium cations on titania strongly retards the interfacial charge recombination compared to dimethylimidazolium, contributing to an over one order of magnitude of enhancement of electron diffusion length. The improvement of electron diffusion length has a noticeable Effect on the charge collection yield, which can also be observed by measuring monochromatic incident photon-to-electron conversion efficiencies. Further interface engineering is needed to enhance both the photovoltage and photocurrent, making use of the full power of metal-free organic dyes.

Difei Zhou – 3rd expert on this subject based on the ideXlab platform

  • the structure property relationship of organic dyes in mesoscopic titania solar cells only one double bond difference
    Energy and Environmental Science, 2011
    Co-Authors: Difei Zhou, Mingfei Xu, Xiaoyan Jing, Peng Wang

    Abstract:

    A photosensitizer plays a crucial role in the conversion of solar light to electricity in dye-sensitized solar cells (DSCs). Thereby an all-sided apprehension on its structure–property relationship should to a large extent expedite rational material design. In this paper, we investigate some general impacts of one double-bond variation upon the optoelectronic features of three pairs of cyanoacrylic acid dyes. One double-bond insertion between a triphenylamine electron donor and π-conjugated heterocycles such as thiophene, 3,4-ethylenedioxythiophene and 4,4-dihexyl-4H-cyclopenta[2,1-b:3,4-b]dithiophene endows a Bathochromic Effect in terms of electronic absorption of a dye-coated titania film, but leads to a relatively lower electron injection yield as indicated by transient emission measurements. Moreover, this style of one more double-bond incorporation brings forth a lower open-circuit photovoltage, owing to the occurrences of a downwards shifted titania conduction band edge and an augmented rate constant of charge recombination at the titania/electrolyte interface as revealed by electrical impedance analyses.

  • The structure–property relationship of organic dyes in mesoscopic titania solar cells: only one double-bond difference
    Energy and Environmental Science, 2011
    Co-Authors: Difei Zhou, Mingfei Xu, Xiaoyan Jing, Peng Wang

    Abstract:

    A photosensitizer plays a crucial role in the conversion of solar light to electricity in dye-sensitized solar cells (DSCs). Thereby an all-sided apprehension on its structure–property relationship should to a large extent expedite rational material design. In this paper, we investigate some general impacts of one double-bond variation upon the optoelectronic features of three pairs of cyanoacrylic acid dyes. One double-bond insertion between a triphenylamine electron donor and π-conjugated heterocycles such as thiophene, 3,4-ethylenedioxythiophene and 4,4-dihexyl-4H-cyclopenta[2,1-b:3,4-b]dithiophene endows a Bathochromic Effect in terms of electronic absorption of a dye-coated titania film, but leads to a relatively lower electron injection yield as indicated by transient emission measurements. Moreover, this style of one more double-bond incorporation brings forth a lower open-circuit photovoltage, owing to the occurrences of a downwards shifted titania conduction band edge and an augmented rate constant of charge recombination at the titania/electrolyte interface as revealed by electrical impedance analyses.

  • Influence of the electrolyte cation in organic dye-sensitized solar cells: lithium versus dimethylimidazolium
    Energy and Environmental Science, 2010
    Co-Authors: Renzhi Li, Difei Zhou, Yinghui Wang, Peng Wang

    Abstract:

    We investigate the influence of electrolyte cations such as lithium and dimethylimidazolium on the spectroscopic and electrical characteristics of dye-sensitized solar cells based on a metal-free chromophore C218. An evident Bathochromic Effect of lithium with respect to dimethylimidazolium is noticed for the C218 dye-coated nanocrystalline titania film via measuring electronic absorption and photocurrent action spectra. In comparison with dimethylimidazolium, the use of lithium as the electrolyte cation evokes a downward shift of the excited-state redox potential of the C218 sensitizer by 120 mV, and that of the conduction band edge of the nanocrystalline TiO2 film by 390 meV. The resultant remarkable variation in the energy alignment at the titania/dye interface brings on dissimilar electron injection yields as revealed by transient emission measurements. Modulating the titania surface states distribution with lithium relative to dimethylimidazolium induces a slightly declining electron diffusion coefficient in the mesoporous titania film. However, the adsorption of lithium cations on titania strongly retards the interfacial charge recombination compared to dimethylimidazolium, contributing to an over one order of magnitude of enhancement of electron diffusion length. The improvement of electron diffusion length has a noticeable Effect on the charge collection yield, which can also be observed by measuring monochromatic incident photon-to-electron conversion efficiencies. Further interface engineering is needed to enhance both the photovoltage and photocurrent, making use of the full power of metal-free organic dyes.