Последние добавленные документы

  • Dynamics of photoinduced electron transfer in multiporphyrin nanoassemblies 

    Kilin, D.; Zenkevich, E.; von Borczyskowski, C. (World Scientific Publishing Co., 2015)
    In self-assembled nanoscale porphyrin triads based on Zn-octaethylporphyrin chemical dimer (donor, D) and dipyridyl substituted porphyrin free base (acceptor, A), fluorescence quenching of D (down to 1.7-10 ps) and A (by ~1.3-1.6 times) subunits is strongly dependent on the solvent polarity (toluene-acetone mixtures) and temperature (77-350 K). The obtained experimental findings ...
    2017-05-27
  • Structural Dynamics and Relaxation Processes with Participation of Excited Singlet and Triplet States in Sterically Hindered Porphyrins and Their Chemical Dimers 

    Zenkevich, E. I. (2014)
    Paper presents an overview of mutual Belarussian-Russian collaboration in the field of sterically hindered porphyrins compared with the relevant literature data. Typically, the conformational dynamics of a non-planar tetrapyrrole macrocycle at 295 K manifests itself in bathochromic absorption and fluorescence shifts (∆ν ~ 1100 cm⁻¹), the increase of the Stokes shift (∆νₛ ~ 900 ...
    2017-05-27
  • Self-organization principles in the formation of multiporphyrin complexes and “semiconductor quantum dot-porphyrin” nanoassemblies 

    Zenkevich, E. I.; von Borczyskowski, C. (2014)
    In this paper, we review several aspects of molecular recognition (based on non-covalent binding interactions) occurring between meso-pyridyl substituted tetrapyrrole extra-ligands and chemical dimers of tetrapyrrolic macrocycles containing central Zn ions and spacers of various nature and flexibility. Experimental results obtained by us earlier are analyzed using a novel approach ...
    2017-05-27
  • Ligand dynamics and temperature effects upon formation of nanocomposites based on semiconductor CdSе/ZnS quantum dots and porphyrins 

    Zenkevich, E. I.; Blaudeck, T.; Kowerko, D.; Stupak, A. P.; Cichos, F.; von Borczyskowski, C. (2012)
    Dye molecules with pyridyl side substituents (porphyrins and heterocyclic perylene diimides) coordinatively attached to semiconductor CdSe/ZnS quantum dots (QDs) surface form quasi-stable “QD-Dye” nanocomposites of various geometry in the competition with capping molecules (tri-n-octyl phosphine oxide or long chain amines) exchange. This results in photoluminescence (PL) quenching ...
    2017-05-27
  • Resonant Raman Scattering of ZnS, ZnO, and ZnS/ZnO Core/shell quantum dots 

    Milekhin, A. G.; Yeryukov, N. A.; Sveshnikova, L. L.; Duda, T. A.; Himcinschi, C.; Zenkevich, E. I.; Zahn, D. R. T. (2012)
    Resonant Raman scattering by optical phonon modes as well as their overtones was investigated in ZnS and ZnO quantum dots grown by the Langmuir–Blodgett technique. The in situ formation of ZnS/ZnO core/shell quantum dots was monitored by Raman spectroscopy during laser illumination.
    2017-05-27
  • Influence of Single Dye Molecules on Temperature and Time Dependent Optical Properties of CdSe/ZnS Quantum Dots 

    Zenkevich, E. I.; Stupak, A. P.; Kowerko, D.; von Borczyskowski, C. (2012)
    Optical spectroscopy on ensembles and single CdSe/ZnS semiconductor quantum dots (QDs) demonstrates a competition of trap and near band edge photoluminescence (PL). This competition can be markedly influenced by a few surface attached pyridyl functionalized dye molecules (porphyrins or perylene diimides) forming nanoassemblies with well defined geometries. Temperature variation ...
    2017-05-27
  • Formation Principles and Ligand Dynamics for Nanoassemblies of CdSe Quantum Dots and Functionalized Dye Molecules 

    Blaudeck, T.; Zenkevich, E.; Abdel-Mottaleb, M.; Szwaykowska, K.; Kowerko, D.; Cichos, F.; von Borczyskowski, C. (2012)
    Functional dye molecules, such as porphyrins, attached to CdSe quantum dots (QDs) through anchoring meso-pyridyl substituents, form quasi-stable nanoassemblies. This fact results in photoluminescence (PL) quenching of the QDs both due to Förster resonance energy transfer (FRET) and the formation of non-radiative surface states under conditions of quantum confinement (non-FRET). ...
    2017-05-27
  • Size-Dependent Non-FRET Photoluminescence Quenching in Nanocomposites Based on Semiconductor Quantum Dots CdSe/ZnS and Functionalized Porphyrin Ligands 

    Zenkevich, E. I.; Blaudeck, T.; Milekhin, A.; von Borczyskowski, C. (2011)
    We review recent experimental work to utilize the size dependence of the luminescence quenching of colloidal semiconductor quantum dots induced by functionalized porphyrin molecules attached to the surface to describe a photoluminescence (PL) quenching process which is different from usual models of charge transfer (CT) or Foerster resonant energy transfer (FRET). Steady-state ...
    2017-05-27
  • Assembly principles and relaxation processes in nanosized heterogeneous complexes 

    Zenkevich, E. I.; von Borczyskowski, C. (2009)
    Based on the extra-ligand addition effect, the principles of targeted self-assembly of nanosized multiporphyrin complexes of various types with controllable geometry and composition (up to 8 tetrapyrroles) and heterogeneous composites based on trioctylphosphine oxide-stabilized CdSe/ZnS semiconductor nanocrystals and organic compounds were developed. The dynamics and mechanisms ...
    2017-05-27
  • Photoinduced relaxation processes in self-assembled nanostructures 

    Zenkevich, E. I.; von Borczyskowski, C. (2009)
    Here, we discuss self-assembled multicomponent organic/inorganic nanostructures. Self-assembled multiporphyrin triads were formed via non-covalent interactions of meso-phenyl bridged ZnOEP chemical dimer, (ZnOEP)₂Ph, with dipyridyl substituted tetrapyrrole extra-ligand. In tetrads, the dimer (ZnOEP)₂Ph is covalently linked via 5-mesoposition to additional electron acceptors ...
    2017-05-27
  • Dynamics of photoinduced electron transfer in multiporphyrin nanoassemblies 

    Kilin, D.; Zenkevich, E.; von Borczyskowski, C. (World Scientific Publishing Co., 2015)
    In self-assembled nanoscale porphyrin triads based on Zn-octaethylporphyrin chemical dimer (donor, D) and dipyridyl substituted porphyrin free base (acceptor, A), fluorescence quenching of D (down to 1.7-10 ps) and A (by ~1.3-1.6 times) subunits is strongly dependent on the solvent polarity (toluene-acetone mixtures) and temperature (77-350 K). The obtained experimental findings ...
    2017-05-27
  • Structural Dynamics and Relaxation Processes with Participation of Excited Singlet and Triplet States in Sterically Hindered Porphyrins and Their Chemical Dimers 

    Zenkevich, E. I. (2014)
    Paper presents an overview of mutual Belarussian-Russian collaboration in the field of sterically hindered porphyrins compared with the relevant literature data. Typically, the conformational dynamics of a non-planar tetrapyrrole macrocycle at 295 K manifests itself in bathochromic absorption and fluorescence shifts (∆ν ~ 1100 cm⁻¹), the increase of the Stokes shift (∆νₛ ~ 900 ...
    2017-05-27
  • Self-organization principles in the formation of multiporphyrin complexes and “semiconductor quantum dot-porphyrin” nanoassemblies 

    Zenkevich, E. I.; von Borczyskowski, C. (2014)
    In this paper, we review several aspects of molecular recognition (based on non-covalent binding interactions) occurring between meso-pyridyl substituted tetrapyrrole extra-ligands and chemical dimers of tetrapyrrolic macrocycles containing central Zn ions and spacers of various nature and flexibility. Experimental results obtained by us earlier are analyzed using a novel approach ...
    2017-05-27
  • Ligand dynamics and temperature effects upon formation of nanocomposites based on semiconductor CdSе/ZnS quantum dots and porphyrins 

    Zenkevich, E. I.; Blaudeck, T.; Kowerko, D.; Stupak, A. P.; Cichos, F.; von Borczyskowski, C. (2012)
    Dye molecules with pyridyl side substituents (porphyrins and heterocyclic perylene diimides) coordinatively attached to semiconductor CdSe/ZnS quantum dots (QDs) surface form quasi-stable “QD-Dye” nanocomposites of various geometry in the competition with capping molecules (tri-n-octyl phosphine oxide or long chain amines) exchange. This results in photoluminescence (PL) quenching ...
    2017-05-27
  • Resonant Raman Scattering of ZnS, ZnO, and ZnS/ZnO Core/shell quantum dots 

    Milekhin, A. G.; Yeryukov, N. A.; Sveshnikova, L. L.; Duda, T. A.; Himcinschi, C.; Zenkevich, E. I.; Zahn, D. R. T. (2012)
    Resonant Raman scattering by optical phonon modes as well as their overtones was investigated in ZnS and ZnO quantum dots grown by the Langmuir–Blodgett technique. The in situ formation of ZnS/ZnO core/shell quantum dots was monitored by Raman spectroscopy during laser illumination.
    2017-05-27

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