Recently synthesized pyrrolanthrone, naphtho[1,2,3-cd]indole-6(2H)-one (PyAn), and its water-soluble derivative, 3(naphtho[1,2,3-cd]indole-6(2H)-one-2-yl) sodium propylsulfonate, are very promising for anticancer therapy due to both the fluorescent and cytotoxic properties. The present study is focused on the spectroscopic analysis of solvent effects in PyAn and its derivative. An increase of the solvent polarity results in the bathochromic shift in emission and absorption spectra that indicates the involvement of ππ*-type transition. The double linear correlation of Stokes shift with bulk solvent polarity functions (in terms of Lippert’s, Bakhshiev’s and Chamma-Viallet’s models) and microscopic solvent polarity parameter ( ) 30 N ET for aprotic and protic solvents is observed. Both general and specific solvent effects are revealed for the solute-solvent systems. Fluorescence quantum yield, fluorescence lifetime and excited-state dipole moment were defined for PyAn and its derivative in different solvents for the first time. The obtained information is of a great importance for the characterization of intermolecular interactions of drugs with biomolecules for the development of new drug delivery systems.
Doping of polymer particles by a fluorophores results in the sensitization within the visible spectral region becoming very promising materials for sensor applications. Colloids of biocompatible chitosan-based polyelectrolyte complexes (PECs) doped with quantum dots (QD) of CdTe and CdSe/ZnS (with sizes of 2.0-2.4 nm) were synthesized and characterized by scanning electron microscopy, dynamic light scattering, ζ-potential measurements, absorption and luminescence (including time-resolved) spectroscopy. The influence of ionic strength (0.02-1.5 M) on absorption and photoluminescence properties of encapsulated into PEC and unencapsulated quantum dots was investigated. The stability of the emission intensity of the encapsulated quantum dots has been shown to be strongly dependent on concentration of quantum dots.
Modeling of kinetics of photoprocesses in polyatomic molecules based on four-level energy scheme is carried out. The
model includes the processes in dye under cw photoexcitation and takes into account a reverse intersystem crossing and
photochemical reaction from the upper triplet states. The analytical time-dependent relation for dye concentration of the
initial form was obtained taking into account the contrast of rates of various photoprocesses and using of quasistationary
approximation. It was shown that rate constant of photolysis correlates with probability of intersystem crossing of the
dyes. For the xanthene dyes in gelatin it was shown that simple experimental method of cw laser photolysis combined
with the kinetic model could be effective technique of study of upper excited states participation.