Intramolecular Photo-Physical Processes and Spectral-Luminescence Properties of a Dye Merocyanine 540 and its Complexes with Water

摘要

Merocyanine 540 (M540) is famous dye that used in electronics and medicine. An important feature of the dye is a significant intramolecular transfer of the electron density in the excited state. Experimentally was investigated the electronic absorption and fluorescence spectra in different solvents M540. Electronic structure, spectra and rate constants of photo-physical processes of an isolated molecule and its complexes with water molecules were calculated by INDO method with spectroscopic parameterization. Analysis of the results allowed establishing the effect of individual fragments and hydrogen bonds with water on the electronic charge transfer between the terminal units in the state S_1. Examination of photo-physical processes of decomposition of the fluorescent state was showed that the intramolecular processes of decay of the S_1 state are not the cause of the differences calculated and experimental fluorescence quantum yield. Consideration of trans-cis photo-isomerization leads to the elimination of this non-compliance.