Photophysical processes in bis-cyanines

By using of semi empirical method of intermediate neglect of differential overlap (INDO) with spectroscopic parameterization the energy and the nature of the electronic-excited states, oscillator strength are determined, polarization of transitions, the dipole moments are calculated, rate constants of photophysical processes and the quantum yield of fluorescence from the fluorescent state in monomer molecule of indocarbocyanine and its bis-derivatives are estimated. On the basis of cyanine monomer it is shown, how reorganization of geometry during a trans-cis-photoisomerization process influences on deactivation of S1-state energy. It is established that a decrease of a quantum yield of fluorescence in cyclic bis-cyanines occurs due to the decrease of a rate constant of radiating decay by two order and an increase of a rate constant of internal conversion. The most probable orientation of the connected monomers in angular dimers is offered