Gnap B. Luminescent spectroscopy of intermolecular interaction of cyanine dyes DiO, DiI and DiD in nanoporous matrices SiO2.

This thesis is devoted to studying influence of the SiO2 matrices pore nanovolume on luminescence properties of the cyanine dyes DiO, DiI and DiD embedded into matrices. It has been shown a significant increasing local dye concentration in the pores comparing with the dye solution concentration due to an effective dye adsorption to the nanoporous matrices from the selected solvent. It causes strong influence of an intermolecular interaction on the luminescence properties of the studied dyes. In particular it has been found that an inhomogeneous distribution of DiI and DiD dyes in the nanoporous SiO2 matrices with a fractal dimensionality leads to much effective nonradiative energy transfer of an electronic excitation comparing with that in other nanostructured systems (micelles and liposomes). In the case of interaction of the dyes of the same type it has been revealed an excimer formation that is non-typical for the cyanine dyes DiO, DiI and DiD. It has been shown that due to restricted geometry of the pore nanovolume the cyanine dyes under concentration increasing form ground state dimers in which dipole momenta of optical transitions of the molecules are perpendicular to each other. After excitation the dipole momentum of the one dimer molecules is changing its orientation and the excimer is forming.