INFLUENCE OF MOLECULAR STRUCTURE OF SQUARAINE DYES ON THEIR AGGREGATION IN AQUEOUS SOLUTIONS
The influence of a molecular structure of several squaraine dyes on their aggregation in aqueous solutions and its spectral manifestation were studied. The results obtained are analyzed using quantum-chemical modeling. It is shown that a transverse dipole moment in squaraine molecules contributes to the aggregation with the antiparallel orientation of molecules, whereas a longitudinal dipole moment leads to formation of the J-type aggregation with the longitudinal orientation of molecules. In some cases both aggregate types are present in the solution in a wide concentration range.