Study of the preferential solvation effects in binary solvent mixtures with the use of intensely solvatochromic azobenzene involving [2]rotaxane solutes

Abstract

In this work we utilize the marked solvatochromism of two cyclodextrin (CD) containing [2]rotaxanes and their CD-free linear precursor in order to investigate preferential solvation (PS) effects in water/ethylene glycol mixtures. Two well-known models of PS are employed in order to quantify the PS and rationalize local solute-solvent and solvent-solvent effects. Structural effects among the solvatochromic probes are furthermore examined in terms of the involvement or not of a CD macrocycle and also in terms of the size of CD involved, between the two [2]rotaxanes.