Diphenylpolyene-cholesterol conjugates as fluorescent probes for microheterogeneous media

Extrinsically conjugated fluorescent diphenylpolyene cholesterol derivatives are synthesized and spectroscopic investigations in homogeneous and aqueous micellar solutions are described. The emission of these cholesterol conjugates reveals characteristic intra-molecular charge transfer (ICT) behaviour in homogeneous solvents with a mono-exponential decay. Spectroscopic evidence in micellar aqueous solutions reveals a bi-exponential decay. This indicates the presence of two preferred locations of the cholesterol conjugated diphenylpolyenes sites of lower polarity and interfacial sites. The sensitivity of these fluorophores was utilized to determine the critical micelle concentrations.