Spectroscopic study of non-amphiphilic 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-l,3,4-oxadiazole aggregates at air–water interface and in Langmuir–Blodgett films

This Letter reports the spectroscopic characteristics of a non-amphiphilic 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (buPBD) molecule, in Langmuir and Langmuir–Blodgett (LB) films mixed with polymethyl methacrylate (PMMA) as well as with arachidic acid (AA). The π–A isotherms of buPBD mixed with PMMA/AA at different molefractions show that at very low surface pressure, a phase transition corresponding to a reorientation of the buPBD molecules occur, whereas at high surface pressure, buPBD molecules form aggregates among the hydrophobic tail part of PMMA/AA. Absorption and fluorescence spectroscopic study of the mixed LB films reveal formation of different types of aggregates.