SPECTROSCOPIC CHARACTERIZATIONS OF NONAMPHIPHILIC 2,5-BIS (5-TERT-BUTYL-BENZOXAZOLYL)-THIOPHENE MOLECULES AT THE AIR–WATER INTERFACE AND IN LANGMUIR–BLODGETT FILMS

This paper reports the π–A isotherm and spectroscopic characterizations of mixed Langmuir and Langmuir–Blodgett films of a nonamphiphilic thiophene derivative, namely, 2,5-Bis (5-tert-butyl-benzoxazolyl)-thiophene (BBOT) molecules, mixed with polymethyl methacrylate (PMMA) and stearic acid (SA). The π–A isotherms and molefraction vs. area per molecule studies indicate some repulsive interaction between sample (BBOT) and matrix (PMMA or SA) molecules. At higher surface pressure in the SA mixed BBOT Langmuir monolayer, a phase transition occurs, which has been revealed by π–A isotherm studies. UV-vis absorption and fluorescence spectroscopic studies confirm this phase transition and closer association of BBOT molecules. Spectroscopic studies of LB films lifted at higher surface pressure clearly confirm the presence of dimmers and higher-order n-meric sites.