Organization of amphiphiles, part XIV: Studies on the interaction of a novel organic molecule with surfactant in solution and at air–water interface

Abstract

The interaction between a novel organic molecule (3E, 5E)-bis(4-butyloxy)benzylidene-8-(4-butyloxy)phenyldicyclopentano[2,3-b:3,2-e]pyridine(BP4) independently with a cationic surfactant, cetyltrimethylammonium bromide (CTAB) as well as with a nonionic surfactant, Triton-X-100 (TX-100) has been investigated through a number of analytical techniques such as conductivity, spectral analyses (fluorescence, UV–visible absorbance) and area/molecule measurements (Langmuir–Blodgett film method) in solution and at air–water interface. Both CTAB and TX-100 aggregate at lower concentration in the presence of BP4 compared to the absence of later, indicating the generation of synergism in the solution mixture. The hydrocarbon chain of BP4 interacts with the cetyl chain of CTAB or 1,1,3,3-teramethyl butyl chain of TX-100 through hydrophobic interaction thereby enhancing the surface activity of the mixture. Subsequently, CMC decreases. On the contrary, CMC of BP4 increases upon addition of both CTAB and TX-100 due to the inefficiency of BP4 to interact aptly with the CTAB/TX-100 to form hydrophobic complex (U. Dash, P. K. Misra, JCIS, 357(2011)407-418). But both the surfactants and BP4 adsorb as monomer in the presence of each other and form a mixed monolayer at the air–water interface by associating through lateral interaction of their hydrocarbon chain. This leads to an increase of the cooperative effect as evidenced by the decrease in area per molecule at the air–water interface.