Formation of complex Langmuir and Langmuir–Blodgett films of water soluble rosebengal

Abstract

This communication reports the formation of complex Langmuir monolayer at the air–water interface by charge transfer types of interaction with the water soluble N-cetyl N , N , N -trimethyl ammonium bromide (CTAB) molecules doped with rosebengal (RB), with the stearic acid (SA) molecules of a preformed SA Langmuir monolayer. The reaction kinetics of the formation of RB-CTAB-SA complex monolayer was monitored by observing the increase in surface pressure with time while the barrier was kept fixed. Completion of interaction kinetics was confirmed by FTIR study. This complex Langmuir films at the air–water interface was transferred onto solid substrates at a desired surface pressure to form multilayered Langmuir–Blodgett films. Spectroscopic characterizations reveal some molecular level interactions as well as formation of microcrystalline aggregates depending upon the molar ratios of CTAB and RB within the complex LB films. Presence of two types of species in the complex LB films was confirmed by fluorescence spectroscopy.