Evidence of molecular complex formation between asphaltene and o-chloranil in aqueous micellar medium: A spectrophotometric study

The spectral (both absorption and steady-state fluorescence) studies of interaction of asphaltene with o-chloranil have been carried out in aqueous micellar media of cationic cetyl trimethyl ammonium bromide (CTAB), and neutral triton X-100 (TX-100). Spectroscopic results indicate formation of a complex between asphaltene and o-chloranil. The fluorescence band positions of the complexes are identical in both the medium. The absorption spectrum of the complex has been detected by difference spectral method. The position of maximum absorption of the complex in these micellar media have been compared and found in the order of SDS > CTAB > TX-100. The formation constant (K) has been determined using Benesi-Hildebrand equation utilizing absorption spectral data. Formation of ground state complex involving asphaltene and o-chloranil has also been observed from the study of quenching of asphaltene fluorescence by o-chloranil. The value of K, as obtained by Stern-Volmer plot, agrees well with that obtained by absorption spectrophotometric method.