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Coal-derived asphaltene (CDA) has been shown to form electron donor–acceptor-type molecular complexes with electron acceptor such as 2,5-cyclohexadiene-1,4-diylidene also known as tetracyanoquinodimethane (TCNQ) in homogeneous medium of carbon tetrachloride and heterogeneous medium of aqueous SDS. This has been investigated both by UV-Vis and fluorescence spectrophotometric method. The Charge transfer (CT) absorption peaks have been detected by difference spectral method and the wavelengths of the CT peaks are close in both the medium. The formation constants (K) have been determined using the Benesi–Hildebrand equation. The magnitudes ofKare in the order of 103 L mol−1that are comparable to some supramolecular or inclusion complexes. The study reveals the presence of π-donor (i.e., aromatic) type of compounds in CDA molecule. It also supports the view that CDA molecules exist in solution forming micellar aggregate, in the cavities of which the TCNQ molecules are included. The remarkable increase (three fold) in the formation constant in the SDS medium compared to CCl4further indicates that the CDA aggregate in SDS undergoes some preorganization to further facilitate inclusion. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Coal derived asphaltene (CDA) forms molecular complex with [60]-, [70]fullerene in CCl4 medium. [•] The order of complexation for CDA:[60]fullerene is 2:1 and for CDA:[70]fullerene is 3:1. [•] Respective charge transfer absorption peaks have been detected by difference spectral method. [•] The values of Δ calculated indicate that the complexation process in both the cases is predominantly entropy-driven. [ABSTRACT FROM AUTHOR]

Highlights: [•] Coal derived asphaltene studied in aqueous micellar media of CTAB and TX-100. [•] Asphaltene forms 1:1 complex with o-chloranil. [•] The formation constant determined by fluorescence and absorbance are in good agreement. [•] The wavelength of maximum absorption of the complexes are in the order of SDS>CTAB>TX-100. [Copyright &y& Elsevier]