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Both petroleum and coal derived asphaltene finds important place on the present research areas of hydrocarbon based liquid and solid fuels. It has earned a name of ‘unwanted’ fame for its deleterious impacts arising mainly due to its self aggregational phenomenon. Over the period of time the asphaltene aggregation has been seriously investigated worldwide even at the molecular scale. Besides several methods, the spectroscopic findings (UV Vis and Fluorescence), in this regard, contribute to substantial meaningful data. The major spectroscopic researches on the aggregation of asphaltene over the last ten years have been reviewed in this present study. A brief discussion on the asphaltene molecular structure and molecular weight also comes as a prelude. Asphaltenes derived from both petroleum and coal have been considered. [ABSTRACT FROM AUTHOR]

Steady state fluorescence spectroscopic technique has been used to investigate the aggregation of coal derived asphaltene (CDA) sourced from Lodna Coke Plant situated at Dhanbad, India. The emission spectra of CDA provide information regarding the various stages of onset of aggregation in carbon tetrachloride medium. Almost similar results have also been inferred from the analysis of corresponding excitation spectra. It has been observed that the onset of aggregation of CDA occurs at concentration beyond a concentration of 10 mg L −1 . Studies indicate the formation of a trimer at this concentration range. The association constant ( K ) for the trimer formation has also been evaluated from the spectroscopic data. [ABSTRACT FROM AUTHOR]

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]

The structure of coal derived asphaltene (CDA) proposed by Mullins et al has been corroborated through theoretical and experimental examination by the virtue of its electron donor property. Here, o -chloranil has been used as an electron acceptor. Investigation of o -chloranil/CDA complex in gas phase has been performed by density functional theory (DFT) methods. The Charge transfer (CT) transition energy of the complex in gas phase was calculated by the time-dependent density function theory (TD-DFT) using the ground state optimized geometry at the respective levels of theory. For this, the three semi empirical methods AM1, PM3 and PM3MM were computed under the MPW1PW91, B3PW91, PBE1PBE, BPV86 and RCIS formalism. It is found that the two formalisms MPW1PW91 and PBEPBE under PM3 and PM3MM reproduced values close to the experimental one. However, all of them provide lower charge transfer (CT) transition energy values than that has been experimentally determined. Experimentally, FTIR spectra of the donor, acceptor and the complex further supported the understanding of complex formation and demonstrated close similarity with the theoretically determined CDA frequencies. These findings support the validity of the CDA structure to an extent. [ABSTRACT FROM AUTHOR]