The author of 《Absorptimetric and fluorimetric study of solvent dependence and prototropism of 2-substituted benzimidazole derivatives》 were Sinha, Hemant K.; Dogra, Sneh K.. And the article was published in Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry (1972-1999) in 1987. Quality Control of 5-Chloro-2-(trichloromethyl)-1H-benzo[d]imidazole The author mentioned the following in the article:
A study of the effects of solvents on the absorption and fluorescence spectra of 2-substituted benzimidazoles showed that the lowest-energy transition of the chloromethyl, dichloromethyl, and cyanomethyl derivatives is of π-π* character, and that of the 5-chloro-2-(trichloromethyl), 2-(trifluoromethyl), and 2-chloro derivatives is of charge-transfer character. In the case of the monocations and monoanions of these compounds, the lowest-energy transitions are of charge-transfer and π-π* nature, resp. The presence of the methylene group between the benzimidazole and the heteroatom substituent reduces direct interaction; this is apparent from the study of proton-transfer reaction as well as from the spectral changes. The pKa values for these reactions in the ground and excited states were determined and discussed. MeCN quenches the fluorescence of the mono-, di-, and trichloromethyl compounds The mechanism could involve charge-transfer complexation.5-Chloro-2-(trichloromethyl)-1H-benzo[d]imidazole(cas: 3584-66-5Quality Control of 5-Chloro-2-(trichloromethyl)-1H-benzo[d]imidazole) was used in this study.
5-Chloro-2-(trichloromethyl)-1H-benzo[d]imidazole(cas: 3584-66-5) belongs to imidazoles.Although other azole heterocycles are ubiquitous in a wide range of biologically active natural products, imidazole rings occur predominantly in the natural amino acid histidine. In addition, imidazole rings are part of unnatural cyclic peptides and are used as ester isosteres in peptidomimetic studies. Quality Control of 5-Chloro-2-(trichloromethyl)-1H-benzo[d]imidazole
Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem