Aggregation of 2-Aminobenzimidazole-A Combined Experimental and Theoretical Investigation

• Published in: Chemphyschem Vol. 12; no. 9; pp. 1747 - 1755
• Main Authors: Angelova, Silvia E., Spassova, Milena I., Deneva, Vera V., Rogojerov, Marin I., Antonov, Liudmil M.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 20.06.2011; WILEY‐VCH Verlag; Wiley
• Subjects: Benzimidazoles - chemistry; Chemistry; Dimerization; Exact sciences and technology; General and physical chemistry; hydrogen bonds; IR spectroscopy; Molecular Structure; Quantum Theory; Solution properties; Solutions; Solvents; Spectrum Analysis; theoretical calculations; Thermodynamics; UV/Vis spectroscopy; Five membered ring; Quantum chemistry; Nitrogen heterocycle; Theory; Theoretical study; Equilibrium; IR spectroscopy; UV/Vis spectroscopy; hydrogen bonds; Aggregation; Infrared spectrometry; theoretical calculations; Density functional; Bicyclic compound; Calculation; Aromatic compound; Dimerization; Hydrogen bond; Ultraviolet visible spectrometry
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201100002

An investigation of 2‐aminobenzimidazole was carried out by calculations at HF, MP2, and DFT levels of theory and also by UV and IR spectroscopy. The quantum chemical calculations predict a full shift of the equilibrium towards the amino form, but the absorption spectra in different solvents distinctly show a two‐component equilibrium system. Examination of possible equilibria in solution shows that an equilibrium between two dimeric forms of the amino tautomer of 2‐aminobenzimidazole explains the spectral observations. Dynamic equilibria: The tautomerism and the intermolecular interactions (hydrogen bonding) of 2‐aminobenzimidazole, leading to the formation of molecular aggregates has been studied. Theory and experiment complement each other in the recognition of the individual components of the studied samples in solution and conclusions about the hydrogen bonding and cooperative effects can be drawn (see picture).