Abstract

The crystal structures of three benzimidazole esters containing aryl or heterocyclic substituents at position 2 are reported, and all three exhibit disorder of mol-ecular entities. In ethyl 1-methyl-2-[4-(prop-2-yn-oxy)phen-yl]-1H-benzimidazole-5-carboxyl-ate, C20H18N2O3, (I), the prop-2-yn-1-oxyphenyl unit is disordered over two sets of atomic sites having effectively equal occupancies, 0.506 (5) and 0.494 (5). The propyl substituent in ethyl 1-propyl-2-(pyren-1-yl)-1H-benzimidazole-5-carboxyl-ate, C29H24N2O2, (II), is disordered over two sets of atomic sites having occupancies 0.601 (8) and 0.399 (8), and the ester unit in ethyl 1-methyl-2-(5-chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)-1H-benzimidazole-5-carboxyl-ate, C21H19ClN4O2 (III), is disordered over two sets of atomic sites having occupancies 0.645 (7) and 0.355 (7). In each of the C-H⋯π(arene) hydrogen bonds in (I), the donor and acceptor form parts of different disorder components, so that no continuous aggregation is possible. The mol-ecules of (II) are linked by a single C-H⋯O hydrogen bond into C(10) chains, which are linked into sheets by a π-π stacking inter-action, whereas those of (III) are just linked into C(13) chains, again by a single C-H⋯O hydrogen bond. Comparisons are made with the structures of some related compounds.

Highlights

  • The use of compounds containing the benzo[d]imidazole unit as chemotherapeutic agents having antimicrobial, antiparasitic, antitumour and antiviral activity has been comprehensively reviewed (Boiani & Gonzalez, 2005)

  • 2-substituted benzo[d]imidazoles have recently been evaluated for their antimicrobial and antioxidant activity (Zhou et al, 2013; Bektaset al., 2020). With these considerations in mind, we have synthesized some new 2-substituted benzo[d]imidazoles and here we report the structures of two new benzimidazole esters, namely ethyl 1-methyl-2-[4-(prop-2-ynoxy)phenyl]-1H-benzimidazole-5-carboxylate (I) (Fig. 1) and ethyl 1-propyl-2-(pyren-1-yl)-1H-benzimidazole-5-carboxylate (II) (Fig. 2) carrying aromatic substituents at position 2 of the heterocyclic ring

  • In compound (I) (Fig. 1), thephenyl unit is disordered over two sets of atomic sites having essentially equal occupancies, 0.506 (5) and 0.494 (5), such that the two orientations of the phenyl ring make almost identical dihedral angles with the adjacent imidazole ring, 27.8 (4) and 27.0 (4) respectively, and with a dihedral angle of 54.7 (3) between the planes of the two disorder components

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Summary

Chemical context

The use of compounds containing the benzo[d]imidazole unit as chemotherapeutic agents having antimicrobial, antiparasitic, antitumour and antiviral activity has been comprehensively reviewed (Boiani & Gonzalez, 2005).

Structural commentary
Supramolecular features
Database survey
Synthesis and crystallization
Refinement
Full Text
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