Influence of the haloaryl moiety over the molecular packing in N-phenacylbenzimidazoles crystallizing in the same space group

•Three N-phenacylbenzimidazoles obtained under Ultrasound were crystallized/analyzed.•Products crystallize in the monoclinic P21/c space group with different packing.•The 4-FPh derivative crystallizes as a cocrystal with a 4-fluorobenzoic acid molecule.•The N-phenacylbenzimidazoles analyzed are potential antifungal agents. In this study, a family of N-phenacylbenzimidazoles 1–3 synthesized in high yields (90–93%) by the N-phenacylation reaction of NH-benzimidazole (4) under ultrasonic conditions was recrystallized from the mixture EtOH:AcOEt (1:1 V/V). These compounds crystallize in the same Monoclinic P21/c space group, though the molecular packing is affected by the haloaryl group varying the final crystal structure. The para substitution of the halogen atom in the aryl ring influences a more pronounced electronic deficiency over the methylene bridge allowing the formation of intermolecular C‒H‧‧‧O hydrogen bonds in compounds 1 and 3. Additionally, in compound 2, the ortho substitution of an F atom, not only affects the electron density but also blocks this CH2 group with an intramolecular C‒H‧‧‧O hydrogen bond. Remarkably after the crystallization process, compound 3 crystallizes as a cocrystal with a 4-fluorobenzoic acid molecule obtained by hydrolysis of 3. This co-crystallization affects dramatically the total packing energies from values of -138.7/-135.2 kJ/mol for 1 and 2, respectively, to -229.7 kJ/mol for compound 3. [Display omitted]