The first observation of cis and trans isomers for bibenzo[d]imidazole-based compounds influenced by halogen substituent effects

A pair of bibenzo[d]imidazole-based cis–trans positional isomers have been obtained via the condensation between biphenyl-3,3′,4,4′-tetraamine and 3,5-dichloro-2-hydroxybenzaldehyde, and they can be isolated by the following spontaneous crystallization in N,N-dimethylformamide (DMF) and manual separation. Halogen substituent effects are believed to be responsible for the successful isolation of cis and trans isomers, which could be further supported by density function theory (DFT) calculations. To our knowledge, this is the first structural report on the cis–trans isomerism for this family of compounds.