Hitchhiker’s Guide to the Preparation of Novel Benzimidazoline-Based n-Type Dopants

1H-Benzimidazoline-based molecular n dopant precursors, such as 4-(2,3-dihydro-1,3-dimethyl-1H-benzimidazol-2-yl)-N,N-dimethylbenzenamine (N-DMBI-H), enable efficient doping of high-electron affinity (EA) organic semiconductors. Chemical modification of the molecular structure of such compounds proved to be a fundamental tool to tune their properties and doping efficiencies according to the desired application. Versatile and efficient synthetic strategies, giving access to the widest range of substitution motifs, are expected to improve access to known derivatives and enable the preparation of new and improved ones. The literature reports several synthetic approaches, but due to a lack of rationalization and a comprehensive analysis, the selection of that best suited for a specific target derivative still mostly relies on a trial and error approach. In this work, we compare the features of the two most popular synthetic strategies in the preparation of a wide variety of benzimidazoline dopants having diverse substitution patterns and electronic features. We thus propose guidelines for the selection of the best synthetic approach depending on the structure of the target dopant, known as well as original.