Exploring the Versatility of Dithieno[2,3-b;3?,2?-e]-4-keto-1,4-dihydrophosphinines

Abstract

A less studied alteration of the dithienophosphole is the dithieno[2,3-b;3’,2’-e]-4-keto-1,4-dihydrophosphinine. Its relatively untouched chemistry and various sites for functionalization, makes it an appealing scaffold that can be tailored to the needs of various applications. Herein we report a range of targeted approaches to functionalizing each site of the dithienoketophosphinine with an emphasis on understanding the resulting properties. Based on the innate ability of phosphorus to be functionalized and alter the properties of entire molecular scaffolds, the first series of compounds focuses on phosphorus functionalization. The second series is derived from the synthetic versatility of carbonyl groups wherein Knoevenagel condensation was performed to create a series of dicyanomethylene-dithienophosphinines with enhanced acceptor character. Finally, a third series focusing on extending the conjugation of the dithienoketophosphinine by various aryl groups differing in their donor/acceptor behaviour and unlocking emission are presented. For each of the three series we report the optical, electrochemical, structural and synthetic details.