Abstract
PS, I love you! Novel mixed phosphole/thiophene π‐conjugated systems were synthesized and their electronic properties have been studied both experimentally by UV/Vis spectroscopy and electrochemistry and by theoretical calculations. Exploiting the chemistry of both P‐ and S‐heteroles allows the generation of a diverse range of novel ring‐fused benzophosphole–thiophene derivatives. magnified image
Two series of phospholes and 1,1′‐biphospholes bearing either 2‐ or 3‐thienyl substituents at the C atoms are prepared by using the Fagan–Nugent route. Their optical (UV/Vis absorption, fluorescence spectra) and electrochemical properties are systematically evaluated. Of particular interest, the first ever reported 3‐thienyl‐substituted phospholes exhibit higher LUMO levels than their 2‐thienyl analogues, and show accordingly different physical properties. This study also reveals that the 1,1′‐biphospholes exhibit σ–π conjugation. The phosphole and 1,1′‐biphosphole derivatives bearing 3‐thienyl substituents are characterized by X‐ray diffraction study. The structure–property relationship established following the experimental data are fully supported by theoretical studies including time‐dependent(TD)‐DFT spectra. A photocyclization reaction performed on the thioxo‐ and oxophospholes having 3‐thienyl substituents affords a novel ring‐fused phosphole–thiophene derivative, which was characterized by an X‐ray diffraction study. The structure and electronic properties of this novel dithienophosphole are discussed based on experimental and theoretical data.