Design and synthesis of phosphole-based pi systems for novel organic materials.

Phospholes are known to exhibit characteristic optical and electrochemical properties derived from the phosphorus-bridged 1,3-dienic pi system. Particular interest has recently been paid to their pi-conjugated derivatives, such as non-fused phospholes, dibenzo[b,d]phospholes, benzo[b]phospholes, benzo[c]phospholes and related compounds. This perspective focuses on recent advances in the synthesis of these phosphole-based pi systems with representative examples that would give valuable guidelines for designing phosphole-containing opto-electrochemical materials.