C. Hay et al., 2,5-Di(2-pyridyl)phospholes: model compounds for the engineering of pi-conjugated donor-acceptor co-oligomers with a chemically tunable HOMO-LUMO gap, CHEM COMMUN, (4), 1999, pp. 345-346
2,5-Di(2-pyridyl)phospholes possess an extended pi-conjugated system with a
charge transfer structure; high yielding chemical modifications involving
the phosphorus atom allow fine tuning of the HOMO-LUMO gap.