Cyclometallated iridium(iii) complexes with substituted 1,10-phenanthrolines: a new class of highly active organometallic second order NLO-phores with excellent transparency with respect to second harmonic emission

Abstract

[Ir(ppy)₂(5-R-1,10-phen)][PF₆] (ppy = cyclometallated 2-phenylpyridine, phen = phenanthroline, R = H, Me, NMe₂, NO₂) and [Ir(ppy)₂(4-R′,7-R′-1,10-phen)][PF₆] (R′ = Me, Ph) complexes are characterized by one of the highest second order NLO response (measured by the EFISH technique) reported for a metal complex, mainly due (as suggested by a theoretical SOS-TDDFT investigation) to MLCT processes from the ppy–Ir based moiety acting as donor push system to π* orbitals of phen, acting as an acceptor pull system; the good transparency to the second harmonic emission renders these NLO-phores appealing as building blocks for molecular materials with second harmonic generation.