Synthesis and Photophysical Properties of Bis‐Cyclometallated Iridium(III)–Styryl Complexes and Their Saturated Analogues

Abstract

AbstractThis manuscript reports the synthesis and photophysical investigation of a series of IrIII complexes Ir(C∧N)2(O∧O) which are functionalized in the para position of the pyridine ring by styryl groups substituted with electron‐donor and ‐acceptor end groups. The saturated derivative Ir(C∧N‐ppy‐4‐CH2CH2C6H4OMe)2(O∧O‐acac) (4a‐H2) was formed from [Ir(C∧N‐ppy‐4‐CH=CHC6H4OMe)2]2(μ‐Cl)2 (3a) at 140 °C, whereas at 80 °C the parent unsaturated complexes Ir(C∧N‐ppy‐4‐CH=CHC6H4R)2(O∧O) [OO = acac, R = OMe (4a), NEt2 (4b), H (4c), NO2 (4d); OO = dpm, R = OMe (5a), NEt2 (5b)] were isolated. The saturated complex 4a‐H2 exhibits intense green emission with a 36 % quantum yield at 298 K. The styryl complexes 4a–4d, 5a and 5b are very weakly emissive at 298 K, but show intense red luminescence in alcohol glass at 77 K. The amino‐ and nitro‐substituted complexes 4b and 4d give low‐energy emission (λem = 651 and 647 nm, respectively). The emissive states of these complexes are believed to possess predominant triplet intra‐ligand charge‐transfer (3ILCT) and metal‐to‐ligand charge‐transfer (3MLCT) character, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)