4 '-Functionalized 2,2 ':6 ',2 ''-terpyridines as the (NN)-N-boolean AND domain in [Ir((CN)-N-boolean AND)2((NN)-N-boolean AND)][PF6] complexes

摘要

The cyclometallated iridium(III) complexes [Ir(ppy)(2)(N N)][PF6] (Hppy = 2-phenylpyridine) with N<^>N = 4'-chloro-2,2':6',2 ''-terpyridine (1), 4'-methoxy-2,2':6',2 ''-terpyridine (2), 4'-ethoxy-2,2':6',2 ''-terpyridine (3), 4'-methylthio-2,2':6',2 ''-terpyridine (4), 4'-phenylthio-2,2':6',2 ''-terpyridine (5) and 4'-dimethylamino-2,2':6',2 ''-terpyridine (6) are reported including the single crystal structures of 2{[Ir(ppy)(2)(1)][PF6]}.0.6Et(2)O.CH2Cl2, [Ir(ppy)(2)(5)][PF6].0.5CH(2)Cl(2) and [Ir(ppy)(2)(6)][PF6]. The single crystal structure of [Ir(ppy)2(3)]Cl.2H(2)O.MeCN is also reported. In each complex, the 2,2':6',2 ''-terpyridine (tpy) ligand binds to the metal centre in a bidentate fashion with the non-coordinated pyridine ring folded into the coordination sphere and engaging in a pyridine-phenyl p-stacking interaction. Solution NMR spectra are consistent with hindered rotation of the non-coordinated pyridine ring at 298 K, with intra-cation CH...N(pyridine)hydrogen bond formation between adjacent [ppy](-) and tpy ligands. Trends in the electrochemical HOMO-LUMO gaps and emission maxima of the complexes (in CH2Cl2 solution) are consistent with the electron-withdrawing or releasing properties of the 4'-tpy substituent; in degassed solution, [Ir(ppy)(2)(6)][PF6] has a quantum yield of 24.8% and emission lifetime of 441 ns, while the other complexes exhibit significantly lower quantum yields and shorter lifetimes. (C) 2015 Elsevier B.V. All rights reserved.