Structure and Spectros copic Property of Bis(1-(3',5'-difluorophenyl)isoquinolinato-C2,N)(1-methylimidazole-2-carboxylato-N3O)Ir(III) Hydrate

Abstract

The luminescent cyclometalated Ir(III) complexes have received great interest in the development of organic light emitting diodes. Many bisand tris-cyclometalated complexes of Ir(III) with relatively high quantum efficiency have been synthesized and characterized. The color of phosphorescent complexes used in light emitting devices are tuned by the variation of both cyclometalating and ancillary ligands. The purpose of the present study is the molecular design of a highly efficient phenylisoquinoline-based redphosphorescent complex suitable for red organic light emitting diodes devices. Herein, we report the synthesis, electroluminescent properties and crystal structure of the phenylisoquinoline-based iridium complex, bis(1-(3',5'difluorophenyl)isoquinolinato-C,N)(1-methylimidazole-2carboxylato-N,O)Ir(III). The title compound is a hydrated, neutral mononuclear complex. Bond lengths and angles for the coordination of Ir are summarized in Table 1. The Ir atom has a distorted octahedral geometry involving two difluorophenylisoquinoline ligands and a 1-methylimidazole-2-carboxylate ligand with trans-N1-N2 disposition. The Ir-N1(2.025(6) A) and IrN2(2.055(6) A) bond lengths are shorter than the Ir-N3 bond length of 2.121(6) A. Similar observations were made concerning bond lengths in mer-bis[2-(6-fluoro-3-methylquinoxalin-2-yl-κN)-phenyl] [3-phenyl-5-(2-pyridyl-κN)1,2,4-triazol-1-yl]-iridium. The three trans angles are in the range of 170.4(2)-177.6(3)°. The three five-membered, chelating rings are nearly planar and orthogonal to each other; the r.m.s. deviations are 0.040, 0.075 and 0.025 A for the rings involving Ir/N1/C15(ring A), Ir/N2/C30(B) and Ir/ N3/O1(C), respectively, and the angles between rings are 86.5(2)(A/B), 78.7(2)(B/C) and 89.0(2)°(C/A), respectively. Within difluorophenylisoquinoline ligands, the difluorophenyl rings are inclined with respect to the isoquinoline ring systems, based on N1 and N2, by 14.5(2) and 30.3(2)°, respectively. The crystal structure is stabilized by strong aromatic π-π stacking associations formed between adjacent isoquinoline[N2, C16-C24] rings from two centrosymmetric related molecules. The short C...C contact includes C21...C21 (−x, −y, −z+1) = 3.315(12) and C17...C27 (−x−1, −y, −z+1) = 3.470(14) A. Furthermore, there are cyclic, eight-membered, hydrogen-bonded rings involving two water molecules. The oxygen atom of the water molecule donates two hydrogen bonds of O2...H-O3w-H...O2 (−x, −y−1, −z+1). Two