Bimetallic Cyclometalated Iridium(III) Diastereomers with Non‐Innocent Bridging Ligands for High‐Efficiency Phosphorescent OLEDs

Abstract

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Synthesis, Diastereomer Separation, and Optoelectronic and Structural Properties of Dinuclear Cyclometalated Iridium(III) Complexes with Bridging Diarylhydrazide Ligands

“…These data are, therefore, directly comparable to previous computational studies on Ir(ppy) 3 and other diiridium complexes. 16,39 As a general trend in the optimized geometries, the central bridge CNNC dihedral angle is calculated to be planar (180º) for the meso (a) isomers, whereas it is twisted for the rac (b) isomers and displays greater variation between complexes (144-156º). This is ascribed to the greater steric restriction encountered in the meso isomers which forces the bridging units to adopt more planar conformations.…”

“…5 Å. 23,26,27,32,34,40,47 (It is noteworthy that with [Ir(ppy) 2 µ-Cl] 2 -type complexes where the Ir-Ir distances are <4 Å only the less sterically congested rac ΔΔ/ɅɅ diastereomers have been reported to date [15][16][17][18]39,[48][49][50][51][52][53][54][55] ). For 13-16 the diastereomers were separated by fractional crystallization, silica column chromatography, or a combination of the two techniques.…”

“…[44][45][46] In diiridium complexes, which incorporate conjugated bridging ligands, theoretical calculations often predict that a degree of frontier orbital character is localized on the bridging unit. 23,26,29,32,35,[37][38][39][40]42 In these cases a highly flexible bridge is expected to promote nonradiative processes and weaken emission. Consequently, the majority of the reported diiridium complexes that possess high solution state PLQYs incorporate rigid bridging units (such as compounds 4 and 6).…”

“…35 The aim of the present work is to explore the potential of diarylhydrazide bridging ligands, which we first introduced in an initial communication on complex 5. 39 An interesting design feature of these bridges is that they provide a short conjugative pathway between the two Ir centers. We now present a series of new diiridium complexes (13)(14)(15)(16) featuring different cyclometalated ligands.…”

Anion-specific aggregation induced phosphorescence emission (AIPE) in an ionic iridium complex in aqueous media

“…This is a rare example where the cis-and transconformations of a dinuclear metal complex have been separated. 18 (Fig. S21).…”