Variable Photophysical Properties of Phosphorescent Iridium(III) Complexes Triggered by closo‐ and nido‐Carborane Substitution

Abstract

Scheme 1. The structures of closo-carborane-functionalized facial and meridional iridium(III) complexes.

Intramolecular charge transfer induced emission from triphenylamine-o-carborane dyads

“…[18][19][20][21][22][23][24][25][26] We have recently explored a series of ICT-emissive organic materials and carborane-based phosphorescent iridium(III) complexes that have been successfully applied in optoelectronic devices and cellular bioimaging. [27][28][29][30] Since 2001, various working mechanisms based on AIEactive materials have been proposed, including conformational planarization, 31 J-aggregate formation, 32 E/Z isomerization, 33 and excited state intramolecular proton transfer (ESIPT), [34][35][36][37] restriction of intramolecular rotations (RIR), 31 restriction of intramolecular vibrations (RIV) 32 and restriction of intramolecular motions (RIM). 34 For o-Cab-based materials, when the aromatic plane is perpendicular to the C1-C2 bond in oCab, the donor-acceptor interactions can be signicantly enhanced.…”

Boron‐Functionalized Phosphorescent Iridium(III) Complexes

“…[36] All of their meridional Ir III complexes were practically non-emissive, but their facial complexes with m-and p-Cbs displayed strong phosphorescent emission with quantum yields similar to that of fac-Ir(ppy) 3 (Table 3). However, the emission properties of o-Cb-substituted fac complex 26a exhibited a high dependence on the medium.…”

“…In particular, the devices based on 29c exhibited the highest performance, with maximum efficiencies of 29.6 cd A , and 4.7 % EQE for those containing facIr(ppy) 3 . The high photoluminescence (PL) quantum yields of the host films doped with 29c at high dopant concentrations - [36] 26b 507…”

“…[a] -0.48 [a,d] 0.44 [a] - [36] 29a 493 [a] 487 [a] 0.95 [a,b] 1.11 [a] OLEDs [37] 29b 488 [a] 479 [a] 0.98 [a,b] 1.13 [a] OLEDs [37] 29c 487 [a] 481 [a] 0.78 [a,b] 0.87 [a] OLEDs [37] 30a 524…”

Luminescent metal complexes featuring photophysically innocent boron cluster ligands

“…From DFT calculations and analysis of the emission spectra, these authors determined the C-bound o -carboranyl unit remains uninvolved in electronic transitions and that phosphorescent emission results from MLCT of the Ir(III)-based HOMO to the arylpyridine-based LUMO. Furthermore, several groups have functionalized biaryl ligands with C-connected carboranyl moieties ( ortho, meta, para , and nido ) to tune luminescent properties 8 (see SI for molecular structures). To the best of our knowledge, attempts to design a tunable, exclusively carborane-based ligand scaffold for phosphorescent emitter molecules have not been explored thus far.…”