Organoiridium Quinolinolate Complexes: Synthesis, Structures, Thermal Stabilities and Photophysical Properties

Abstract

The syntheses, solid-state structures, thermal properties and photophysics of a series of heteroleptic iridium(III) complexes with phenylpyridine as the cyclometalating ligands and quinolinolates are reported. The title compounds were formed by reaction of di-µ-chloro-tetrakis[κ 2 (C 2 ,N)-2-phenylpyridine]-diiridium(III) with the corresponding 8-hydroxyquinolines in 56 to 86 % yield. The crystal structures of two of the complexes have been determined. Both complexes show the two carbon ligands in a cis disposition and the 2-phenylpyridine nitrogen atoms in a trans disposition. Assessment of the thermal stabilities of the compounds revealed huge differences

Detailed Molecular and Structural Analysis of Dual Emitter IrQ(ppy)2 Complex

“…These results are similar to the literature for mononuclear iridium(III) complexes displaying the IrN 4 C 2 coordination [44]. Kappaun et al described a similar compound, ppy 2 Irq, together with other quinolinolate complexes, but from the NMR measurements, the authors concluded a cis disposition for the two carbon ligands and the trans position for the 2-phenylpyridine nitrogen atoms [46]. Their organometallic molecule was not found to be luminescent, even in degassed solvents, the explanation being connected with an unfavorable mixing of singlet and triplet excited states for this compound.…”

Phosphorescent Organic Light-Emitting Devices: Working Principle and Iridium Based Emitter Materials

“…In contrast to the difficulties with the preparation of tris -cyclometalated iridium complexes, an alternative synthesis approach is based on incorporating ancillary ligands such as acetylacetonates (cf. Figure 4 ), picolinates, triazolates, tetrazolates or quinolinolates [ 65 – 67 ]. Although the preparation of heteroleptic iridium(III) compounds starts, again, from the corresponding μ-chloro bridged precursor materials, the subsequent bridge-splitting step is clearly facilitated giving the products in better or even quantitative yields.…”

“…In this context, the energies of the lowest excited states play a major role as they can be tuned by adjusting the metal and ligand orbitals through substituent effects or via changing the ligand structures (some frequently used cyclometalating and ancillary ligands are shown in Figure 6 ). In other words, chemical modifications and/or complete alterations of the cyclometalating and/or ancillary ligands pave the way to very efficient emission color tuning but also provide the possibility of tuning the corresponding absorption characteristics towards particular needs [ 66 , 67 ].…”

Absorption, phosphorescence and Raman spectra of IrQ(ppy)2 organometallic compound

“…For the Ir atom, the LANL2DZ basis set was used. To reduce the calculation time, an effective core potential (ECP) was added to maintain (5d) 6 valence electrons of the Ir 3þ ion. .…”