The synthesis and photophysics of tris-heteroleptic cyclometalated iridium complexes

Abstract

Herein we report the synthesis and photophysical study of tris-heteroleptic complexes of the general formula IrLL'(acac), where L and L' are two differently substituted 2-phenylpyridines (ppyH) and acacH is 2,4-pentanedione, using a combinatorial approach that could be employed for many ligand combinations. The tris-heteroleptic complexes and the analogous bis-heteroleptic complexes of the form IrL(2)(acac) have been studied by a combination of absorption and photoluminescence spectroscopies in conjunction with modelling by DFT and TD-DFT to elucidate the nature and location of the excited state in the novel species.

A comparative study of Ir(iii) complexes with pyrazino[2,3-f][1,10]phenanthroline and pyrazino[2,3-f][4,7]phenanthroline ligands in light-emitting electrochemical cells (LECs)

“…The assignment of these protons required65 COSY experiments, which clearly indicated correlation with coupled protons. Geometrical parameters such as bond lengths and angles around the Ir atom80 are also in a similar range reported for other analogous complexes 42,44,45. The corresponding structures are depicted inFigure 2and selected bond lengths and angles of the iridium coordination spheres are reported inTable 2.…”

The use of organolithium reagents for the synthesis of 4-aryl-2-phenylpyridines and their corresponding iridium(iii) complexes

“…Stirring was continued overnight before the reaction was quenched with a saturated NH 4 Cl (aq) solution. 4-Mesityl-1,2,3,6-tetrahydropyridine (8). The product was purified by column chromatography on silica, eluted by a solvent gradient of neat hexane to neat DCM, to give the title product as a colourless oil that solidified upon standing.…”

Heteroleptic iridium (III) complexes with three different ligands: Unusual triplet emitters for light-emitting electrochemical cells

“…More precisely, among them, only two trisheteroleptic cationic complexes with two different cyclometalated ligands are known (see Fig. 1), the eleven others being neutral complexes [41,42]. This new and as yet unknown class of cationic complexes still suffers from the low availability of synthetic procedures to access to these structures.…”

“…This inseparable mixture is then engaged in reaction with acetylacetone (acac) to furnish after reaction three different complexes (step 2). At this stage, the two homoleptic complexes Ir(C^N) 2 (acac) and Ir(C 0^N0 ) 2 (acac) must have a sufficient difference of polarity with the targeted heteroleptic complex Ir(C^N)(C 0^N0 )(acac) to be separable by simple chromatography on silica gel [42,44]. The second key point is the regeneration of the pure [Ir(C^N)(C 0^N0 )m-Cl] 2 dimer under acidic conditions (step 3).…”