Creation of cationic iridium(iii) complexes with aggregation-induced phosphorescent emission (AIPE) properties by increasing rotation groups on carbazole peripheries

Abstract

Three cationic iridium complexes containing 4,7-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)-1,10-phenanthroline (L(1)) and 4,7-bis(3',6'-di-tert-butyl-6-(3,6-di-tert-butyl-9H-carbazol-9-yl)-3,9'-bi(9H-carbazol)-9-yl)-1,10-phenanthroline (L(2)) as the ancillary ligands, namely, [Ir(ppy)(2)(L(1))]PF(6) (1), [Ir(ppy)(2)(L(2))]PF(6) (2) and [Ir(oxd)(2)(L(2))]PF(6) (3) (ppy is 2-phenylpyridine, oxd is 2,5-diphenyl-1,3,4-oxadiazole), have been designed and prepared. With more intramolecular rotational units on the ancillary ligand (L(2)), 2 and 3 possess a unique aggregation-induced phosphorescent emission (AIPE) property. This phenomenon was unprecedentedly observed in the cationic iridium(III) complexes. In order to investigate the underlying mechanism of this AIPE behavior, their photophysical, temperature-dependent aggregation properties as well as theoretical calculations, were performed. The results suggest that restricted intramolecular rotation is responsible for the AIPE of cationic complexes. Moreover, photoluminescent quantum yields in the neat film, thermal stabilities and off/on luminescence switching of 2 were investigated, revealing its potential application as a candidate for LECs and organic vapor sensing.

Synthesis, structure, and luminescence of the “octahedral” cluster Cu4I4(rac-IsMePCH2PMeIs)2 (Is=2,4,6-(i-Pr)3C6H2)

“…As observed for the related complexes in Table 3, 1 showed dual emission at 77 K from 3 CC (LE) and 3 XLCT (HE) excited states, and only LE emission at 293 K. The Cu-Cu distance in the solvate 1Á4CHCl 3 , whose structure should be a good model for the mixture of diastereomers studied, was longer than those seen before in related complexes, for which a correlation between Cu-Cu distances and luminescence had been reported. The sterically demanding P-isityl substituents in 1, which are expected to rigidify the structure of the complex, especially in the solid state, reducing the rate of nonradiative decay pathways [16], may be more generally useful in preparation of luminescent metal complexes.…”

Deep-red excimer emission from Ir doped organic light-emitting devices

“…4 In that case, some pendant groups of rigid scaffolds appended to the polymer to prevent strong interactions between the polymer backbones displayed bright excimer emission. 17,18 This phenomenon has been reported in neutral [19][20][21][22] as well as in cationic 23,24 Ir complexes. Similar examples of efficient intermolecular emission have been reported in cyano-substituted CPs 5 and heavy metal organometallic phosphor molecules.…”

Synthesis, structure and photophysical properties of cationic Ir(III) complexes with functionalized 1,10-phenanthroline ancillary ligands

“…The intermediates 4,7-dichloro-1,10-phenanthroline was prepared according to the literature procedure [23]. Then the nucleophilic aromatic substitution reactions were used to synthesize the ligands L1, L2, and L3 (Scheme 1).…”