A facile color-tuning strategy for constructing a library of Ir(iii) complexes with fine-tuned phosphorescence from bluish green to red using a synergetic substituent effect of –OCH₃ and –CN at only the C-ring of C^N ligand

Abstract

–OCH3 and –CN will show a favorable synergetic substituent effect on the color-tuning direction when they are grafted at the meta- and para-sites of the C-ring of the C^N ligand.

Bis-Heteroleptic Cationic Iridium(III) Complexes Featuring Cyclometalating 2-Phenylbenzimidazole Ligands: A Combined Experimental and Theoretical Study

“…3 On an other hand, such distortions are encountered in other 2-phenylbenzimidazole based iridium cationic and neutral complexes, regardless of the presence of alkyl or aryl group on the nitrogen atom (namely methyl or phenyl groups). 43,45,53,57 For example, dihedral angles up to 14.4 ° and 11.3 °, for the N-methyl substituted 2-phenylbenzimidazole and bipyridine respectively, have been encountered. 53 The solid-state structure of complex IrL 2 2 displays interesting supramolecular architecture.…”

“…As was mentioned above, the majority of the reported cationic iridium­(III) complexes are derived directly from the introduction of substituents on the 2-phenylpyridine ligand. In comparison, a smaller number of iridium­(III) complexes based on the use of 2-phenylbenzimidazole as the cyclometalating ligand for neutral − and cationic − complexes have been described. From a purely synthetic point of view, this ligand presents many advantages as a scaffold for the cyclometalating ligand, as it gives several divergence points (Figure ).…”

“…The synthesis does not require the use of palladium-catalyzed cross-coupling reactions. , Fine tuning of the emission properties can be achieved by the introduction of electron-withdrawing/-donating groups in (ii) and (iii) and the bulkiness of the final complex can be monitored, notably by the substitution in (i). Yet, the investigations of this ligand have been limited to the modification of the phenyl group, ,,,− ,, the replacement of the benzimidazole by a π-extended imidazole ring, and a modification of the substitution of secondary amine with charge carrier units ,, or different alkyl chains or aryl groups, to name a few. ,, …”

“…However, it has been demonstrated for neutral iridium­(III) complexes with acetylacetonate as ancillary ligand that the introduction of electron-withdrawing/-donating groups over the phenyl moiety efficient tuning of the emission. For example, the introduction of OMe groups in a meta and para positions of the phenyl group shifted the emission wavelength of the complex to 555 nm (Φ = 0.29) and 507 nm (Φ = 0.91), respectively, in comparison with the unsubstituted complex (520 nm, Φ = 0.64) in deaerated CH 2 Cl 2 . Despite these promising results, deeper investigations have not been undertaken.…”

Study of a phosphorescent cationic iridium(iii) complex displaying a blue-shift in crystals

“…20 On another hand, cationic complexes featuring 2-phenylbenzimidazole cyclometallating ligands are less common. 29,36,[47][48][49][50][51] This ligand presents as advantages to give several divergence points (i) the benzimidazole ring (phbnz), (ii) phenyl ring and (iii) the substitution of the nitrogen atom in position 3 (Figure 3) and its synthesis does not require the use of palladium-catalyzed crosscoupling reactions. 52,53 The three positions could give access to a fine tuning of the emission properties and modification of the bulkiness of the final complex.…”