Synthesis, Structure, and Optical Properties of Cyclometalated Iridium(iii) Complexes With 1,2-Diphenylbenzimidazole and N-Substituted Perimidines

Two novel bis-cyclometalated iridium(III) complexes with 1,2-diphenylbenzimidazole (pbi) and ancillary 1-methyl-2-(pyridin-2-yl)-1-perimidine (L, complex 1) and ethyl 2-(2-(pyridin-2-yl)-1-perimidin-1-yl)acetate (L, complex 2) were synthesized and characterized by set of physicochemical methods. Comparison of the results of crystal packing analysis and electronic absorption spectroscopy demonstrates that while exclusion of the rigid perimidine system from conjugation does not allow red-shifting of absorption maxima, both complexes exhibit broad absorption up to 600 nm (ε = 27 000 − 800 M cm), comparable to iridium analogs. The results of the study clarify the influence of steric factors on the absorption properties of the complexes and will be used for further development of strongly light-absorbing materials.