Synthesis, Characterization, Properties and DFT Calculations of 2-(Benzo[b]thiophen-2-yl)pyridine-based Iridium(III) Complexes with Different Ancillary Ligands.

A series of new cyclometalated btp-based iridium(III) complexes with three different ancillary ligands, Ir(btp)2(bozp) (3a), Ir(btp)2(btzp) (3b) and Ir(btp)2(izp) (3c) (btp = 2-(benzo[b]thiophen-2-yl)pyridine, bozp =2-(benzo[d]oxazol-2-yl)phenol, btzp =2-(benzo[d]thiazol-2-yl)phenol, izp = 2-(2 H-indazol-2-yl)phenol), have been synthesized and fully characterized. The crystal structure of 3b has been determined by single crystal X-ray diffraction analysis. A comparative study has been carried out for complexes 3a - 3c by UV-vis absorption spectroscopy, photoluminescence spectroscopy, cyclic voltammetry and DFT calculations. This observation illustrates that the substitution of N or S in ancillary ligand can lead to a marked bathochromic shift of absorption and emission wavelengths. The spectroscopic characterisation of these complexes has been complemented by DFT and TD-DFT calculations, supporting the assignment of (3)MLCT/(3)LC to the lowest energy excited state.

Synthesis, Crystal Structure, Photophysical Properties and Theoretical Study of a New Iridium(III) Complex Containing 2-phenylbenzothiazole Ligand.

A new bis-cyclometalated iridium(III) complex [Ir(dmabt)(2)(bipy)][PF(6)] (3) (dmabt = 4-(benzo[d]thiazol-2-yl)-N,N-dimethylaniline, bipy = 2,2'-bipyridine) has been synthesized and fully characterized. The complex 3 has been determined by X-ray structure analyses which shows that the central iridium(III) ion assumes distorted octahedral geometry. The photoluminescence spectrum exhibits orange emission maximum at 612 nm with quantum yield of 17% at 298 K. The frontier molecular orbital diagrams and the spin-allowed singlet-singlet electronic transitions of 3 have been calculated with density functional theory (DFT) and time-dependent DFT (TD-DFT), and the UV-Vis spectra are discussed based on the theoretical calculations.