Neutral 2-phenylbenzimidazole-based iridium(III) complexes with picolinate ancillary ligand: tuning the emission properties by manipulating the substituent on the benzimidazole ring.

We report the synthesis and characterization of ten neutral bisheteroleptic iridium(III) complexes with 2-phenylbenzimidazole cyclometallating ligand and picolinate as ancillary ligand. The 2-phenylbenzimidazole has been modified by selected substituents introduced on the cyclometallating ring and/or on the benzimidazole moiety. The integrity of the complexes has been assessed by NMR spectroscopy, by high-resolution mass spectrometry and by elemental analysis. The complexes are demonstrated to be highly phosphorescent at room temperature and a luminescence study with comprehensive ab initio calculations allow us to determine the lowest emitting excited state which depends on the substituent nature and its position on the cyclometallating ligand.

Luminescence Properties of Al2O3:Ti in the Blue and Red Regions: A Combined Theoretical and Experimental Study.

Using jointly experimental results and first-principles calculations, we unambiguously assign the underlying mechanisms behind two commonly observed luminescence bands for the Al2O3 material. Indeed, we show that the red band is associated with a Ti3+ d-d transition as expected, while the blue band is the combination of the Ti3+ + O- → Ti4+ + O2- and VO•+e- → VO× de-excitation processes. Thanks to our recent developments, which take into account the vibrational contributions to the electronic transitions in solids, we were able to simulate the luminescence spectra for the different signatures. The excellent agreement with the experiment demonstrates that it should be possible to predict the color of the material with a CIE chromaticity diagram. We also anticipated the luminescence signature of Al2O3:Ti,Ca and Al2O3:Ti,Be that were confirmed by experiment.

Modeling Luminescence Spectrum of BaZrO3:Ti Including Vibronic Coupling from First Principles Calculations.

Herein, we present a methodology based on constrained density functional theory and vibrational mode computations to simulate and interpret the luminescence spectra of periodic solids. A multi-dimension harmonic model is used to combine electronic and vibrational contributions into an overall vibrationally resolved emission spectrum. We applied it to Ti-doped BaZrO3 to accurately reproduce its blue luminescence and unambiguously assign the observed luminescence to a Ti3+ + O- → Ti4+ + O2- charge transfer.