Novel NIR-Phosphorescent Ir(III) Complexes: Synthesis, Characterization and Their Exploration as Lifetime-Based O Sensors in Living Cells.

A series of [Ir()()] NIR-emitting orthometalated complexes (-) has been prepared and structurally characterized using elemental analysis, mass-spectrometry, and NMR spectroscopy. The complexes display intense phosphorescence with vibrationally structured emission bands exhibiting the maxima in the range 713-722 nm. The DFT and TD DFT calculations showed that the photophysical characteristics of these complexes are largely determined by the properties of the metalating ligands, with their major contribution into formation of the lowest S and T excited states responsible for low energy absorption and emission, respectively.