Iridium(III)porphyrin arrays with tuneable photophysical properties

The photophysical properties of iridium(III) porphyrins complexes with two different axial ligands (Cl(CO) and bipyridine (bpy)) in solution and in cellulose acetate polymer matrix were investigated. The axial ligands substitution was made aiming to evaluate the photophysical properties and the solubility in different solvents. Therefore, dissimilar from the free porphyrin, non-polar solvents (as toluene) favours the quantum yield of iridium(III)porphyrins and ligands with a more extended π-conjugated compound as bpy results in higher yields. Moreover, despite all the porphyrins reveals a negative solvatochromism, the substitution of Cl(CO) ligand by bpy ligand exhibits similar solubility either on non-polar or polar solvents. The observed photoluminescence (PL) at room temperature appears at NIR region in contrast to the previously reported iridium(III) porphyrins. Comparing with free porphyrin H2TTP, the red/NIR PL spectra of the iridium(III)porphyrins (either in solution and in the polymer matrix) reveals remarkable changes. Particularly, a more significative decrease of the red/NIR intensity ratio was detected for [Ir(ttp)(bpy)2] 2 where the maxima of the NIR emission can be adjusted under suitable excitation wavelength. [Display omitted] •Study of photophysical properties of Ir(III) porphyrins complexes in solution and in cellulose acetate matrix.•Porphyrin with extended conjugated ligand, as 4,4-bipyridine, decrease red/NIR emission intensity ratio.•Ir(III) porphyrins immobilized in cellulose acetate revealed two main emitting broad bands at red/NIR wavelengths.•PL spectra of Ir(III)porphyrins can be tunable by suitable choice of solvent, ligand framework and excitation wavelength.