Synthesis, characterisation and theoretical studies of a series of Iridium (III) heteroleptic complexes with Schiff base ligands

A series of Iridium (III) complexes of general formula [Ir(ppy)2(L)]0/+ (ppy = 2-phenyl pyridine, L = Schiff base) were synthesised from the dichloro bridged dimeric starting material, [(ppy)2Ir(μ-Cl)2Ir(ppy)2]. Three Schiff bases used as ligand were obtained from condensation of 2-amino phenol with benzaldehyde (L1), salicylaldehyde with 2-aminopyridine (L2) and pyridine 2-aldehyde with 2-aminopyridine (L3). All the complexes were characterised by IR, 1H NMR, electronic absorption spectroscopy and cyclic voltammetry studies. Molecular structure of two of these complexes were determined by single crystal X-ray structure analysis. Complexes displayed several weak absorptions in visible region in the range of 401–499 nm. TDDFT calculations on complexes revealed the ligand orbital dominance in both HOMO and LUMO orbitals and subsequent ligand centred transitions were observed in absorption spectra. New Iridium(III) heteroleptic complexes were prepared from three different Schiff base ligands. Each complex consists of two phenyl pyridines and a Schiff base. They were characterised through single crystal structure determination, different spectroscopic methods and DFT calculations. [Display omitted] •Novel Ir(III) complexes were prepared from Schiff base ligands with phenyl pyridine backbone.•All three complexes were characterised through different spectroscopic methods and two of them were structurally characterised through single crystal X-ray structure determination.•Theoretical calculations were carried out to make better understanding of the observed properties of the new complexes.