Synthesis and characterization of heteroleptic iridium(III) complexes incorporating 5-arylazo-8-hydroxyquinoline as coligands : DFT/TDDFT studies on the electronic structures and spectral properties

Inorganic Chemistry Section, Department of Chemistry, Jadavpur University, Kolkata-700 032, India

E-mail : kajalrajak@rediffmail.com, kkrajak@chemistry.jdvu.ac.in, maity.amit345@gmail.com

Manuscript received 30 August 2017, revised 16 September 2017, accepted 18 September 2017

The orange coloured complexes of general formula [Ir(2-pypy)₂ (hq)] have been prepared in exceptional yield by reaction of [Ir(2-pypy)₂ (Cl)]₂ with Hhq under argon atmosphere in 1 : 1 mixture of ethanol and dichloromethane in alkaline condition. Here hq– is deprotonated form of 5-phenylazo-8-hydroxyquinoline (Hhq¹ ), 5-(2-naphthylazo)-8-hydroxyquinoline (Hhq² ) and 5-(2-fluorineazo)-8-hydroxyquinoline (Hhq3 ). The elemental analysis, ESI mass spectroscopic measurements, IR spectroscopy and 1H NMR spectroscopy guarantee the formation of desired complexes. The ground and excited-state geometries, absorption, and phosphorescence properties of three Ir^III complexes were investigated by DFT and TDDFT methods. The natural transition orbital (NTO) and spin density analysis reveals the nature of excitations. The lowest lying triplet excited is connected with the ³IL and ³ML excited state is consistent with the emission like transition.