DFT-D investigation of the interaction between Ir (III) based photosensitizers and small silver clusters Agn (n = 2–20, 92)

Abstract

A dispersion-corrected density functional theory study of the photosensitizer [Ir(ppy)2(bpy)]+ and its derivatives bound to silver clusters Agn (n=2–20,92) is performed. The goal is to provide a new system-specific set of C6 interaction parameters for Ag and Ir atoms. To this end a QM:QM scheme is employed using the PBE functional and RPA as well as MP2 calculations as reference. The obtained C6 coefficients were applied to determine dissociation curves of selected IrPS–Agn complexes and binding energies of derivatives containing oxygen and sulphur as heteroatoms in the ligands. Comparing different C6 parameters it is concluded that RPA-based dispersion correction produces binding energies close to standard D2 and D3 models, whereas MP2-derived parameters overestimate these energies.