Theoretical insights into the effect of ligands on platinum(II) complexes with a bidentate bis(o-carborane) ligand structure

Carboranes feature a wealth of unique structures and properties in phosphorescent transition-metal complexes (PTMCs). Herein, we identify the influence between the electronic structure in carboranes and the main ligand based on the density functional theory (DFT) and time-dependent density functional theory (TD-DFT), which affects the phosphorescence properties of carborane-containing Pt compounds. Furthermore, the mechanism, including singlet–triplet splitting energies ΔE(Sn – T1), transition dipole moment for S0 – Sn transitions, the zero-field splitting (ZFS), the radiative decay rate constant (kr), the Huang–Rhys factor (S), and the spin–orbit coupling (SOC) matrix elements have been carefully investigated. The results presented here reveal the functional action 1,1′-bis(o-carborane) contributes to the emission process owing to the manipulation of main ligand dtb-bpy and complex 1a shows promising prospects for achieving highly efficient phosphorescence via engineering the conjugation of the main ligand dtb-bpy.