The structural effects of ligands on the emission properties of Pt(ii) complexes and promising applications of luminescent Pt(ii) complexes in various areas are discussed.

Significance: Metallophilicity is widely regarded as a driving force in the self-assembly of closed-shell d⁸and d¹⁰metal complexes. The self-assembled metal complexes have applications in organic semiconductors, biosensing, organic light-emitting diodes, and photocatalysis. The attractive metallophilicity in the ground state is believed to originate from spd orbital hybridization or electron correlation interaction strengthened by relativistic effect. These two models have remained controversial for a long time. Our findings conclude that the M–M′ closed-shell interaction is repulsive due to strong M–M′ Pauli repulsion strengthened by (n + 1)s-nd orbital hybridization and relativistic effect. The M–M′ repulsion is counterbalanced by the ligand–ligand dispersion and electrostatic interaction, leading to a close unsupported M–M′ distance.