Luminescent Pincer Platinum(II) Complexes with Emission Quantum Yields up to Almost Unity: Photophysics, Photoreductive CC Bond Formation, and Materials Applications

Luminescent pincer-type PtII complexes supported by C-deprotonated π-extended tridentate R[BOND]C^N^N[BOND]R′ ligands and pentafluorophenylacetylide ligands show emission quantum yields up to almost unity. Femtosecond time-resolved fluorescence measurements and time-dependent DFT calculations together reveal the dependence of excited-state structural distortions of [Pt(R[BOND]C^N^N[BOND]R′)(C[TRIPLE BOND]C-C6F5)] on the positional isomers of the tridentate ligand. Pt complexes [Pt(R-C^N^N[BOND]R′)(C[TRIPLE BOND]C-Ar)] are efficient photocatalysts for visible-light-induced reductive C[BOND]C bond formation. The [Pt(R-C^N^N[BOND]R′)(C[TRIPLE BOND]C-C6F5)] complexes perform strongly as phosphorescent dopants for green- and red-emitting organic light-emitting diodes (OLEDs) with external quantum efficiency values over 22.1 %. These complexes are also applied in two-photon cellular imaging when incorporated into mesoporous silica nanoparticles (MSNs)