Pt^II Phosphors with Click-Derived 1,2,3-Triazole-Containing Tridentate Chelates

A series of PtII complexes featuring 1,2,3-triazole-derived N∧N∧N-, N∧C∧N- and C∧N∧C-coordinating ligands were studied both experimentally and computationally aiming at the design of new PtII phosphors. By virtue of click chemistry, the new complexes were readily functionalized, e.g., with bulky groups in order to suppress aggregation of the complexes. For a N∧C∧N-type cyclometalated PtII complex, the high energy of the π* orbitals of the 1,2,3-triazole units gave rise to deep-blue phosphorescence; the poor luminescence quantum yield was attributed to an inadequate energy separation between the emissive state and the d–d states. However, when the 1,2,3-triazole donor moiety acted as a spectator/ancillary ligand only, an intense green emission could be achieved (ΦPL = 0.57, τ = 4.6 μs).