Synthesis and photophysical properties of luminescent platinum(II) complexes with terdentate polypyridine ligands: [Pt(bpqb)X] and [Pt(tbbpqpy)X](PF6) (bpqb-H = 1,3-bis(4′-phenyl-2′-quinolinyl) benzene; tbbpqpy = 4-tert-butyl-1,3-bis(4′-phenyl-2′-quinolin

A series of square planar platinum(II) complexes, [Pt(bpqb)X] (Xdouble bond; length as m-dashCl (1), Ctriple bond; length of mdashCC6H5 (2), Ctriple bond; length of mdashCC6H4NMe2-4 (3), Ctriple bond; length of mdashCC6H4NO2-4 (4)), [Pt(tbbpqpy)X](PF6) (Xdouble bond; length as m-dashCl (5), Ctriple bond; length of mdashCC6H5 (6), Ctriple bond; length of mdashCC6H4NMe2-4 (7), Ctriple bond; length of mdashCC6H4NO2-4 (8)), bearing terdentate polypyridine ligands have been prepared. Their electronic absorption spectra and emission characteristics at room temperature have been investigated. These complexes display room temperature photoluminescence. The emission energies are sensitive to the nature of the acetylide ligands with different substituents on the phenyl ring. An emission origin of a dπ(Pt) → π∗(bpqb or tbbpqpy) 3MLCT excited state, with some mixing of a π(Ctriple bond; length of mdashCR) → π∗(bpqb or tbbpqpy)3LLCT state, is assigned. All the complexes display two quasi-reversible reduction couples and one irreversible oxidation wave in the cyclic voltammograms. The reactivity of [Pt(bpqb)Cl] with π-acceptor ligands and the X-ray crystal structures of tbbpqpy, 1, and [Pt(bpqb)(PEt3)2Cl] (9) are also described.