Near-infrared emission from binuclear platinum (II) complexes containing pyrenylpyridine and pyridylthiolate units: Synthesis, photo-physical and electroluminescent properties

Two novel binuclear platinum (II) complexes of (Rpypy) 2 Pt 2 (pyt) 2 were synthesized and characterized, in which Rpypy represents 2-(1-pyrenyl) pyridine (pypy) and 2-(7- tert -butyl-1-pyrenyl)pyridine ( t Bupypy), pyt refers to pyridyl-2-thiolate, respectively. Their binuclear framework was evidenced by the single crystal of (pypy) 2 Pt 2 (pyt) 2 with a short Pt Pt bond distance of 2.8814(3) Å. The intense near-infrared (NIR) emission peaks at 692 and 753 nm were exhibited for both dinuclear platinum complexes, which is similar to the emission of the mono-nuclear platinum complex of (pypy)Pt(acac) under photo-excitation. However, a red-shifted NIR electroluminescence (EL) peaked at 692 nm with a shoulder at 753 nm was observed in their doped polymer light-emitting diodes using PVK/OXD-7 as the host blend, which presented intrinsic character of MMLCT. Better EL performances with the maximum external quantum efficiency of 0.74% and a radiate emittance of 123.4 μw.cm −2 were obtained in the ( t Bupypy) 2 Pt 2 (pyt) 2 doped device. To our best knowledge, this is a first reported example on the NIR EL of binuclear platinum complex using pyridyl-2-thiolate as auxiliary ligand.