Novel luminescent homo/heterometallic platinum(ii) alkynyl complexes based on Y-shaped pyridyl diphosphines

Abstract

A series of dinuclear platinum(II) alkynyl complexes [Pt₂L₂(CCC₆H₄R-4)₄] (R = H 1, CH₃2, Bu^t3) and unusual tetranuclear Pt(II)–Ag(I) clusters [Pt₂Ag₂L(CCC₆H₄R-4)₆] (R = H, 4; CH₃, 5; Bu^t, 6), together with novel polymer crystals [Pt₂Ag₂L(CCC₆H₅)₆]_∞ ([4]_∞), were synthesized by a self-assembly reaction between [NBu₄]₂[Pt(CCC₆H₄-R-4)₄] and [Ag₆L₆]⁶⁺ (L = 4-(3,5-(diphenylphosphine)phenyl)pyridine). These complexes were characterized by using a range of spectroscopic techniques and complexes 1, 3, 5, and [4]_∞ were analysed by X-ray crystallography. Each platinum atom of the Pt(II)–Ag(I) clusters shows an unusual asymmetric distorted square planar geometry with three alkynyl groups and one bridging L phosphorus atom. Dinuclear complexes 1–3 demonstrate solid-state weak blue luminescence, while tetranuclear Pt(II)–Ag(I) clusters 4–6 show intense blue-green or yellow-green emission. Furthermore, the crystalline samples of polymer [4]_∞ display bright yellow emission (518 nm) that is significantly red-shifted as compared to monomer crystal 4.