title: Intensely luminescent alkynyl-phosphine gold(I)-copper(I) complexes: synthesis, characterization, photophysical, and computational studies.
abstract: The reactions between the diphosphino-alkynyl gold complexes (XC6H4C2Au)PR2-C6H4-PR2(AuC2C6H4X) with Cu+ lead to the formation of a family of heterometallic clusters of the general formula [{Au3Cu2(C2C6H4X)6}Au3(PR2C6H4PR2)3][PF6]2 (X = NO2, H, OMe, NMe2; R = C6H5, NC4H4). These complexes adopt the same structural pattern and consist of a heterometallic alkynyl cluster [Au3Cu2(C2C6H4X)6]- "wrapped" by the cationic [Au3(PR2C6H4PR2)3]3+ "belt". The novel compounds were characterized by NMR spectroscopy and ESI-MS measurements. A systematic study of their luminescence properties revealed efficient room-temperature phosphorescence in solution with remarkably weak quenching by molecular oxygen. The photophysical experiments demonstrate that the increase in the electron donor ability of the alkynyl ligands and the electron-withdrawing character of the diphosphines results in the bathochromic shift of emission maxima (in the 576-686 nm range) and a decrease in the luminescence quantum yield. The electronic structure calculations showed that variations of X or R substituents have very little effect on the structural parameters but display a significant influence on the electronic properties of the clusters and characteristics of luminescence. The metal-centered triplet emission within the heterometallic alkynyl cluster is suggested to play a key role in the observed phosphorescence.
authors.affiliation: Department of Chemistry, University of Joensuu, FI-80101, Joensuu, Finland. igor.koshevoy@joensuu.fi
authors.forename: Igor O
authors.initials: IO
authors.lastname: Koshevoy
authors.forename: Yi-Chih
authors.initials: YC
authors.lastname: Lin
authors.forename: Antti J
authors.initials: AJ
authors.lastname: Karttunen
authors.forename: Pi-Tai
authors.initials: PT
authors.lastname: Chou
authors.forename: Pirjo
authors.initials: P
authors.lastname: Vainiotalo
authors.forename: Sergey P
authors.initials: SP
authors.lastname: Tunik
authors.forename: Matti
authors.initials: M
authors.lastname: Haukka
authors.forename: Tapani A
authors.initials: TA
authors.lastname: Pakkanen