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Synthesis, Characterization, Photophysical, and Theoretical Studies of Supramolecular Gold(I)−Silver(I) Alkynyl-Phosphine Complexes

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journal contribution
posted on 09.03.2009, 00:00 by Igor O. Koshevoy, Antti J. Karttunen, Sergey P. Tunik, Matti Haukka, Stanislav I. Selivanov, Alexei S. Melnikov, Pavel Yu. Serdobintsev, Tapani A. Pakkanen
The reactions of diphosphino-alkynyl gold complexes (PhC2Au)PPh2(C6H4)nPPh2(AuC2Ph) (n = 1, 2, 3) with Ag+ lead to the formation of supramolecular heterometallic aggregates, which consist of the [AuxAgy(C2Ph)2x]yx clusters (x = (n+1)(n+2)/2; y = n(n+1)) “wrapped” in gold-diphosphine “belts”. The composition of the “belts” depends on the size of the heterometallic cluster; for n = 1 it is an open-loop tetrametallic diphosphine-alkynyl [Au(C2Ph)Au2Ag(PPh2(C6H4)2PPh2)3]3+ complex, and for n = 2, 3 it is a symmetrical closed triangle [Au3{PPh2(C6H4)nPPh2}3]3+. The complex for n = 1 was characterized crystallographically and spectrally; the larger ones (n = 2, 3) were investigated in detail by NMR spectroscopy. Their luminescence behavior has been studied, and an intense room-temperature solution emission with maximum quantum yield of 0.35 (n = 2) was detected. Computational studies have been performed to provide additional insight into the structural and electronic properties of these supramolecular complexes. Theoretical results obtained are in good agreement with the experimental data, supporting the proposed structural motif. These studies also suggest that the observed efficient long-wavelength luminescence is associated with transitions within the central Au(I)−Ag(I) heterometallic fragment.