Stepwise 1D Growth of Luminescent Au(I)−Ag(I) Phosphine−Alkynyl Clusters: Synthesis, Photophysical, and Theoretical Studies

Reactions between the diphosphino-gold cationic complexes [Au2(PPh2-C2-(C6H4)n-C2-PPh2)2]2+ (n = 0, 1, 2, 3) and polymeric acetylides (AuC2Ph)n and (AgC2Ph)n lead to the formation of a new family of heterometallic clusters with the general formula [Au8+2nAg6+2n(C2Ph)8+4n(PPh2C2(C6H4)nC2PPh2)2]2+, n = 0 (1), 1 (2), 2 (3), 3 (4). Compounds 1−4 were characterized in detail by NMR and ESI-MS spectroscopy. Complex 1 (n = 0) crystallizes in two forms (orange (1a) and yellow (1b)), one of which (1a) has been analyzed by X-ray crystallography. The luminescence behavior of 1−4 has been studied. Compounds 2 and 3 exhibited orange-red phosphorescence with quantitive quantum efficiency in both aerated and degassed CH2Cl2, implying O2-independent phosphorescence due to efficient protection of the emitting chromophore center by the organic ligands. Complex 3 exhibits reasonable two-photon absorption (TPA) property with a cross section of σ ≈ 45 GM (800 nm), which is comparable to the value of commercially available TPA...