Synthesis, structural characterization and luminescence studies of di- and trinuclear gold(I) alkynyl-phosphine complexes

摘要

Reactions of the polymer (Au~IC_2Ph)_n with polyphosphine ligands [l,4-bis(2-diphenylphosphino-lH-imidazol-l-yl)-benzene (dpib), l,3,5-tris(4-diphenylphosphinophenyl)benzene (tppb), 2,2'-bis(diphenylphosphanyl)-4,4'-bipyridine (dpbp), and 3,6- bis(diphenylphosphanyl)pyridazine (dppz)] afforded four gold(I) alkynyl-polyphosphine complexes [ (AuC_2Ph }_2(μ-dpib)] (1), [{AuC_2Ph}_3(μ3-tppb)] (2), [{AuC _2Ph}_2(μ-dpbp)] (3), and [{AuC_2Ph} _2(u-dppz)] (4) in nearly quantitative yield. The compounds obtained were characterized using elemental analysis, ESI-MS, X-ray crystallography, and polynuclear NMR spectroscopy. Intermolecular aurophilic interaction together with π-π and σ-π stacking build up the supramolecular 3D network of complex 3, whereas none of these intermolecular bondings were found in the crystal structures of compounds 1,2, and 4. Complexes 1-4 are luminescent both in solution (CH_2Cl_2 and in solid state under laser irradiation (λ_(ex) = 308 nm). In solution, the diphosphine complexes 1-4 display dual emission corresponding to ligand centered transitions (λ_(em) = 360375 nm) along with weaker contribution from MLCT excited states at ca. 490 nm. The long wavelength component of the emission plays a dominant role in the solid state luminescence spectra of complexes 1, 3, and 4 (460, 544, 520 nm, respectively) whereas the triphosphine complex 2 shows dual luminescence (372 and 520 nm) with, considerable contribution from ligand centered excited state.