Search

Methylene bridged 2,2′-dipyridylamine (dpa) derivatives and their metal complexes possess outstanding properties due to their inherent structural flexibility. Synthesis of such complexes typically involves derivatization of dpa followed by coordination on metals, and may not always be very efficient. In this work, an alternative synthetic approach, involving the derivatization step after – rather than prior to – coordination of dpa on metal center, is proposed and applied to synthesis of a number of platinum(II) complexes with substituted benzyldi(2-pyridyl)amines. Comparison with the more conventional synthetic route reveals greater efficiency and versatility of the proposed approach. The obtained complexes are not luminescent in solution at room temperature, but display blue phosphorescence emission (ca. 415 nm) with the lifetimes of μs order in glassy matrix at 77 K, with additional green (ca. 485 nm) and relatively long living (τ = 3.7 ms) emission in the case of iodine substituted derivative. peerReviewed

A series of alkynyl gold(I) tri and tetratopic metallaligands of the type [Au3(CuC-R)3(μ3-triphosphane)] (R = 2,2'-bipyridin-5-yl or C10H7N2, 2,2':6',2''-terpyridin-4-yl or C15H10N3; triphosphane = 1,1,1-tris(diphenylphosphanyl) ethane or triphos, 1,3,5-tris(diphenylphosphanyl)benzene or triphosph) and [Au4(CuC-R)4 (μ4-tetraphosphane)] (R = C10H7N2, C15H10N3; tetraphosphane = tetrakis(diphenylphosphanylmethyl)methane or tetraphos, 1,2,3,5-tetrakis(diphenylphosphanyl)benzene or tpbz, tetrakis(diphenylphosphaneylmethyl)-1,2- ethylenediamine or dppeda) were obtained in moderate to good yields. All complexes could be prepared by a Q4 reaction between the alkynyl gold(I) polymeric species [Au(CuC-R)]n and the appropriate polyphosphane. An alternative strategy that required the previous synthesis of the appropriate acetylacetonate precursors [Aun(acac)n(μn-polyphosphane)] ('acac method') was assayed, nevertheless only the polyacac derivatives [Au3(acac)3(μ3-triphosphane)] (triphosphane = triphos and triphosph) and [Au4(acac)4(μ4-tetraphos)] could be isolated and characterized. All compounds were characterized by IR, multinuclear NMR spectroscopy and ESI (+) mass spectrometry. The X-ray crystal structure of complexes [Au4(CuC-C10H7N2)4(μ4-tetraphos)] and [Au4(CuC-C10H7N2)4(μ4-tpbz)] showed the involvement of all the gold atoms in close intramolecular Au⋯Au contact as well as intermolecular π stacking interactions between the aromatic rings of the polypyridyl ligands. The photophysical properties of the synthesized compounds were carefully studied and used as a probe of their possible use as multidentate ligands for Cu(I) and Zn(II). The UV-Vis speciation studies of the complexation reactions were conducted via metal titration and, in most cases the dangling units of the ligand were found to behave in a fairy independent manner. While in the case of Cu(I) multiple equilibria exist in solution a single complex is detected for Zn(II) under the conditions studied.