Dual Luminescent Dinuclear Gold(I) Complexes of Terpyridyl-Functionalized Alkyne Ligands and Their Efficient Sensitization of EuIII and YbIII Luminescence

Reaction of (tpyC(6)H(4)C equivalent to CA(u))(n) (tpyC(6)H(4)C equivalent to CH = 4'-(4-ethynylphenyl)-2,2':6',2 ''-terpyridine) with diphosphane ligands Ph2P(CH2)(x)PPh2 (x = 2 dppe, 3 dppp, 4 dppb, 5 dpppen, 6 dpph) in CH2Cl2 afforded the corresponding dual luminescent binuclear gold(l) complexes [(tpyC(6)H(4)C equivalent to CAu)(2)-(mu-dPPe)] (1), [(1tpyC(6)H(4)C equivalent to CAu)(2)(mu-dPPP)] (2), [(tpyC(6)H(4)C equivalent to CAu)(2)(mu-dPPb)] (3), [(tpyC(6)H(4)C equivalent to CAu)(2)(mu-dpppen)] (4), [(tpyC(6)H(4)C equivalent to CAu)(2)(mu-dppph)] (5). Crystal structural analysis of complexes 1 center dot 2CH(2)Cl(2) and 2 center dot 2CH(2)Cl(2) show that the terpyridine moieties are free of coordination in these gold(l)-acetylide-phosphane complexes. Spectrophotometric titration between complex 1 and [Eu(tta)(3)] (Htta = 2-thenoyltrifluoro-acetone) or [Yb(hfac)(3)(H2O)(2)] (Hhfac = hexafluoroacetyl-acetone) gave a 2:1 ratio between Ln(beta-diketonate)(3) (Ln = Eu, Yb) units and the complex 1 moiety, indicating the formation of Au(2)Ln(2) complexes. Both the luminescence titrations and the luminescence quantum yields of Au2Ln2 (Ln = Eu, Yb) solutions show that the energy transfer occurs efficiently from the binuclear gold(I) antennas 1-5 to Eu-III and Yb-III centers, and all complexes 1-5 are good energy donors for sensitization of visible and NIR luminescence of Eu-III and Yb-III ions.