Dual Luminescent Tetranuclear Organogold(I) Macrocycles of 5,5′-Diethynyl-2,2′-bipyridine and Their Efficient Sensitization of Yb(III) Luminescence

Reaction of (AuC CbpyC CAu)(n) (HC CbpyC CH = 5,5'-diethynyl-2,2'-bipyridine) with diphosphine ligands Ph2P(CH2)(n)PPh2 (n = 1 dppm, 3 dppp, 5 dpppen, 6 dpph), 1,1'-bis(diphenylphosphino)ferrocene (dppf), and 1,2-bis(diphenylphosphino)-benzene (bdpp) in CH2Cl2 afforded the corresponding dual luminescent gold(I) complexes [(AuC CbpyC CAu)(2)(mu-dppm)(2)] (1), [(AuC CbpyC CAu)(2)(mu-dppp)(2)] (2), [(AuC CbpyC CAu)(2)(mu-dppf)(2)] (3), [(AuC CbpyC CAu)(2)(mu-dpph)(2)] (4), [(AuC CbpyC CAu)(2)(mu-dppf)(2)] (5), and [(AuC CbpyC CAu)(2)(mu-bdpp)(2)] (6). The solid structures of complexes 1 and 2 are confirmed to be tetranuclear macrocyclic rings by single crystal structure analysis, and those of complexes 3-6 are proposed to be similar to those of complexes 1 and 2 in structure because their good solubility in CH2Cl2, their HRMS results, and the P center dot center dot center dot P separations of 20.405-20.697 angstrom in the same linear rigid P-Au-C CbpyC C-Au-P unit are all favorable to form such 2:4:2 macrocycles. Each of the absorption spectral titrations between complexes 1-6 and Yb(hfac)(3)(H2O)(2) (Hhfac = hexafluoroacetylacetone) gives a 2:1 ratio between the Yb(hfac)(3) unit and the complex 1-6 moieties. The energy transfer occurs efficiently from the gold(I) allcynyl antennas 1-6 to Yb(III) centers with the donor ability in the order of 1 similar to 2 similar to 3 similar to 4 > 6 > 5.