Dual luminescent tetranuclear organogold(I) macrocycles of 5,5'-diethynyl-2,2'-bipyridine and their efficient sensitization of Yb(III) luminescence.

ABSTRACT

Reaction of (AuC≡CbpyC≡CAu)(n) (HC≡CbpyC≡CH = 5,5'-diethynyl-2,2'-bipyridine) with diphosphine ligands Ph(2)P(CH(2))(n)PPh(2) (n = 1 dppm, 3 dppp, 5 dpppen, 6 dpph), 1,1'-bis(diphenylphosphino)ferrocene (dppf), and 1,2-bis(diphenylphosphino)benzene (bdpp) in CH(2)Cl(2) afforded the corresponding dual luminescent gold(I) complexes [(AuC≡CbpyC≡CAu)(2)(µ-dppm)(2)] (1), [(AuC≡CbpyC≡CAu)(2)(µ-dppp)(2)] (2), [(AuC≡CbpyC≡CAu)(2)(µ-dpppen)(2)] (3), [(AuC≡CbpyC≡CAu)(2)(µ-dpph)(2)] (4), [(AuC≡CbpyC≡CAu)(2)(µ-dppf)(2)] (5), and [(AuC≡CbpyC≡CAu)(2)(µ-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 CH(2)Cl(2), their HRMS results, and the P···P separations of 20.405-20.697 Å in the same linear rigid P-Au-C≡CbpyC≡C-Au-P unit are all favorable to form such 242 macrocycles. Each of the absorption spectral titrations between complexes 1-6 and Yb(hfac)(3)(H(2)O)(2) (Hhfac = hexafluoroacetylacetone) gives a 21 ratio between the Yb(hfac)(3) unit and the complex 1-6 moieties. The energy transfer occurs efficiently from the gold(I) alkynyl antennas 1-6 to Yb(III) centers with the donor ability in the order of 1 ~ 2 ~ 3 ~ 4 > 6 > 5.