Luminescent Au(I)/Cu(I) alkynyl clusters with an ethynyl steroid and related aliphatic ligands: an octanuclear Au4Cu4 cluster and luminescence polymorphism in Au3Cu2 clusters.
Gold(I) bis(acetylide) complexes [PPN][AuR(2)] (1-3) where PPN = bis(triphenylphosphine)iminium) and R = ethisterone (1); 1-ethynylcyclopentanol (2); 1-ethynylcyclohexanol (3) have been prepared. The reaction of 1 with [Cu(MeCN)(4)][PF(6)] in a 1:1 or 3:2 ratio provides the octanuclear complex [Au(4)Cu(4)(ethisterone)(8)] (4) or pentanuclear complex [PPN][Au(3)Cu(2)(ethisterone)(6)] (5). Complexes 2 and 3 react with [Cu(MeCN)(4)][PF(6)] to form only pentanuclear Au(I)/Cu(I) complexes [PPN][Au(3)Cu(2)(1-ethynylcyclopentanol)(6)] (6) and [PPN][Au(3)Cu(2)(1-ethynylcyclohexanol)(6)] (7). X-ray crystallographic studies of 1-3 reveal nontraditional hydrogen bonding between hydroxyl groups and the acetylide units of adjacent molecules. Complexes 6 and 7 each form polymorphs in which the structures (6 a,b and 7 a,b,c) differ by Au...Au, Au...Cu, and Cu-C distances. The polymorphs exhibit different emission energies with colors ranging from blue to yellow in the solid state. In solution, pentanuclear clusters 5-7 emit with lambda(max) = 570-580 nm and Phi = 0.05-0.19. Complex 4 emits at 496 nm in CH(2)Cl(2) with a quantum yield of 0.65. Complex 5 exists in equilibrium with 1 and 4 in the presence of methanol, ethanol, ethyl acetate, or water. This equilibrium has been probed by X-ray crystallography, NMR spectroscopy, and luminescence experiments. DFT calculations have been performed to analyze the orbitals involved in the electronic transitions of 4, 6, and 7.
Manbeck
Gerald F
GF
Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.
Brennessel
William W
WW
Stockland
Robert A
RA
Eisenberg
Richard
R
D000480:Alkynes / Q000737:chemistry*; D000497:Alloys / Q000737:chemistry*; D003300:Copper / Q000737:chemistry; D018360:Crystallography, X-Ray; D006046:Gold / Q000737:chemistry; D008024:Ligands; D049449:Luminescence; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013256:Steroids / Q000737:chemistry*
D000480:Alkynes; D000497:Alloys; D008024:Ligands; D009942:Organometallic Compounds; D013256:Steroids; D006046:Gold; D003300:Copper