title: Design, synthesis, photophysics, and anion-binding studies of bis(dicyclohexylphosphino)methane-containing dinuclear gold(I) thiolate complexes with urea receptors.
abstract: A series of bis(dicyclohexylphosphino)methane (dcpm)-containing gold(I) thiolate complexes with urea receptors, 1-3, has been successfully designed and synthesized, and their photophysical and anion-binding properties have been studied. The linker between the thiolate and the urea group, and the electronic environment of the urea moiety, have been found to exert a great influence on the photophysical and anion-binding properties of the complexes. Complex 3 displays an intense long-lived orange-red luminescence at around 620 nm in the solid state and in the glass state at 77 K, which is considerably red shifted from the band seen in a solution of dichloromethane at room temperature, suggesting the presence of AuAu interactions. Upon introducing an electron-withdrawing NO(2) group, complex 1 was found to show high selectivity and sensitivity for F(-) through a drastic color change from yellow to red. The anion-binding constants of the complexes have been determined from electronic absorption and (1)H NMR spectroscopy titration studies and the data were found to fit well to a 1:1 binding model for the interactions between the complexes and the anions. Complexes 1 and 2 show the same anion selectivity trend of F(-) > AcO(-) > H(2)PO(4)(-) > Cl(-) approximately Br(-) approximately I(-), which is consistent with the trend in anion basicity. In addition, complex 1 has been shown to exhibit higher binding affinity for anions compared with those of complexes 2 and 3, probably due to the higher acidity of the urea moiety as a result of the introduction of the NO(2) group.
authors.affiliation: Centre for Carbon-Rich Molecular and Nano-Scale, Metal-Based Materials Research, Department of Chemistry and HKU-CAS Joint Laboratory on New Materials, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: He
authors.forename: Fernando
authors.initials: F
authors.lastname: Herranz
authors.forename: Eddie Chung-Chin
authors.initials: EC
authors.lastname: Cheng
authors.forename: Ramon
authors.initials: R
authors.lastname: Vilar
authors.forename: Vivian Wing-Wah
authors.initials: VW
authors.lastname: Yam
mesh_terms: D000465:Algorithms; D006046:Gold / Q000737:chemistry*; D008024:Ligands; D049449:Luminescence; D008697:Methane / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D050607:Organogold Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D014508:Urea / Q000737:chemistry
chemical_list: D008024:Ligands; D050607:Organogold Compounds; D013438:Sulfhydryl Compounds; D006046:Gold; D014508:Urea; D008697:Methane