title: Design and synthesis of luminescence chemosensors based on alkynyl phosphine gold(I)-copper(I) aggregates.
abstract: Receptor-containing polynuclear mixed-metal complexes of gold(I)-copper(I) 1-3 based on a [{Au(3)Cu(2)(C≡CPh)(6)}Au(3){PPh(2)-C(6)H(4)-PPh(2)}(3)](2+) (Au(6)Cu(2)) core with benzo-15-crown-5, oligoether and urea binding sites were designed and synthesized, respectively. These complexes exhibited remarkably strong red emission at ca. 619-630 nm in dichloromethane solution at room temperature upon photoexcitation at λ > 400 nm, with the emission quantum yield in the range 0.59-0.85. The cation-binding properties of 1 and 2 and the anion-binding properties of 3 were studied using UV-vis, emission and (1)H NMR techniques. Complex 1, with six benzo-15-crown-5 pendants, was found to show a higher binding preference for K(+), with a selectivity trend of K(+)≫ Cs(+) > Na(+) > Li(+). The addition of metal ions (Li(+), Na(+), K(+) and Cs(+)) to complex 1 led to a modest emission enhancement with a concomitant slight blue shift in energy and well-defined isoemissive points, which is attributed to the rigidity of the structure and the inhibited PET (photo-induced electron transfer) process from the oxygen to the aggregate as a result of the binding of the metal ion. The six urea receptor groups on complex 3 were found to form multiple hydrogen bonding interactions with anions, with the positive charge providing additional electrostatic interaction for anion-binding. The anion selectivity of 3 follows the trend F(-) > Cl(-)≈ H(2)PO(4)(-) > Br(-) and the highest affinity towards F(-) is attributed to the stronger basicity of F(-), as well as its good size match with the cavity of the urea pocket.
authors.affiliation: Institute of Molecular Functional Materials, Areas of Excellence Scheme, University Grants Committee, Hong Kong, PR China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: He
authors.forename: Nianyong
authors.initials: N
authors.lastname: Zhu
authors.forename: Vivian Wing-Wah
authors.initials: VW
authors.lastname: Yam
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D005456:Fluorescent Dyes; D009942:Organometallic Compounds; D010720:Phosphines; D006046:Gold; D003300:Copper; C044646:phosphine