Design and synthesis of luminescence chemosensors based on alkynyl phosphine gold(I)-copper(I) aggregates

Dalton Trans. 2011 Oct 14;40(38):9703-10. doi: 10.1039/c1dt10197h. Epub 2011 Aug 22.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkynes / chemistry*
  • Copper / chemistry*
  • Crystallization
  • Crystallography, X-Ray
  • Fluorescent Dyes / chemical synthesis
  • Fluorescent Dyes / chemistry*
  • Gold / chemistry*
  • Models, Molecular
  • Molecular Structure
  • Organometallic Compounds / chemical synthesis
  • Organometallic Compounds / chemistry*
  • Phosphines / chemistry*
  • Stereoisomerism

Substances

  • Alkynes
  • Fluorescent Dyes
  • Organometallic Compounds
  • Phosphines
  • Gold
  • Copper
  • phosphine