Aminoethylglycine-functionalized Ru(bpy)3(2+) with pendant bipyridines self-assemble multimetallic complexes by copper and zinc coordination

Inorg Chem. 2008 Aug 4;47(15):6738-47. doi: 10.1021/ic800285s. Epub 2008 Jun 21.

Abstract

Directed self-assembly using inorganic coordination chemistry is an attractive approach for making functional supramolecular structures. In this article, the synthesis and characterization of Ru(bpy) 3 (2+) compounds derivatized with aminoethylglycine (aeg) substituents containing pendant bipyridine (bpy) ligands is presented. The free bpy ligands in these complexes are available for metal chelation to form coordinative cross-links; addition of Cu (2+) or Zn (2+) assembles heterometallic structures containing two or three transition-metal complexes. Control over relative placement of metal complexes is accomplished using two strategies: two bipyridine-containing aeg strands tethered to Ru(bpy) 3 (2+) allow intramolecular coordination and result in a dimetallic hairpin motif. Ru(bpy) 3 (2+) modified with a single strand forms intermolecular cross-links forming the trimetallic complex. Each of these is characterized by a range of methods, and their photophysical properties are compared. These data, and comparison to an acetyl aeg- modified Ru(bpy) 3 (2+) complex, confirm that the metal ions cross-link bpy-containing aeg strands. Heterometallic complexes containing bound Cu (2+) cause a dramatic reduction in the Ru(bpy) 3 (2+) quantum yields and lifetimes. In contrast, the Ru(bpy) 3 (2+) hairpin with coordinated Zn (2+) has only a slight decrease in quantum yield but no change in lifetime, which could be a result of steric impacts on structure in the dimetallic species. Analogous effects are not observed in the trimetallic Ru-Zn-Ru structures in which this constraint is absent. Each of these heterometallic structures represents a facile and reconfigurable means to construct multimetallic structures by metal-coordination-based self-assembly of modular artificial peptide units.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • 2,2'-Dipyridyl / analogs & derivatives*
  • 2,2'-Dipyridyl / chemical synthesis
  • 2,2'-Dipyridyl / chemistry
  • Absorption
  • Coordination Complexes
  • Copper / chemistry*
  • Glycine / analogs & derivatives*
  • Glycine / chemistry*
  • Ligands
  • Peptides / chemistry
  • Spectrophotometry
  • Titrimetry
  • Zinc / chemistry*

Substances

  • Coordination Complexes
  • Ligands
  • Peptides
  • tris(2,2-bipyridine)-ruthenium(II)
  • 2,2'-Dipyridyl
  • Copper
  • Zinc
  • Glycine