Cooperative assembly of Zn cross-linked artificial tripeptides with pendant hydroxyquinoline ligands

Inorg Chem. 2012 Nov 5;51(21):11315-23. doi: 10.1021/ic3004504. Epub 2012 Oct 5.

Abstract

An artificial peptide with three pendant hydroxyquinoline (hq) ligands on a palindromic backbone was designed and used to form multimetallic assemblies. Reaction of the tripeptide with zinc acetate led to a highly fluorescent tripeptide duplex with three Zn(II) coordinative cross-links. The binding process was monitored using spectrophotometric absorbance and emission titrations; NMR spectroscopy and mass spectrometry confirmed the identity and stoichiometry of the product structure. Titrations monitoring duplex formation of the zinc-tripeptide structure had a sigmoidal shape, equilibrium constant larger than the monomeric analogue, and a Hill coefficient >1, all of which indicate positive cooperativity. Photophysical characterization of the quantum yield, excited state lifetime, and polarization anisotropy are compared with the monometallic zinc-hq analogue. A higher than expected quantum yield for the trimetallic complex suggests a structure in which the central chromophore is shielded from solvent by π-stacking with neighboring Zn(II) complexes.

Publication types

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

MeSH terms

  • Coordination Complexes / chemical synthesis
  • Coordination Complexes / chemistry*
  • Fluorescent Dyes / chemical synthesis
  • Fluorescent Dyes / chemistry*
  • Magnetic Resonance Spectroscopy
  • Models, Molecular
  • Oxyquinoline / chemical synthesis
  • Oxyquinoline / chemistry*
  • Peptidomimetics / chemical synthesis
  • Peptidomimetics / chemistry*
  • Spectrometry, Fluorescence
  • Spectrophotometry, Ultraviolet
  • Zinc / chemistry*

Substances

  • Coordination Complexes
  • Fluorescent Dyes
  • Peptidomimetics
  • Oxyquinoline
  • Zinc