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

Meng Zhang, Joy A. Gallagher, Matthew B. Coppock, Lisa M. Pantzar, Mary Elizabeth Williams

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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.

Original languageEnglish (US)
Pages (from-to)11315-11323
Number of pages9
JournalInorganic Chemistry
Volume51
Issue number21
DOIs
Publication statusPublished - Nov 5 2012

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All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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