title: Cooperative assembly of Zn cross-linked artificial tripeptides with pendant hydroxyquinoline ligands.
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.
authors.affiliation: Department of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16802, USA.
authors.forename: Meng
authors.initials: M
authors.lastname: Zhang
authors.forename: Joy A
authors.initials: JA
authors.lastname: Gallagher
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Coppock
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Pantzar
authors.forename: Mary Elizabeth
authors.initials: ME
authors.lastname: Williams
mesh_terms: D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015125:Oxyquinoline / Q000138:chemical synthesis / Q000737:chemistry*; D057786:Peptidomimetics / Q000138:chemical synthesis / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D015032:Zinc / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D005456:Fluorescent Dyes; D057786:Peptidomimetics; D015125:Oxyquinoline; D015032:Zinc