Metal array fabrication based on ultrasound-induced self-assembly of metalated dipeptides

Dalton Trans. 2013 Dec 7;42(45):15953-66. doi: 10.1039/c3dt51696b. Epub 2013 Aug 21.

Abstract

Pd- and Pt-bound bis-metalated peptides were synthesised by the condensation of Pd- or Pt-aldimine-complex-bound glutamic acids to afford the four possible metal isomers of bis-Pd and bis-Pt-homometalated dipeptides and PdPt- and PtPd-heterometalated dipeptides without metal disproportionation. Ultrasound-induced self-assembly of these bis-metalated peptides proceeded effectively to afford supramolecular gels that displayed well-ordered metal arrays. The formation of parallel β-sheet type aggregates through interpeptide amide-amide hydrogen bonding was confirmed by IR, scanning electron microscopy (SEM), and synchrotron X-ray diffraction analyses (WAXS and SAXS). The mechanism of the ultrasound-induced self-assembly of the metalated dipeptides was elucidated via kinetic and association experiments by (1)H NMR, in which ultrasound-triggered dissociation of intramolecular hydrogen bonds between the chloride ligands of the Pd- and Pt-complexes and amides initially occurred. This was followed by the formation of intermolecular amide-amide hydrogen bonds, which afforded the corresponding oligomeric peptide self-assembly as the nucleus for supramolecular aggregation. The observed first-order relationship of the gelation rate versus the sonication frequency suggested that the microcavitation generated under sonication conditions acted as a crucial trigger and provided a reaction field for efficient self-assembly.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Coordination Complexes / chemistry
  • Dipeptides / chemistry*
  • Gels / chemistry*
  • Glutamic Acid / chemistry*
  • Hydrogen Bonding
  • Imines / chemistry
  • Models, Molecular
  • Palladium / chemistry*
  • Platinum / chemistry*
  • Scattering, Small Angle
  • Sonication*
  • X-Ray Diffraction

Substances

  • Coordination Complexes
  • Dipeptides
  • Gels
  • Imines
  • Glutamic Acid
  • Platinum
  • Palladium