title: Metal array fabrication based on ultrasound-induced self-assembly of metalated dipeptides.
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.
authors: Department of Chemistry, Graduate School of Engineering Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
authors: Katsuhiro
authors: K
authors: Isozaki
authors: Yusuke
authors: Y
authors: Haga
authors: Kazuki
authors: K
authors: Ogata
authors: Takeshi
authors: T
authors: Naota
authors: Hikaru
authors: H
authors: Takaya
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry; D004151:Dipeptides / Q000737:chemistry*; D005782:Gels / Q000737:chemistry*; D018698:Glutamic Acid / Q000737:chemistry*; D006860:Hydrogen Bonding; D007097:Imines / Q000737:chemistry; D008958:Models, Molecular; D010165:Palladium / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*; D053838:Scattering, Small Angle; D013010:Sonication; D014961:X-Ray Diffraction
chemical_list: D056831:Coordination Complexes; D004151:Dipeptides; D005782:Gels; D007097:Imines; D018698:Glutamic Acid; D010984:Platinum; D010165:Palladium