Spectroscopic Investigation of Interactions between Dipeptides and Vanadate(V) in Solution

Abstract

The reaction of vanadate(V) with a series of dipeptides (Val-Gln, Ala-Gln, Gly-Gln, Gly-Glu, and Ala-Gly) was investigated by UV-visible spectroscopy and multinuclear ((51)V, (14)N, (13)C) NMR spectroscopy in solution. It was possible to evaluate the formation constants of the corresponding complexes for which a molecular structure was proposed. Complex formation is favored by the presence of a functionalized or a sterically demanding side chain. The Val-Gln dipeptide which combines both properties exhibits one of the highest formation constant reported so far for dipeptides.

Ex Situ X-ray Diffraction, X-ray Absorption Near Edge Structure, Electron Spin Resonance, and Transmission Electron Microscopy Study of the Hydrothermal Crystallization of Vanadium Oxide Nanotubes: An Insight into the Mechanism of Formation

“…The 51 V NMR spectra (see Figure S3 of the Supporting Information) display resonances at −552 and −585 ppm, which can be assigned, respectively, to metavanadates [H x VO 4 ] (−3+ x ) and cyclic metavanadates [V 4 O 12 ] 4– /[V 5 O 15 ] 5– . The signal at −552 ppm may correspond also to a vanadium–amine complex since this chemical shift is close to those of vanadium complexes with amino ligands (amino acids) . These results are consistent with a redissolution–precipitation mechanism which would imply a progressive dissociation of the vanadium oxide intercalates and the crystallization of VO x -NT.…”

Vanadium Oxide Nanotubes: New Synthesis Route and Mechanism of Formation.

“…The 51 V NMR spectrum displays resonances at -578 and -580 ppm which can be assigned respectively to the cyclic metavanadates [V 4 O 12 ] 4-and [V 5 O 15 ] 5-. However in addition to these resonances, a new signal at -550 ppm may be assigned to a vanadium-amine complex since this chemical shift is close to those of vanadium complexes with amino ligands (amino acids, dipeptides) [7]. Therefore in this reaction medium, the amines may act not only as bases and structure directing agents but probably also as complexing ligands for vanadium.…”

N-Boc Deprotection and Isolation Method for Water-Soluble Zwitterionic Compounds

“…The slurry was stirred for 2 h. The product was isolated by filtration of the slurry followed by a DCM wash to afford the desired peptide. Compounds 9 , 10 , 11 , and 12 are known compounds.…”