ISSN:
0030-4921
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The conformations of Gly-Phe and Phe-Gly dipeptides and those of their complexes with the Pd(II) ion has been established by means of 1H n.m.r. spectra over various pH ranges. In the most stable rotamer of both dipeptides the bulkiest groups, i.e. carboxylate (or carbonyl) and the aromatic ring, are in trans position to each other. In the 1:1 molar ratio complexes, the dipeptides are the tridentate ligands within the 3-10 pH region. In the predominant conformer the aromatic ring lies over the complex plane, which suggests its interaction with the metal ion. At pH above 13, the carboxyl group becomes non-coordinated. The dipeptides are then bidentate and the most stable rotamers are the same as those found for the metal-free ligands, i.e. the carboxyl or carbonyl group is in the trans position to the aromatic ring. The glycine chelate ring in the Pd(II) Gly-Phe complex is planar up to pH 10 and its distortion from planarity follows when the ligand becomes bidentate.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1270100134
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