Metal(II) binding ability of a novel N-protected amino acid. A solution-state investigation on binary and ternary complexes with 2,2'-bipyridine.
The binary and ternary systems 2,2'-bipyridine (bpy)-M(II)-NO2psglyH2 (M(II) = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pb(II); NO2psglyH2 = N-(2-nitrophenylsulfonyl)glycine) were investigated in aqueous solution by means of potentiometry and electron spectroscopy in order to identify the type, number and stability of the complex species as a function of pH and metal-to-ligand molar ratio. The aim is to evaluate the effect of a substituent on the phenyl ring of the N-sulfonyl amino acids on their coordination properties. The prevailing species in the binary systems is the [ML] (M = Co(II), Ni(II), Cu(II), Cd(II), Pb(II)) where the amino acid molecule is in the dianionic form and coordinates the metal ion through both carboxylic oxygen and deprotonated sulfonamidic nitrogen, while in the Mn(II)- and Zn(II)-containing binary system the only complex species found are those with the amino acid in the monoanionic form. In the ternary 2,2'-bipyridine-containing systems the chelating coordination mode of the dianionic amino acid is maintained with M(II) = Co(II), Ni(II), Cu(II), Cd(II), Pb(II) and the addition of the aromatic base also enables the Zn(II) ion to substitute for the sulfonamide nitrogen-bound hydrogen of NO2psglyH2.
Saladini
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Department of Chemistry, University of Modena and Reggio Emilia, Italy. saladini@pascal.unimo.it
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D015082:2,2'-Dipyridyl / Q000378:metabolism*; D002104:Cadmium / Q000378:metabolism; D003035:Cobalt / Q000378:metabolism; D003300:Copper / Q000378:metabolism; D004583:Electrons; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007700:Kinetics; D007854:Lead / Q000378:metabolism; D008345:Manganese / Q000378:metabolism; D008670:Metals / Q000378:metabolism*; D009532:Nickel / Q000378:metabolism; D011199:Potentiometry; D013057:Spectrum Analysis; D015032:Zinc / Q000378:metabolism
D007477:Ions; D008670:Metals; D002104:Cadmium; D007854:Lead; D003035:Cobalt; D008345:Manganese; D015082:2,2'-Dipyridyl; D003300:Copper; D009532:Nickel; D015032:Zinc