caa a22 4500 467919275 CHVBK 20180406152912.0 cr unu---uuuuu 170328e20060601xx s 000 0 eng 10.1007/s00706-005-0470-0 doi (NATIONALLICENCE)springer-10.1007/s00706-005-0470-0 Potentiometric and Multinuclear Magnetic Resonance Study of the Solution Equilibria Between Aluminium(III) Ion and L -Aspartic Acid [Elektronische Daten] [Predrag Djurdjević, Ratomir Jelić, Ljubinka Joksović, Mirjana Cvijović] Summary.: Solution equilibria between aluminium(III) ion and L-aspartic acid were studied by potentiometric, 27Al, 13C, and 1H NMR measurements. Glass electrode equilibrium potentiometric studies were performed on solutions with ligand to metal concentration ratios 1:1, 3:1, and 5:1 with the total metal concentration ranging from 0.5 to 5.0 mmol/dm3 in 0.1 mol/dm3 LiCl ionic medium, at 298 K. The pH of the solutions was varied from ca. 2.0 to 5.0. The non-linear least squares treatment of the data performed with the aid of the Hyperquad program, indicated the formation of the following complexes with the respective stability constants log βp,q,r given in parenthesis (p, q, r are stoichiometric indices for metal, ligand, and proton, respectively): Al(HAsp)2+ (log β1,1,1 = 11.90 ± 0.02); Al(Asp)+ (log β1,1,0 = 7.90 ± 0.03); Al(OH)Asp0 (log β1,1,−1 = 3.32 ± 0.04); Al(OH)2Asp− (log β1,1−2 = −1.74 ± 0.08), and Al2(OH) Asp3+ (log β2,1,−1 = 6.30 ± 0.04). 27Al NMR spectra of Al3+ + aspartic acid solutions (pH 3.85) indicate that sharp symmetric resonance at δ∼10 ppm can be assigned to (1, 1, 0) complex. This resonance increases in intensity and slightly broadens upon further increasing the pH. In Al(Asp)+ complex the aspartate is bound tridentately to aluminum. The 1H and 13C NMR spectra of aluminium + aspartic acid solutions at pH 2.5 and 3.0 indicate that β-methylene group undergoes the most pronounced changes upon coordination of aluminum as well as α-carboxylate group in 13C NMR spectrum. Thus, in Al(HAsp)2+ which is the main complex in this pH interval the aspartic acid acts as a bidentate ligand with -COO− and -NH2 donors closing a five-membered ring. Springer-Verlag, 2006 Keywords. Aluminium nationallicence Aspartic acid nationallicence Complex formation nationallicence Potentiometry nationallicence Multinuclear NMR nationallicence Djurdjević Predrag Faculty of Science, Chemistry Department, Kragujevac aut Jelić Ratomir Faculty of Science, Chemistry Department, Kragujevac aut Joksović Ljubinka Faculty of Science, Chemistry Department, Kragujevac aut Cvijović Mirjana The Copper Mill, Sevojno-Uzice, State Union of Serbia and Montenegro, Yugoslavia (Former) aut Monatshefte für Chemie / Chemical Monthly Springer-Verlag 137/6(2006-06-01), 717-735 0026-9247 137:6<717 2006 137 706 https://doi.org/10.1007/s00706-005-0470-0 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00706-005-0470-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Djurdjević Predrag Faculty of Science, Chemistry Department, Kragujevac aut NATIONALLICENCE 700 1- Jelić Ratomir Faculty of Science, Chemistry Department, Kragujevac aut NATIONALLICENCE 700 1- Joksović Ljubinka Faculty of Science, Chemistry Department, Kragujevac aut NATIONALLICENCE 700 1- Cvijović Mirjana The Copper Mill, Sevojno-Uzice, State Union of Serbia and Montenegro, Yugoslavia (Former) aut NATIONALLICENCE 773 0- Monatshefte für Chemie / Chemical Monthly Springer-Verlag 137/6(2006-06-01), 717-735 0026-9247 137:6<717 2006 137 706 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer