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https://hdl.handle.net/10316/10518
Title: | Potentiometry and NMR studies of 1,5,9-triazacyclododecane-N,N',N''-triacetic acid and its metal ion complexes | Authors: | Cortes, S. Brucher, E. Geraldes, C. F. G. C. Sherry, A. D. |
Issue Date: | Jan-1990 | Publisher: | American Chemical Society | Citation: | Inorganic Chemistry. 29:1 (1990) 5-9 | Abstract: | A new chelating macrocycle, 1,5,9-triazacyclododecane-N,N’,N’’-triacetiacc id (DOTRA), has been synthesized, and its complexes with Zn2’, Cd2+, Ca2+, Mg2+, and Mn2+ have been examined by potentiometry and NMR spectroscopy. The first protonation constant of the free ligand (log K, = 12.8) was determined spectrophotometrically, while the remaining were evaluated from potentiometric data (log K2 = 7.55, log K, = 3.65, log K4 = 2.1). DOTRA forms complexes with Mn2+, Mg2’, and Ca2+ rather slowly but reacts much more rapidly with Zn2+ and Cd2+. As reported previously for the nine-membered-ring triaza analogue NOTA, DOTRA also forms a more stable complex with Mg2+ than with Ca2+ (log K,, = 7.1 versus 6.0). High-resolution NMR spectra of the Zn2+, Cd2+, and Mgzt complexes (log K,, = 19.0, 15.7, and 7.1, respectively) indicate the three six-membered chelate rings are symmetrical and quite rigid in aqueous solution, as evidenced by nonequivalence of all six chelate ring protons. | URI: | https://hdl.handle.net/10316/10518 | ISSN: | 0020-1669 | DOI: | 10.1021/ic00326a003 | Rights: | openAccess |
Appears in Collections: | FCTUC Química - Artigos em Revistas Internacionais |
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