ISSN:
1573-1111
Keywords:
Macrocyclic polyamine
;
inorganic oxa-anions
;
equilibrium constants
;
protonation sequence
;
NMR pH-titration
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The aqueous protonation and anion-binding SeO 2 −/4 SO 2− 4 , and NO − 3 ) constants of the macrocyclic polyamine ligand, dipyridino-hexaaza-28-crown-8(L), were measured in 0.1M KCl using a potentiometric titration technique. The protonation sequence of the aza groups of L was studied in D2O from the chemical shifts of the nonlabile protons so as to find the charge distribution geometry as a function of pD. The study indicates that in 0.1M KC1 fully protonated L forms stable l: 1 complexes with SeO 2− 4 (logK=3.68) and SO 2− 4 (logK=3.55), but not with NO − 3 (logK 〈 l.5). All of the amine pK values were above 6.3, thus allowing the use of the protonated form of this ligand over a wide pH range.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01053635
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