Kristian E. Dalle, Lena J. Daumann, G. Schenk
Mar 22, 2013
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0
Influential Citations
12
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Journal
Polyhedron
Abstract
Complexation of dimethyl-6,6'-(2-hydroxy-5-methyl-1,3-phenylene)bis(methylene)bis((2-hydroxyethyl) azanediyl)bis(methylene)dipicolinate (Me(2)H(3)L4) and 2,2'-(2-hydroxy-5-methyl-1,3-phenylene)bis(meth ylene)bis(((6-methylpyridin-2-yl)methy)azanediyl)diethanol (H(3)L5) with Zn(II) afforded the complexes [Zn-2(H(2)L4)(H2O)(2)](ClO4) and [Zn-2(H(2)L5)(CH3CO2)(H2O)](PF6)(2)center dot 2H(2)O, which were characterized by H-1 and C-13 NMR spectroscopy, mass spectrometry, microanalysis, and the former by X-ray crystallography. Functional studies of the zinc complexes with the substrate bis(2,4-dinitrophenyl)phosphate (BDNPP) showed the complexes to be competent catalysts with k(cat) = 3.52 +/- 0.03 x 10(-4) and 1.27 +/- 0.04 x 10(-3) s(-1) (K-m = 6.7 +/- 0.9; 13.8 +/- 1.5 mM), with catalytically relevant pK(a)s of 9.4 and 6.6, respectively. The pK(a) values are discussed with respect to the potential nucleophilic species and the effect of the donor environment. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.