Publication Type Journal Article
Title Steric Effects on the Binding of Phosphate and Polyphosphate Anions by Zinc(II) and Copper(II) Dinuclear Complexes of m-Xylyl-biscyclen
Authors Catarina V. Esteves David Esteban-Gomez Carlos Platas-Iglesias Raphael Tripier R DELGADO
Groups MET
Journal INORGANIC CHEMISTRY
Year 2018
Month June
Volume 57
Number 11
Pages 6466-6478
Abstract The triethylbenzene-bis-cyclen (cyclen = 1,4,7,10-tetraazacyclododecane) compound (tbmce) was designed with an imposed structural rigidity at the m-xylyl spacer to be compared to a less restrained and known parent compound (bmce). The framework of both compounds differs only in the substituents of the m-xylyl spacer. The study was centered in the differences observed in the acid base reactions of both compounds, their copper(II) and zinc(II) complexation behaviors, as well as in the uptake of phosphate and polyphosphate anions (HPPi(3-), ATP(4-), ADP(3-), AMP(2-), PhPO42-, and HPO42-). On the one hand, the acid base reactions showed lower values for the third and constants of tbmce than for bmce, suggesting that the ethyl groups of the spacer in tbmce force the two cyclen units to more conformational restricted positions. On the other hand, the stability constant values for copper(II) and zinc(II) complexes revealed that bmce is a better chelator than tbmce pointing out to additional conformational restraints imposed by the triethylbenzene spacer. The binding studies of phosphates by the dinuclear copper(II) and zinc(II) complexes showed much smaller effective association constants for the dicopper complexes. Single-crystal X-ray and computational (density functional theory) studies suggest that anion binding promotes the formation of tetranuclear entities in which anions are bridging the metal centers. Our studies also revealed the dinuclear zinc(II) complex of bmce as a promising receptor for phosphate anions, with the largest effective association constant of S.94 log units being observed for the formation of [Zn(2)bmce(HPI]+. Accordingly, a colorimetric study via an indicator displacement assay to detect phosphates in aqueous solution found that the [Zn(2)bmce](4+) complex acts as the best receptor for pyrophosphate displaying a detection limit of 2.5 nM by changes visible to naked eye.
DOI http://dx.doi.org/10.1021/acs.inorgchem.8b00539
ISBN
Publisher
Book Title
ISSN 0020-1669
EISSN 1520-510X
Conference Name
Bibtex ID ISI:000434491700031
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