AUTHOR=Horn Jr. Adolfo , Englert Daniel , Roberts Asha E. , Comba Peter , Schenk Gerhard , Krenske Elizabeth H. , Gahan Lawrence R. 

TITLE=Synthesis, Magnetic Properties, and Catalytic Properties of a Nickel(II)-Dependent Biomimetic of Metallohydrolases

JOURNAL=Frontiers in Chemistry

VOLUME=6

YEAR=2018

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2018.00441

DOI=10.3389/fchem.2018.00441

ISSN=2296-2646

ABSTRACT=<p>A dinickel(II) complex of the ligand 1,3-bis(bis(pyridin-2-ylmethyl)amino)propan-2-ol (HL1) has been prepared and characterized to generate a functional model for nickel(II) phosphoesterase enzymes. The complex, [Ni<sub>2</sub>(L1)(μ-OAc)(H<sub>2</sub>O)<sub>2</sub>](ClO<sub>4</sub>)<sub>2</sub>·H<sub>2</sub>O, was characterized by microanalysis, X-ray crystallography, UV-visible, and IR absorption spectroscopy and solid state magnetic susceptibility measurements. Susceptibility studies show that the complex is antiferromagnetically coupled with the best fit parameters <italic>J</italic> = −27.4 cm<sup>−1</sup>, <italic>g</italic> = 2.29, <italic>D</italic> = 28.4 cm<sup>−1</sup>, comparable to corresponding values measured for the analogous dicobalt(II) complex [Co<sub>2</sub>(L1)(μ-OAc)](ClO<sub>4</sub>)<sub>2</sub>·0.5 H<sub>2</sub>O (<italic>J</italic> = −14.9 cm<sup>−1</sup> and <italic>g</italic> = 2.16). Catalytic measurements with the diNi(II) complex using the substrate bis(2,4-dinitrophenyl)phosphate (BDNPP) demonstrated activity toward hydrolysis of the phosphoester substrate with <italic>K</italic><sub><italic>m</italic></sub> ~10 mM, and <italic>k</italic><sub><italic>cat</italic></sub> ~0.025 s<sup>−1</sup>. The combination of structural and catalytic studies suggests that the likely mechanism involves a nucleophilic attack on the substrate by a terminal nucleophilic hydroxido moiety.</p>