New La(III) Complex Immobilized on 3‑Aminopropyl-Functionalized
Silica as an Efficient and Reusable Catalyst for Hydrolysis of Phosphate
Ester Bonds
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Abstract
Described
herein is the synthesis, structure, and monoesterase and diesterase
activities of a new mononuclear [La<sup>III</sup>(L<sup>1</sup>)(NO<sub>3</sub>)<sub>2</sub>] (<b>1</b>) complex (H<sub>2</sub>L<sup>1</sup> = 2-bis[{(2-pyridylmethyl)-aminomethyl}-6-[<i>N</i>-(2-pyridylmethyl) aminomethyl)])-4-methyl-6-formylphenol) in the
hydrolysis of 2,4-bis(dinitrophenyl)phosphate (2,4-BDNPP). When covalently
linked to 3-aminopropyl-functionalized silica, <b>1</b> undergoes
disproportionation to form a dinuclear species (<b>APS-1</b>), whose catalytic efficiency is increased when compared to the homogeneous
reaction due to second coordination sphere effects which increase
the substrate to complex association constant. The anchored catalyst <b>APS-1</b> can be recovered and reused for subsequent hydrolysis
reactions (five times) with only a slight loss in activity. In the
presence of DNA, we suggest that <b>1</b> is also converted
into the dinuclear active species as observed with <b>APS-1</b>, and both were shown to be efficient in DNA cleavage