New La(III) Complex Immobilized on 3‑Aminopropyl-Functionalized Silica as an Efficient and Reusable Catalyst for Hydrolysis of Phosphate Ester Bonds

Described
herein is the synthesis, structure, and monoesterase and diesterase
activities of a new mononuclear [LaIII(L1)­(NO3)2] (1) complex (H2L1 = 2-bis­[{(2-pyridylmethyl)-aminomethyl}-6-[N-(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, 1 undergoes
disproportionation to form a dinuclear species (APS-1), 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 APS-1 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 1 is also converted
into the dinuclear active species as observed with APS-1, and both were shown to be efficient in DNA cleavage.