Dinuclear zinc(II) complexes with hydrogen bond donors as structural and functional phosphatase models

Area of Science:

• Coordination Chemistry
• Biomimetic Chemistry
• Catalysis

Background:

• The secondary coordination sphere plays a vital role in the functional properties of biomimetic metal complexes.
• Hydrogen bonding interactions can modulate primary coordination sphere structure and substrate binding.
• Phenolate-based ligands are established for developing metallo-hydrolase mimics.

Purpose of the Study:

• To design and synthesize novel ligands for metallo-hydrolase mimics with controlled secondary coordination spheres.
• To investigate the impact of hydrogen bonding on the structure-function relationship of dinuclear zinc(II) complexes.
• To assess the phosphatase activity of these model systems and correlate it with secondary coordination sphere modifications.

Main Methods:

• Synthesis and structural characterization of new phenolate-based ligands (H3L(2), H3L(3), HL(4), H4L(6)).
• Preparation and solid-state structural characterization of five dinuclear Zn(II) complexes.
• Solution-state characterization of four dinuclear Zn(II) complexes.
• Enzymatic assays to evaluate phosphatase activity and determine Michaelis-Menten constants.

Main Results:

• Developed ligands with site-specific modifications in the secondary coordination sphere, incorporating pivaloylamide and amine moieties.
• Structurally characterized dinuclear Zn(II) complexes, confirming similar primary coordination spheres but varied secondary coordination environments.
• Observed that complexes facilitating hydrogen bonding exhibited smaller Michaelis-Menten constants, indicating stronger catalyst-substrate binding.
• Demonstrated higher catalytic efficiency and turnover numbers in complexes with effective hydrogen-bonding networks.

Conclusions:

• Secondary coordination sphere engineering is a powerful strategy to tune the activity of biomimetic metallo-hydrolases.
• Hydrogen bonding networks are crucial for optimizing substrate positioning and product release.
• The designed metallo-hydrolase mimics show enhanced catalytic performance due to strategic secondary coordination sphere interactions.