Introduction -- Experimental -- Understanding the Overall Structure of GpdQ and Metal Binding -- Structural and Mechanistic Studies of Zn(II) Complexes as Phosphoesterase Models -- Mechanistic Studies of Cd(II) Complexes as Phosphoesterase and Metallo-β-lactamase Models -- Spectroscopic and Mechanistic Studies of Co(II) Phosphoesterase and Metallo-β-lactamase Biomimetics -- Asymmetric Zn(II) Complexes as Structural and Functional Models for GpdQ -- Immobilization of GpdQ and Related Models for Bioremedial Applications -- Conclusion and Outlook.