A thermodynamic "vocabulary" for metal ion interactions in biological systems
1Chemistry Department, Wayne State University, Detroit, MI 48202, USA.
Abstract:
This Account focuses on metal ion-ligand complexes of biological relevance and measurements of the bond dissociation energies (BDEs) of such species. These complexes yield thermochemistry that begins to provide a thermodynamic "vocabulary" for thinking quantitatively about the strength of interactions in biological systems. The method utilized is threshold collision-induced dissociation in a guided ion beam tandem mass spectrometer. Accurate determination of BDEs requires attention to many details of the experiments and data analysis, as outlined here. Trends in metal ion-ligand BDEs are examined as a function of the metal ion, ligand, and extent of ligation. We elucidate the importance of ion-dipole and ion-induced dipole interactions, chelation, conformation, tautomeric form, steric interactions, and electronic effects such as hybridization and promotion. Interactions of metal ions with nucleobases and amino acids are quantified and the effects of hydration on these values are explored for the amino acid systems. Although data limitations restrict the present discussion to monocations, the trends elucidated here should be relevant to multiply charged metal ions, for which data is forthcoming.
Related Concept Videos
Formation of Complex Ions
Metal-Ligand Bonds
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
Complexation Equilibria: Overview
The equilibrium constant of the complexation reaction is represented as the formation constant...
Complexation Equilibria: The Chelate Effect
Complexation Equilibria: Factors Influencing Stability of Complexes
Electrochemical Systems


