Divalent metal ion binding to carboxylate groups is ubiquitous in biochemical and industrial processes. Cellular signaling, protein interactions, industrial surfactants, and carboxylate-functionalized nanoscale materials are often influenced by divalent metal ion binding. Divalent metal ions mediate the adsorption and self-assembly behavior of nanoscale materials; the behavior of which is often dependent on the identity of the metal ion. An understanding of the underlying physical interactions that govern divalent metal ion binding to carboxylate-terminated nanoscale materials may provide insight into these ion-specific effects. Experimentally, alkaline earth metal ion binding to a carboxylate-terminated alkanethiol monolayer has been studied by atomic force microscopy and infrared and Raman spectroscopy. Additional physical insight may be gained by atomistic molecular dynamics simulations, but divalent metal ions often require specialized force field parameters. Numerous force field parameters have been proposed for Mg2+ and Ca2+, and, to a lesser extent, Sr2+ and Ba2+. Here, we systematically compare available force field parameters for Mg2+, Ca2+, Sr2+, and Ba2+ in classical molecular dynamic simulations of divalent metal ion binding to a deprotonated 11-mercaptoundecanoic acid monolayer. Results are compared to available experimental data to identify accurate force field parameters. Analysis of the simulations reveal preferred binding motifs and estimate ion affinities. Results from this work provide a framework from which the ion-specific effects of alkaline earth metal ion binding to other nanoscale materials may be simulated using classical molecular dynamics simulations.

Alkaline earth metal ion binding to a carboxylate-terminated monolayer

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.