Designing enantioselectivity in chiral self-assembly at a solid substrate: a theoretical study of competing interactions

Abstract

Chiral structure formation is ubiquitous in surface self-assembly. Molecules that do not undergo chiral recognition in solution or fluid phases can do so when their configurational freedom is restricted in the two-dimensional field of a substrate. The process holds promise in the manufacture of functional materials for chiral catalysis, sensing or nonlinear optics. The present work investigates the relationships between molecular features, specifically molecular geometry and charge distribution, and chiral recognition at surface self-assembly. Simple model molecules are considered, having two prochiral centers and four partial charges. These model features embody the fundamental interactions involved in supramolecular structure formation in experimental systems, but allow the in-depth investigation of key parameters. The molecules have previously shown polymorphic behavior, with the formation of homochiral clusters in metastable states, but not in their equilibrium configurations, and are used here to show how molecular substitution can be manipulated to induce chiral recognition and homochiral structure formation, in molecules that were previously unable to segregate at surface assembly. Furthermore, the analysis of pair and multibody interactions provides an avenue for in-depth understanding and even prediction of the result of the surface adsorption process.