Harnessing Noncovalent Interactions for a Directed Evolution of a Six-Component Molecular Crystal

Building up on weak orthogonal interactions in supramolecular chemistry, a six-component crystal is designed. Using five distinctly different noncovalent forces, namely, hydrogen bonding, halogen bonding, cation-pi, anion-pi, and ion-pair interactions, three six-component crystals were designed with crown-ether (I), thiourea (II), 2,3,5,6-tetrafluoro-1,4-dibromobenzene (III), lone-pair donating anion (IV), ammonium cation (V), and electron-rich aromatic ring (VI). The M06-2X functional which is highly suitable in describing other weak interactions fails for ion-pairs. Tuned range-separated (RS)-DFT calculations are found to be capable in describing the ionic interactions in molecular solids. Molecular dynamics simulations show that the predicted multicomponent crystals are stable at room temperature and reducing the ionic charges for the ion-pairs destabilizes them. The strong electrostatic interactions between the three ion-pairs, NH4+center dot center dot center dot ClO4-, NH4+center dot center dot center dot HSO4-, and NH4+center dot center dot center dot HCO3- is the primary driving force for the stabilization of the six-component crystal. Using a hybrid of strong and weak intermolecular interactions, one may generate exotic molecular complexity like n-component crystals.

Automated summary

A six-component crystal is designed based on weak orthogonal interactions in supramolecular chemistry, utilizing five distinctly different noncovalent forces. The use of tuned range-separated (RS)-DFT calculations is found effective in describing ionic interactions in molecular solids, and the strong electrostatic interactions between ion-pairs are the primary driving force for stabilizing the six-component crystal. Mixing strong and weak intermolecular interactions may lead to the generation of exotic molecular complexity like n-component crystals.