Computational approach to understanding the structures, properties, and supramolecular chemistry of pagoda[n]arenes

Abstract

Studies on the synthesis, characterization, and applications of new macrocyclic host species have greatly promoted the development of supramolecular chemistry. Recently, pagoda[n]arenes (Pa[n]As), a class of anthracene-based macrocyclic arenes, were reported by Chen's group. Pa[n]As are inherently endowed with many fascinating properties. In order to fully understand Pa[n]As and expand their potential applications, the structures, properties, and supramolecular chemistry of Pa[n]As are systematically studied by using a computational approach. Based on density functional theory (DFT) calculations, nine homogenous Pa[n]As (n = 4∼6) and six hybrid Pa[4]As are discussed in detail because of their rigid pagoda molecular frameworks and their lower energies. The frontier molecular orbitals and electrostatic potential maps reveal the nature of their electronic structures. Correspondingly, UV–vis spectra are predicted by time-dependent (TD)-DFT calculations. Moreover, Pa[n]A molecules are capable of forming host‒guest complexes and self‒assemblies by noncovalent interactions. H-bonding, ion···pi, CH···pi, and van der Waals (vdW) interactions are addressed with the reduced density gradient (RDG) analysis. Finally, molecular dynamics (MD) simulations in the solvent show that Pa[n]As are able to recognize guests and maintain a dynamic equilibrium in the form of host-guest complexes.