Comparative Conformational Study of a New Terpenoid-like Chalcone

Abstract Chalcones constitute an important class of flavonoids, which are naturally or synthetically obtained with relevant biological activities such as anti-inflammatory, antioxidant, antileishmanial, antitubercular, anticancer, anti-HIV, antibacterial, antimalarial, antituberculosis, and antiulcer. Conformational differences in these compounds influence their physical-chemistry properties, and the comparative structural analysis is relevant to describe changes in their properties. In this way, we aim to evaluate the conformational changes of three (1E,4E)-1-(4-nitrophenyl)-5-(2,6,6-trimethylcyclohex-2-en-1-yl)penta-1,4-dien-3-one (CHL) crystal structure polymorphs. In addition, Hirshfeld surfaces and theoretical calculations were used to analyze intermolecular interactions responsible for the supramolecular arrangement and molecular stability. The molecular packing of these terpenoid-like chalcones is stabilized by semi-classical C–H…O interactions, and hydrophobic C–H•••π interactions. The HOMO-LUMO gap confirmed the order of kinetic stability in the gas phase CHL-m1 > CHL-o > CHL-m2 showing the difference that polymorphism can cause; these differences can affect the properties of the compound and thus influence its applications.