Effect of the methanol molecule on the stabilization of C18H18O4 crystal: combined theoretical and structural investigation.

The ability of the chalcone, C18H18O4, to form solvates was theoretically and experimentally investigated. The unit cell with Z' > 1, composed of two independent chalcone molecules (α and ß), shows the formation of a stable molecular complex which is related with the presence of methanol in this crystal lattice. Aiming to understand the process of crystal lattice stabilization, a combination of techniques was used, including X-ray diffraction (XRD), computational molecular modeling, and an ab initio molecular dynamic. The results show that α and ß molecules are sterically barred from forming a direct hydrogen bond with one other. In addition, the presence of the methanol molecule stabilizes the crystal structure by a bifurcated O-H···O interaction acting as a bridge between them. The theoretical thermodynamic parameter and the rigid potential energy surface scan describe the role of methanol in the energy stabilization of the crystal. The absence of the methanol compound in the asymmetric unit destabilizes the crystalline structure, making the formation process of the asymmetric unit nonspontaneous. The energy difference between α and ß molecules is around 0.80 kcal·mol(-1), indicating that both are stable and equally possible in the crystal lattice. The analysis of the energy profile of the C14-O2···H1-O3 and O2-H1···O3-C17 torsion angles in the crystal packing shows that the α and ß molecules are confined in the stable potential region, in agreement with the two conformers in the asymmetric unit. The Molecular Electrostatic Potential (MEP) shows that the methanol has no steric effects, which prevents small motion around the torsion angles.

Structural and Anticancer Studies of Methoxyflavone Derivative from Strychnos pseudoquina A.St.-Hil. (Loganiaceae) from Brazilian Cerrado.

The Cerrado biome is the world's largest and most diversified tropical savanna. Despite its diversity, there remains a paucity of scientific discussion and evidence about the medicinal use of Cerrado plants. One of the greatest challenges is the complexity of secondary metabolites, such as flavonoids, present in those plants and their extraction, purification, and characterization, which involves a wide range of approaches, tools, and techniques. Notwithstanding these difficulties, the search for accurately proven medicinal plants against cancer, a leading cause of death worldwide, has contributed to this growing area of research. This study set out to extract, purify, and characterize 3-O-methylquercetin isolated from the plant Strychnos pseudoquina A.St.-Hil. (Loganiaceae) and to test it for antiproliferative activity and selectivity against different tumor and nontumor human cell lines. A combined-method approach was employed using 1H and 13C nuclear magnetic resonance, thermogravimetric analysis, differential scanning calorimetry, single-crystal X-ray diffraction, Hirshfeld surface analysis, and theoretical calculations to extensively characterize this bioflavonoid. 3-O-methylquercetin melts around 275 °C and crystallizes in a nonplanar conformation with an angle of 18.02° between the pyran ring (C) and the phenyl ring (B), unlike quercetin and luteolin, which are planar. Finally, the in vitro cytotoxicity of 3-O-methylquercetin was compared with data from quercetin, luteolin, and cisplatin, showing that structural differences influenced the antiproliferative activity and the selectivity against different tumor cell lines.

Cyclohexanone-Based Chalcones as Alternatives for Fuel Additives.

The use of small molecules, such as chalcones and their derivatives, for more efficient fuels is in increasing demand due to environmental factors. Here, three crystal structures (BH I, II, and III) of cyclohexanone-based chalcones were synthesized and described by single-crystal X-ray diffraction and Hirshfeld surface analysis. The supramolecular modeling analysis on the hyperconjugative interaction energies and QTAIM analysis at the ωB97XD/6-311++G(d,p) level of theory were carried out to analyze the intermolecular interactions in the solid-state. The structure-property relationship, frontier molecular orbital, molecular electrostatic potential, and the experimental calorific value analysis show that the three compounds are a good alternative to be used as an additive for some fuels. Our findings represent a further step forward in the development of cheaper and more efficient fuel additives and pose an opportunity for further investigation on similar analogues.

A new isostructural halogenated chalcone with optical properties.

Chalcones are organic compounds that present a number of properties. This study presents a comprehensive structural description of a new derivative of a chlorine-substituted chalcone in comparison with a bromine chalcone. Also, supermolecule and sum-over-state approach were used to describe the optical properties of these structures regarding the substitution of the bromine by the chlorine atom. In addition, the electrical properties, dipole moment, linear polarizability, and second IDRI hyperpolarizability were calculated. The linear refractive index and the third-order nonlinear macroscopic susceptibility were evaluated as a function of the applied electric field frequency. Furthermore, the quantum mechanics calculations that were implemented at the M06-2X/6-311++G(d,p) level of the theory for these isostructural chalcones indicate that the change in halogen atoms does not cause meaningful changes in their conformation. Finally, we can postulate that side-to-side and the antiparallel interactions are the interaction forces that drive the crystal growth for new isostructural chalcones. The NLO properties showed title compounds that are good candidates for use as NLO materials.