A calix[4]arene derivative and its selective interaction with drugs (clofibric acid, diclofenac and aspirin)

The supramolecularly complexes of calix[4]arene derivatives toward favipiravir antiviral drug (used to treatment of COVID-19): a DFT study on the geometry optimization, electronic structure and infrared spectroscopy of adsorption and sensing

While the world is in search of a vaccine that can cure COVID-19 disease, favipiravir is the most commonly used antiviral drug in the treatment of patients during the pandemic process. In this study, we investigated the host-guest interaction between the popular supramolecule calix[4]arene derivatives and the favipiravir drug by using the DFT (Density Functional Theory) method. The B3LYP hybrid method and 6-31G (d,p) basis set were utilized to determine the optimized structures of the host and guest molecules and their complexes. The negative adsorption energy (∆E) and adsorption enthalpy (∆H) calculated for the complexes formed between calix[4]arene compounds and favipiravir drug molecule mentioned that adsorption of favipiravir molecule was an exothermic process on calix[4]arene structures. On the other hand, among the calixarene derivatives in the study, Gibbs free energy change (∆G) value for the adsorption was only negative on calix[4]arene4 molecule. The infrared spectroscopy (IR) calculations were performed by examining the C=O, O-H and NH2 vibrational frequencies to see the adsorption behavior in the favipiravir-calix[4]arene complex. After adsorption of the favipiravir molecule, HOMO-LUMO gap values decreased significantly for the structures and therefore electrical conductivity increased proportionally. In addition, sensor response factors, Fermi energy levels and workfunction changes of calix[4]arene derivatives were calculated and examined. Charge transfer between the four calix[4]arene compounds and the favipiravir molecule has occurred after adsorption. This attributes that calix[4]arene derivatives can be used as a well-suited favipiravir sensor (electronic and workfunction) and adsorbent at room temperature. Based on the calculations made to see the solvent effect on the adsorption of favipiravir it was determined that it did not affect the interaction between the drug molecule and the calix[4]arene compound too much and the adsorption energy turned into a slightly less negative value.

Hydration of the Carboxylate Group in Anti-Inflammatory Drugs: ATR-IR and Computational Studies of Aqueous Solution of Sodium Diclofenac

Diclofenac (active ingredient of Voltaren) has a significant, multifaceted role in medicine, pharmacy, and biochemistry. Its physical properties and impact on biomolecular structures still attract essential scientific interest. However, its interaction with water has not been described yet at the molecular level. In the present study, we shed light on the interaction between the steric hindrance (the intramolecular N-H···O bond, etc.) carboxylate group (-CO₂^-) with water. Aqueous solution of sodium declofenac is investigated using attenuated total reflection-infrared (ATR-IR) and computational approaches, i.e., classical molecular dynamics (MD) simulations and density functional theory (DFT). Our coupled classical MD simulations, DFT calculations, and ATR-IR spectroscopy results indicated that the -CO₂^- group of the diclofenac anion undergoes strong specific interactions with the water molecules. The combined experimental and theoretical techniques provide significant insights into the spectroscopic manifestation of these interactions and the structure of the hydration shell of the -CO₂^- group. Moreover, the developed methodology for the theoretical analysis of the ATR-IR spectrum could serve as a template for the future IR/Raman studies of the strong interaction between the steric hindrance -CO₂^- group of bioactive molecules with the water molecules in dilute aqueous solutions.