The formation of host-guest between piperine and cucurbit [n] uril (n = 6,7) molecules were studied using experimental and density functional theory (DFT) calculations. The host-guest complexation was monitored using UV-Visible and isothermal calorimetric (ITC) methods. The obtained Jobs plot indicate the formation of 1:1 complex. ITC analysis shows a moderate binding of the guest to the host molecules. The enthalpy of binding and the free energy of formation were negative indicating the facile formation of inclusion complex at room temperature. DFT studies confirm the formation of stable inclusion complexes. In stable inclusion complex of piperine with cucurbit[6]uril, the aromatic moiety was found to be inside the cucurbituril cavity, while in the cucurbit[7]uril inclusion complex, the piperidine moiety was inside the cavity, which was further confirmed by time dependent-DFT study. The global reactivity descriptors analysis, indicate the formation of piperine inclusion complex with cucurbit[7]uril, could prevent the isomerization reaction of piperine. Atoms-in-molecules analysis shows the presence of extra inter and intramolecular bond critical points in the piperine inclusion complex with cucurbit[7]uril, which accounts for its extra stability. The computed intermolecular bond parameters confirm the existence of a non-covalent with partial electrostatic interactions between the guest and host molecules. Energy decomposition analysis, suggest the Pauli repulsion to be higher for the cucurbit[6]uril inclusion complex, while the dispersion plays a major role in stabilizing the cucurbit[7]uril inclusion complex, which was further corroborated by noncovalent index analysis.

We have used density functional theory, Grand canonical Monte Carlo (GCMC), and ideal adsorption solution theory (IAST) to understand the selective adsorption of flue within the cavity of porous metallocavitand pillarplex (PPX) molecule. Energies associated with the guest@PPX complex formation depict the effectiveness of encapsulation of guest within PPX. PPX is noted to have high selectivity toward the adsorption of Br 2 , HBr, CS 2 , H 2 S, and NO 2 over their respective congeners. The strength of bonding and nature of the interaction is deciphered via quantum theory of atoms in molecule, noncovalent interaction, and energy decomposition analysis scheme. The molecules containing acidic hydrogen, viz., H 2 O, H 2 S, HF, HCl, and HBr, make hydrogen bonding with the −N atom of the pyrazole ring, and F 2 and Cl 2 make partially covalent bonding interaction with the −Au atom of PPX. The interaction is mostly of the van der Waals type, except in F 2 , Cl 2 , NO, and HF, in which the cumulative contribution of orbital, electrostatic, and dispersion terms are important. Furthermore, GCMC and IAST predict the quantitative capture of guest molecules and selectivity of the guest. Among the studied gases, Br 2 is the potential candidate at ambient condition, followed by CS 2 , Cl 2 , and H 2 S. At high pressure and temperature, CS 2 selectivity is more predominant.

Herein, we have reported a blue LED-induced tandem Boc-deprotection and NH-alkylation of benzimidazole derivatives with methyl aryl diazoacetates. The reactions occur in water at room temperature. The desired products are obtained in good to excellent yields. The putative mechanism of this reaction is discussed based on control experiments and supported by DFT studies. Additionally, the strategy is used to alkylate various purine derivatives via site-selective N1-alkylation to generate acyclic nucleoside analogues.

Functions of a biological system are governed by a molecular recognition process which may turn baffling in the case of polymorphic drugs with distinct modes of action. To examine the electronic factors that direct the interactions at the active site of a target leading to the diverse binding affinities, here, we study three polymorphic forms of an anticancer agent. We perform experimental charge density analyses to highlight the differences and similarities of their topological properties. At the molecular level, we compare their geometries, orbital energies, binding energies, and topological properties of electron densities to monitor the changes that polymorphic ligands may undergo upon complexation with human γ-enolase. Further, we investigate the preferential binding mechanism of the ligands based on both electrostatic complementarity analysis and the study of enzyme−ligand interactions in the molecular dynamics simulated complex structure via noncovalent interactions analysis. Thus, we probe the root of the diversity in binding affinities of the polymorphs using quantum crystallographic approaches. The findings from these experimental and computational studies are expected to assist the drug development process.

The light hydrocarbon C1–C4 has been adsorbed and separated by using the pillarplex as the separating medium. The distinctive high binding energy and selective separation at ambient conditions is the unique strength of this novel metallocavitand.