Non-covalent Interaction Analysis Research Articles

Quenching Rate Constants of Lewis Base-Boryl Radical by Substrates: a Laser Flash Photolysis Study.

The advanced strategy using Lewis base-boryl radicals (LBRs) has recently been proposed for the addition of alkyl substituents to the full-carbon quaternary center of an organic molecule. However, as the rate-determining step in the whole route, reaction rate constants of LBRs with substrates are extremely lacking. In this paper, 4-dimethylaminopyridine (DMAP)-BH2• was selected as a representative of LBRs, and its reactions with six monochloro-substituted substrates, including three methyl chlorobenzoates and three chlorinated acetanilides were studied in experiments and theoretical calculations. The bimolecular reaction rate constants, kq, were determined using laser flash photolysis approach. By comparing activation energies along the two addition pathways, we have clarified the rate-determining step as the attacking to carbonyl oxygen instead of chlorine atom. Furthermore, noncovalent interaction (NCI) analyses on these substrates indicate that weak interactions, such as hydrogen-bonding and van der Waals interactions, have significant influence on the reactivity of these substrates. Our study provides concrete clues to extend this synthetic strategy.

Engaging Two Anions with Single Cation in Energetic Salts: Approach for Optimization of Oxygen Balance in Energetic Materials.

The field of high energy density materials faces a long-standing challenge to achieve an optimum balance between energy and stability. While energetic salt formation via a combination of oxygen- and nitrogen-rich anions (providing energy) with nitrogen-containing cations (providing stability) has been a proven approach for improving physical stability, constraints such as lowering density and energetic performance remain unresolved. This can be addressed by utilizing oxygen-containing cations for salt formation. However, this approach is rarely explored because its synthesis is challenging. In this work, we have designed an oxygen-rich cationic precursor 2 by incorporating 4-amino-3,5-dinitropyrazole with 3,4-diaminotriazole via an N-methylene-C bridge. Further combination with energetic acids resulted in the formation of high-performing, physically stable energetic salts 3-10. The salts were found to be generally more energetic than the salts of respective energetic acids with previously reported cations and showed prominent improvement in physical stability with respect to their anionic precursors. All the compounds were thoroughly characterized through IR, NMR spectroscopy, HRMS, and elemental analysis. Salt 9 was confirmed through 15N NMR analysis, and salts 2 and 8 were confirmed through single-crystal X-ray diffraction. Additional analyses such as Hirshfeld surface analysis, noncovalent interaction (NCI) analysis, and electrostatic potential studies were also carried out to correlate the structure-property relationship.

Behaviour of 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimdazolium thiocyanate and 1-butyl-1-methypyrrolidium chloride in dimethyl sulfoxide: Experimental, NCI and QTAIM analysis

The aim of this study is to examine the cation and anion influence on intermolecular interactions of mixtures comprising ionic liquids (ILs): 1-butyl-3-methylimidazolium chloride [Bmim][Cl], 1-butyl-3-methylimdazolium thiocyanate [Bmim][SCN] and 1-butyl-1-methylpyrrolidium chloride [Bmpym][Cl] with dimethyl sulfoxide (DMSO) at various temperatures. To understand the influence of cation and anion as well as temperature on interactions between the mixtures, thermodynamics parameters: apparent molar properties were calculated from the measured density (ρ) and sound velocity (u) data and fitted to the Redlich-Mayer type equation in order to obtained limiting apparent molar properties of the studied mixtures. A detailed non-covalent interaction (NCI) and quantum theory of atoms in molecules (QTAIM) analysis was done using density functional theory calculations. These calculations provided information on the electrostatic interactions between the anion, cation, and solvent. The experimental and computational results show that there is hydrogen bonding and strong ionic interactions in the studied systems.

Vibrational Spectra and Computational Study of Amyl Acetate: MEP, AIM, RDG, NCI, ELF and LOL Analysis

This work is focused on biologically active neat amyl acetate and its solutions in ethanol/heptane. According to the experimental results, when the concentration of amyl acetate in the amyl acetate-ethanol solution decreases, the additional band appears on the low-frequency side. The primary reason for the formation of such additional band is the intermolecular hydrogen bonding between amyl acetate and ethanol. In the amyl acetate-heptane solution, as the concentration of amyl acetate in the solution decreases, the band corresponding to the C=O stretching vibrations shifted to a higher frequency. This is explained by the fact that heptane breaks intermolecular interactions in solution, resulting in a simpler spectral band corresponding to the C=O stretching vibrations. Calculations are also used to study interactions in amyl acetateethanol complexes and their spectral manifestations. When the complex formation energies are calculated, this energy increases with the number of molecules, but the average hydrogen bond energy per one bond remains unchanged. The density functional theory (DFT) method is used to analyze molecular structural parameters: Mulliken atomic charge distribution; thermodynamic parameters; molecular electrostatic potential (MEP) surface; atoms in molecules (AIM) analysis; quantum chemical parameters such as reduced density gradient (RDG) and noncovalent interaction (NCI) analysis; electron localization functions (ELF) analysis; and localized orbital locator (LOL) analysis.

Mechanistic studies on phosphine-catalyzed [4 + 3] annulation of β′-acetoxy allenoate with 1C,3N-dinucleophile

The mechanism and role of catalyst on the PPh3-catalyzed [4 + 3] annulation reaction have been systematically investigated using density functional theory (DFT) method. Based on the calculations, the possible mechanism contains six steps: nucleophilic addition of PPh3 to allenoate to give Z-configured intermediate, cleavage of CO bond for forming phosphonium diene, nucleophilic addition of phosphonium diene with anionic 1C,3N-dinucleophile, intramolecular [1,5]-proton shift, ring-closure, and dissociation of catalyst. Non-covalent interaction (NCI) analysis shows that the O⋯P interaction would be the key for leading to the Z-configured pathway more favorable and electron localization function (ELF) analysis indicates that the implication of PPh3 can significantly lower the energy barrier involved in CO cleavage process, which mainly because the addition of PPh3 reduces the electron density of CO bond and thus facilities the cleavage of CO bond. This theoretical study would provide some clues for understanding the role of catalyst in a catalytic reaction.

Conformations of α-cyclodextrin and its role on the stability of inclusion complexes in aqueous solution

α-Cyclodextrin (αCD), a cyclic carbohydrate polymer, presents a wealth of opportunities for drug delivery and various industrial applications. Its high affinity and selectivity in encapsulating target molecules have been well-documented. However, the influence of αCD's conformational variations on its encapsulation capacity remains a promising area for further exploration. This study explores the conformational dynamics of αCD and its relationship with the formation of inclusion complexes (ICs) in aqueous solutions, focusing on understanding the forces driving these dynamics and the formation of stable ICs. Classical molecular dynamics (CMD) demonstrate that αCD solvated in water can adopt two conformations: a truncated cone shape with a suitable cavity for encapsulation and a distorted cone shape with a collapsed cavity. The predominant conformation observed in the CMD trajectory of pristine αCD is the distorted cone. However, under complexation conditions with aliphatic molecules, the guest molecule's size dictates the ICs' stability, forcing αCD to maintain the truncated cone conformation. Quantum chemistry methods and electron density analyses (Quantum Theory of Atoms in Molecules and Non-Covalent Interactions index) support CMD observations by characterizing and quantifying non-covalent interactions. Findings indicate that the shift from the truncated to the distorted cone conformation in αCD is primarily driven by intramolecular non-covalent interactions and the reconfiguration of water molecules surrounding αCD. The ICs' analysis displays a significant correlation between the size of the aliphatic chain and the intensity of intermolecular interactions. The strength of these interactions can effectively disrupt the αCD intramolecular non-covalent interactions that lead to a conformational change and, consequently, the loss of the inclusion complex. In conclusion, although αCD's conformational change can affect encapsulation, guest molecules can manipulate the conformational preference. The systematic analysis of non-covalent interactions offers a way to characterize and quantify these forces, enhancing our ability to understand and predict the stability of inclusion complexes.

Empirical, computational studies and non-covalent interactions analysis of a novel salt with cadmium transition metal precursor

In this research paper, (C3H5N2)6[CdCl4][CdCl6] was successfully synthesized using a slow evaporation process. The structure was confirmed through single-crystal X-ray crystallography, FT-IR, and thermal analysis. The material was found to crystallize in the tetragonal system (space group I41/a) and the following parameters a = b = 12.0872 (8) Å; c = 24.6985 (16) Å, the crystal packing shows parallel layers of cations and stacks of discrete anions positioned at y = 1/4 and 3/4. The junction between the monoprotonated imidazolium cations and the anions, along with the crystal structure stability, relies on Cl···H−N, and Cl···H−C hydrogen bonds. Computational investigations, conducted using the B3LYP method with 6–311++G(d,p) and LANL2DZ mixed basis set, demonstrated close alignment between the computed and the experimental data, providing insights into the material's geometrical and vibrational properties. The non-covalent interactions were studied through Atoms-In-Molecule (AIM) and Reduced Density Gradient (RDG) analysis and quantitatively using the Hirshfeld surfaces associated with 2D fingerprint plots. Furthermore, thermal stability was assessed through Thermogravimetric and Differential Scanning Calorimetry (TG–DSC) analysis.

Supradecoration induced novel Properties: A comparative study of Ferrocene and Ferrocenyl α-aminophosphonate

Decorating chemical motifs with appropriate functional groups capable of supramolecular interactions hold key in modulating these novel systems for targeted applications. This work by means of a comparative study of Ferrocene and Ferrocenyl α- aminophosphonate highlight supradecoration induced multi paradigm properties across materials to medicine. The observed results indicate an increase in crystal framework energy with induction of mechanochromism and aggregation-induced emission in case of Ferrocenyl-α-amino phosphonate as novel supra decorated Ferrocene motif. Comparative BSA and BLC studies indicated improved biocompatibility with enhancement of catalase enzyme activity in case of Ferrocenyl-α- aminophosphonate compared to pristine Ferrocene. The relative quantification of intermolecular non covalent interactions of Ferrocene and Ferrocenyl-α- aminophosphonate evaluated using Quantum crystallographic methods and non-covalent interaction analysis were used to corroborate the supramodulation effects. The observed influence of Ferrocenyl α-aminophosphonate on the enzymatic activity of catalase was also examined using a comparative molecular docking analysis. The docking results corroborated influence of supradecoration on binding affinity and binding site, which are vital for designing ligands of enhanced catalase activity and also helpful in prediction of newer regulatory sites on enzyme. Taken together this work signifies how supra decoration of Ferrocene motif with functionalities capable of diverse intermolecular non-covalent interactions modulate molecular properties for newer applications.

Charge-Assisted Anion-π Interaction and Hydrogen Bonding Involving Alkylpyridinium Cations.

Competition and cooperation of charge-assisted anion-π interactions and hydrogen bonding were explored in the solid state and in solutions of 1-ethyl-4-carbomethoxypyridinium iodide, the compound utilized by Kosower to calculate solvent polarity Z-indices. X-ray structural analysis of this salt revealed multiple short contacts of iodide anions with hydrogen atoms and aromatic rings of pyridinium cations. Geometric characteristics, quantum theory of atoms in molecules (QTAIM), and noncovalent interaction (NCI) analysis of these contacts indicated comparable interaction energies of the anion-π and hydrogen bonding between iodide and pyridinium cation. 1H NMR (indicating the presence of the hydrogen-bonded complexes) and UV-vis measurements (which were consistent with the formation of anion-π associations) pointed out that both these supramolecular interactions also coexist in solutions. The comparable interaction energies (ΔE) of these modes were confirmed by the DFT computations. Also, while the variations of ΔE with the dielectric constant of the solvents for the complexes of iodide with the neutral π-acceptors were related to the increase of the effective radii of hydrogen- or anion-π bonded iodides, the changes in ΔE for the complexes with pyridinium followed interaction energies between two unit charges. However, the distinction of the bonding in hydrogen-bonded and anion-π complexes of iodide with pyridinium led to a switch of their relative energies with an increase of the polarity of the medium.

End Group Effects on Anion Binding in Tetraglycine Peptide: A Computational Study.

The importance of anions in various processes has led to a search for molecules that can effectively recognize and interact with these anions. This study explores how the tetraglycine (Gly)4 peptide in its zwitterionic, neutral, and terminally capped forms acts as a receptor for H2PO4- and HSO4- anions within the framework of supramolecular host-guest chemistry. Using molecular dynamics (MD) simulations, we obtained the conformations of the receptor-anion complexes. Density functional theory (DFT), quantifies the complexes' interaction energies in both gas and solvent phases. Proton transfer within the zwitterionic complex with H2PO4- anion alters peptide charge distribution, affecting its conformation and binding site arrangement, as analysed by quantum mechanics/molecular mechanics (QM/MM) methods. Symmetry-adapted perturbation theory (SAPT) and noncovalent interactions analysis highlight the role of electrostatic interactions in these receptor-anion complexes. It emphasizes the key interactions such as N-H···O and O-H···O=C between the peptide backbone and anions and elucidates the molecular recognition mechanism driven by crucial noncovalent interactions. The termination of the peptide's end groups modulates anion binding sites from the backbone to the charged N-terminal, resulting in distinct binding sites. Our findings provide insights for designing peptides tailored to function as anion receptors in diverse supramolecular chemistry applications.

Structure and noncovalent interaction analysis of half-sandwich chiral-at-metal organoruthenium complexes with planar and η6-arene-metal axial chirality

The preparation of organometallic compounds has provided new molecular complexity in molecular science. The stereochemistry of organometallics has long been a great challenge due to the large atom radius and more valency. Herein, eight ruthenium piano-stool shaped Ru complexes 2a-d and 3a-d with η6-planar chirality and Ru-center chirality were successfully synthesized and resolved, and the absolute configurations were determined by X-ray diffraction analysis. Racemization experiment revealed the stability differences of the Ru complexes in various solvents. Furthermore, in asymmetric unit of complex 3b, there are two conformers bearing opposite η6-arene-Ru axial chirality. In the supramolecular organization, all of the Ru complexes are stabilized by hydrogen bonding, C-H···π and Cl/I···π interactions. π···π interaction was only observed in complex 3b. The Hirshfeld surface analysis and 2D fingerprint plot show that the eight complexes have a similar contribution composed of different noncovalent interactions to the stabilization of crystal packing. Interestingly, only complex 3b has 3.5% C···C interaction. The pairwise interaction energies were calculated using CE-B3LYP energy model and further visualized by 3D-energy framework, which show that the dominant interaction for all complexes is dispersion. Theoretical energies of each conformer of complex 2a-d and 3a-d with η6-arene rotated at different angles was calculated by DFT method, and the energy barrier between the two conformations was around 2-3 kcal/mol. Halide ligand exchange experiments on complex (SRu)-1a were performed and the plausible mechanism was proposed. These results have provided new evidence for the design of molecules with specific fine stereochemical information for potential applications in medicinal and material chemistry.

Chalcogenides encapsulated Pt-doped carbon quantum dot (Pt@CQD) as a carrier for the controlled release of lapachone: Outlook from theoretical calculations

While cancer remains a significant health concern for humans, and is a serious and life-threatening disease, this research introduces an innovative drug delivery strategy employing platinum-doped carbon quantum dots (Pt@CQD) decorated with chalcogenide (O, S, Te) atoms for targeted delivery of the anti-inflammatory drug lapachone (LPC), which was analysed through density functional theory (DFT) at the ωB97XD/def2svp level of theory. Adsorption studies indicated exothermic behaviour, with negative energies for LPC_Pt@CQD, LPC_OdecPt@CQD, LPC_SdecPt@CQD, and LPC_TedecPt@CQD with corresponding values of −25.549 kcal/mol, −24.583 kcal/mol, −24.629 kcal/mol and − 24.419 kcal/mol respectively, indicating their chemisorption strengths. The quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) analyses highlight weak and partial interactions among the complexes. Significantly, the engineered systems exhibit notable drug-release properties, especially LPC_OdecPt@CQD, where we observed a considerably slight physisorption and an adsorption energy of 10.277 kcal/mol and a protonation energy gap (ΔE) of 2.648 eV which balances effective adsorption and the ability to release the drug when needed. Furthermore, molecular dynamics and reactivity analysis revealed high stability and biological activity respectively among the designed systems, making them promising candidates for therapeutic delivery and holding potential for further in vivo and clinical investigations.

Mapping the Interaction Landscape of Adenosine and Minoxidil Sulfate Using an Independent Gradient Model Based on Hirshfeld Partition and Interaction Region Indicator.

Using theoretical techniques, the interactions between adenosine (AD) and minoxidil sulfate (MS) were studied using the DFT/M06-2X/aug-cc-pVDZ level of theory. The formation of the complex was thermodynamically favorable, so we carried out further studies. Frontier molecular orbital analysis shows that the HOMO-LUMO- gap is high (6.81 eV), which means that the complex is kinetically stable. The global reactivity parameters were also calculated to get insight about the chemical reactivity of the complex. Molecular electrostatic potential and charge analyses were carried out for the optimized complex. To study the charge transfer and inter- and intramolecular interactions present in the complex molecule, we employed natural bond orbital analysis. Noncovalent interaction (NCI) analysis along with IGMH and IRI analyses further helped us find the weak interactions. The presence of hydrogen bonds between the N atom (N27) of MS and H atom (H66) of AD and O atom (O32) of MS and H atom (H46) of AD was the main finding of these analyses. QTAIM investigation also supports this finding. EDA analysis was carried out to further study the intermolecular interactions present within the complex. Thus, the present investigation unveils the existence of weak NCIs in the complex.

Integrating strategy to investigate the formation and stabilization mechanisms of Curcumin-Cyclodextrin inclusion complexes: experimental characterizations and multi-scale computational simulations.

The Cyclodextrin (CD) encapsulation technology can significantly enhance the water solubility of Curcumin (CUR) and effectively protect it against chemical degradations. In the current study, a combination of experimental and multi-scale computational approaches was used to investigate the binding mechanism between CUR and β-CDs (β-CD, 2-HP-β-CD, Me-β-CD, and DM-β-CD). Phase solubility studies showed that β-CDs exhibited a strong binding affinity with CUR and significantly enhanced its solubility. SEM, PXRD, DSC, and TG analysis confirmed the formation of inclusion complexes, resulting in the transition of CUR from crystalline to an amorphous state. FTIR, 1H, and 13CNMR spectra deduced that CUR may have multiple binding conformations with β-CDs. The rationality of molecular dynamics simulation systems was confirmed by comparing the simulated IR spectrum from quantum mechanics with the experimental IR spectrum. MM-PBSA and umbrella sampling simulation calculated the binding free energy of the CUR/CD inclusion complexes, ranking Me-β-CD > DM-β-CD > 2-HP-β-CD > β-CD, and clarified that van der Waals interaction played a major role in stabilizing the inclusion complexes. RDF analysis confirmed that the release of high-energy water molecules drove the formation of the CUR/CD inclusion complex, and the β-CD substituents affected their exterior hydration layer. Additionally, principal component analysis (PCA) and non-covalent interaction analysis revealed three CUR/CD binding modes: bead-on-string, terminal insertion, and V-shaped-folding. The research strategy adopted here can serve as a paradigm for investigating the encapsulation mechanism of poorly soluble drugs with CDs.

The Effect of Hyperconjugation and Hydrogen Bonding on the Conformers of Methylated Monosaccharides.

The conformational landscapes of four 1-O-methylated monosaccharides-methyl a-glucose, methyl b-glucose, methyl a-galactose, and methyl b-galactose-were characterized using jet-cooled broadband rotational spectroscopy, supported by density functional theory calculations. A newly designed, simple pulsed nozzle assembly was used to introduced the sugar samples into a jet expansion without thermal degradation, eliminating the need for a complex and expensive laser ablation system. Ten conformers were experimentally identified by assigning their rotational spectra, and the intricate methyl internal rotation splittings were analysed. Notably, methylation alters the directionality of intramolecular hydrogen bonding of a-galactose highlighting its impact on structural preference. Natural bond orbital, intrinsic bond strength, and non-covalent interaction analyses were conducted to explore the interplay between hydrogen bonding and hyperconjugation. A set of σ to σ* neutral hyperconjugative interactions were found to override a strong hydrogen bond, driving a preference for the gauche conformers.

Efficient Self‐Sorting Behaviours of Metallacages with Subtle Structural Differences

AbstractInvestigating the self‐sorting behaviour of assemblies with subtle structural differences is a captivating yet challenging endeavour. Herein, we elucidate the unusual self‐sorting behaviour of metallacages with subtle structural differences in batch reactors and microdroplets. Narcissistic self‐sorting of metallacages has been observed for two ligands with identical sizes, shapes, and symmetries, with only minor differences in the substituted groups. In particular, the self‐sorting process in microdroplets occurs within 1 min at room temperature, in stark contrast to batch reactors, which require equilibration for 30 min. To reveal the mechanism of self‐sorting and the role of microdroplets, we conducted a series of experiments and theoretical calculations, including competitive self‐assembly, cage‐to‐cage transformation, control experiments involving model metallacages with larger cavities, noncovalent interaction analysis, and root mean square deviation (RMSD) analysis. This research demonstrates an unusual case of self‐sorting of very similar assemblies and provides a new strategy for facilitating the self‐sorting efficiency of supramolecular systems.

Experimental and Theoretical Studies for Noncovalent Interactions Analysis of 2-Phenyl Imidazole Derivative: Perspective for Anti-Inflammatory Activity

Synthesis of 2-Phenyl imidazole derivative has been carried out for the studies of quantitative non-covalent interactions and anti-inflammatory activity. Hirshfeld surface analysis, crystal structure, and non-covalent interaction computation have all been used to do quantitative investigations of non-covalent interactions. The intermolecular interactions calculations have been done with crystalexplorer 17. Further, anti-inflammatory activities of synthesized molecules were evaluated by molecular docking studies through autodock vina and in-vivo studies through carrageenan rat model. The molecular docking and in-vivo studies revealed that all molecules have shown significant anti-inflammatory activity, compared to standard drugs nimesulide.

Computational study of the supramolecular complexation of azocompounds with cucurbit[7]uril: effects on the production and release of free radicals.

An inclusion complex between 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH), a widely employed azocompound, and cucurbit[7]util (CB[7]), has shown an increased yield of radicals derived from the homolytic cleavage of the azo bond. Aimed to get insights about the formation of complexes and their effect on the yield of radicals production, complexes of CB[7] with seven azocompounds were studied by computational methods. Molecular electrostatic surfaces and structural analysis showed that the inclusion of symmetrical azocompounds inside of CB[7] depends mainly on the charge density and position of the functional groups at the main chain of the azoderivative. Analysis of non-covalent interactions and thermodynamic outcomes revealed that positively charged azocompounds with amidinium or imidazolium groups presented strong favorable interactions (multiple hydrogen bonds) with the oxygens of CB[7] portals. Additionally, carbon-centered radicals generated from the complexes (azocompounds@CB[7]) were corroborated using the electron localization function (ELF). Results evidenced that the strength of the interactions and the level of inclusion (partial or complete) between the azocompound and CB[7] determined the final orientation of the radicals (located out- or inside of the CB[7] cavity). Obtained results could be employed to design new supramolecular systems based on the properties of azocomplound@CB[7] complexes for new scientific or industrial applications. First-principles calculations at B3LYP-D3BJ/6-311g(d,p) level theory in the gas phase and in solvent (PCM, water) were performed in Gaussian 16 software package. The dispersion energy correction was included through the Grimme's dispersion with Becke-Johnson damping D3(BJ). Thermodynamical data and the minimum character of all structures were obtained from vibrational frequency calculations. NBO, Multiwfn, Chemcraft, and NCIPLOT software were used to perform population analysis, analyze outcomes, visualize data, and display non-covalent interactions respectively.

Rosmarinic Acid as a Potential Multi-targeted Inhibitor for SAR-CoV-2: An In silico Virtual Screening Approach

Background: Rosmarinic acid, a natural compound found in various plants like rosemary and lemon balm, may have potential as a multi-targeted inhibitor for SARS-CoV-2, a strain of virus responsible for COVID-19. SARS-CoV-2, a fusion protein of S1 and S2 subunits, has multiple precursors angiotensin-converting enzyme2 (ACE2), transmembrane serine protease 2 (TMPRSS2), papain-like protease (PLpro), and 3-chymotrypsin-like protease (3CLpro). The chemical interaction of Rosmarinic acid with SARS-CoV-2 is of major interest reported here. Objective:: The quantitative study of Rosmarinic acid with various precursors of SARS-CoV-2 has been accounted for in detail. Furthermore, the conformational flexibility of Rosmarinic acid has also been investigated during the interaction with four different precursors of SARS-CoV-2. Methods: This investigation delves deeply into the analysis of various aspects, including geometric parameters, atomic charge, the energy gap between the highest occupied and lowest unoccupied molecular orbitals, dipole moments, and the analysis of non-covalent interactions (NCI). Furthermore, the study incorporates molecular docking techniques in conjunction with thorough quantum chemical calculations to provide comprehensive insights. Results: Rosmarinic acid shows promise as a versatile inhibitor of SARS-CoV-2, the virus responsible for COVID-19. It can target multiple key precursors of the virus, including TMPRSS2, angiotensin- converting enzyme2, 3CLpro, and PLpro, found in the fusion protein comprising S1 and S2 subunits. This study delves into the quantitative analysis of Rosmarinic acid's interactions with these precursors. Its adaptable structure allows it to engage with them effectively. Various molecular parameters, including atomic charge, energy gap between molecular orbitals, dipole moment, and noncovalent interactions, are comprehensively explored. Conclusion: Combining molecular docking and quantum mechanics, the findings suggest Rosmarinic acid's potential as a multi-targeted SARS-CoV-2 inhibitor.

Investigating the Structure of Defects in Heterometallic Zeolitic Imidazolate Frameworks ZIF-8(Zn/Cd) and Its Interaction with CO2 Using First-Principle Calculations

Inducing defect in metal-organic frameworks (MOFs) is one of the strategies to modify the structure and properties of this functional material. Defect may occur in a pristine MOF due to missing organic linkers, metal centres and/or other structural behaviours. In this study, the structure of defects in multicomponent MOFs especially heterometallic MOFs of zeolitic imidazolate framework (ZIF-8(Zn/Cd)) was examined to unveil the possible preference defect formation due to missing 2-methylimidazolate (MeIm) and metal centres of Cd2+ and Zn2+. Assuming defect formation due to the reaction between ZIF-8(Zn/Cd) and water, MeIm linker removal is energetically lower than removing metal centres of either Cd2+ or Zn2+. But, the MeIm linker is easier to be removed when it is connected to Cd2+ (Cd-MeIm-Cd) than when it is connected to Zn2+ (Zn-MeIm-Zn). Defect in ZIF-8(Zn/Cd) affects the band gap energy to give slightly lower value than it in pristine ZIF-8(Zn/Cd). Non-covalent interaction (NCI) and interaction region indicator (IRI) analyses were also performed to indicate possible intermolecular forces such as van der Waals and attractive forces present in non-defective and defective ZIF-8(Zn/Cd). The presence of defects in mixed-metal ZIF-8(Zn/Cd) was also tested for its potential use on CO2 adsorption. The interaction energy of CO2 inside defective ZIF-8(Zn/Cd) indicates an exothermic behaviour where CO2 molecule has a preference to be adsorbed inside the framework. This is especially when the capping agents at the defective ZIF-8(Zn/Cd) sites are removed to give open metal sites. This study provides insight how defects in multicomponent MOFs might presence affecting the structural and properties changes. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).