Reduced Density Gradient Research Articles

Formulating Reduced Density Gradient Approaches for Noncovalent Interactions.

This work elucidates several forms of reduced electron density gradient (RDG) to describe noncovalent interactions (NCIs). By interpreting the RDG as a local moment function, we systematically leveraged Weizacker's and Fermi's local moments. This resulted in high-fidelity RDG representations consistent with the NCI analysis. In addition, the RDG version derived from the Lagrangian kinetic energy density is conveniently normalized. These results suggest the nonexistence of a particular RDG formulation when performing NCI analysis. Thus, an in-depth examination of the theoretical foundations connecting the RDG function with the nature of noncovalent interactions is necessary.

Menadione sodium bisulfite as an efficient anti-corrosion additive for mild steel in acid corrosion: Electrochemical, surface morphological and theoretical studies

The corrosion inhibition behavior of Menadione Sodium Bisulfite (MSB) in 1.0 M HCl medium was evaluated using weight loss, electrochemical techniques (Tafel polarisation and Electrochemical impedance spectra), surface analysis (SEM and EDX), Density Functional Theory (DFT), Noncovalent interaction- Reduced Density Gradient (NCI-RDG) and Monte Carlo (MC) simulation techniques. Weight loss measurement showed that as inhibitor concentration increased, the corrosion rate decreased which means that a protective film formed on the metal surface. At 300 ppm, the inhibitor showed a maximum inhibition efficiency of 89.7 %. Tafel polarisation studies indicate that the inhibitor is mixed-type in nature. The inhibitor adsorption on the mild steel is the best fit for the Langmuir isotherm model. As the weak interaction of sodium and oxygen in the inhibitor molecules, the inhibitor exhibits two distinct equilibrium behaviors. (i) inhibitor with sodium (solid-state) and inhibitor without sodium (in liquid-state). These two behaviors were theoretically investigated using DFT and MD simulation studies. The inhibitor and metal interaction is further supported using these theoretical studies. The electron population of the inhibitor was analyzed using molecular electrostatic potential, NCI-RDG, Fukui function, and natural bond orbital analysis. These studies further give an understating of the inhibitor and metal interactions.

Pharmacoinformatics and quantum chemicals‐based analysis of aromatic molecule decanal as a potent drug against breast cancer

AbstractThis study's primary goal is to perform density functional theory and molecular docking simulation to determine decanal's structural stability and biological activity against proteins allied to breast cancer in order to validate its anti‐cancer potential. Initially, the drug‐likeness features of decanal was predicted and the outcomes confirmed that it is non‐toxic and follows Lipinski's rule. Through basis set 6‐311++G (d, p), the structural optimization was performed and molecular geometry was investigated. The FT‐IR and UV–Visible spectroscopic analysis was theoretically performed and validated via experimental analysis. The reactive surface of decanal was further investigated using a calculated molecular electrostatic potential surface. The molecular structural stability and bio‐reactivity of decanal was determined by using the HOMO‐LUMO energies and energy gap calculated is 6.215 eV. The charge distribution among the atoms of decanal was ascertained through the analysis of Mulliken and natural population distribution. To look at the decanal molecule's topological properties, electron localization function and localized orbital locator were used. The decanal's weak interactions were investigated via reduced density gradient assessment. The docking evaluation was performed against the proteins involved in breast cancer and the highest binding ability was calculated against the protein Bcl‐2 with the score of −6.5 kcal/mol. These theoretical findings will pave a way to understand the decanal's structural stability, reactivity and breast cancer inhibitory property and can be used as a drug candidate against tumor after in vitro and clinical evaluation.

Synthesis, structural analysis, and molecular docking of a novel 1,3,4-thiadiazole derivative: An experimental and molecular modeling studies

This study reports on the synthesis and characterization of a new thiadiazole derivative, (E)-N-(5-(2-nitrostyryl) -4-acetyl -4,5-dihydro -1,3,4-thiadiazol -2-yl) -N-phenylacetamide (ETDZ). The crystal structure was determined by single-crystal X-ray diffraction. ETDZ belongs to the monoclinic I2/a space group. The contribution of intermolecular interactions was assessed by Hirshfeld surface analysis and fingerprint plots. FT-IR, UV–Vis, and NMR (1H and 13C) techniques were used for spectroscopic characterization. The 1H and 13C NMR spectra were recorded in CDCl3 solvent. Density functional theory, employing the B3LYP functional and 6–311G(d,p) basis set in chloroform solvent, was used to calculate the structural and spectroscopic parameters of the molecule in the ground state. The vibrational wavenumbers were calculated and compared with the experimental FT-IR spectrum using the scaled quantum mechanics method. Isotropic chemical shifts were calculated using the Gauge invariant atomic orbital method. The calculated NMR chemical shifts and absorption wavelengths were compared with the experimental values, indicating good results from the DFT and TD-DFT methods. To get more information about charge transfer within the molecule, electronic properties such as HOMO and LUMO energies were studied using the DFT approach. The molecular electrostatic potential, frontier molecular orbital analysis, energy band gap, density of state, global chemical reactivity descriptors, and some thermodynamic functions were also calculated. Reduced density gradient and atom-in-molecule analysis were performed to investigate inter- and intra-non-covalent interactions. Molecular docking was carried out with the Eg5 kinesin protein, confirming the biological assets of the ETDZ ligand as a mitochondria disease and cancer agent.

Theoretical evaluation of C24 nanocage functionalization with protons for enhanced sulfacetamide drug delivery: A DFT study with non-covalent interaction analyses

In the realm of drug design, achieving precise and effective drug delivery poses a significant challenge. In this computational study, we explore the capacity of pristine C24 nanocages and those modified with 1H+ and 2H+ ions to serve as carriers for the sulfacetamide (SA) drug, employing density functional theory (DFT) calculations. Geometry optimizations of the SA&C24, SA&H+C24, and SA&2H+C24 complexes were conducted at the cam-B3LYP/6–31+G (d, p) level of theory. The optimized structures of all complexes exhibit local minima on the potential energy surface, indicated by the absence of imaginary frequencies, which confirms their thermodynamic stability. The negative values of adsorption energy (Eads) denote an exothermic and favorable adsorption process, with H+ ion functionalization enhancing the drug's binding affinity to the nanocages. Further analysis of the structural properties of the complexes was conducted through natural bond orbital (NBO) charge distribution, dipole moment calculations, and frontier molecular orbital analysis. Additionally, Atoms in Molecules (AIM), reduced density gradient (RDG), and electron localization function (ELF) analyses were employed to elucidate the nature of intermolecular interactions governing the drug-nanocage binding. UV-visible and nonlinear optical (NLO) response calculations reveal the potential of both pristine and functionalized C24 nanocages as optical sensors for SA drug detection. Our findings suggest that these nanocages hold promise for the development of sensitive drug delivery vehicles and targeted therapeutic agents.

Ab Initio Study of the Graphyne-like γ-SiC Nanoflake for Toxic Gas-Sensing Applications.

This study focuses on the geometrical, electronic, and optical properties of the γ-graphyne-like novel γ-SiC nanoflake of the γ-silicon carbide (SiC) monolayer using density functional theory calculations. γ-SiC was revealed to be a stable semiconducting nanoflake confirmed by a negative cohesive energy, real vibrational frequencies, and a 1.749 eV energy gap. The adsorption of COCl2, HCN, PH3, AsH3, CNCl, and C2N2 toxic gases on the γ-SiC nanoflake is also studied, which revealed an attractive gas-nanoflake interaction with the adsorption energy ranging from -0.21 to -0.38 eV. The adsorption results in a significant charge transfer between gas-adsorbent complexes. A significant variation in the energy gap and electrical conductivity was observed due to gas adsorption. γ-SiC showed maximum sensitivity at room temperature for CNCl gas. The entire process of adsorption is exothermic and thermodynamically stable. γ-SiC showed a high absorption coefficient over 104 orders with a significant variation in the absorption peak intensity and blue peak shifting. According to the quantum theory and reduced density gradient analysis, all of the gases are physisorbed on the γ-SiC nanoflake due to van der Waals interactions. The obtained results signify the usability of γ-SiC as a potential toxic gas sensor.

Quantum chemical investigations, Hirschfeld surface analysis, FMO, MESP, topology analyses, in-silico analysis and pharmacokinetics properties of 3-chloro-N-(4-hydroxy-3-methoxy-benzyl)-2,2-dimethyl propanamide [CHMBDP]

This article reports a comprehensive theoretical investigation of 3-chloro-n-(4-Hydroxy-3-Methoxy-Benzyl)-2,2-Dimethyl Propenamide (CHMBDP). Hirshfeld surface analysis provided a detailed visualization of intermolecular interactions within the crystal structure of CHMBDP. Analyses of Molecular Electrostatic Potential (MESP), Electron Localization Function (ELF), Localized Orbital Locator (LOL), and Reduced Density Gradient (RDG) offered insights into the compound’s reactivity and stability. The energies of the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) indicated significant charge transfer within the molecule. In-silico analysis explored the compound’s interactions with TRPV1 (Transient Receptor Potential Vanilloid subtype 1), DNA, and BSA (Bovine Serum Albumin). The pharmacokinetic properties of CHMBDP were assessed using the Swiss ADME online tool to interpret its ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) characteristics. Overall, this study presents a thorough computational investigation of CHMBDP, characterizing its structure, properties, and potential applications.

Size-Dependent Fullerenes for Enhanced Interaction of l-Leucine: A Combined DFT and MD Simulations Approach.

Fullerene-based biosensors have received great attention due to their unique electronic properties that allow them to transduce electrical signals by accepting electrons from amino acids. Babies with MSUD (maple syrup urine disease) are unable to break down amino acids such as l-leucine, and excess levels of the l-leucine are harmful. Therefore, sensing of l-leucine is foremost required. We aim to investigate the interaction tendencies of size-variable fullerenes (CX; X = 24, 36, 50, and 70) toward l-leucine (LEU) using density functional theory (DFT-D3) and classical molecular dynamics (MD) simulation. The C24 fullerene shows the highest affinity of the LEU biomolecule in the gas phase. Smaller fullerenes (C24 and C36) show stronger interactions with leucine due to their higher curvature in water environments. Moreover, recovery times in the ranges of 1010 and 104 s make it a viable candidate for the isolation application of LEU from the biological system. Further, the interaction between LEU and fullerenes is in line with the natural bond order (NBO) analysis, Mulliken charge analysis, quantum theory atom in molecule (QTAIM) analysis, and reduced density gradient (RDG) analysis. At 310 K, employing the explicit water model in classical MD simulations, fullerenes C24 and C36 demonstrate notably elevated binding free energies (-24.946 kJ/mol) in relation to LEU, showcasing their potential as sensors for l-leucine. Here, we demonstrate that the smaller fullerene exhibits a higher potential for l-leucine sensors than the larger fullerene.

A DES or LTTM: Eco-friendly solvent mediums for conversion of biomass to levulinic acid as a key chemical

In this study, the effect of using environmentally friendly, less toxic, low cost, and easily recyclable deep eutectic solvent (DES) and low-transition temperature mixture (LTTM), which are alternatives to ionic liquids, on the conversion of biomass to levulinic acid (LA) was investigated. The reaction conditions such as temperature, the amount of feedstock, and the water ratio were optimized to ensure maximum product formation in DES (ChCl-EG)-water medium. The highest amount of LA (143.2 ± 2.5 mg) under optimum reaction conditions was achieved by using glucose in a newlydesignedLTTM (SA:EG)-water solvent medium. Newly designed low-transition temperature mixture (SA:EG) characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and differential scanning calorimetry (DSC) analyses. A comprehensive theoreticalstudy was also performed to provide a deep understanding of the formation mechanisms of new LTTM by density functional theory (DFT), reduced density gradient (RDG), frontier molecular orbitals (FMOs), and molecular electrostatic potential (MEP) methods. The glucose conversion ratio increased from 70.2 % to 96.1 % in SA:EG-water medium. When microcrystalline cellulose, corn straw, and sorghum were used under the same conditions, 118.9 ± 5.4, 36.8 ± 9.4, and 32.6 ± 3.4 mg of LA were obtained per g of feedstock. A typical Brønsted acid; phosphotungstic acid (H3O40PW12) showed high catalytic activity, resulting in 229.0 ± 0.32 mg of LA per g of glucose in SA:EG-water medium. This shows that the use of SA:EG LTTM for cellulosic/lignocellulosic biomass sources can be used favorably in conversion reactions.

Investigating the potential of monocyclic B9N9 and C18 rings for the electrochemical sensing, and adsorption of carbazole-based anti-cancer drug derivatives: DFT-based first-principle study.

For the first time, the use of monocyclic rings C18 and B9N9 as sensors for the sensing of carbazole-based anti-cancer drugs, such as tetrahydrocarbazole (THC), mukonal (MKN), murrayanine (MRY), and ellipticine (EPT), is described using DFT simulations and computational characterization. The geometries, electronic properties, stability studies, sensitivity, and adsorption capabilities of C18 and B9N9 counterparts towards the selected compounds confirm that the analytes interact through active cavities of the C18 and B9N9 rings of the complexes. Based on the interaction energies, the sensitivity of surfaces towards EPT, MKN, MRY, and THC analytes is observed. The interaction energy of EPT@B9N9, MKN@B9N9, MRY@B9N9, and THC@B9N9 complexes are observed - 20.40, - 19.49, - 20.07, and - 18.27kcal/mol respectively which is more exothermic than EPT@C18, MKN@C18, MRY@C18, and THC@C18 complexes are - 16.37, - 13.97, - 13.96, and - 11.39kcal/mol respectively. According to findings from the quantum theory of atoms in molecules (QTAIM) and the reduced density gradient (RDG), dispersion forces play a significant role in maintaining the stability of these complexes. The electronic properties including FMOs, density of states (DOS), natural bond orbitals (NBO), charge transfer, and absorption studies are carried out. In comparison of B9N9 and C18, the analyte recovery time for C18 is much shorter (9.91 × 10-11 for THC@C18) than that for B9N9 shorter recovery time value of 3.75 × 10-9 for EPT@B9N9. These results suggest that our reported sensors B9N9 and C18 make it faster to detect adsorbed molecules at room temperature. The sensor response is more prominent in B9N9 due to its fine energy gap and high adsorption energy. Consequently, it is possible to think of these monocyclic systems as a potential material for sensor applications.

Synthesis, experimental and theoretical spectroscopic electronic elucidation along with biological assessment and molecular docking studies on 2-(3-(1,4-diazepan-1-yl)propyl)isoindoline-1,3-dione − Antidepressant drug

The title compound, 2-[3-(1,4-diazepan-1-yl)propyl]-1H-isoindole-1,3(2H)-dione (2DPID), was synthesized from Boc-protected 2-[3-(1,4-diazepan-1-yl)propyl]-1H-isoindole-1,3(2H)-dione by treating it with trifluoroacetic acid in dichloromethane. This reaction involves the hydrolysis of the tert-butyloxycarbonyl (Boc) group under acidic conditions. The crude product was then purified by column chromatography. The purity and identity of 2DPID were confirmed through spectroscopic techniques, including 1H NMR, 13C NMR, and FT-IR. Additionally, the compound was theoretically investigated using density functional theory (DFT) to complement the experimental findings. This comprehensive approach ensured the accuracy and reliability of the synthesized compound’s characterization and confirmed its structure and purity. The research includes estimating the compound’s optimal structure and molecular geometry in both the gas and solvent phases (water, CCl4, and chloroform). Topological analysis utilizing Multiwfn 3.8 analyzer involved to elucidate the electron localization function (ELF), localized orbital locator (LOL), & Reduced density gradient (RDG) studies to locate important bonding sites and weak interactions inside the molecule. The IEFPCM framework was utilized to analyze the consequences of solvation on distinct solvents. Investigations into the effects of solvation on the electrical characteristics (Frontier molecular orbital (FMO) & UV–visible), Molecular electrostatic potential (MEP), and nonlinear optics (NLO) attributes revealed differences in the compound’s action among the gas & liquid phases. The significant presence of the solvent has a major impact on the compound’s reactivity, as the FMO’s study demonstrates by showing a higher electrophilicity index m4-descriptive value. Natural bond orbital (NBO) simulations were implemented to evaluate inter and intramolecular charge transferand stabilization. According to the MEP study, the electronegative atoms act as electrophiles, whereas the hydrogen & carbon atoms are nucleophilic. Investigations utilizing thermodynamics confirmed that significant molecular characteristics improved with temperature. Drug-likeness evaluations were used to describe the chemical’s drug attributes. Lastly, targeted protein stability was ensured by molecular docking towards antidepressant protein receptors, which was demonstrated by Ramachandran graphs. The chemical interacted with four desired protein targets (3MDM, 4HRG, 5KZN, and 7LWD) according to the molecular docking data; 4HRG had the best binding energy, at −7.63 kcal/mol.

Single crystal, conformational, quantum reactivity, hirshfeld surface, molecular interactions, ADMET, and molecular docking investigations on HIV-1 site of 3-isopropyldiphenyl-1-(2-(thiophen-2yl)acetyl)piperidin-4-one

The 3-isopropyl-2,6-diphenyl-1-(2-(thiophen-2yl)acetyl)piperidin-4-one (IPTP) single crystals were grown by slow evaporation method and the structure is confirmed through FT-IR, 1H NMR, and 13C NMR spectral analyses. Single crystal X-ray diffraction revealed that the title compound having chair conformation of the piperidine ring, with an axial orientation of phenyl rings at C-2 and C-6 positions and an isopropyl group at C-3. Hirshfeld surface analysis was employed to examine intermolecular contacts and strong and weak attractive, repulsive, and van der Waals interactions in the molecule were determined using the reduced density gradient method (RDG). The geometrical parameters obtained through Density Functional Theory are compared with experimental values and also conducted to optimize structural parameters, frontier molecular orbitals (FMOs), and molecular electrostatic potential surface analysis (MEPS). NBO calculations were employed to investigate intermolecular and intramolecular charge movement, as well as the molecule's stability. Vibrational Energy Distribution Analysis (VEDA) software facilitated potential energy decomposition (PED) analysis using FT-IR wave numbers. The title compound molecular docking data were compared with the markedly available FDA-approved anti-HIV drug of Nelfinavir and their results were discussed, ADME analysis studies were discussed concerning FDA-approved anti-HIV drugs, including Nelfinavir, Betulinic Acid, Haloperidol, and Donepezil.

Optimization and mechanistic insight of phenol removal using an effective green kaolin adsorbent through experimental and computational approaches

The discharge of phenols into the aquatic environment has detrimentally affected human health and the aquatic ecosystem. Hence, removing phenols from polluted water bodies has been a global concern. In this study, a natural and low-cost adsorbent, kaolin, was used to remove phenol from aqueous solutions. Experimental and computational approaches were applied to optimize the removal efficiency and provide mechanistic insight into the phenol removal process. Based on the response surface methodology findings, the optimum conditions were pH 1.6, 40 min, 50 mg/L, and 2 g with 92.19 % maximum percentage removal. The regeneration test shows that kaolin retained over 76.76 % of adsorption capacities. SEM and FESEM reveals the surface morphology and effectiveness of kaolin as phenol removal. The best fit for the Isotherm adsorption for the phenol on kaolin is Freundlich isotherm, which indicated multilayer adsorption. The hydroxyl group from phenol (-OH) and the siloxane group of kaolin (Si-O-Si) shifted, suggesting the presence of a hydrogen bond between kaolin and phenol during adsorption, as determined by one- and two-dimensional IR spectroscopy. Density functional theory calculations were used to support the experimental results by providing information on the Mulliken charge and electronic transition of the complex to improve understanding of the adsorption of phenol on kaolin. Based on the quantum theory of atoms in molecules analysis (QTAIM) and the reduced density gradient non-covalent interaction (RDG-NCI) technique, the chemical reaction occurring during the removal of phenol by kaolin was determined to occur through hydrogen bonding and classified as an intermediate type (∇2ρ(r) > 0 and H < 0). Further characterizations employing molecular electrostatic potential, global reactivity, and local reactivity descriptors were conducted to investigate the mechanism of the phenol adsorption on kaolin. The findings demonstrated that phenol functions as an electrophile while kaolin acts as a nucleophile during the formation of hydrogen bonds, where the interaction occurred between the O2 atom of kaolin (electron donor) and the H13 atom of phenol (electron acceptor).

Investigation on molecular and biomolecular spectroscopy of the novel 2BCA molecule to analyse its biological activities and binding interaction with nipah viral protein

The molecule of 2-Biphenyl Carboxylic Acid (2BCA), which contains peculiar features, was explored making use of density functional theory (DFT) and experimental approaches in the area of quantum computational research. The optimised structure, atomic charges, vibrational frequencies, electrical properties, electrostatic potential surface (ESP), natural bond orbital analysis and potential energy surface (PES) were obtained applying the B3LYP approach with the 6–311++ G (d,p) basis set.. The 2BCA molecule was examined for possible conformers using a PES scan. The methods applied for spectral analyses included FT-IR, FT-RAMAN, NMR, and UV–Vis results. Vibrational frequencies for all typical modes of vibration were found using the Potential Energy Distribution (PED) data. The UV–Vis spectrum was simulated using the TD-DFT technique, which is also seen empirically. The Gauge-Invariant Atomic Orbital (GIAO) approach was employed to model and study the 13C and 1H NMR spectra of the 2BCA molecule in a CDCL3 solution. The spectra were then exploited experimentally to establish their chemical shifts. To predict the donor and acceptor interaction, the NBO analysis was used. The electrostatic potential surface was employed to anticipate the locations of nucleophilic and electrophilic sites. Hirshfeld surfaces and their related fingerprint plots are exploited for the investigation of intermolecular interactions. Reduced Density Gradient (RDG) helps to measure and illustrate electron correlation effects, offering precise insights into chemical bonding, reactivity, and the electronic structure of 2BCA. According to Lipinski and Veber’s drug similarity criteria, 2BCA exhibits the typical physicochemical and pharmacokinetic properties that make it a potential oral pharmaceutical candidate. According to the findings of a molecular docking study, the 2BCA molecule has promise as a treatment agent for the Nipah virus (PDB ID: 6 EB9), which causes severe respiratory and neurological symptoms in humans.

Effects of amino‐ and dimethylamine‐groups on the fluorescent properties of novel flavone‐based derivatives with ESIPT behavior: A TD‐DFT study

AbstractIn this work, the effects of different functional groups on the excited‐state intramolecular proton transfer behavior and fluorescent features of 3‐hydroxy‐2‐(naphthalen‐2‐yl)‐4H‐chromen‐4‐one (HFN) are explored in detail. Three new compounds (HFN‐1, HFN‐2, and HFN‐3) are designed based on the HFN by introducing the electron‐donating groups (–NH2, –N(CH3)2). The mainly geometrical parameters of optimized configuration showed that the intramolecular hydrogen bonds of the studied compounds are enhanced in the excited (S1) state, confirming by the ground (S0) and excited states infrared spectra, electron densities and reduced density gradient isosurfaces. The S0 → S1 transitions of HFN derivatives are dominated by ππ* charge transfer transition. The introduction of electron‐donating group (–NH2, –N(CH3)2) weakens the intramolecular hydrogen bond, increases the excited‐state intramolecular proton transfer barrier and red‐shifts the absorption/fluorescence peak. The coexistence of –NH2 and –N(CH3)2 make the absorption and fluorescence wavelengths of HFN‐1/HFN‐2 red‐shift/blue‐shift.

Removal of phenolic compounds from aqueous solution using Hydrophobic deep eutectic Solvent: Liquid-Liquid phase behavior and intermolecular interactions

Hydrophobic deep eutectic solvent (HDES, menthol: decanoic acid: octanoic acid = 1:1:1), as a green and eco-friendly solvent was evaluated for the extraction of the phenolic compounds (phenol, m-cresol, and o-cresol) in terms of their toxicity in water. The liquid-liquid equilibrium (LLE) data for the mixtures (water + phenol / m-cresol / o-cresol + HDES) were determined at a temperature of 298.15 K and 101.3 kPa. The efficacy of HDES as an extractant was evaluated by computing the selectivity (S) and distribution coefficient (D). The calculated values of D and S, greater than unity, showed that the extraction of phenol, m-cresol, and o-cresol from water by HDES is feasible. The results indicated that HDES performs better for the extraction of m-cresol and o-cresol from their aqueous solutions than phenol. The tie-line data were fitted using the NRTL model, with calculated RMSD values less than 0.0104, indicating the model’s suitability for representing the mixtures. Furthermore, the interactions between HDES and phenol / m-cresol / o-cresol were studied by calculating the molecular electrostatic potentials, interaction energy, and reduced density gradient. Quantum chemical calculations showed that the interaction between m-cresol and o-cresol with HDES is more favorable than that of phenol.

Theoretical Analysis of Coordination Geometries in Transition Metal-Histidine Complexes Using Quantum Chemical Calculations.

A theoretical investigation utilizing density functional theory (DFT) calculations was conducted to explore the coordination complexes formed between histidine (His) ligands and various divalent transition metal ions (Mn2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+). Conformational exploration of the His ligand was initially performed to assess its stability upon coordination. Both 1:1 and 1:2 of metal-to-ligand complexes were scrutinized to elucidate their structural features and the relative stability of the complexes. This study examined the ability of His to act as a bidentate or tridentate coordinating ligand, along with the differences in coordination geometry when solvent effects were incorporated. The reduced density gradient (RDG) analysis and local electron attachment energy (LEAE) analysis were employed to elucidate the interaction planes and the nucleophilic and electrophilic properties. The electronic properties were analyzed through electrostatic potential (ESP) maps and natural population analysis (NPA) of atomic charge distributions. This computational study provides valuable insights into the diverse coordination modes of His and its interactions with divalent transition metal ions, contributing to a better understanding of the role of this amino acid ligand in the formation of transition metal complexes. The findings can aid in the design and construction of self-assembled structures involving His-metal coordination.

Single-crystal X-ray structure, theoretical (Hirshfeld, electronic properties, NBO, NLO, RDG), and molecular docking studies of three phthalimidoethanesulfonamide derivatives

The three N-substituted-2-phtalimidoethanesulfonamide derivatives, 2-(1,3-dioxoisoindolin-2- yl)-N-(2-isopropylphenyl)ethane-1-sulfonamide (I), N-(2,6-dimethylphenyl)-2-(1,3-dioxoiso indolin-2-yl)ethane-1-sulfonamide (II) and 2-(2-(morpholinosulfonyl)ethyl) isoindoline-1,3‑dione (III), were analyzed using a combined approach including single-crystal X-ray diffraction (SC-XRD), theoretical calculations with Density Functional Theory (DFT), and molecular docking studies. Phthalimide and sulfonamide compounds have recently attracted attention for their inhibitory properties against AChE and BChE enzymes. In this study, molecular and crystal structures of compounds have been confirmed by the SC-XRD technique. Optimized molecular geometries and vibrational modes have been examined and compared to experimental results. Frontier molecular orbital (HOMO-LUMO) energies, molecular electrostatic potential (MEP), natural bond orbital (NBO) analysis, and non-linear optical (NLO) properties have been investigated by DFT/B3LYP/6–311G++(d,p) method. The reduced density gradient (RDG) analysis has been performed to analyze the non-covalent interactions. The Hirshfeld surfaces and 2D fingerprint analyses have been used to determine the intermolecular interactions of compounds. Moreover, in silico docking studies are performed to investigate the interactions between N-substituted-2-phtalimidoethane sulfonamide derivatives and AChE and BChE enzymes.

Natural deep eutectic solvent-ultrasound for the extraction of flavonoids from Fructus aurantii: Theoretical screening, experimental and mechanism

To reduce the environmental pollution caused by organic solvents and improve the extraction efficiency, a green and high-effective natural deep eutectic solvent (NADES) was screened out and prepared for the extraction of flavonoids from Fructus aurantii based on the COMOS-RS and experimental verification. The results showed the results of theoretical screening and experimental verification were consistent, and Ch-Lea was the best extraction solvent, which further proved the COMOS-RS was an efficient tool for the solvent screening. Then, the extraction conditions were investigated. The optimum extraction conditions were as follows: molar ratio (1:2), water content (30%), solid–liquid ratio (1/60 g/g) and extraction time (15 min), yet the extraction temperature and power did not significantly affect the extraction yield. Under the optimal extraction condition, the extraction yield of flavonoids was 122.68 mg/g. Compared with the traditional extraction solvents (methanol and ethanol), Ch-Lea has a higher extraction yield. And the green assessment was conducted based on Eco-Scale methodology, which results indicated the Ch-Lea was more environmentally friendly than methanol and ethanol. Meanwhile, the Ch-Lea has good reusability, and the extraction yields from four reuses were 122.68 mg/g, 125.13 mg/g, 122.56 mg/g and 105.63 mg/g, respectively. Moreover, the extraction mechanism was delved into using molecular dynamics (MD) simulation and reduced density gradient (RDG) analysis. The hydrogen bond interaction, particularly the O-H bonds, between Ch-Lea and the naringin molecule emerged as the primary force driving the extraction process. In summary, Ch-Lea is a green, economical, and highly effective solvent, making it a promising candidate for flavonoid extraction from Fructus aurantii. Its potential as an alternative to traditional extraction solvents further underscores its value.

Novel series of hydrazones carrying pyrazole and triazole moiety: Synthesis, structural elucidation, quantum computational studies and antiviral activity against SARS-Cov-2

The novel series of hydrazones carrying both pyrazole and triazole moiety were synthesized and characterized using single crystal X-ray diffraction studies. It is found that the compound crystallizes in the triclinic system in the space group P1̅. Hirshfeld analysis was carried out to visualize the noncovalent intermolecular interactions which are responsible for molecular packing in the crystal. Further, density functional theory (DFT) calculations were used to calculate optimized molecular structure, stability, and a few of the quantum chemical parameters. Derived results are in good agreement with the experimentally obtained results. Analysis of frontier molecular orbitals (HOMO and LUMO) and their energy gap of the optimized structure revealed that the compound is stable in the gaseous state. Molecular electron densities, and electrostatic potential maps provide the reactive site and charge distribution of triazole group. Quantum theory of atoms in molecules (QTAIM) and reduced density gradient (RDG) analysis were carried out to explore the weak interactions present in the molecule. In addition, the synthesized compound was investigated as an inhibitor for SARS CoV-2 protease using in-silico molecular docking analysis to understand the mode of binding. The docking results showed the good binding score with Mpro protease 6LU7. Further, molecular dynamics (MD) were carried out for the best hit docked complexes.