Electrostatic Potential Maps Research Articles

Molecular structure, optical, first-order hyper polarizability, electronic properties, reactivity (ELF and LOL) − computational analysis using DFT and Multiwfn for 2, 3-diaminopyridinium selenate

A detailed study on the first principle calculations of 2,3-diaminopyridinium selenite (2,3-DAPS) – an organometallic salt has been performed using B3LYP/6–311++G(d,p). Single crystal X-ray diffraction (XRD) analysis confirms that the crystal formed exhibits a monoclinic crystal structure, specifically belonging to the centrosymmetric space group P21/c. The obtained primitives and interfacial angles are as follows: a = 7.4978(15)Å, b = 7.6681(15) Å, c = 14.314(3) Å, α = γ = 90°, β = 93.75(3)°, and the volume of the unit cell V = 821.2(3) (Å)3. The structure was optimized with a global minimum. The natural bonding orbital charge transfer studies between the cation and anion was performed to gain insights into their electronic interactions. Energy gap and other global chemical reactivity descriptors have been computed with the aid of molecular orbital studies. The influence of solvent on the absorption spectra provided the evidence of solvent–solute interactions and their impact on the electronic transitions within the molecule. The presence of electrophilic and nucleophilic reactivity in the chemical is indicated by the molecular electrostatic potential (MEP) map. From the nonlinear optical (NLO) studies, it has been found that the first-order hyperpolarizability value is 30.771 × 10−31 esu, which is 8.252 times that of urea. This suggests that the compound may be a better non-linear optical material and suitable for laser applications. To calculate the proportion of intermolecular interactions and examine the distribution compound's electrostatic potential, a Hirshfeld surface analysis was conducted. The analysis provided insights into the spatial arrangement of molecules and their interactions. Additionally, topology path calculations elucidated the intrinsic connectivity between critical points, shedding light on the bonding characteristics within the compound. The likelihood of electron density at bonding and anti-bonding sites was also determined using the Electron Localization Function (ELF) and Localised Orbital Locator (LOL) plots. These analyses aided in understanding the electron distribution and the nature of chemical bonding within the compound, providing valuable information about its electronic structure and reactivity.

Spectroscopic characterization and quantum chemical calculations on Favipiravir-Guanine biomolecular complex

Favipiravir, a medication, has drawn a lot of interest recently as a possible therapeutic option for viral illnesses such as the COVID-19 pandemic. In the current work, Favipiravir + Guanine combination is being spectroscopically characterized using Fourier Transformed Infrared Spectroscopy, Raman, and Surface-Enhanced Raman Spectroscopy tools. Density functional theory along with the Becke 3-Parameter, Lee-Yang-Parr method and the basis set 6-311++ G(d,p) is used to explore the molecular interactions between the monomers of Guanine and Favipiravir. The stability of the complex resulting from the charge delocalization is thoroughly examined by natural bond orbital analysis that demonstrates the C=O∙∙∙H intermolecular hydrogen bond formation. The nature of the intermolecular hydrogen bond is described using atoms in molecules analysis. Molecular electrostatic potential mapping depicts various regions of electrostatic potential for the molecules, characterizing their reactive nature. The complex’s frontier molecular orbital gap of 2.39 eV indicates a higher possibility of electronic charge transfer, which in turn enhances the chemical reactivity of the complex. An analysis of the complex’s hyperpolarizability reveals a good non-linear optical response. The antiviral activity of the Favipiravir + Guanine complex is demonstrated by its molecular docking against the 6LU7 receptor (−5.61 kcal/mol).

Synthesis and Experimental Structure of a Multifunctional Catechol‐Azomethinebenzoic Acid, DFT/DMol3 Calculations, and Molecular Docking with Hsp90

AbstractThe multifunctional catechol‐azomethine‐benzoic acid derivative 4‐[(E)‐[(2,3‐dihydroxyphenyl)methylidene]amino]benzoic acid (1) was prepared and the structure were confirmed by EI‐MS and 1H and 13C NMR spectroscopy. A Single‐crystal X‐ray diffraction study revealed coplanarity of the two aromatic rings within the imine function, supported by intramolecular N−H⋯O hydrogen bonds. In the crystal structure intermolecular O−H⋯O hydrogen bonds form chains, propagating along [010]. FT‐IR and Hirshfeld surface analysis confirms the multiple hydrogen bonding. DFT/DMol3 calculations localized the highest occupied molecular orbital (HOMO) on the o‐catechol unit, while the lowest unoccupied molecular orbital (LUMO) is delocalized over the entire molecule. The calculated map of electrostatic potential (MEP) showed relatively low values for both electrophilic and nucleophilic susceptibility. A molecular docking study of 1 in comparison with the established inhibitor geldanamycin (G) using the protein structure of the heat shock protein 90 co‐crystallized with G (Hsp90⋅G) showed that 1 occupies the same binding pocket as G in the Hsp90⋅G structure, indicating that the title structure might be a suitable inhibitor. The Swiss ADME approach showed promising general drug‐likeness properties for 1 with a relatively high lipophilicity (logP=1.68) and a logS value of −2.99 which lies in the middle of the logS distribution of traded drugs.

Liquid-solid interface diffusion behaviors of furfural in the insulation systems of natural ester-cellulose paper and mineral oil-cellulose paper

Furfural as an ageing product of cellulose paper can be detected by the furfural content in the oil. With the construction of green power grid, more and more power equipment adopts environmentally friendly insulating fluids. The investigation of the diffusion behaviors of furfural at different oil-paper interfaces can provide a basis for fault detection in power transformers. The liquid-solid interface diffusion behaviors of furfural in natural ester-cellulose paper and mineral oil-cellulose paper insulating systems are investigated by molecular dynamics simulation in this paper. Results show that the range of center-of-mass movement distances of furfural in mineral oil-cellulose paper is about 5 times that of natural ester-cellulose paper. The main reason for this is that the long-chain macromolecules composing the natural ester undergo curling in the extended flow. As polar molecules, natural ester can attract furfural, which is also a polar molecule. And the electrostatic potential mapping interval of furfural is about 4.4 times that of mineral oil, but 1.1 times that of natural ester, with which it overlaps more. These hinder the diffusion of furfural molecules in the natural ester-cellulose paper liquid-solid interface. This research provides theoretical support for the diffusion of furfural in the insulation systems of natural ester-cellulose paper and mineral oil-cellulose paper. It also provides useful guidance for fault detection in transformers using natural ester insulating fluids.

Exploring the spectral and nonlinear optical properties of phenyl isothiocyanate through density functional theory and molecular docking studies: A comprehensive analysis of a potent biologically active phytochemical

Quantum chemical calculations employing Density Functional Theory (DFT) with 6–31G (d,p) basis sets have yielded valuable insights into the molecular structure, Frontier Molecular Orbitals (FMOs), Mulliken Charges, and Molecular Electrostatic Potential Maps of the phenyl isothiocyanate (PITC) molecule. Spectral analysis of PITC has been conducted including Fourier transform infrared (FTIR), Fourier transform Raman (FT-RAMAN), Nuclear Magnetic Resonance (NMR), and ultraviolet–visible (UV–Vis) spectroscopy by theoretical method. Additionally, global descriptive parameters and thermal properties have also been determined. The Nonlinear Optical characteristic (NLO) has been assessed in the gas phase using the same level of theory. The investigation into toxicity revealed that the studied molecule exhibits drug-like characteristics and is non-toxic. Molecular docking studies have been employed to investigate hydrogen bond interactions, elucidating the minimal binding energy of the compound. The outcomes of the docking studies strongly suggest the significant biological activity of Phenyl Isothiocyanate, emphasizing its potential as a potent phytochemical.

Quantum computational, charge density, optical, molecular reactivity and thermodynamical analysis of Di-Halogen substituted nicotinic acid derivatives

6-Chloro-3-fluoro-2-(trifluoromethyl) isonicotinic acid (6C3F2TINA) and 6-Chloro-5-fluoronicotinic acid (6C5FNA) are currently being studied using the DFT method for the detailed examination of structural and molecular character alterationsin gas as well as in several organic solvent media. Implementing electrostatic potential maps and Fukui functions analyses the reactive environment of compounds. The occurrence of the transfer of electrons and holes within the molecule is reported by a charge transfer study along with the heat maps. The orbital study investigates the electronic density and interactions within themolecules. Optical examination of compounds revealed an enhancement with the solvents. Thebonding typefound in molecules isdetermined by topographical investigation, which examines the concentration and localisationof electrons present in them. The UV–Vis spectra exhibit the absorption characteristics of these compounds. The thermodynamic investigation reveals the compound’s stability at various temperatures at 1 atm pressure.

Solvent Effects on the Absorption and Emission Spectra of the [5-amino-1-bromoindolizin-3-yl](4-bromophenyl)methanone Molecule.

The effects of solvent on the absorption and emission spectra and dipole moments of the 5ABBM have been extensively studied in a series of solvents. The dipole moments in the excited state are observed to be greater than those in the ground-state in all the solvents studied for the chosen molecule. The dipole moment increase in the excited singlet state ranges from 2.42 to 24.14 D. The experimentally calculated ground state and excited state dipole moments were determined using the solvatochromatic shifts in the absorption and emission spectra as a function of dielectric constant (ɛ) and refractive index (n). These data are used to estimate the excited-state dipole moment using the experimentally determined ground-state dipole moment. A series of fifteen different organic solvents (toluene, methanol, n-butyl alcohol, ethyl acetate, DMS, acetonitrile, benzene, isopropyl alcohol, water, DMF, DCM, DIO, THF, ethanol, and octanol) were investigated at constant dye concentrations. Small changes in the fluorescence spectrum were observed for the different solvents; the highest fluorescence intensity was observed for DMS, and the lowest was observed for water. The Stokes shift in different solvents was studied for the 5ABBM molecule. This results in molecule being more polar in the excited state than in the ground state for the solvents used. The ground state dipole moments, HOMO-LUMO, and molecular electrostatic potential maps were also computed via ab initio calculations and evaluated via Gaussian 09W software.

Enhanced antioxidant activity in Imidazolium-based protic organic salts: An insight into structure activity relationship via experimental and modelling approaches

Sulfonyl hydroxide functionalized imidazolium based protic ionic liquids (PILs) have been evaluated as a new form of antioxidants. The antioxidant activity was performed using free radical quenching using UV–visible spectroscopy and cyclic voltammetry. The studies confirmed that the investigated ILs with variable anions exhibited substantial radical scavenging activity. In UV–Visible study, Glutamine based-IL ([1MeimPS][Gln]) showed least IC50 value of 95 µM indicating maximum radical quenching activity as an oxidant, while proline based-IL ([1MeimPS]Pro]) exhibited highest IC50 value of 675 µM, demonstrating least anti-oxidant activity. Moreover, cyclic voltammetry results complemented well the UV–visible findings with least IC50 value of 90 µM for [1MeimPS][Gln], showing maximum antioxidant activity, and highest IC50 value of 593 µM for [1MeimPS]Pro], exhibiting the least antioxidant activity. The presence of two primary amines moieties in glutaminate anion may be responsible for enhanced antioxidant activity by providing more active sites for radical quenching. Contrarily, lack of primary amine functionality in prolinate anion may contribute to reduced antioxidant activity of respective IL. The Density Functional Theory (DFT) calculations predicted that the trend of radical scavenging potential was comparable with the experimentally obtained IC50 values. Molecular Electrostatic Potential (MESP) Maps illustrated that [1MeimPS][Pro] has the maximum red zones indicating a poor potential against electron scavenging capacity among all the studied ILs, while blue region in [1MeimPS][Gln], corresponding to low electron density, suggested strong attraction for the incoming electrons. Also, the high electronic distribution of HOMO orbital, appreciable stability, and significant chemical potential to attack on radical species provided by [1MeimPS][Gln] with the maximum radical scavenging potential. Furthermore, the associated LUMO energy for [1MeimPS][Pro] (−1.297 eV) is quite higher than that of [1MeimPS][Gln] (−1.422 eV) which reduced the ability of [1MeimPS][Pro] to attack free radicals of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and thus have higher associated IC50 values. This is also supported by the results of chemical hardness (η) and chemical potential (μ) descriptors values indicating [1MeimPS][Pro] is least stable and reactive than [1MeimPS][Gln]. These findings further explain the least IC50 values observed experimentally and consequent enhanced antioxidant potential of [1MeimPS][Gln].

Quantum Chemical-Based Investigations and Lipophilicity Evaluations on Some Structurally Related Quinazoline Derivatives

This work was chiefly conceived to explore the substituent effects on thermodynamic, electronic and lipophilic characteristics of some quinazoline derivatives (Q1-Q4) from theoretical aspects. The variations caused by methyl, ethyl, chlorine and bromine substituents on the same carbon of the aromatic ring were evaluated with a computational approach. In accordance with this purpose, simultaneously, DFT-based calculations were performed for vacuum and two different surroundings (DMSO and water) on methaqualone (Q1), etaqualone (Q2), mecloqualone (Q3), and mebroqualone (Q4) compounds by using the B3LYP functional and 6-311++G(d, p) split-valence triple zeta basis set. The computed thermodynamic quantities revealed that the halogen substitution was more preferable. The effect of substituent modification on electrostatic surface features was evaluated visually by molecular electrostatic potential (MEP) mapping technique. To shed light on the chemical reactivity behaviors of the Q1-Q4, DFT-based reactivity identifiers were computed. Also, the intramolecular interactions affected by substitution were evaluated on the basis of the Natural Bond Orbital (NBO) theory. The NBO results revealed that π-π* interactions predominate for each compound. The lipophilic character analyzes of the mentioned compounds were evaluated both numerically and visually. The data of both methods support each other.

Synthesis and density functional theory study of functionalized Oxazolidine-2-ones using a novel MnFe2O4@SiO2-SiO3H magnetic nanocatalyst

This study introduces MnFe2O4@SiO2-SiO3H as a novel magnetic catalyst and thoroughly investigates its structure, catalytic activity, and reusability. The synthesis of the magnetic catalyst was meticulously characterized using an array of analytical techniques. Utilizing MnFe2O4@SiO2-SiO3H, the synthesis of functionalized oxazolidine-2-ones were performed, versatile compounds widely employed in chiral auxiliaries, protecting groups, and medicinal chemistry. Remarkably, the two-step process from chalcones demonstrated one of the shortest reported pathways, highlighting the efficiency of our novel nanocatalyst. To elucidate the stability and reactivity of the synthesized products, we employed Density Functional Theory (DFT) calculations, including molecular electrostatic potential (MEP) mapping and reactivity indices such as electronegativity, electrophilic index, softness, and hardness, as well as frontier molecular orbitals (HOMO-LUMO). Furthermore, our investigations extended to the recycling capabilities of the nanocatalyst. Through a comprehensive evaluation of at least five reaction cycles, MnFe2O4@SiO2-SiO3H showcased a remarkable retention of activity (97–92 %), reaffirming its reusability and long-term potential. Our research presents MnFe2O4@SiO2-SiO3H as a highly effective and recoverable nanomagnetic catalyst for organic reactions, with demonstrated applications in synthesizing functionalized oxazolidine-2-ones. As such, our findings offer a promising alternative to traditional methods, presenting new opportunities in catalysis and materials science.

Theoretical Study of Radical Scavenging Antioxidant Activity of Coumarin Derivatives in Licorice Using DFT

Nowdays, much research is focused on exploring antioxidant activity based on natural compounds. Licorice, a traditional natural product rich in antioxidant components, has been widely used in clinical medicine. However, there is a lack of theoretical studies on the active components in licorice. In this context, the antioxidant activity of several common active components of coumarin derivatives in licorice was investigated using a density flooding theory (DFT) approach. The free radical scavenging ability of the compounds was achieved by hydrogen atom transfer (HAT), sequential electron transfer proton transfer (SET-PT) and sequential proton loss electron transfer (SPLET) mechanisms. The effect of solvent on antioxidant activity was also investigated. It was found that in the gas and benzene phases, the compounds studied preferred to undergo the HAT mechanism, while SPLET was favoured in polar solvents. In addition to the above mechanism, the HOMO and LUMO energies of the compounds as well as molecular descriptors and electrostatic potential maps were calculated and applied to predict the antioxidant activity of the compounds. The above studies allow a better understanding of the mechanism of free radical scavenging activity of coumarin derivatives from licorice.

Thermal, X-ray spectroscopy, morphological, density functional theory and molecular modeling studies on yttrium(III), germanium(IV), tungsten(VI), and silicon penicillinate antibiotic complexes

This manuscript elucidates the thermal stability analysis of four distinct penicillinate complexes, comprising yttrium(III), germanium(IV), tungsten(VI), and silicon, over a temperature ranging from 25 to 800°C. Thermal data revealed the high thermal stability nature of the decomposition steps. According to the spectroscopic measurements, the chemical formula of penicillinate complexes were [Y(Pin)2].Cl.6H2O complex (1), [Ge(Pin)2].2Cl.2H2O complex (2), [W(Pin)2].4Cl complex (3), and [Si(Pin)2].2Cl.2H2O complex (4). The powder XRD pattern revealed crystalline to polycrystalline natures. The synthesized penicillinate complexes were subjected to theoretical calculations utilizing density functional theory (DFT) calculations, employing the lanL2DZ/6-311G++ level of theory. The optimized geometry of each penicillinate complex was discerned, and a comprehensive evaluation of various properties, including the HOMO→LUMO electronic energy gap, molecular electrostatic potential map, and additional physical parameters, was conducted and validated against experimental findings. Molecular docking tool was used to explore the anticancer activity of the synthesized penicillinate complexes in comparison with penicillin potassium drug (Pin). For the computational investigation, two kinases — CSF1R (PDB ID: 7MFC) and MEK2 (PDB ID: 1S9I) associated with breast cancer progression and estrogen-dependent breast cancer were utilized. This comprehensive analysis provides a deeper understanding of the synthesized penicillinate complexes and their potential applications. KEY WORDS: Penicillinate complexes, TGA-DrTGA, TEM, XRD, DFT/TD-DFT, Molecular docking Bull. Chem. Soc. Ethiop. 2024, 38(4), 973-988. DOI: https://dx.doi.org/10.4314/bcse.v38i4.13

Exploring the adsorption of five emerging pollutants on activated carbon: A theoretical approach

The identification and management of contaminants of emerging concern (CECs) in water systems is crucial for protecting public and environmental health. This paper reports a theoretical approach to studying the adsorption of five CECs: Atrazine (ATZ), Caffeine (CAF), Carbamazepine (CBZ), Sulfamethoxazole (SMX), and Ibuprofen (IBU) - onto Activated Carbon (AC). A set of computational methods, including electrostatic molecular potential maps, conceptual density functional theory, Fukui functions, thermodynamic analysis, and tight-binding molecular dynamics simulations, were employed to analyze the electronic/energetic interactions and mechanisms involved in the adsorption of CECs on AC. The theoretical methodology offered valuable predictions on reactivity sites, stability, and binding mechanisms. Results showed that adsorption primarily occurred through non-covalent interactions like π-π electron donor-acceptor interactions, van der Waals forces, and hydrophobic interactions. Thermodynamic properties suggested the adsorption process was spontaneous and exothermic. However, for the AC/SMX system, the Gibbs free energy reveals that adsorption may be unfavorably compared to the other study systems. Molecular dynamics simulations validated the kinetic stability in the following order CAF (0.13 Å)>CBZ (0.23 Å)>ATZ (0.75 Å)> IBU (1.28 Å)>SMX (1.54 Å). This exploratory theoretical study provides a deep understanding of the interactions between AC and five CECs, aiding in the rational design and optimization of AC-based treatment systems for environmental and industrial applications.

Amplifying the nonlinear optical response of sunflower-like C16S8 through superhalogen doping

Superhalogens, known for their higher electron affinity compared to halogens, exhibit a unique ability to accept electrons from any electron donor specie. Leveraging this property, the doping of superhalogens onto electron-rich surfaces has emerged as a potent approach to augment nonlinear optical (NLO) response. Herein, we investigated the doping of beryllium trifluoride (BeF3), calcium trifluoride (CaF3) and magnesium trifluoride (MgF3) superhalogens on thia[8]circulene (C16S8) sunflower through density functional theory (DFT) calculations, to observe the improvement in the NLO response of resultant complexes. The study explores the thermal stability of complexes through interaction energy analysis, revealing robust structural properties. Conducting properties of the resultant complexes are examined via frontier molecular orbitals (FMOs) analysis, demonstrating notable changes. Molecular electrostatic potential (MEP) and Fukui function analyses gave an idea about the reactivity of the pure C16S8 and superhalogen doped C16S8 complexes. To quantify the NLO response, we assessed the first hyperpolarizability (β o) via comprehensive analysis. Remarkably, the MgF3@C16S8 complex reflects the highest hyperpolarizability value (1.85 × 104 au), signifying its exceptional NLO enhancement potential. Ultra-violet visible (UV–vis) analysis illustrated the increase in the wavelengths (red shift) of C16S8 complexes after doping of superhalogen. To elucidate the underlying factors contributing to the improved NLO response, a rationalization is provided through a two-level model.

The influence of catalyst structure on acidic strength of –SO3H groups for alkyl levulinate synthesis from biomass–derived feedstocks using sulfonic acid functionalized flexible MOF catalyst

A Brönsted acidic BUT−8(Cr)–SO3H metal–organic framework was used for the synthesis of ethyl levulinate from two different biomass–derived platform chemicals viz. furfuryl alcohol and levulinic acid. The catalyst was well characterized using various methods such as PXRD, FTIR spectroscopy, acid–base titration, NH3–TPD, TGA–DTA, SEM, TEM as well as the computational density functional theory (DFT) method. The performance of BUT–8(Cr)–SO3H catalysts was found to be superior to other catalysts (HZSM–5, H–Beta, and amberlyst –15) taken in this study. The sulfonic acid moieties bound to the aromatic naphthalene structure of BUT–8(Cr)–SO3H MOF were found to have a much stronger influence on the catalytic performance than the sulfonic acid moieties bound to the styrene framework of amberlyst–15. The key discoveries regarding the Brönsted acidic characteristics were computed via DFT incorporating the hydrogen removal energy, molecular electrostatic potential maps, and stability of the conjugate base of –SO3H moieties. The trend in the DFT–derived values was in the following order: BUT–8(Cr)–SO3H > Linker–naph –SO3H > Amberlyst–15. The results also indicate the influence of Cr metal on MOF structure to increase the acidic strength of the –SO3H group. The reaction optimization using DOE, recyclability, leaching study, and substrate scope study for both pathways using BUT–8(Cr)–SO3H were obtained.

Insight into the solution thermodynamic properties of cimetidine form A and form B based on experiments and molecular simulations

Cimetidine (CIM) is an antagonist of the type II histamine receptors, and act as a significant agent in the treatment of stomach ulcers. In this work, the effect of polymorphism and solvent type on the thermodynamic properties of CIM was investigated based on experimental results and molecular simulations. The solubility data of two polymorphs for CIM (forms A and B) in organic solvents were measured and correlated with four thermodynamic models. It could be found that the solubility of CIM form A is higher compared to form B. In addition, molecular simulations were adopted to investigate the mechanism of the solubility and stability of the two forms. Hirshfeld surface analysis shows that strong H···N interaction contributes to better stability of form B. Meanwhile, molecular electrostatic potential surface and radial distribution function results indicate that the solubility behavior is significantly influenced by the intensity of the solute–solvent interactions. Finally, the dissolution thermodynamic properties, including the enthalpy change, the Gibbs energy change, and the entropy change, were calculated and the results show that the dissolution process of CIM is endothermic, entropy-driven and spontaneous.

Synthesis, in vitro Anti-HIV-1RT evaluation, molecular modeling, DFT and acute oral toxicity studies of some benzotriazole derivatives

This study synthesized and evaluated a series of benzotriazole derivatives denoted 3(a-j) and 6(a-j) for their anti-HIV-1 RT activities compared to the standard drug efavirenz. Notably, compound 3 h, followed closely by 6 h, exhibited significant anti-HIV-1 RT efficacy relative to the standard drug. In vivo oral toxicity studies were conducted for the most active compound 3 h, confirming its nontoxic nature to ascertain the safety profile. By employing molecular docking techniques, we explored the potential interactions between the synthesized compounds (ligands) and a target biomolecule (protein)(PDB ID 1RT2) at the molecular level. We undertook the molecular dynamics study of 3 h, the most active compound, within the active binding pocket of the cocrystallized structure of HIV-1 RT (PDB ID 1RT2). We aimed to learn more about how biomolecular systems behave, interact, and change at the atomic or molecular level over time. Finally, the DFT-derived HOMO and LUMO orbitals, as well as analysis of the molecular electrostatic potential map, aid in discerning the reactivity characteristics of our molecule.

Impact of the Position of the Hydroxyl Group in Monohydroxy Chalcones with 2-Hydroxypropyl-β-Cyclodextrin on Their Spectral, Biological, and Theoretical Properties

3-Hydroxychalcone (3HOCH) and 4-hydroxychalcone (4HOCH) compounds were synthesized from the reaction between acetophenone and either 3-hydroxybenzaldehyde or 4-hydroxy benzaldehyde, using KOH as a catalyst. Then the synthesized compounds were further reacted with two cyclodextrins (CDs) (2-hydroxypropyl-β-cyclodextrin and β-cyclodextrin), by a co-precipitation method to investigate their spectral (absorption, fluorescence, and Fourier transform infrared), biological, and theoretical properties. Two absorption maximums appeared at 307 and 253 nm for 3HOCH and 346 and 254 nm for 4HOCH in aqueous solution by absorption spectrophotometry. In the excited state, dual emission was observed at 362 nm and 426 nm for 3HOCH and 360 nm and 486 nm for 4HOCH in the same medium of H2O by fluorescence spectrophotometry. The apparent changes in the absorption and emission spectra were the result of the inclusion complex with a 1:1 molar stoichiometric ratio. The interaction of 3HOCH, 4HOCH, and the CDs in the solid state was characterized by Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction patterns (PXRD), scanning electron microscopy (SEM), antioxidant and antibacterial studies concerning the position of the hydroxyl (-OH) group at the m- or p-positions in chalcone. The optimized highest occupied molecular orbital (HOMO) diagram, lowest unoccupied molecular orbital (LUMO) diagram and molecular electrostatic potential (MEP) map for the isolated molecules and their inclusion complexes were done by Becke’s three-parameter (B3) hybrid functional method using the Lee-Yang-Parr (LYP) correlation levels of density functional theory (DFT) method with 3-21 G basis set.

A comparative study of NH3 and H2S sensing performance on monolayer nanosheets through first-principle studies

This study investigates the sensing of H2S and NH3 over 2D nanosheets, namely graphene (GRA), boron nitride (BN), silicon carbide (SiC) and boron carbon nitride (BCN), using the first principle density functional theory. A CAM-B3LYP/6–31 G level of theory was used for all the computations and evaluation of the geometric and electronic properties. The optimized clusters indicated the chemisorption between the gas molecules and the SiC nanosheet. The Fourier transform infrared (FTIR) spectra were obtained to study the N-H and S-H shifts in the post-adsorption clusters. Based on the magnitude of the computed adsorption energies, SiC (-0.61 eV for the H2S cluster and −1.21 eV for the NH3 cluster) was found to adsorb both the gas molecules most effectively. The electrostatic potential maps and the molecular orbitals' distribution were studied to investigate the electronic properties. The analysis showed that the adsorption of H2S and NH3 over GRA, BN, and BCN was physical, whereas, on SiC, nanosheet chemisorption was observed. Atom-In-Molecule (AIM) analysis was carried out to account for the possible weak interactions. The study concluded that the SiC nanosheet was the most suitable for the adsorption of H2S and NH3 gases.

Evaluating the reactivity of polyvinyl alcohol/graphene nanocomposites

The synthesis and characterization of polyvinyl alcohol (PVA)/graphene nanocomposite films, through the solution casting technique, were thoroughly explored and studied. The integration of varying concentrations of graphene was systematically explored to enhance the structural and optical attributes of the PVA matrix. Comprehensive characterization employing X-ray Diffraction (XRD), Fourier-Transform Infrared (FTIR) Spectroscopy, and Ultraviolet–Visible (UV–Vis) Spectrophotometry revealed significant interactions between PVA and graphene, manifesting in a decrease in crystallinity and optical bandgap with increasing graphene content. DFT:B3LYP/6-31g(d,p) quantum mechanical level, corroborated these findings by indicating a diminished HOMO/LUMO bandgap energy. Additionally, molecular electrostatic potential mapping underscored an increase in PVA's reactivity post-graphene integration. The investigation further extends to evaluating global reactivity descriptors, providing insights through PDOS plots and QSAR analysis. The outcomes of this research underscore the potential of PVA/graphene nanocomposites for next-generation applications in flexible photovoltaic cells, transistors, and diodes.