Molecular Orbital Calculations Research Articles

Synthesis, X-ray Crystallography, Spectroscopic Characterizations, Density Functional Theory, and Hirshfeld Surface Analyses of a Novel (Carbonato) Picket Fence Iron(III) Complex

An Fe(III)-carbonato six-coordinate picket fence porphyrin complex with the formula [K(2,2,2-crypt)][FeIII(TpivPP)(CO3)]·C6H5Cl·3H2O (I) has been synthesized and characterized by UV-Vis and FT-IR spectra. The structure of (carbonato)(α,α,α,α-tetrakis(o-pivalamidophenyl)porphinato)ferrate(III) was also established by XRD. The iron atom is hexa-coordinated by the four nitrogen atoms of the pyrrol rings and the two oxygen atoms of the CO32− group. Complex I, characterized as a ferric high-spin complex (S = 5/2), presented higher Fe-Np (2.105(6) Å) and Fe-PC (0.654(2) Å) distances. Both X-ray molecular structure and Hirshfeld surface analysis results show that the crystal packing of I is made by C-H⋯O and C-H⋯Cg weak intermolecular hydrogen interactions involving neighboring [FeIII(TpivPP)(CO3)]− ion complexes. Computational studies were carried out at DFT/B3LYP-D3/LanL2DZ to investigate the HOMO and LUMO molecular frontier orbitals and the reactivity within the studied compound. The stability of compound I was investigated by analyzing both intra- and inter-molecular interactions using the 2D and 3DHirshfeld surface (HS) analyses. Additionally, the frontier molecular orbital (FMO) calculations and the molecular electronic potential (MEP) analyses were conducted to determine the electron localizations, electrophilic, and nucleophilic regions, as well as charge transfer (ECT) within the studied system.

Discovery of Unprecedented Human Stercobilin Conjugates.

Two unique metabolites (M18 & M19) were detected in feces of human volunteers dosed orally with [14C]inavolisib with a molecular ion of parent plus 304 Da. They were generated in vitro by incubation with fecal homogenates and we have evidence that they are formed chemically and possibly enzymatically. Structural elucidation by high resolution mass spectrometry and NMR spectroscopy showed that the imidazole ring of inavolisib was covalently bound to partial structures derived from stercobilin, an end-product of heme catabolism produced by the gut microbiome. The structural difference between the two metabolites was the position of methyl and ethyl groups on the pyrrolidin-2-one moieties. We propose a mechanism of M18 and M19 generation from inavolisib and stercobilin whereby nucleophilic attack from the imidazole ring of inavolisib occurs to the bridging carbon of a stercobilin molecule. The proposed mechanism was supported by computational calculations of molecular orbitals and transition geometry. Significance Statement We report the characterization of two previously undescribed conjugates of the PI3K inhibitor inavolisib, generated by reaction with stercobilin, an end-product of heme catabolism produced by gut microbiome. These conjugates were confirmed by generating them using in vitro fecal homogenate incubation via non-enzymatic and possibly enzymatic reactions. Given the unique nature of the conjugate, it is plausible that it may have been overlooked with other small molecule drugs in prior studies.

Synthesis and Characterization of Octacyano-Cu-Phthalocyanine.

Octacyano-metal-substituted phthalocyanine MPc(CN)8 is a promising n-type stable organic semiconductor material with eight cyano groups, including a strong electron-withdrawing group at its molecular terminals. However, most MPc(CN)8 have not been thoroughly investigated. Therefore, CuPc(CN)8 was synthesized in this study and its crystal structure, chemical and electronic states, thermal stability, and electrical properties were investigated. This article discusses the various properties of CuPc(CN)8, as compared to those of CuPc and FePc(CN)8. The previously reported FePc(CN)8 is an organic semiconductor molecule with a molecular structure similar to that of CuPc(CN)8. X-ray diffraction (XRD) measurements revealed that CuPc(CN)8 has a crystalline structure in the P1̅ space group. The crystal structure forms an in-plane network parallel to the molecular plane through multiple hydrogen bonds by the cyano groups at the molecular terminals. Interestingly, the crystal structure, especially the molecular stacking, of CuPc(CN)8 differs from that of FePc(CN)8. The absorption edge observed in the ultraviolet-visible spectrum of CuPc(CN)8 shifted to a longer wavelength than that of CuPc, which was attributed to the energy gap of CuPc(CN)8 being smaller than that of CuPc owing to the influence of the cyano groups at the molecular terminals, according to the molecular orbital calculation results using density functional theory. Ultraviolet photoelectron spectroscopy measurements confirmed that CuPc(CN)8 had a stronger n-type character than CuPc because of the orbital energy stabilization by the cyano groups. Thermogravimetry/differential thermal analysis measurements revealed that the thermal stability of CuPc(CN)8 was significantly higher than that of FePc(CN)8. CuPc(CN)8 exhibited photoconduction upon visible-light irradiation, and its electrical conductivity was higher than that of CuPc, which was attributed to a reduction in the electron injection barrier at the electrode interfaces.

Influence of tartaric acid on the electron transfer between oxyanions and lepidocrocite

Iron oxide minerals control the environmental behavior of trace elements. However, the potential effects of electron transfer directions by iron oxides between organic acids and trace elements remain unclear. This study investigates the redox capacity of tartaric acid (TA) with chromate (Cr(Ⅵ)) or arsenate (As(V)) on lepidocrocite (Lep) from the perspective of electron transfer. The results demonstrated the configurations of TA (bidentate binuclear (BB)), As(V) (BB), and Cr(Ⅵ) (BB and protonated monodentate binuclear (HMB)) on Lep. Frontier molecular orbital calculations and X-ray photoelectron spectroscopy (XPS) binding energy shifts further indicated different electron transfer directions between TA and the oxyanions on Lep. The iron of Lep might act as electron acceptors when TA is adsorbed, whereas the iron and oxygen of Lep act as electron donors when As(V) is adsorbed. The iron of Lep might accept electrons from its oxygen and subsequently transfer these electrons to Cr(Ⅵ). Macroscopic validation experiments showed the reduction of Cr(VI), whereas no reduction of As(V). The XPS analysis showed a peak shift, with the possible formation of As–Fe–TA ternary complexes and electron transfer on Lep. These findings indicate that mineral interfacial electron transfer considerably influences the transport and transformation of oxyanions.

Photophysical, Cyclic Voltammetry, Electron Paramagnetic Resonance, X-ray Molecular Structure, DFT Calculations and Molecular Docking Study of a new Mn(III) Metalloporphyrin

Herein, we have presented a new manganese(III) metalloporphyrin, named, based on the X-ray molecular structure, the bis(4-dimethylaminopyridine)[meso-tetra(para-chlorophenyl)porphyrinato]manganese(III) triflate 1.56 chloroform solvate 0.22 n-hexane solvate 0.22 hydrate with the following formula:[MnIII(TClPP)(DMAP)2](SO3CF3)•0.22(C6H14)•1.56(CHCl3)•0.22(H2O) (complex I).This coordination compound was characterized by FT-IR and cyclic voltammetry. The dichloromethane solution UV/Vis spectrum of I is typical of a Mn(III) high-spin (S =2) porphyrin complex with a redshifted Soret band with λmax value of 487 nm. The single crystal X-diffraction technique was used to determine the molecular structure of our new Mn(III) bis(DMAP) porphyrin complex. Electron paramagnetic resonance (EPR) spectroscopy confirms that this new 3d4 Mn(III) metalloporphyrin (a non-Kramers system) in solid state is high-spin (S = 2). DFT/TD-DFT calculations on complex I were investigated, including (i) the molecular structure optimization using the DFT/B3LYP-D3/LanL2DZ level of theory, (ii) the frontier molecular orbital calculations and the deduction of the global indices of activities, (iii) the molecular electronic potential analysis (MEP), and (iv) the QTAIM and NCI-RDG analyses. Furthermore, complex I was tested against diverse amino acids of the selected Bcl-2 proteins using docking calculations.

Low-Migration Compounds with Amine Functionality as Coinitiators of Radical Polymerization.

The utilization of two-component systems comprising camphorquinone (CQ) and aromatic amines has become prevalent in the photopolymerization. However, there are still concerns about the safety of this CQ/amine system, mainly because of the toxicity associated with the leaching of aromatic amines. In light of these concerns, this study aims to develop novel coinitiator combinations featuring CQ and amines which cannot be leached out of materials, enabling free radical polymerization of representative dentalmethacrylate resins under blue light irradiation. This approach involves the initial design and analysis of hydrogen donors with low C─H bond dissociation energy through molecular modeling. Subsequently, copolymerizable methacrylate functional groups are incorporated via chemical modification, allowing it to act as both coinitiator and copolymerization monomer to achieve low migrationand leachability properties. This work presents, for the first time, the synthesis of the innovative coinitiator and compares its performance with the benchmark CQ/ethyl-4-dimethylaminobenzoate (EDB)-based photoinitiation system (PIS). The results demonstrate the effectiveness of the newly proposed PIS. Finally, an in-depth investigation is conducted into the reaction mechanism associated with this PIS through molecular orbital calculations and electron spin resonance studies.

2,4-dichloro-6-(1,4,5-triphenyl-1H-imidazol-2-yl) phenol: synthesis, DFT analysis, Molecular docking, molecular dynamics, ADMET properties against COVID-19 main protease (Mpro: 6WCF/6Y84/6LU7)

ABSTRACT New derivatives of 2,4-dichloro-6-(1,4,5-triphenyl-1H-imidazol-2-yl) phenol (DPIP) have been successfully synthesised and characterised using spectral methods such as FT-IR, 1H NMR and 13C NMR. Density functional theory (DFT) approach at B3LYP/6-311 G (d, p) level of theory is used to determine optimised bond parameters and single crystal XRD investigation of related derivatives confirms the structure of DPIP bond parameters. The single crystal XRD measurements and the optimised geometrical parameters produced by the DFT calculation agree well. The FT-IR bands seen in the experiment were attributed to distinct normal modes of the molecule. Frontier molecular orbital computations described the molecule stability, chemical reactivity and charge transfer. Atomic charges determined via Mulliken population analysis on the different DPIP atoms. MEP, which is mapped to the electron density surfaces, has discovered potential reactive sites of the molecule. The reported molecule is used as a potential NLO material since it has a high μβ0 value. Binding affinities were discovered using molecular docking against the COVID-19 major protease (Mpro: 6WCF/6Y84/6LU7). The behaviour of the complex structure formed by the Covid-19 protein under in silico physiological conditions was then confirmed by a 100 ns molecular dynamic simulation which looked at the structure stability over time and revealed a stable conformation and binding pattern in an environment of imidazole derivatives. Furthermore, favourable to moderate anti-viral activity was revealed by an in-silico analysis that anticipated the compound absorption, distribution, metabolism, excretion and toxicity profiles (ADMET).

Novel disposable screen-printed sensors based on copper oxide nanoparticles for sensitive voltammetric assay of antazoline

The fabrication and electroanalytical validation of a novel homemade screen-printed carbon electrode enriched with copper oxide nanoparticles (CuONPs/SPCEs) were demonstrated for sensitive and selective voltammetric determination antazoline (ANT) in eye drop solution and spiked serum samples. With a reported electrocatalytic activity, CuONPs catalyzed the oxidation of ANT at the electrode surface showing an irreversible anodic oxidation peak at 0.9 V under a diffusion-controlled electrode reaction. Based on the electroanalytical and molecular orbital calculation studies, oxidation of ANT molecule undergoes via oxidation of the aliphatic nitrogen atom within the ANT moiety. Linear calibration curves were illustrated covering the ANT concentration ranged from 0.01 to 3.819 µg mL−1 with and limit of detection 3 ng mL−1. The fabricated sensors enriched with CuONPs exhibited high fabrication and measurement reproducibility with a prolonged shelf lifetime (6 months). The electroanalytical approach presented adequate sensitivity and selectivity with a short analysis time, applying low-cost instrumentation and simple pretreatment protocol avoiding handling hazardous organic solvents. Trace ANT was monitored in the presence of different interfering species, degradation products, and xylometazoline hydrochloride (ZYL) in the co-formulated ophthalmic pharmaceutical samples. The CuONPs based voltammetric sensors were introduced as a reliable eco-friendly analytical tool for monitoring ANT in ophthalmic solutions and biological fluids with acceptable recovery values.

Organocatalyst 1,4-diazabicyclo [2.2.2]octane (DABCO)-catalyzed Sustainable Synthesis of Bis-thiazolidinones Derivatives and their Spectral and DFT Analysis

Abstract: Organocatalyst 1,4-diazabicyclo [2.2.2]octane (DABCO) has proven to be an efficient and environmentally friendly catalyst in the multicomponent reaction involving aldehydes, ethylenediamine, and thioglycolic acid under microwave conditions. DABCO stands out among other organic catalysts due to its cost-effectiveness, non-toxic nature, and environmentally conscious profile. The method employed in this study exhibited exceptional attributes, such as high yields, swift reaction times, atom economy, catalyst reusability, and minimal catalyst loading. Additionally, there were excellent yields of products (90-94%). The melting points, UV-Vis, IR, 1HNMR, 13CNMR, were used to analyze the produced compounds. The invitro antibacterial activity of the synthesized compounds was investigated against pathogenic strains E. coli and Bacillus supstalis, and the results obtained were further explained with the help of DFT and molecular orbital calculations. Moreover, the compound 4b was found to be the most potent antibacterial agent amongst all tested compounds.

DPD simulation to reproduce lipid membrane microdomains based on fragment molecular orbital calculations

Lipid domains play a critical role in signal transduction and transport across cell membranes. The formation of domains in “HLC” ternary lipid bilayers composed of high transition temperature (high-Tm) lipids, low-Tm lipids, and cholesterol (Chol) has been extensively studied as a raft-like system. Recently, experiments were performed to control the formation of submicron domains in LLC lipid bilayers containing low-Tm phosphatidylethanolamine (PE), low-Tm phosphatidylcholine (PC), and Chol by manipulating the presence or absence of Chol. The formation of microdomains in this LLC mixture was replicated by dissipative particle dynamics simulation. The results show that domain formation can be replicated.

Separation of indium and tin from ITO powders with short-chain dicarboxylic acid-ChCl deep eutectic solvents: Indium tin leaching and splitting mechanism

The substitution of corrosive mineral acids with green deep eutectic solvents (DESs) for extracting rare and precious metals from discarded electronic devices has a sustained appeal for developing clean hydrometallurgical processes. However, the dissolution mechanism of DESs on specific metals still requires an exhaustive understanding. In this work, short-chain dicarboxylic acid-choline chloride DESs were used to dissolve indium tin oxide (ITO) to achieve the separation of indium and tin. Kinetic and thermodynamic studies have shown that the leaching of indium and tin was considered a mixed control of diffusion and chemical reaction, with low activation energies (Ea(In) = 39.93 kJ/mol, Ea(Sn) = 39.52 kJ/mol). The electrospray ionization mass spectrometry (ESI-MS) analysis of the leaching solution and molecular orbital calculations revealed that tin was leached in the main form of [Sn4+(OH−)3(H2O)]+ cation as well as slight [Sn4+MA2−(Cl−)3]− anion, while the dominant ions of indium were [In3+(Cl−)4]− ligand as well as small amounts of [In3+MAH−(Cl−)4]2−, [In3+(MA2−)3]3− and [In3+MA2−(Cl−)2]−. The tin-containing species in the leaching solution can be completely precipitated in the form of cassiterite SnO2 through water dilution and hydrothermal treatment, in which amorphous indium-containing substances were mixed. Most of the indium was retained in the form of [In3+(Cl−)4]− in the liquid. After adjusting the pH of the solution, over 99% of the indium precipitated out as In(OH)3, and after calcination at 600 °C in air for 1 hour, In2O3 was obtained. This study unveiled the leaching mechanism of short-chain dicarboxylic acid-choline chloride DESs on ITO powders. It developed a green, simple, and mild process for potentially recovering ITO-based materials.

Intermolecular interactions in 4-bromoaryl derived aldimines: X-ray structure, Hirshfeld surface analysis, DFT and molecular docking studies

A convenient and facile synthesis of (E)-N-(4-bromophenyl)-1-phenylmethanimine (b), (E)-N-(4-bromophenyl)-1-(2,4-dinitrophenyl) methanimine (c) and (E)-4-(((4-bromophenyl)imino) methyl)-2-methoxyphenol (d) was accomplished by refluxing 4-bromo aniline(a) with an appropriate aldehyde in solvent methanol. X-ray crystallography, theoretical computations, and spectroscopic techniques were utilized to describe and detect interactions between and among various groups of synthesized imines (b-d). Compound b-d crystallize in monoclinic crystal systems with space groups Pnma, P21, P21/c, and P21/c, respectively, whereas compound a crystallize in orthorhombic crystal systems. To identify the intermolecular interactions, Hirshfeld surface analysis was also used, emphasizing the importance of hydrogen bonding, van der Waals forces, and the impact of substituents. Hirshfeld surface fingerprint plots were used to study crystal packing motifs. Energy frameworks examined the electrostatic energy input that stabilizes solid state structures. Additionally, studies pertaining to the optimization of the structure, frontier molecular orbital (highest occupied–lowest unoccupied) and molecular electrostatic potential calculations were conducted. Lastly, using the membrane protein of the naturally occurring fungus Candida albicans SC5314, molecular docking investigations of compounds a–d were conducted (PDB-ID 7RJE)

Novel Deliberately Sensitive and Selective Tetrahydrozoline Voltammetric Sensors Integrated with a Copper Oxide Nanoparticle/Zeolite Platform.

The present study introduced a novel disposable screen-printed carbon electrodes (SPCEs) modified with copper oxide/zeolite nanostructures for eco-friendly selective differential pulse voltammetric quantification of tetrahydrozoline (THZ) in eyedrop samples and biological fluids. Modification of the electrode matrix with copper oxide nanoparticles/zeolite nanostructures (CuONPs/ZY) with their effective and synergistic electrocatalytic activity enhanced the electrode performance against electrooxidation of THZ at 0.960 V in BR at pH 9.0 with a diffusion-controlled reaction mechanism. The tentative oxidation mechanism based on molecular orbital calculations postulates the oxidation of THZ molecules through oxidation of a nitrogen atom five-membered ring and the participation of two electrons/protons in the electrode reaction. Linear calibration curves were illustrated within a wide THZ concentration range from 0.24 to 57.2 μg mL-1 recording a limit of detection (LOD) value of 0.0799 μg mL-1. The CuONPs/ZY/SPEs exhibited improved performance compared with the sole reported THZ sensor-based gold film-plated carbon paste electrodes, in addition to their high reproducibility of fabrication and measurement and prolonged shelf lifetime. Tetrahydrozoline was successfully assayed in the presence of excipients, degradation products, and chloramphenicol. The presented voltammetric sensor can be considered as an eco-friendly and reliable analytical approach for monitoring THZ residues in eye drop samples and biological fluids with high recovery compared with the official pharmacopeial analytical protocol. The presented sensors were assessed according to an EcoScale tool and also compared with the reported THZ sensor.

Prediction of Binding Pose and Affinity of Nelfinavir, a SARS-CoV-2 Main Protease Repositioned Drug, by Combining Docking, Molecular Dynamics, and Fragment Molecular Orbital Calculations.

A novel in silico drug design procedure is described targeting the Main protease (Mpro) of the SARS-CoV-2 virus. The procedure combines molecular docking, molecular dynamics (MD), and fragment molecular orbital (FMO) calculations. The binding structure and properties of Mpro were predicted for Nelfinavir (NFV), which had been identified as a candidate compound through drug repositioning, targeting Mpro. Several poses of the Mpro and NFV complexes were generated by docking, from which four docking poses were selected by scoring with FMO energy. Then, each pose was subjected to MD simulation, 100 snapshot structures were sampled from each of the generated MD trajectories, and the structures were evaluated by FMO calculations to rank the pose based on binding energy. Several residues were found to be important in ligand recognition, including Glu47, Asp48, Glu166, Asp187, and Gln189, all of which interacted strongly with NFV. Asn142 is presumably regarded to form hydrogen bonds or CH/π interaction with NFV; however, in the present calculation, their interactions were transient. Moreover, the tert-butyl group of NFV had no interaction with Mpro. Identifying such strong and weak interactions provides candidates for maintaining and substituting ligand functional groups and important suggestions for drug discovery using drug repositioning. Besides the interaction between NFV and the amino acid residues of Mpro, the desolvation effect of the binding pocket also affected the ranking order. A similar procedure of drug design was applied to Lopinavir, and the calculated interaction energy and experimental inhibitory activity value trends were consistent. Our approach provides a new guideline for structure-based drug design starting from a candidate compound whose complex crystal structure has not been obtained.

Study of Interactions of Nucleoside Anticancer Drugs, Capecitabine and Gemcitabine, with SWNT and BNNT using Molecular and Quantum Mechanical Calculations

Abstract: Using single-wall carbon nanotubes (SWCNTs) and boron nitride nanotubes (BNNTs), this study evaluated the interactions between Capecitabine (CAP) and Gemcitabine (GEM). Molecular mechanics and quantum mechanics were used in the analysis. : The interaction between CP and GM with SWCNTs and BNNTs under various solvents was analyzed using the self-consistent reaction field (SCRF) as a model and DFT as the analytical method. Additionally, the effect of temperature on the stability of the molecule interactions during the experiment was examined. The thermodynamic properties of the title compounds were analyzed based on theoretical calculations. It included the calculation of Frontier Molecular Orbitals (FMOs) and Total Density of States (DOS). In addition to studying the ionization potential (I), we also examined the other molecular properties of the structures, such as electrophilicity (ω), electron affinity (A), chemical hardness (η), and electronic chemical potential (μ). To investigate the interaction between CAP and GEM with SWCNTs and BNNTs, molecular mechanics methods (MM) including AMBER, OPLS, CHARMM, and MM+ force fields, were employed. Monte Carlo simulation techniques were used to calculate the results at different temperatures. : The effects of the liquid phase and mixed solvent media with varying dielectric constants (Water, DMSO, Methanol, and Ethanol) on the interaction between CAP and GEM using the force fields described above were examined in this study. The correlation between data generated by Monte Carlo, Quantum Mechanics, and Molecular Mechanics was demonstrated. There was a striking similarity in the thermodynamic properties and conformer populations of all three materials.

Developing high-power Li||S batteries via transition metal/carbon nanocomposite electrocatalyst engineering.

The activity of electrocatalysts for the sulfur reduction reaction (SRR) can be represented using volcano plots, which describe specific thermodynamic trends. However, a kinetic trend that describes the SRR at high current rates is not yet available, limiting our understanding of kinetics variations and hindering the development of high-power Li||S batteries. Here, using Le Chatelier's principle as a guideline, we establish an SRR kinetic trend that correlates polysulfide concentrations with kinetic currents. Synchrotron X-ray adsorption spectroscopy measurements and molecular orbital computations reveal the role of orbital occupancy in transition metal-based catalysts in determining polysulfide concentrations and thus SRR kinetic predictions. Using the kinetic trend, we design a nanocomposite electrocatalyst that comprises a carbon material and CoZn clusters. When the electrocatalyst is used in a sulfur-based positive electrode (5 mg cm-2 of S loading), the corresponding Li||S coin cell (with an electrolyte:S mass ratio of 4.8) can be cycled for 1,000 cycles at 8 C (that is, 13.4 A gS-1, based on the mass of sulfur) and 25 °C. This cell demonstrates a discharge capacity retention of about 75% (final discharge capacity of 500 mAh gS-1) corresponding to an initial specific power of 26,120 W kgS-1 and specific energy of 1,306 Wh kgS-1.

DFT study on the effects of substituents on the structure and properties of dithiophosphate collectors

AbstractThe structures and properties of seven substituted dithiophosphate (DTP) collectors containing three types of functional groups (O2PS2, C2PS2, and N2PS2) were studied using density functional theory. The collectors studied were dibutyl dithiophosphate (DNBDTP), diisobutyl dithiophosphate (DIBDTP), dibutoxyethyl dithiophosphate (DBOEDTP), xylenol dithiophosphate (DMPDTP), diisobutyl dithiohypophosphite (3418A), diphenylamine dithiophosphate (DTADTP), and dicyclohexylamine dithiophosphate (DCADTP). The structural analysis showed that the PS bond lengths in the C2PS2 and N2PS2 types are longer than those in the O2PS2 type, indicating that the strength of the PS bond is weaker in the former two. The frontier molecular orbital studies showed that the energy differences between the highest occupied molecular orbitals (HOMO) of 3418A (C2PS2 type) and DCADTP (N2PS2 type) and the lowest unoccupied molecular orbital (LUMO) of galena are significantly lower than those of the other collectors, suggesting that C2PS2 type and N2PS2 type with cyclohexane could enhance the interaction with galena. Using the Fukui function to calculate the nucleophilicity and electrophilicity of the sulfur atom indicated that the S atom exhibits nucleophilicity, especially in DMPDTP and DTADTP, which contain benzene rings, and the S atom exhibits strong nucleophilicity without electrophilicity. However, due to the lack of contribution from S atoms to the LUMO orbitals, the S atoms in these two compounds are not participate in any LUMO reactions. The adsorption results demonstrated that 3418A (C2PS2 type) and DCADTP (N2PS2 type) exhibit the strongest adsorption on Pb2+ ions, while DMPDTP (C2PS2 type) and DTADTP (O2PS2 type) which contain benzene rings, as well as DBOEDTP (C2PS2 type) which does not contain a benzene ring, exhibit weaker interaction compared to the other compounds. These are consistent with the results of the frontier molecular orbital and electrophilic nucleophilicity calculations.

Synthesis and Antibacterial Activity of Azomethine Ligand and Their Metal Complexes: A Combined Experimental and Theoretical Study

An asymmetrical Schiff base triazole ligand (4-((3-mercapto-5-(naphthalen-1-ylmethyl)-4H-1,2,4-triazol-4-yl)imino)methyl)methoxy) (L) was used to generate novel micro complexes of Cr(III), VO(IV), and Mn(II) ions. Different spectroscopic techniques, including UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), flame atomic absorption, conductivity tests, CHNS elemental analysis, and magnetic susceptibility, were used to determine the structures of the Schiff base micro complexes. The density functional theory (DFT) calculation was screened to consider selected complexes. The observed data indicated their stability, and the expected chemical formula of vanadium(IV) was square pyramidal geometry in VO(L) complex formula. In contrast, the Cr(III) and Mn(II) complexes have octahedral geometry in the formulas. Frontier molecular orbitals calculations (MO) have also been performed to better understand the nature of orbitals, EHOMO, and ELUMO, allowing us to confirm the experimental finding. Pseudomonas aeruginosa and Bacillus subtilis, two types of potentially dangerous bacteria, were subjected to tests to see whether L and its metal complexes have any antibacterial activities or not. All compounds were also tested for their antifungal activity against two different types of fungi, Penicillium spp. and Aspergillus flavus. There is significant action has been noted in all cases for the complexes.

XRD/DFT, Hirshfeld surface analysis and molecular modelling simulations for unfolding reactivity of newly synthesized vanillin derivatives: excellent optical, NLO and protein binding efficiency

New vanillin derivatives, namely, ethyl (4-formyl-2-methoxyphenoxy)acetate (2a) and 2-(4-formyl-2-methoxyphenoxy)-N-phenylacetamide (2b), respectively, were synthesized and characterized by NMR (1H and 13C), IR, mass spectra and confirmed by single-crystal X-ray analysis. Hirshfeld surface (HS) analysis was performed to probe intra- and intermolecular interactions and surface reactivity. 2D fingerprint plots (FP) were used to study the nature and percentage contribution of intermolecular interactions leading to the formation of the crystal unit. Density functional theory (DFT) simulations were used to obtain the electronic structure and reactivity of the new molecules. Natural population analysis (NPA) and frontier molecular orbital (FMO) calculations reveal significant charge transfer and a reduced HOMO-LUMO gap up to 4.34 eV for 2b. Bader’s quantum theory of atoms in molecules (QTAIM) study is utilized to understand the surface topological and bonding nature of 2a and 2b. The performed molecular electrostatic potential (MESP) and density of states (DOS) study further suggest sites likely to be attractive to incoming reagents. At the same time, hyperpolarizability (βo) is used to characterize the nonlinear optical properties, and TD-DFT study shows the excitation energy and absorption behavior. In silico studies were performed, including docking, binding free energies (MMBGSA) and molecular dynamics simulations. Compounds 2a and 2b were docked with RdRp of SARS-Cov-2, and the MMBGSA for 2a and 2b were −30.70 and −28.47 kcal/mol, respectively, while MD simulation showed the stability of protein-ligand complexes. Communicated by Ramaswamy H. Sarma

Synthesis of Hybrid Porphyrin(2.1.2.1)s and Their Complexation.

Novel hybrid porphyrin(2.1.2.1)s and their boron and copper complexes were synthesized using the "toy bricks" synthetic method. Crystal data, frontier molecular orbital calculations, and electrostatic potential surface maps reveal that hybridization in the porphyrin(2.1.2.1) donor-acceptor unit controls the selective coordination of BF2.