Molecular Electrostatic Potential Calculations Research Articles

Electrostatic Surface Potentials and Chalcogen-Bonding Motifs of Substituted 2,1,3-Benzoselenadiazoles Probed via 77Se Solid-State NMR Spectroscopy.

Chalcogen bonds (ChB) are moderately strong, directional, and specific non-covalent interactions that have garnered substantial interest over the last decades. However, ChB applications are currently hampered by a lack of methods to characterize and control chalcogen bonds. We report on the influence of various substituents (halogens, cyano, and methyl groups) on the observed self-complementary ChB networks of 2,1,3-benzoselenadiazoles. From molecular electrostatic potential calculations, we show that the electrostatic surface potentials (ESP) of the σ-holes on selenium are largely influenced by the electron-withdrawing character of these substituents. Structural analyses via X-ray diffraction reveal a variety of ChB geometries and binding modes that are rationalized via the computed ESP maps, although the structure of 5,6-dimethyl-2,1,3-benzoselenadiazole also demonstrates the influence of steric interactions. 77Se solid-state magic-angle spinning NMR spectroscopy, in particular the analysis of the selenium chemical shift tensors, is found to be an effective probe able to characterize both structural and electrostatic features of these self-complementary ChB systems. We find a positive correlation between the value of the ESP maxima at the σ-holes and the experimentally measured 77Se isotropic chemical shift, while the skew of the chemical shift tensor is established as a metric which is reflective of the ChB binding motif.

Oppositely-charged silver nanoparticles enable selective SERS molecular enhancement through electrostatic interactions

Label-free surface-enhanced Raman spectroscopy (SERS) has attracted extensive attention as an emerging technique for molecular phenotyping of biological samples. However, the selective enhancement property of SERS mediated by complicated interactions between substrates and analytes is unfavorable for molecular profiling. The electrostatic force is among the most dominating interactions that can cause selective adsorption of molecules to charged substrates. This means if only negatively- or positively-charged SERS substrates are applied, then considerable SERS information from a portion of analytes would be lost, hindering comprehensive SERS sensing. In this work, we utilize both negatively- and positively-charged colloidal silver (Ag) nanoparticles (NPs) to detect various charged molecules. The negatively-charged citrate-stabilized Ag and the positively-charged Ag prepared via a cetyltrimethyl-ammonium chloride-based charge reversal protocol have been adopted as SERS substrates. The Ag NPs are all relatively well-dispersed with a good uniformity. After applying the oppositely-charged NPs to detection of charged molecules, we find the SERS results explicitly demonstrate the electrostatically-driven SERS selective enhancement, which are further supported and clarified by. molecular electrostatic potential calculations. Our work highlights the importance of developing SERS substrates modified with appropriate surface charges for various analytes, and enlightens us that potentially more molecular SERS information can be acquired from complex bio-samples using combinations of oppositely-charged substrates.

Synthesis, spectro-themal characterization, DFT calculations and biochemical evaluation of a newly synthesized tridentate Schiff base transition metal complexes

An appropriate conventional method has been utilised to synthesie new tridentate Schiff base ligand 4-chloro-2-((2,4-dihydroxybenzylidene)amino)benzoic acid with Co (II), Ni (II), Cu (II), and Zn (II) complexes. Several spectroscopic(FT-IR, 1H NMR, 13C NMR, UV–Vis, Mass), TGA-DTA, powder X-ray diffraction, and DFT calculations, were used to characterise these complexes. According to these spectroscopic investigations, the ligand coordinated with the metals via carboxylic oxygen, azomethine nitrogen, and hydroxyl oxygen, acting as a tridentate ligand. Appropriate geometry for every complex has been proposed based on spectroscopic and analytical data. In tetrahedral geometry with Co(II), Ni(II), Zn(II), and square planner with Cu(II) ion, the ligand functions as a tridentate via ONO donors. The optimal structure (bond length and bond angle) and chemical reactivity of the ligand and its metal complexes from their Frontier Molecular Orbitals (FMO) and Molecular electrostatic potential (MESP) calculations have been investigated using Density Functional Theory (DFT/B3LYP,6-31G**/6-311G**(d,p), and LanL2DZ basis sets) calculations. In vitro DPPH radical scavenging techniques were used to assess the antioxidant activity of the ligand and its metal complexes. The results indicated that all of the complexes exhibited good antioxidant activity, with the Cu (II) complex being the most potent with the lowest IC50 values. The ligand and complexes in vitro antibacterial activities were further explored by screening them against Gram(+ve) bacteria (Bacillus subtilis) and Gram(−ve) bacteria (E. coli). Significant activity was demonstrated by all synthesised compounds against the tested strains of bacteria. The antifungal activity of complexes against Aspergillus niger and Candida albicans was determined. The results indicated that Cu(II) complex exhibited good antifungal activity against Candida albicans, but not against Aspergillus niger. The fungal strain Aspergillus niger was not significantly inhibited by complexes. The complexes have greater antimicrobial activity than the Schiff base ligand, as indicated by the MIC values.

Kumquat peel-derived biochar to support zeolitic imidazole framework-67 (ZIF-67) for enhancing peracetic acid activation to remove acetaminophen from aqueous solution

This study presents the synthesis of a novel composite catalyst, ZIF-67, doped on sodium bicarbonate-modified biochar derived from kumquat peels (ZIF-67@KSB3), for the enhanced activation of peracetic acid (PAA) in the degradation of acetaminophen (APAP) in aqueous solutions. The composite demonstrated a high degradation efficiency, achieving 94.3% elimination of APAP at an optimal condition of 200 mg L−1 catalyst dosage and 0.4 mM PAA concentration at pH 7. The degradation mechanism was elucidated, revealing that superoxide anion (O2•−) played a dominant role, while singlet oxygen (1O2) and alkoxyl radicals (R–O•) also contributed significantly. The degradation pathways of APAP were proposed based on LC-MS analyses and molecular electrostatic potential calculations, identifying three primary routes of transformation. Stability tests confirmed that the ZIF-67@KSB3 catalyst retained an 86% efficiency in APAP removal after five successive cycles, underscoring its durability and potential for application in pharmaceutical wastewater treatment.

Zn(II), Mn(III), and Co(III) complexes of Schiff base derived from 2‐hydroxy‐1‐naphthaldehyde: Synthesis, spectral surveys, single crystal structure studies, Hirshfeld surface analysis, density functional theory calculation, molecular electrostatic potential, and molecular docking evaluations

A new series of transition metal complexes of bidentate Schiff base compound derived from 2‐hydroxy‐1‐(2‐methoxyethylimino)‐naphthalene (HL) were synthesized and characterized using elemental analysis, Fourier transform infrared spectroscopy (FT‐IR), and UV–vis spectroscopies. X‐ray single crystal structures of Zn(II), Mn(III), and Co(III) complexes (1–4) have also been determined, and it was indicated that these Zn(II) and Co(III) complexes (1, 4) are in an octahedral geometry. Whereas, it was found that the Zn complex (2) is in quite a regular tetrahedral environment. Also, the Mn center in complex (3) is ligated by two azomethine nitrogen atoms, two ligand oxygen atoms, and one Cl atom of metal salt forming five coordinated tetragonal pyramid geometry around the Mn atoms. The cyclic voltammetry of the complexes specifies an irreversible redox behavior for all complexes (1–4). Next, DFT/B3LYP theoretical method was used to determine the optimal geometrical configurations and comparison between experimental and theoretical data, as well as for calculations of molecular electrostatic potential, highest‐occupied molecular orbital (HOMO)‐lowest‐unoccupied molecular orbital (LUMO) energy values of selected compounds. The study of non‐covalent interactions was done by Hirshfeld surface analysis using CrystalExplorer program. Furthermore, molecular docking inspection was carried out to study the binding affinity of the tested complexes towards protein B‐cell lymphorna (PDB ID: 4LXD). Using the results obtained from the molecular docking and the summarized interaction of the binding processes, these structures show the validity of effective inhibition against liver cancer.

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)

Ultra-stable hollow nanotube conjugated microporous polymer incorporating fluorenyl moieties for Co-capture of PM and CO2

Conjugated microporous polymers have a highly delocalized π-π conjugated porous skeleton connected by covalent bonds, which can combine their excellent stability with high adsorption, in order to be applied to the study of co-capture of harmful particulate matter (PM) and carbon dioxide (CO2) under high temperature and high humidity conditions. In this paper, fluorene-based coupled conjugated microporous polymers (D-CMPs) with functionalized hollow nanotubes and abundant microporous structures were proposed. Through mechanism exploration and molecular electrostatic potential (MESP) calculation, the capture efficiency, adsorption capacity and selectivity of PM and CO2 in the waste gas stream of carbon-based combustion were analyzed. The results indicate that D-CMPs, with their rigid carbon-based π-conjugated framework, exhibit excellent tolerance under prolonged high-humidity conditions, with a capture efficiency exceeding 99.87% for PM0.3 and exceeding 99.99% for PM2.5. Meanwhile, based on its chemical/thermal stability, it can realize the recycling of adsorption-regeneration. On this basis, the "slip effect" induced by the open three-dimensional hierarchical porous structure of D-CMPs significantly enhances airflow dispersion and improves gas throughput (with a minimal permeation resistance of only 15 Pa). At a pressure of 1 bar and a temperature of 273.15 K, D-CMP-2 exhibited a CO2 adsorption capacity of up to 2.69 mmol g−1. The fitting results of three isothermal adsorption models demonstrate that D-CMPs exhibit an outstanding equilibrium selectivity towards CO2. Therefore, prior to the widespread adoption of low-carbon and clean energy technologies, porous solid materials exhibiting excellent structural stability, equilibrium selectivity, environmental tolerance, and high adsorption capacity emerge as optimal candidates for the treatment of industrial waste gases.

Synthesis, Characterization, in silico DFT, Molecular docking, ADMET Profiling Studies and Toxicity Predictions of Ag(I) Complex Derived from 4‐Aminoacetophenone

AbstractThe reaction of the synthesized (E)‐1‐(4‐((2,4‐dihydroxy‐6‐methylphenyl)diazenyl)phenyl)ethan‐1‐one, (DMPDE) ligand with Ag(I) ion at room temperature resulted in the formation of the complex; [Ag(DMPDE)(H2O)2]. 1H NMR, 13C NMR, FTIR, UV‐Vis, mass spectra, elemental analyses, thermal analysis (TGA/DTA), and molar conductance measurements were done to elucidate the structure of synthetic compounds. The results revealed an interesting geometrical variation; tetrahedral for Ag(I) complex. FT‐IR spectra demonstrated that the ligand (DMPDE) under investigation behaves as a bidentate ligand (N,O) through the nitrogen atom of the azo group which is the farthest of the acetophenone moiety and oxygen phenolic for benzene moiety and forms a stable five‐membered chelating ring. The electronic structure, molecular electrostatic potential (MEP) and quantum chemical calculations of the newly synthesized compounds are investigated theoretically at the DFT/B3LYP level of theory. Additionally, the ligand (DMPDE) and Ag(I) complex were screened against the growth of pathogenic bacteria [Actinomycosis (G+), E. Escherichia Coli (G−)] and fungi (Penicillium spp.) compared with the reference antibiotics, Chloramphenicol and Nystatin. Furthermore, 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) was used to evaluate the antioxidant activities of the ligand and its complex, which showed they both possess significant antioxidant properties in comparison with L‐ascorbic acid (Vit. C) as standard. Based on docking studies, (DMPDE) and Ag(I) complex demonstrated a greater affinity for (PDB ID: 3T88), which corresponds to Escherichia coli protein (−6.7818 kcal/mol) and (−6.7928 kcal/mol), respectively. Interestingly, the most active Ag(I) complex inside the active site of cervical cancer receptor (PDB ID: 4XR8) demonstrated a higher binding energy (−6.2631 kcal/mol) than free ligand (−5.8561 kcal/mol). In silico, ADMET displayed that compounds obey the Lipinski rule and the “Veber's rule. Consequently, is likely to exhibit oral bioavailability with good LD50 and a safety profile that includes non‐cytotoxicity, non‐immunotoxicity, and non‐skin sensitization. Finally, the compounds synthesized showed significant anticancer activity in human cervical cancer cell lines HeLa and SiHa compared with positive controls (cisplatin) and normal human hepatic cells (WRL‐68). In the present study, all tested cancer cell lines showed promising activity against Ag(I) complex, whose IC50 value ranged from (61.02 to 71.09) μg/mL.

On the influence of metal nanoparticle and π-system sizes in the stability of noncovalent adducts: a theoretical study.

Herein we have computationally evaluated the relationship between Ag and Au nanoparticle (Ag/AuNP) size and π-surface extension in the formation of noncovalent complexes at the PBE0-D3/def2-TZVP level of theory. The NP-π interaction is known in supramolecular chemistry as a Regium-π bond (Rg-π), and differentiates from classical coordination bonds in strength and type of metal orbitals involved. In this study, the Rg-π complexes involved small Ag/AuNPs composed by 1 to 5 atoms and benzene, naphthalene and anthracene as π-systems, being characterized using several molecular modeling tools, including molecular electrostatic potential (MEP) calculations, energy decomposition analysis (EDA), quantum theory of atoms in molecules (QTAIM), non covalent interaction plot (NCIplot) and natural bonding orbital (NBO) methodologies. We believe the results reported herein will be useful for those scientists working in catalysis, molecular recognition and materials science fields, where structural-energetic relationships of weak interactions are crucial to achieve product selectivity, a particular molecular recognition mode or a specific molecular assembly.

Antimicrobial activity prediction, inter- and intramolecular charge transfer investigation, reactivity analysis and molecular docking studies of adenine derivatives

The utilization of the density functional theory (DFT) methodology has developed as a highly efficient method for investigating molecular structure and vibrational spectra, and it is increasingly being employed in various applications relating to biological systems. This study focuses on conducting investigations, both experimental and computed, to analyze the molecular structure, electronic properties and features of (E)-4-(((9H-purin-6-yl)imino)methyl)-2-methoxyphenol (ANVA). The expression ANVA should be rewritten as follows: the compound is a derivative of adenine (primary amine), specifically a vanillin (aldehyde). The present study reports the synthesis, characterization, DFT, docking and antimicrobial activity of ANVA. The optimization of the molecular structure was conducted, and the determination of its structural features was performed using DFT with the B3LYP/cc-pVDZ method. The vibrational assignments were determined in detail by analyzing the potential energy distribution. A strong correlation was observed between the spectra that were observed and the spectra that were calculated. The calculation of intramolecular charge transfer was performed using natural bond orbital analysis. In addition, several computational methods were employed, including highest occupied molecular orbital–least unoccupied molecular orbital analysis, molecular electrostatic potential calculations, non-linear optical, reduced density gradient, localization orbital locator and electron localization function analysis. This paper examines the present use of adenine derivatives in combatting bacterial and fungal infections, as well as the inclusion of spectral and quantum chemical calculations in the discussion. Communicated by Ramaswamy H. Sarma

Multi-selective reaction of azinane bearing oxadiazoles and substituted haloalkanes catalyzed by alkali metal hydride to access anti-enzymatic agents

The diverse biological activities of 1,3,4-oxadiazole derivatives are very significant due to structural complexity. Concentrating on metal free synthesis of 1,3,4-oxadiazole hybrids, 5a-s were obtained by two methodologies including conventional and microwave assisted. The microwave assisted synthesis was proved to be better option for selection in future due to time saving and excellent yield. 1,3,4-Oxadiazole, 3, was synthesized in three consecutive phases and finally reacted with a series of electrophiles, 4a-s, acknowledged as alkyl halide to get the anticipated compounds. Final compounds were acquired through two different routes including conventional and microwave assisted methods. IR, 1H-NMR, 13C-NMR and elemental analysis were performed for the structural elucidation of synthesized derivatives. B3LYP method and the basis set of 6-311++G (d,p) were used for natural bond orbital and structural optimization. The time-dependent density functional theory (TD-DFT) helped for the calculation of frontier molecular orbitals (FMOs) and molecular electrostatic potential (MEP) at the same level of selected compounds as potential candidates against the enzymes taken into account. The screenings of all the nineteen derivatives were performed against alpha-glucosidase, urease and butyryl cholinesterase enzymes. Six compounds actively inhibited alpha-glucosidase in comparison with acarbose; four actively inhibited urease in comparison with thiourea; and five actively inhibited butyryl cholinesterase in comparison with eserine. Three compounds, 5n, 5a and 5q showed good inhibition potential and found the best in the synthesized series.

Improving the physicochemical and pharmacokinetic properties of olaparib through cocrystallization strategy

Olaparib (OLA) is the first PARP inhibitor worldwide used for the treatment of ovarian cancer. However, the oral absorption of OLA is extremely limited by its poor solubility. Herein, pharmaceutical cocrystallization strategy was employed to optimize the physicochemical and pharmacokinetic properties. Four cocrystals of OLA with oxalic acid (OLA-OA), malonic acid (OLA-MA), fumaric acid (OLA-FA) and maleic acid (OLA-MLA) were successfully discovered and characterized. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed the formation of cocrystals rather than salts, and the possible hydrogen bonding patterns were analyzed through molecular surface electrostatic potential calculations. The in vitro and in vivo evaluations indicate that all of the cocrystals demonstrate significantly improved dissolution performance, oral absorption and tabletability compared to pure OLA. Among them, OLA-FA exhibit sufficient stability and the most increased Cmax and AUC0-24h values that were 11.6 and 6.1 times of free OLA, respectively, which has great potential to be developed into the improved solid preparations of OLA.

Spectroscopic, Quantum Chemical and Molecular Docking Studies on N-(9H-Purin-6-yl) Benzamide: A Potent Antimalarial Agent

This study presents a comprehensive analysis of N-(9H-purin-6-yl) Benzamide (NPB) using a combination of Density Functional Theory (DFT) calculations and experimental techniques. The molecular configuration of NPB was optimized using DFT/B3LYP method employing the 6-311++G (d,p) basis set. The fundamental frequencies were calculated and assigned, which agree well with the experimental results. The UV-Vis spectroscopic analyses, HOMO-LUMO energy gap assessment, Molecular Electrostatic Potential calculation, and Mulliken charge analysis, Fukui function calculation and Natural bond orbital analysis were performed for the NPB molecule. The UV-Visible spectral analysis, which predicts the transition of bonding and anti-bonding π-electrons from the purine ring to the aromatic ring of the NPB molecule. A smaller energy gap in the HOMO-LUMO analysis reveals that the NPB molecule is more reactive and Mulliken atomic charge distribution analysis indicates that the carbon atoms are highly influenced by their substituents. Natural Bond Orbital (NBO) analysis was employed to investigate the bonding within the NPB molecule. The Fukui function analysis indicates that the biological activity of the NPB molecule. In order to analyze the structure of NPB molecule, the thermodynamic properties in the temperature range 100–1000 K were obtained by thermodynamic analysis software SHERMO calculator. The molecular docking analysis was carried out for antimalarial proteins (5ZNC, 2BMA, 7E27, 7E26) using auto-docking simulations. This computational method confirms the bioactivity and drug-likeness parameters of the NPB molecule. The molecular docking results predicts the formation of hydrogen bonds between the ligand (NPB) and the protein receptors. Based on these findings, this study establishes that the distinctive methodology applied to identify NPB molecule as a potential candidate for an antimalarial drug designing, which is suitable for in vivo and in vitro investigations.

Antimalarial drug discovery against malaria parasites through haplopine modification: An advanced computational approach.

The widespread emergence of antimalarial drug resistance has created a major threat to public health. Malaria is a life-threatening infectious disease caused by Plasmodium spp., which includes Apicoplast DNA polymerase and Plasmodium falciparum cysteine protease falcipain-2. These components play a critical role in their life cycle and metabolic pathway, and are involved in the breakdown of erythrocyte hemoglobin in the host, making them promising targets for anti-malarial drug design. Our current study has been designed to explore the potential inhibitors from haplopinederivatives against these two targets using an in silico approach. A total of nine haplopine derivatives were used to perform molecular docking, and the results revealed that Ligands 03 and 05 showed strong binding affinity compared to the control compound atovaquone. Furthermore, these ligand-protein complexes underwent molecular dynamics simulations, and the results demonstrated that the complexes maintained strong stability in terms of RMSD (root mean square deviation), RMSF (root mean square fluctuation), and Rg (radius of gyration) over a 100 ns simulation period. Additionally, PCA (principal component analysis) analysis and the dynamic cross-correlation matrix showed positive outcomes for the protein-ligand complexes. Moreover, the compounds exhibited no violations of the Lipinski rule, and ADMET (absorption, distribution, metabolism, excretion, and toxicity) predictions yielded positive results without indicating any toxicity. Finally, density functional theory (DFT) and molecular electrostatic potential calculations were conducted, revealing that the mentioned derivatives exhibited better stability and outstanding performance. Overall, this computational approach suggests that these haplopine derivatives could serve as a potential source for developing new, effective antimalarial drugs to combat malaria. However, further in vitro or in vivo studies might be conducted to determine their actual effectiveness.

Effect of resolution enhancement using metal ion assisted strategy based on electrospray ionization-ion mobility spectrometry: A case study of carbendazim and thiabendazole in fruits

A method for the rapid and simultaneous determination of carbendazim and thiabendazole residues by electrospray ionization-ion mobility spectrometry (ESI-IMS) combined with a metal ion-assisted technique was developed and validated in different fruit matrices. The metal ion assisted strategy was performed instead of tedious pre-separation procedures to overcome the limitation of low resolution of IMS. Four transition metal cations, Co(II), Ni(II), Cu(II), and Zn(II), were screened and their interactions with carbendazim and thiabendazole were investigated. The injection flow rate and metal ion concentration were optimized. The Cu(II) assisted approach helped to achieve well-separated peaks with a peak-to-peak resolution of 3.61. This method was then applied to detect carbendazim and thiabendazole simultaneously in apples, pears, bananas, and mangoes. The limit of detection (LOD) were 0.03 mg kg−1 and 0.13 mg kg−1 for carbendazim and thiabendazole, respectively, while spiked recoveries were 61.5–122.0% and 83.5–119.8%, respectively, with RSDs less than 13.9%. These satisfactory evaluation parameters indicated that the approach was capable of performing quantitative analysis of multi-pesticide residues. In addition, the feasibility of using metal ion assisted-ESI-IMS for the simultaneous detection also was theoretically demonstrated through molecular electrostatic potential analysis and binding energy calculation based on density functional theory (DFT). Both experimental and theoretical results revealed the effectiveness of the metal ion assisted strategy in improving the resolution of ESI-IMS.

Preparation, Characterizations and Theoretical Calculations of a Mg(II) Porphyrin Complex with Axial O-bonded 4-Pyrrolidinopyridine

We hereby report the synthesis of a new hexacoordinated magnesium(II) metalloporphyrin with the formula [Mg(TBrPP)(4-pypo-κO)2] (1) where TBrPP is the meso-tetra(para-bromophenyl)porphyrinate and (4-pypo-κO) is the O-bonded 4-pyrrolidinopyridine axial ligand. This Mg(II) coordination is considered the linking isomer of the already known N-bonded 4-pyrrolidinopyridine (4-pypo-κN) with the formula [Mg(TTP)(4-pypo-κN)2] where TTP is the meso-tetra(p-tolyl)porphyrinate. Complex 1 was characterized by elemental analysis, IR, 1H NMR, UV/Vis and fluorescence spectrometric techniques, cyclic voltammetry measurements as well as single-crystal X-ray diffraction analysis. The Wingx supported program PLATON and the Hirshfeld surface analysis were both used to elucidate the intermolecular interactions in the crystal lattice of complex 1.Computational studies at DFI/B3LYP-D3/6-31G(d,p)-LanL2DZ level of DFT were used to elucidate the minimum energy geometry, the HOMO and LUMO molecular orbitals characteristics and the reactivity of complex 1. The molecular electrostatic potential (MEP) calculations on complex 1 have been made to determine the electrophilic-nucleophilic character of our new Mg(II) metalloporphyrin. Furthermore, the quantum theory atom in molecule (QTAIM) calculations were performed to get more insights into the type of interactions between the [Mg(TBrPP)] moiety and the two 4-pyrrolidinopyridine axial ligands of complex 1.

Differences in tissue distribution ability of evodiamine and dehydroevodiamine are due to the dihedral angle of the molecule stereo-structure.

Introduction: This researcher focused at the evodiamine and dehydroevodiamine tissue distribution and structure-pharmacokinetics (PK) relationship after intravenous injection in mice. Methods: Using a transmembrane transport experiment, the permeability of evodiamine and dehydroevodiamine on Caco-2 cells was evaluated. The tissue distribution and pharmacokinetics (PK) of evodiamine and dehydroevodiamine in mice were studied. To comprehend the connection between structure and tissue distribution, physicochemical property evaluations and molecular electrostatic potential (MEP) calculations were performed. Results: Dehydroevodiamine's Papp values in vitro were 10-5cm/s, whereas evodiamine's were 10-6cm/s. At a dose of 5mg/kg, the brain concentration of dehydroevodiamine was 6.44 times more than that of evodiamine. By MEP or physicochemical measures, the permeability difference between evodiamine and dehydroevodiamine is unaffected. The dihedral angle of the stereo-structure appears to be the main cause of the difference in tissue distribution ability between evodiamine and dehydroevodiamine. Discussion: Dehydroevodiamine has a dihedral angle of 3.71° compared to 82.34° for evodiamine. Dehydroevodiamine can more easily pass through the phospholipid bilayer than evodiamine because it has a more planar stereo-structure. Dehydroevodiamine is therefore more likely to pass cross the blood-brain barrier and enter the brain in a tissue-specific manner.

Molecular insight into the effect of the number of introduced ethoxy groups on the calcium resistance of anionic-nonionic surfactants at the oil/water interface

The salinity seriously affects the recovery efficiency of surfactant flooding, and it is demonstrated the introduced ethoxy (EO) groups can enhance the interfacial activity of surfactants at harsh salinity via various experimental methods. In this study, sodium dodecyl sulfate (SDS) and sodium dodecyl ether sulfate (AES) are selected to investigate the effects of EO group number on the salt resistance of surfactants at the air/water interface by experiments and molecular dynamics (MD) simulation method. Optical microscopy and static multiple light scattering results show that the AES stabilized emulsions with Ca2+ ions have better stability than those of SDS, which is further explored by molecular MD simulation method. The interface formation energy (IFE) and self-diffusion coefficients (Dα) are calculated to systematically study the effects of introduced EO group number on calcium resistance of surfactants. The interaction between surfactants and Ca2+ ions at the oil/water interface is evaluated by the potential of mean of force (PMF) and the radial direction functions (RDF), which is confirmed by the calculation of molecular electrostatic potential (MEP) and coordination number. The simulation results indicate that the introduced EO groups can combine Ca2+ ions to fabricate salt bridge via intermolecular or intramolecular interactions to highly improve the calcium resistance of surfactants. The present work proposes a microcosmic perspective of the roles of EO group number on the calcium resistance of AES at the oil/water interface.

Reductive Dehalogenation of Herbicides Catalyzed by Pd0NPs in a H2-Based Membrane Catalyst-Film Reactor.

More food production required to feed humans will require intensive use of herbicides to protect against weeds. The widespread application and persistence of herbicides pose environmental risks for nontarget species. Elemental-palladium nanoparticles (Pd0NPs) are known to catalyze reductive dehalogenation of halogenated organic pollutants. In this study, the reductive conversion of 2,4-dichlorophenoxyacetic acid (2,4-D) was evaluated in a H2-based membrane catalyst-film reactor (H2-MCfR), in which Pd0NPs were in situ-synthesized as the catalyst film and used to activate H2 on the surface of H2-delivery membranes. Batch kinetic experiments showed that 99% of 2,4-D was removed and converted to phenoxyacetic acid (POA) within 90 min with a Pd0 surface loading of 20 mg Pd/m2, achieving a catalyst specific activity of 6.6 ± 0.5 L/g-Pd-min. Continuous operation of the H2-MCfR loaded with 20 mg Pd/m2 sustained >99% removal of 50 μM 2,4-D for 20 days. A higher Pd0 surface loading, 1030 mg Pd/m2, also enabled hydrosaturation and hydrolysis of POA to cyclohexanone and glycolic acid. Density functional theory identified the reaction mechanisms and pathways, which involved reductive hydrodechlorination, hydrosaturation, and hydrolysis. Molecular electrostatic potential calculations and Fukui indices suggested that reductive dehalogenation could increase the bioavailability of herbicides. Furthermore, three other halogenated herbicides─atrazine, dicamba, and bromoxynil─were reductively dehalogenated in the H2-MCfR. This study documents a promising method for the removal and detoxification of halogenated herbicides in aqueous environments.

Experimental and Theoretical Investigation on Imidazole Derivatives Using Magnetic Nanocatalyst: Green Synthesis, Characterization, and Mechanism Study

The green synthesis of 4,5-diphenyl-1H-imidazole derivatives was studied experimentally and theoretically through a one-pot, three-component reaction of diverse aldehydes, ammonium acetate, and benzil using Fe3O4@C@PrNHSO3H nanoparticles under solvent-free conditions. The core-shell magnetic nanoparticles of Fe3O4@C@PrNHSO3H were introduced as an effective, environmentally friendly, and magnetically removable catalyst in the reaction. The recovered catalyst could be used eight times with admirable catalytic activity. Before entering the laboratory, the synthesis of imidazoles was studied from a computational point of view to find the most plausible mechanism and select the appropriate raw materials. Three probable mechanistic paths were considered. Density functional theory (DFT) calculations confirmed the following mechanism: (1) reaction of benzil and ammonia to form iminoethanone, (2) reaction of aldehyde and ammonia to form imin, (3) reaction of imin with iminoethanone and ring formation, and (4) rearrangement to produce 4,5-triphenyl-1H-imidazole. The results were affirmed by the frontier molecular orbitals, natural bond orbital analyses, and molecular electrostatic potential calculations. HIGHLIGHTS The green synthesis of 4,5-diphenyl-1H-imidazole derivatives was studied experimentally and theoretically using Fe3O4@C@PrNHSO3H nanoparticles (NPs). Three proposal mechanisms were considered using M062X/6-311++G(d,p) to achieve the most plausible mechanism, The proposed mechanism was verified by the frontier molecular orbitals, natural bond orbital analyses, and molecular electrostatic potential calculations. The Fe3O4@C@PrNHSO3H NPs were introduced as an effective, eco-friendly and magnetically recoverable catalyst in the one-step synthesis of imidazoles. The recovered catalyst could be used eight times with admirable catalytic activity.