Average Local Ionization Energy Research Articles

Effect of pH on the ozonolysis degradation of p-nitrophenol in aquatic environment and the synergistic effect of hydroxy radical.

Density functional theory (DFT) was employed to elucidate the mechanisms for ozonolysis reaction of p-nitrophenol (PNP) and its anion form aPNP. Thermodynamic data, coupled with Average Local Ionization Energies (ALIE) analysis, reveal that the ortho-positions of the OH/O- groups are the most favorable reaction sites. Moreover, rate constant calculations demonstrate that the O3 attack on the C2-C3 bond is the predominant process in the reaction between neutral PNP and O3. For the aPNP + O3 reaction, the most favorable pathways involve O3 attacking the C1-C2 and C6-C1 bonds. The rate constant for PNP ozonolysis positively correlates with pH, ranging from 5.47 × 108 to 2.86 × 109M-1s-1 in the natural aquatic environment. In addition, the formation of hydroxyl radicals in the ozonation process of PNP and the mechanisms of its synergistic reaction of PNP with ozone were investigated. Furthermore, the ozonation and hydroxylation processes involving the intermediate OH-derivatives were both thermodynamically and kinetic analyzed, which illustrate that OH radicals could promote the elimination of PNP. Finally, the toxic of PNP and the main products for fish, daphnia, green algae and rat were assessed. The findings reveal that certain intermediates possess greater toxicity than the original reactant. Consequently, the potential health risks these compounds pose to organisms warrant serious consideration.

Biocompatible citrate-cysteine complexes of manganese as effective antioxidants: Experimental and computational studies

Many clinical studies have evaluated the ability of sulfur-containing antioxidants to prevent oxidative stress, a major cause of cancer, Parkinson's, and Alzheimer's disease. Cysteine complexes of manganese modified with citric acid were synthesized by a one-pot procedure in two molar ratios and at two different temperatures (90°C, 140°C). The synthesized complexes were studied using FT-IR, UV-Vis, NMR, and EDX. At the lower temperature, a hydrogel was formed, and a thiazolopyridine ring was formed at a temperature of 140°C which was complexed with manganese. Infrared and electronic absorption spectroscopy confirmed that manganese binding occurred via the oxygen atoms of COO. The complexes also exhibited strong fluorescence with excitation/emission peak wavelengths of 350/418 nm. The synthesized compounds showed efficient activity for superoxide scavenging (> 70%), which was evaluated by a pyrogallol autoxidation method. MTT assay studies confirmed the noncytotoxic nature of all the prepared samples. The Gaussian 09 program was used to optimize the structural configurations of the ligands and complexes based on DFT by the B3LYP/6-31+G(d) basis set. To evaluate the softness of both the ligand and the complex, an investigation of the HOMO-LUMO gaps was carried out. In addition, UV-vis spectra of Mn complexes obtained from the time-dependent DFT calculations show a strong peak in the range of 380-390 nm, which is in good agreement with our experimental findings. The results revealed that the oxygen atoms of citrate and cysteine are the most potential sites to interact with the Mn atom. Besides, the calculated average local ionization energies showed that the Mn atom is the most energetically favored and vulnerable site to an electrophilic or free radical attack.

Biginelli dihydropyrimidines carrying azole rings: Synthesis, computational studies, and evaluation of alpha‐glucosidase inhibitory and antimicrobial activities

In the current study, we designed three novel compounds by merging two valuable nitrogen-containing pharmacophores, namely dihydropyrimidine (DHPM) and azole, within a single molecule. To obtain the target molecules, azole-linked benzaldehydes were initially synthesized via nucleophilic aromatic substitution reaction between 4-fluorobenzaldehyde and pyrazole, imidazole, or 1,2,4-triazole. Afterward, Biginelli reaction was applied to yield azole-carrying DHPMs. Following structural confirmation, the obtained compounds were tested for their alpha (α)-glucosidase inhibitory and antimicrobial activities. According to the biological data, DHPM-P and DHPM-T showed strong inhibition values whereas DHPM-I failed to effectively inhibit the α-glucosidase enzyme. This situation was explained by molecular docking studies of all compounds into the binding site of alpha-glucosidase. The title compounds also presented moderate antibacterial and antifungal activities. Computational methods based on density functional tight binding (DFTB) and density functional theory (DFT) calculations, along with molecular dynamics (MD) simulations were used to analyze the reactive properties of the compounds. A combination of DFTB and DFT calculations was applied to obtain the lowest energy conformations of the molecules. Further computational analysis included calculations of local reactivity descriptors, such as molecular electrostatic potential and average local ionization energy, by applying DFT calculations. DFT calculations were also used to study intramolecular non-covalent interactions. MD simulations were employed to understand how the title molecules behave in water and to obtain their solubility parameters.

Boiling, critical, and freezing temperatures in light of molecular descriptors: correlation and causation.

In the pursuit of tracking some physicochemical properties of fluids down to the molecular level, ab initio molecular surface analyses were performed on 169 molecules. This included electrostatic potential (EP), average local ionization energy (ALIE), and electron localization function (ELF) mapped onto an electron density isosurface value of 0.001 au. Using stepwise linear regression (SLR) analysis, it was found that besides the well-studied EP, ALIE and ELF played important roles in determining the normal boiling and freezing points and critical temperatures of fluids. Apparently, the ALIE and ELF were relevant to the attractive polarization forces and repulsive Pauli forces, respectively, between molecules. To further demonstrate and rationalize this assumption, a localized molecular orbital energy decomposition analysis (LMO-EDA) was carried out. In the LMO-EDA analysis, the complexes of the helium atom, He, and ClCl, ClBr, ClI, OCO, OCS, OCSe, and CO/OC molecules were investigated, where the helium atom faced different molecular sites in each molecule. Fortunately, the results showed that lower the ALIE value on a molecular site, the stronger (i.e., more attractive) the polarization interaction energy. The results also indicated that higher the ELF value on a molecular site, the stronger (i.e., more repulsive) the Pauli interaction. The work is aimed to present novel molecular-based rationales to physical chemists, chemical engineers, and materials scientists.

Unveiling the Quantitative Relationships between Electron Distribution and Steric Hindrance of Organic Amines and Their Reaction Rates with Carbonyl Sulfur: A Theoretical Calculation Investigation.

The removal of carbonyl sulfide (COS) commonly contained in natural gas is of great significance but still very challenging via a widely employed absorption process due to its low reactivity and solubility in various commercial solvents. Artificial intelligence (AI) is playing an increasingly important role in the exploration of desulfurization solvents. However, practically feasible AI models still lack a thorough understanding of the reaction mechanisms. Machine learning (ML) models established on chemical mechanisms exhibit enhanced chemical interpretability and prediction performance. In this study, we constructed a series of solvent molecules with varying functional groups, including linear aliphatic amines, cyclic aliphatic amines, and aromatic amines and proposed a three-step reaction pathway to dissect the effects of charge and steric hindrance of different substituents on their reaction rates with COS. Chemical descriptors, based on electrostatic potential (ESP), average local ionization energy (ALIE) theory, Hirshfeld charges, and Fukui functions, were used to correlate and predict the electrophilic reactivity of amine groups with COS. Substituents influence the reaction rate by changing the attraction interaction of amine groups to COS molecules and the electron rearrangement in the electrophilic reaction. Furthermore, they have more pronounced steric effects on the reaction rate in the linear amines. The descriptors N_ALIE and q(N) were found to be crucial in predicting the reactivity of amine groups with COS. Present study provides a comprehensive understanding of the reaction mechanisms of COS with amine compounds, offers specific chemical principles for the development of chemistry-driven ML models, sheds light on other types of electrophilic reactions occurring on amine and phosphine groups, and guides the development of chemical solvents in gas absorption processes.

Comprehensive solubility study and inter-molecular interactions on fenbendazole dissolved in some aqueous aprotic and protic co-solvent solutions

The isothermal shake-flask saturation method was used to experimentally determine the mole-fraction solubility of fenbendazole in three aqueous co-solvent blends of 1,4-dioxane/acetone/NMP encompassing the range of 283.15 to 328.15 K. The solubility of fenbendazole in various blended solvents ranks NMP + water (4.852 × 10−2) > 1,4-dioxane + water (14.81 × 10−4) > acetone + water (2.285 × 10−4) with composition of 1,4-dioxane (acetone or NMP) of 1 at 298.15 K. The solubility data rises monotonically with 1,4-dioxane/acetone/NMP concentration at the same temperature. X-ray power diffraction images show that no solvate production or crystal transition appeared throughout the studies. The solubility to solvent composition and temperature was satisfactorily associated by the modified van't Hoff-Jouyban-Acree, quantitative structure–property relationship, and Jouyban-Acree models with relative average deviations of no higher than 7.05 % and root-mean-square deviation of no higher than 1.225 × 10−3. In addition, the 1,4-dioxane/acetone/NMP + water blends studied in this paper and the methanol/ethanol/EG/DMF + water blends previously reported both used the extended Hildebrand solubility approach to quantitatively describe the solubility behavior at 298.15 K. The average relative deviations were kept under 4.06 % on both cases. As stated by the examination of the linear solvation energy relationship, the solubility parameter and dipolarity-polarizability of solutions have a significant influence on the solubility variation. The effective method of inverse Kirkwood-Buff integrals was used to investigate the preferred solvation of fenbendazole at 298.15 K. In blends with intermediate and rich ethanol/DMF/1,4-dioxane/acetone/NMP composition areas, the preferred solvation parameters of ethanol/DMF/1,4-dioxane/acetone/NMP displayed positive values, indicating the preferential solvation of fenbendazole by the co-solvents. Thermodynamic examination of the entropy-enthalpy compensation and dissolution parameters for fenbendazole dissolving in blends led to the identification of an enthalpy and/or entropy-driven mechanism as well as an endothermic process. Moreover, the average local ionization energy and electrostatic potential of molecular surface were utilized as effective instruments to demonstrate the microscopic electrostatic properties of acidity and basicity, respectively. The fenbendazole molecule's groups of –N in the five-membered ring and –NH in the straight chain serve as the main targets for electrophilic and nucleophilic assault. The weak interactions between fenbendazole and several solvents were shown using an independent gradient model based on Hirshfeld partition analysis.

Assembling Nitroamino and Amino Groups on a Pyrazolyl-1,3,4-Oxadiazole Framework for the Construction of High-Performance and Insensitive Energetic Materials

AbstractThe introduction of nitroamino groups onto a nitrogen-rich heterocyclic skeleton is an efficient method for constructing high-performance energetic compounds. In this work, the nitroamino-functionalized compound 4-(5-amino-1,3,4-oxadiazol-2-yl)-N,N′-dinitro-1H-pyrazole-3,5-diamine was synthesized in yields of up to 83%. In addition, its energetic salts were also prepared. All these compounds were characterized by NMR and IR spectroscopy and, in two cases, by single-crystal X-ray diffraction. In addition, the difference in the reactivities of the three amino groups on the pyrazolyloxadiazole system was analyzed by an average local ionization energy analysis. The hydrazinium salt of the diamine exhibits promising detonation properties and good molecular stability, suggesting it has good application potential. Compared with previous works, this strategy gives an improved isolated yield and provides a promising method for the construction of nitroamino-functionalized 1,3,4-oxadiazole derivatives.

Unveiling the potential and mechanisms of 3,3′-bicarbazole-based quaternary ammonium salts as levelers

It is important to introduce an effective leveler into electroplating bath to meet the desired requirement in the electronic industry. This work explored the impact of larger backbone structures of four 3,3′-bicarbazole quaternary ammonium salts on the performance of promising levelers in light of the ambiguous mechanism of action. For the first time, these four compounds have been functionalized and identified as promising levelers for copper electrodeposition in through holes. Electrochemical measurements, theoretical calculations, and dynamics simulations collectively revealed that among these levelers, BCz-BPD exhibits the tendency of optimal adsorption on the cathode with the strongest inhibition of copper deposition. Chronoamperometry tests were carried out to analyze the copper nucleation model during electroplating. By measuring the electrostatic potential, average local ionization energy, and planarity, the leveling mechanism of BCz-BPD leveler was analyzed. In order to confirm the high through-hole filling and excellent leveling performance of BCz-BPD in actual PCB plating, TP value measurement, SEM, and XRD tests were carried out sequentially. In addition, galvanostatic measurements were performed to study the interaction of BCz-BPD leveler with other kinds of additives.

Connection between nuclear and electronic Fukui functions beyond frontier molecular orbitals.

Based on the relationship between average local ionization energy Ī(r) and average local electron affinity Ā(r) with the electronic Fukui functions, i.e., f-(r) and f+(r), respectively, in this paper, we establish a connection between nuclear and electronic Fukui functions beyond frontier molecular orbitals. As a consequence of this connection, we obtain expressions of average nuclear Fukui functions interpreted as a variation of average nucleophilicity or electrophilicity (weighted by the electronic orbital Fukui functions) with respect to nuclear displacements, which goes beyond the highest occupied molecular orbital/or lowest unoccupied molecular orbital consideration. Furthermore, from this connection and considering the frontier molecular orbital approximation, we derive expressions of nuclear Fukui functions in terms of the atom-condensed electronic Fukui functions, which imply a locality in the chemical reactivity and could be used to study the variation of local nucleophilicity or electrophilicity with respect to nuclear displacements. Finally, this new way to interpret the nuclear Fukui function could be useful in the future to study the chemical reactivity related to molecular vibrations, internal rotations, bond dissociation, chemical reaction along the model of reaction coordinate, and so on.

Molecular Mechanisms Involved in the Chemical Instability of ONC201 and Methods to Counter Its Degradation in Solution.

Glioblastoma is one of the most common and aggressive forms of brain tumor, a rare disease for which there is a great need for innovative therapies. ONC201, a new drug substance, has been used in a compassionate treatment program where the choice of dosage form and regimen have yet to be justified. The prior knowledge needed to anticipate ONC201 stability problems has recently been partially addressed, by (i) showing that ONC201 is sensitive to light and oxidation and (ii) identifying the molecular structures of the main degradation products formed. The aim of the work presented here was to improve our understanding of the degradation pathways of ONC201 using data from ab initio calculations and experimental work to supplement the structural information we already published. The C-H bonds located αto the amine of the tetrahydropyridine group and those located alpha to the imine function of the dihydroimidazole group exhibit the lowest bond dissociation energies (BDEs) within the ONC201 molecule. Moreover, these values drop well below 90 kcal.mol-1 when ONC201 is in an excited state (S1; T1). The structures of the photoproducts we had previously identified are consistent with these data, showing that they would have resulted from radical processes following the abstraction of alpha hydrogens. Concerning ONC201's sensitivity to oxidation, the structures of the oxidation products matched the critical points revealed through mapped electrostatic potential (MEP) and average local ionization energy (ALIE). The data obtained from ab initio calculations and experimental work showed that the reactivity of ONC201 to light and oxidation conditions is highly dependent on pH. While an acidic environment (pH < 6) contributes to making ONC201 quantitatively more stable in solution in the face of oxidation and photo-oxidation, it nevertheless seems that certain chemical groups in the molecule are more exposed to nucleophilic attacks, which explains the variation observed in the profile of degradation products formed in the presence of certain antioxidants tested. This information is crucial to better understand the stability results in the presence of antioxidant agents and to determine the right conditions for them to act.

Rapid ultrasound-assisted synthesis, characterization, DFT, molecular docking, and anticancer activity of palladium and zinc complexes with 2,6-dimethoxybenzoic acid: A comprehensive study

In this work, we present a thorough investigation encompassing various aspects of zinc and palladium complexes synthesized with 2, 6-dimethoxybenzoic acid. The complexes were prepared through an ultrasonic reaction, offering a rapid, cost-effective, and environmentally friendly method. Characterization of the complexes, prepared in a 1:2 metal-to-ligand ratio, was carried out using elemental analysis, infrared spectra, proton nuclear magnetic resonance, molar conductivity, and melting point measurements. The results revealed that the ligand exhibited chelating bidentate behavior, forming coordination bonds through both oxygen atoms of the carbonyl group. The prepared complexes were evaluated for their anticancer activity against breast cancer and colon cancer cell lines. Remarkably, the complexes exhibited significantly higher cancer cell-killing potential compared to the commonly used drug 5-fluorouracil, with cell death rates reaching 99% for both complexes. To gain insights into the underlying mechanisms of this enhanced anticancer activity, molecular docking studies were conducted, revealing a binding energy of no more than -9.14 kcal/mol between the complexes and the amino acids of the cancer cells. Furthermore, theoretical studies employing Density Functional Theory (DFT) were performed to provide additional diagnostic insights. These studies encompassed molecular structural analysis, computational vibrational properties, natural bond orbital analysis (NBO) and FMOs, electronic properties (UV–Vis spectra), average local ionization energy (ALIE), electrostatic potential (ESP), electron localization function (ELF), and reduced density gradient (RDG/NCI) analyses. The comprehensive investigation presented in this study sheds light on the synthesis, characterization, theoretical analysis, and remarkable anticancer potential of zinc and palladium complexes with 2,6-dimethoxybenzoic acid.

Fabrication of branch-like Aph@LDH-MgO material through organic-inorganic hybrid conjugation for excellent anti-corrosion performance

Layered double hydroxides (LDH) frameworks have shown significant enhancement in stability and reusability, and their tailorable architecture brings new insight into the development of the next generation of hybrid materials, which attracted considerable attention in many fields over the years. One of the factors contributing to the widespread applicability of layered double hydroxides is their adaptable composition, which can accommodate a wide spectrum of potential anionic guests. This exceptional property makes the LDH system simple to adjust for various applications. However, most LDH systems are synthesized in situ in an autoclave at high temperatures and pressures that severely restrict the industrial use of such coating systems. In this study, LDH was directly synthesized on a magnesium alloy that had undergone plasma electrolytic oxidation (PEO) treatment in the presence of ethylenediaminetetraacetic acid, thereby avoiding the use of hydrothermal autoclave conditions. This LDH system was compared with a hybrid architecture consisting of organic-inorganic self-assembly. An organic layer was fabricated on top of the LDH film using 4-Aminophenol (Aph) compound, resulting in a smart hierarchical structure that can provide a robust Aph@LDH film with excellent anti-corrosion performance. At the molecular level, the conjugation characteristics and adsorption mechanism of Aph molecule were studied using two levels of theory as follows. First, Localized orbit locator (LOL)-π isosurface, electrostatic potential (ESP) distribution, and average local ionization energy (ALIE) on the molecular surface were used to highlight localization region, reveal the favorable electrophilic and nucleophilic attacks, and clearly explore the type of interactions that occurred around interesting regions. Second, first-principles based on density functional theory (DFT) was applied to study the hybrid mechanism of Aph on LDH system and elucidate their mutual interactions. The experimental and computational analyses suggest that the high π-electron density and delocalization characteristics of the functional groups and benzene ring in the Aph molecule played a leading role in the synergistic effects arising from the combination of organic and inorganic coatings. This work provides a promising approach to design advanced hybrid materials with exceptional electrochemical performance.

N-oxidation Regioselectivity and Risk Prediction Using DFT-ALIE Calculations.

The formation ofN-oxide degradants is a major concern in development of new drugs due to potential effects on a compound's pharmacological activity. Such effects include but are not limited to solubility, stability, toxicity, and efficacy. In addition, these chemical transformations can impact physicochemical properties that affect drug manufacturability. Hence identification and control of N-oxide transformations is of critical importance in the development of new therapeutics. This study describes the development of an in-silico approach to identify N-oxide formation in APIs with respect to autoxidation. Average Local Ionization Energy (ALIE) calculations were carried out using molecular modeling techniques and application of Density Functional Theory (DFT) at the B3LYP/6-31G(d,p) level of theory. A total of 257 nitrogen atoms and 15 different oxidizable nitrogen types were used in developing this method. The results show that ALIE could be reliably used to predict the most susceptible nitrogen for N-oxide formation. A risk scale was developed that rapidly categorizes nitrogen's oxidative vulnerabilities as small, medium, or high. The developed process presents a powerful tool to identify structural susceptibilities for N-oxidation as well as enabling rapid structure elucidation in resolving potential experimental ambiguities.

Effect of CO2 and methyl groups reaction kinetics on the ignition and combustion of diesel surrogate fuel: Part Ⅰ. Reaction mechanisms

The study aims to examine the impact of CO2 concentration gradient on the ignition and combustion of a diesel surrogate fuel composed of 70% C7H16 and 30% C7H8. The investigation focuses on the weak oxidation of CO2 through its reaction with methyl groups (CH, CH2, and CH3 radicals). Firstly, the molecular bond-breaking recombination process between CO2 and methyl groups is calculated using Born-Oppenheimer molecular dynamics with the UB3LYP/6–311++g (d, p) level of theory. Subsequently, the electronic distribution and competition of the molecule surface are analyzed through various wave function analyses to identify the reactive sites. Secondly, the precise potential energy surface and reaction rate are calculated based on the acquired reaction process information. This calculation employs the B2PLYP/def2-TZVP level of theory and transition state theory. Finally, extensive molecular dynamics simulations of CO2 and methyl groups are conducted using reaction force fields. These simulations provide insights into the temperature-energy variation within the system and the resulting chemical reaction network. The optimized combustion mechanism for the binary fuel is derived, focusing exclusively on the influences of CO2 and O2 while excluding those of N2 and other extraneous gases. The results demonstrate exothermic reactions of CO2 with CH and CH2 radicals at 850 K, yielding ΔG values of −238.91 kJ/mol and −209.96 kJ/mol, respectively. Conversely, CO2 reacts with CH3 radicals in heat-absorbing reactions at 850 K, resulting in a ΔG of 491.73 kJ/mol. Additionally, the chemical impact of CO2 exhibits both promotional and inhibitory effects on combustion. The CO2 molecule exhibits weak oxidation properties due to the presence of active sites on its surface characterized by minimal values of electrostatic potential (-50.17 kJ/mol) and average local ionization energy (61.92 kJ/mol) at the O-atomic end. The molecular dynamics process involving the methyl groups and CO2 system exhibits a heat absorption phenomenon. This behavior can be attributed to the participation of CO2 not only in the reactions with methyl groups but also with formaldehyde and ethylene, among others.

Conversion of carbonaceous materials into solid acids for tylosin mitigation: effect of preprocessing methods on the reactivity of sulfonation reaction

Carbon-based solid acids have been successfully employed as acidic catalysts for pollutant mitigation in wastewater. To fully tap the potentials of commercially viable carbons for the preparation of solid acids and enhance their catalytic performances is a challenging problem. In this work, three commercialized carbons including biochar, activated carbon and graphite were preprocessed (ball-milling, Hummer exfoliation, HNO3 soaking, and microwave heating in HNO3, etc.), sulfonated, and evaluated as solid-acid catalysts for tylosin mitigation. Graphite-originated solid acid performed the best through a balling-milling preprocess, while biochar-originated solid acids behaved well under all preprocessing treatments, in which 40 mg L−1 of tylosin was mitigated within 8 min by 1 g L−1 of biochar-originated solid acids. The biochar solid acid through the ball-milling preprocess presented high total acidity and large amounts of –SO3H groups, due to dramatically increased surface area and the rise of activation groups (hydroxyl, alkyl and alkoxy groups, etc.) facilitating electrophilic reaction. In addition, decreased particle size and aromaticity and increased structural defects also contributed. Theoretical calculation of average local ionization energy (ALIE) of condensed aromatic model molecules with substituted activation groups confirmed the promoting effects on sulfonation from strong to weak were 8.40–9.06 eV. These findings have deepened the knowledge in tuning carbon surface chemistry for better sulfonation, thus strengthening catalytic degradation of tylosin. The value of this study is in pulling a clear thread for maneuvering solid-acid catalysts using carbons, which holds a novel promise for rationally functionalizing biochar-based catalysts for the remediation of macrolide antibiotics in polluted water.Graphical

Investigation of synthesized carbazole derivative Cz-BPDB as a high-performance leveler for copper electroplating

Electroplating additives, especially levelers of copper electroplating, are the most critical components of electroplating solutions in the manufacture of printed circuit boards and integrated circuits. A series of carbazole derivatives have been synthesized and used as levelers for through-hole electroplating. Electrochemical tests, theoretical calculations, and simulations were used to compare the various properties of the carbazole derivatives. Among them, the carbazole derivative Cz-BPDB was preferably subjected to electroplating which was demonstrated by metallographic microscopy, SEM, and XRD. To further investigate the mechanism of leveler Cz-BPDB, the nucleation model theory was used to explain the phenomenon of flat and smooth electroplating surfaces. The electrostatic potential plot and the average local ionization energy plot were employed to analyze the active sites of the Cz-BPDB. Moreover, the galvanostatic measurements were applied to investigate the interaction of the Cz-BPDB with PEG and SPS. Therefore, a more reasonable through-hole electroplating mechanism was proposed in electroplating solution with Cz-BPDB used as leveler. This work introduced an excellent performance leveler and contributed to the continuing development of the copper electroplating mechanism.

Unraveling Weak Interaction of Kinematic Viscosity of Fatty Acid Methyl Esters in Natural Ester Insulating Oils

Natural ester insulating oil has become a good substitute for mineral insulating oil due to its characteristics of renewability, easy degradation, low carbon emission, and high fire safety. However, the high kinematic viscosity of natural ester insulating oil not only affects the heat dissipation and heat transfer of the transformers but also seriously restricts its safe promotion and application in transformers in cold regions. In this article, in order to explore the influence mechanism of the kinematic viscosity of natural fatty acid methyl ester (FAME), insulating oil molecules from the microscopic scale of weak intermolecular interaction, the electrostatic potential (ESP), van der Waals (vdW) potential, and average local ionization energy (ALIE) of four FAME molecules are analyzed, respectively. The computed results demonstrate that the C=C double bonds in the four FAME molecules weaken the intermolecular electrostatic interaction and vdW interaction, and the weakening effect increases with the increase of the number of the C=C double bonds. This may be for this reason that the C=C double bond reduces the kinematic viscosity. This study can provide theoretical guidance and a basis for quantitative analysis and comparison for the improvement of the kinematic viscosity of natural ester insulating oil, lubricating oil, and biodiesel.

Porous and Stable Zn-Series Metal–Organic Frameworks as Efficient Catalysts for Grafting Wood Nanofibers with Polycaprolactone via a Copolymerization Approach

A hydrothermal method was used to synthesize two highly stable Zn(II) metal-organic frameworks (MOFs), namely, [Zn2(L)2(HIPA)]n (1) and [Zn9(L)6(BTEC)3(H2O)4·6H2O]n (2) (HL = 3-amino-1H-1,2,4-triazole, H2HIPA = 5-hydroxyisophthalic acid, H4BTEC = benzene-1,2,4,5-tetracarboxylic acid). The physicochemical properties of 1 and 2 were characterized using a range of analytical techniques. The scanning electron microscopy images confirmed the stability of the MOFs under heating at 120 °C for 12 h. Following their preparation, the two MOFs were used as catalysts in the grafting of poly(ε-caprolactone) on wood nanofibers (WNFs) by means of a homogeneous ring-opening polymerization protocol in an ionic liquid. The grafting ratio achieved using catalyst 1 was higher than that achieved for catalyst 2, wherein a maximum of 92.43% was obtained using the former. Under comparable reaction conditions, the grafting ratio of 1 was found to be significantly higher than those achieved using 4-dimethylamino pyridine, Sn(Oct)2, and UiO-67 catalysts. In addition, fluorescence emission was detected from the residual catalysts present in the products. The calculated electrostatic potentials and average local ionization energies indicated that the grafting of ε-caprolactone on the WNFs follows a "coordination-insertion" mechanism. Overall, these two new and efficient MOF catalysts have the potential to replace highly toxic traditional catalysts in polymerization reactions. The grafted cellulose material with fluorescence emission may also be suitable for use in biomedical applications.

Copper coordination compounds based on bis-quinolylhydrazone of 2,6-diacetylpyridine: Synthesis, structure and cytotoxic activity

Bis-hetarylhydrazone H2L (1), a condensation product of 2,6-diacetylpyridine with 2-hydrazinoquinoline, has been synthesized. By reaction of 1 with Cu(II) nitrate and perchlorate binuclear mixed-valence coordination compounds [CuICuII(H2L)2](NO3)3⋅2H2O (2) and [CuICuII(H2L)2](ClO4)3 (3) were obtained. Cu(I) Ion in the compounds 2, 3 is in the distorted tetrahedral N-donor environment, while Cu(II) center is in the distorted octahedral one. Cu(II) Chloride and bromide form with 1 asymmetric mononuclear compounds with composition [Cu(H2L)Cl]Cl (4) and [Cu(H2L)Br]Br (5) with tetragonal–pyramidal coordination polyhedron. The structures of the compounds were studied by means of NMR, IR, ESR, UV–vis, X-ray absorption spectroscopy and X-ray single crystal diffraction methods. The effect of compounds on viability of the Hep-2 and HepG2 cell lines was investigated in vitro. The study showed that 1 is non-toxic at tested concentrations (1–100 μM), while all the complexes exhibit significant dose-dependent cytotoxic effect. It is shown that compounds 2–5 demonstrate higher cytotoxicity towards considered cancer cell cultures than widely used commercial anticancer pharmaceuticals – cisplatin and carboplatin. Quantum-chemical modeling of the structure of the ligand 1 and its complexes was performed using density functional theory at B3LYP/6-311G(d) level of theory. Molecular electrostatic potential (MEP) and average local ionization energy (ALIE) surfaces were calculated to rationalize the reactive properties of the compounds.

Photocatalytic Activity of the V2O5 Catalyst toward Selected Pharmaceuticals and Their Mixture: Influence of the Molecular Structure on the Efficiency of the Process.

Due to the inability of conventional wastewater treatment procedures to remove organic pharmaceutical pollutants, active pharmaceutical components remain in wastewater and even reach tap water. In terms of pharmaceutical pollutants, the scientific community focuses on β-blockers due to their extensive (over)usage and moderately high solubility. In this study, the photocatalytic activity of V2O5 was investigated through the degradation of nadolol (NAD), pindolol (PIN), metoprolol (MET), and their mixture under ultraviolet (UV) irradiation in water. For the preparation of V2O5, facile hydrothermal synthesis was used. The structural, morphological, and surface properties and purity of synthesized V2O5 powder were investigated by scanning electron microscopy (SEM), X-ray, and Raman spectroscopy. SEM micrographs showed hexagonal-shaped platelets with well-defined morphology of materials with diameters in the range of 10−65 µm and thickness of around a few microns. X-ray diffraction identified only one crystalline phase in the sample. The Raman scattering measurements taken on the catalyst confirmed the result of XRPD. Degradation kinetics were monitored by ultra-fast liquid chromatography with diode array detection. The results showed that in individual solutions, photocatalytic degradation of MET and NAD was relatively insignificant (<10%). However, in the PIN case, the degradation was significant (64%). In the mixture, the photodegradation efficiency of MET and NAD slightly increased (15% and 13%). Conversely, it reduced the PIN to the still satisfactory value of 40%. Computational analysis based on molecular and periodic density functional theory calculations was used to complement our experimental findings. Calculations of the average local ionization energy indicate that the PIN is the most reactive of all three considered molecules in terms of removing an electron from it.