Molecular Electronegativity Research Articles

11B NMR Together with Infrared Spectroscopy Provides Insight into Structural Elucidation of Quadrivalent Diazaborines & Cyclic Boronate Esters: Intriguing & Little-Explored

Imidazo-fused diazaborines, which serve as intermediary structures somewhat alongside benzene and borazine, had been of particular interest to Dewar and Snyder more than 60 years ago. To this end, Dewar utilised his ‘π-complex theory’so as to represent ‘borazaros’as a ‘quadrivalent’ species; however, sadly, modern representations have deviated and leapt into ‘trivalent’ counterparts. Bonding in boron species has never been straightforward, to such an extent that the orthodox ‘ethane’ like diborane, i.e., H3B–BH3, which conformed to the paradigmatic rules of molecular structure, in particular, hybridisation and electronegativity, was later evolved to a more realistic ‘3-centre 2-electron’ bonding so as to give the lie to the purported diborane structures of X-ray diffractors. Herein 11B NMR together with IR spectroscopy sheds light on the nature of bonding in borazaros, and ‘caged’ cyclic oxazaborons so as to reinforce, and reinvigorate the old literature, which could be of interest to both the synthetic, and medicinal chemist alike.

Molecular Interactions Governing the Rat Aryl Hydrocarbon Receptor Activities of Polycyclic Aromatic Compounds and Predictive Model Development.

Polycyclic aromatic compounds (PACs) exhibit rat aryl hydrocarbon receptor (rAhR) activities, leading to diverse biological or toxic effects. In this study, the key amino residues and molecular interactions that govern the rAhR activity of PACs were investigated using in silico strategies. The homology model of rAhR was first docked with 90 PACs to yield complexes, and the results of the molecular dynamics simulations of 16 typical complexes showed that the binding energies of the complexes range from -7.37 to -26.39 kcal/mol. The major contribution to the molecular interaction comes from van der Waals forces, and Pro295 and Arg316 become the key residues involved in most complexes. Two QSAR models were further developed to predict the rAhR activity of PACs (in terms of log IEQ for PACs without halogen substitutions and log%-TCDD-max for halogenated PACs). Both models have good predictive ability, robustness, and extrapolation ability. Molecular polarizability, electronegativity, size, and nucleophilicity are identified as the important factors affecting the rAhR activity of PACs. The developed models could be employed to predict the rAhR activity of other reactive PACs. This work provides insight into the mechanisms and interactions of the rAhR activity of PACs and assists in the assessment of their fate and risk in organisms.

Experimental and Quantum Chemical Studies of a Green Corrosion Inhibitor for Mild Steel in Acidic Chloride Solution

AbstractA green corrosion inhibitor was prepared from the bio‐based platform compound 5‐hydroxymethylfurfural through a green synthetic route, which avoid the use of toxic reagent. The inhibition performance and mechanism of this compound for the corrosion of mild steel in 0.1 M HCl was investigated by using the weight loss experiments, polarization measurements, EIS measurements and quantum chemical calculations. The corrosion inhibition efficiency by weight loss measurement (ηWLM%) of this inhibitor can reach up to 90.3 % at 303 K with 1.2 mM concentration. Moreover, the electrochemical experiments revealed that this corrosion inhibitor acts as a mixed‐type inhibitor. Thermodynamic studies gave the values of the standard Gibbs free energy , fall within the range of −20 kJ/mol to −40 kJ/mol, suggested the adsorption of this compound is a spontaneous process involving both physisorption and chemisorption. In addition, quantum chemical calculations were conducted to further validate the formation of an effective absorption layer by this inhibitor on metal surfaces, which showed that the electron density iso‐surfaces of HOMO was mainly distributed on chloride ions, while LUMO tended to be distributed on furan rings and aldehyde groups. Besides, the other quantum chemical parameters of this inhibitor were also calculated to explore the molecular activity, such as, the molecular volume (ν, 333.105 Å), global hardness (η, 4.706 eV), global softness (σ, 0.2125 eV), electronegativity (χ, 4.93 eV), dipolemoment (μ, 13.1429 D) and vertical ionization energy (VIE, 7.2646 eV).

K0.72Na1.71Ca5.79Si6O19 - the first oligosilicate based on [Si6O19]-hexamers and its stability compared to cyclosilicates.

Synthesis experiments were conducted in the quaternary system K2O-Na2O-CaO-SiO2, resulting in the formation of a previously unknown compound with the composition K0.72Na1.71Ca5.79Si6O19. Single crystals of sufficient size and quality were recovered from a starting mixture with a K2O:Na2O:CaO:SiO2 molar ratio of 1.5:0.5:2:3. The mixture was confined in a closed platinum tube and slowly cooled from 1150°C at a rate of 0.1°C min-1 to 700°C before being finally quenched in air. The structure has tetragonal symmetry and belongs to space group P4122 (No. 91), with a = 7.3659 (2), c = 32.2318 (18) Å, V = 1748.78 (12) Å3, and Z = 4. The silicate anion consists of highly puckered, unbranched six-membered oligomers with the composition [Si6O19] and point group symmetry 2 (C2). Although several thousands of natural and synthetic oxosilicates have been structurally characterized, this compound is the first representative of a catena-hexasilicate anion, to the best of our knowledge. Structural investigations were completed using Raman spectroscopy. The spectroscopic data was interpreted and the bands were assigned to certain vibrational species with the support of density functional theory at the HSEsol level of theory. To determine the stability properties of the novel oligosilicate compared to those of the chemically and structurally similar cyclosilicate combeite, we calculated the electronegativity of the respective structures using the electronegativity equalization method. The results showed that the molecular electronegativity of the cyclosilicate was significantly higher than that of the oligostructure due to the different connectivities of the oxygen atoms within the molecular units.

Molecular Properties of Monoaminergic Catecholamines in Water.

Three neurotransmitters belonging to catecholamines (dopamine, noradrenaline, adrenaline) and related α-amino acids (DOPA and tyrosine) were studied by quantum-chemical ab initio and DFT calculations using B3LYP and DLPNO-CCSD(T) methods in water. In addition to the three canonical forms, zwitterionic forms were also investigated, each in three oxidation states (molecular cation L+, electroneutral molecule L0, and molecular anion L-). Each species was subjected to geometry optimization followed by vibrational analysis. Electronic properties (adiabatic ionization energy, electron affinity, chemical hardness, molecular electronegativity, electrophilicity index, dipole moment, electric polarizability, and quadrupole moment) and standard thermodynamic quantities (inner energy, entropy, enthalpy, and Gibbs energy) were evaluated, which allows the absolute oxidation and reduction potentials to be calculated. The absolute reduction potential (ARP) was found to correlate with the electrophilicity index ω along a straight line. Moreover, in addition to the standard expression for the absolute redox potential using reaction Gibbs energy, an approximation based on ionization energy and/or electron affinity was also tested. The main finding is that dopamine is a much weaker oxidizing agent with the ARP = 0.99 V relative to tyrosine with ARP = 1.38 V for canonical structures in water. This is also true for the zwitterionic structures in water: for dopamine ARP = 0.63 V is much lower relative to tyrosine with ARP = 1.31 V. The protonated form (DOPAH+) has the highest ARP = 2.02 V. Prediction of the redox potentials is an important factor influencing antioxidant (EC50) and/or antireductant activity. Based on 16 molecular properties for 20 molecules (320 entries), advanced statistical methods (cluster analysis, principal component analysis, pair-correlation) reveal that several groups of similarity exist: {dopamine-noradrenaline}, different from {adrenaline-DOPA-(tyrosine)} and zwitterionic forms of {dopamine-noradrenaline-adrenaline}.

Discovery of 1,2,3–triazoles incorporated benzoxazinones as potent antimicrobial agents: Synthesis, in vitro biological evaluation, DFT interactions and molecular docking

The study of the chemical and biological properties of molecules simultaneously comprising various heterocycles, such as fused 1,2,3–triazoles and benzoxazinones have been conducted as part of our ongoing research in the field of medicinal and organic chemistry. Two classes of 1,2,3–triazoles linked benzoxazinone derivatives were prepared from 2-((prop‑2-yn-1-ylamino) methyl)-4H-benzo[d][1,3]oxazin-4-one 4 and substituted azides successfully CuAAC reaction and more efficient approach. The structures of these new triazole derivatives have been confirmed by Mass, 1H NMR, 13C NMR, and IR spectral data. From antibacterial studies, benzoxazinone–linked 1,2,3–triazoles 5a, 5d, and 6e were found to be most effective against P. aeruginosa was measuring MICs of 4.15 ± 0.03, 4.23 ± 0.02, and 4.43 ± 0.04 μg mL−1, whereas 5a and 6d displayed excellent activity against B. subtilis with MICs 5.33 ± 0.01, and 3.91 ± 0.02 μg mL−1 respectively. In particular, the prepared scaffolds 5b, 6d, and 5a showed remarkable antifungal activity against C. albicans with MICs 4.18 ± 0.04, 4.70 ± 0.01, and 5.10 ± 0.02 μg mL−1 accordingly. Initially, all of the synthesized compounds were evaluated in silico docking against antifungal drug candidate (5TZ1) and further evaluated for their ADMET properties by SwissADME and ADMETlab2.0. The computational modelling of benzoxazinone–1,2,3–triazole 6d revealed better hydrogen bonding patterns with amino acids Arg381(A) [O2—NH] (2.98 Å), Try132(A) [N22—OH] (2.61 Å), Ile471(A) [O28—NH] (3.16 Å) and has predicted to show remarkable affinity with C. albicans. Theoretical evaluation provides an insight about ligand interaction with proteins, highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), electronegativity, hardness, softness, electrophilicity and neucleophilicity of the ligands via molecular docking and density functional theory (DFT) studies; this presents probable evidence for the biological activity of the derivatives.

Corrosion inhibition of two tetracycline‐based expired antibiotics as eco‐friendly inhibitors for mild steel in 1M HCl solution

AbstractTwo expired Tetracycline‐based antibiotics (Oxytetracycline and Tetracycline) were utilized as eco‐friendly corrosion inhibitors for mild steel in 1M HCl solution, employing weight loss analysis, electrochemical measurements, scanning electron microscopy, and so on. The effect and mechanism were discussed using thermodynamic modeling, quantum chemical calculation, molecular dynamics simulation, and so on. The corrosion inhibition rate (η) increases with higher concentration and temperature, leading to reduced heat absorption and increased order degree. The of Oxytetracycline and Tetracycline was 96.14% and 97.92% at 323.15 K of 2 × 10−4 mol L−1, respectively. The key factors affecting η in the kinetic model parameters vary at lower concentrations. Both of them belong to cathodic corrosion inhibitors and undergo Langmuir spontaneous adsorption processes involving both physisorption and chemisorption. The disparity in energy levels between the highest occupied molecular orbital and lowest unoccupied molecular orbital, global hardness, electronegativity, molecular polarizability, dipole moment, and transfer electron number are key factors that enhance a corrosion inhibitor's ability to adsorb chloride ions.

Roles of varying carbon chains and functional groups of legacy and emerging per-/polyfluoroalkyl substances in adsorption on metal-organic framework: Insights into mechanism and adsorption prediction

Metal-organic frameworks (MOFs) are promising adsorbents for legacy per-/polyfluoroalkyl substances (PFASs), but they are being replaced by emerging PFASs. The effects of varying carbon chains and functional groups of emerging PFASs on their adsorption behavior on MOFs require attention. This study systematically revealed the structure-adsorption relationships and interaction mechanisms of legacy and emerging PFASs on a typical MOF MIL-101(Cr). It also presented an approach reflecting the average electronegativity of PFAS moieties for adsorption prediction. We demonstrated that short-chain or sulfonate PFASs showed higher adsorption capacities (μmol/g) on MIL-101(Cr) than their long-chain or carboxylate counterparts, respectively. Compared with linear PFASs, their branched isomers were found to exhibit a higher adsorption potential on MIL-101(Cr). In addition, the introduction of ether bond into PFAS molecule (e.g., hexafluoropropylene oxide dimeric acid, GenX) increased the adsorption capacity, while the replacement of CF2 moieties in PFAS molecule with CH2 moieties (e.g., 6:2 fluorotelomer sulfonate, 6:2 FTS) caused a decrease in adsorption. Divalent ions (such as Ca2+ and SO42−) and solution pH have a greater effect on the adsorption of PFASs containing ether bonds or more CF2 moieties. PFAS adsorption on MIL-101(Cr) was governed by electrostatic interaction, complexation, hydrogen bonding, π-CF interaction, and π-anion interaction as well as steric effects, which were associated with the molecular electronegativity and chain length of each PFAS. The average electronegativity of individual moieties (named Me) for each PFAS was estimated and found to show a significantly positive correlation with the corresponding adsorption capacity on MIL-101(Cr). The removal rates of major PFASs in contaminated groundwater by MIL-101(Cr) were also correlated with the corresponding Me values. These findings will assist with the adsorption prediction for a wide range of PFASs and contribute to tailoring efficient MOF materials.

Synthesis, computational studies and evaluation of benzisoxazole tethered 1,2,4-triazoles as anticancer and antimicrobial agents

A novel series of six compounds, benzisoxazole tethered 1,2,4-triazoles were synthesized in five steps with good yields and characterized. 1H NMR, 13C NMR and mass spectrometry confirmed the formation of the derivatives. Antimicrobial activity was evaluated for the synthesized derivatives against three bacterial strains (Escherichia coli, Mycobacterium smegmatis and Staphylococcus aureus) and a fungal strain (Candida albicans). Similarly, anticancer activity was assessed against MCF-7 cell lines. The biological analysis disclosed that, out of the six compounds, derivative 6c showed better antimicrobial and anticancer activity with MIC of 12.5 μg/mL against Staphylococcus aureus and Mycobacterium smegmatis; and IC50 of 35.57 μM against MCF-7 cancer cell line. Theoretical evaluation provides an insight about ligand interaction with proteins, highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), electronegativity, hardness, softness, electrophilicity and neucleophilicity of the ligands via molecular docking and density functional theory (DFT) studies; this presents probable evidence for the biological activity of the derivatives. Molecular Dynamics (MD) simulation of the ligand 6c with protein HDAC7 (PDB ID: 3ZNR) was studied.

Heterogeneous Photodegradation Behavior of Liquid Crystal Monomers in Dust: Quantitative Structure-Activity Relationship and Product Identification.

The heterogeneous photodegradation behavior of liquid crystal monomers (LCMs) in standard dust (standard reference material, SRM 2583) and environmental dust was investigated. The measured photodegradation ratios for 23 LCMs in SRM and environmental dust in 12 h were 11.1 ± 1.8 to 23.2 ± 1.1% and 8.7 ± 0.5 to 24.0 ± 2.8%, respectively. The degradation behavior of different LCM compounds varied depending on their structural properties. A quantitative structure-activity relationship model for predicting the degradation ratio of LCMs in SRM dust was established, which revealed that the molecular descriptors related to molecular polarizability, electronegativity, and molecular mass were closely associated with LCMs' photodegradation. The photodegradation products of the LCM compound 4'-propoxy-4-biphenylcarbonitrile (PBIPHCN) in dust, including •OH oxidation, C-O bond cleavage, and ring-opening products, were identified by nontarget analysis, and the corresponding degradation pathways were suggested. Some of the identified products, such as 4'-hydroxyethoxy-4-biphenylcarbonitrile, showed predicted toxicity (with an oral rat lethal dose of 50%) comparable to that of PBIPHCN. The half-lives of the studied LCMs in SRM dust were estimated at 32.2-82.5 h by fitting an exponential decay curve to the observed photodegradation data. The photodegradation mechanisms of LCMs in dust were revealed for the first time, enhancing the understanding of LCMs' environmental behavior and risks.

Synthesis, characterization and theoretical aspects of copper and zinc divalent ion complexes with azo dye derived from 4,5-diphenylimidazole

Azo dye ligand derived from 4,5-diphenyl imidazole and 4,4-diaminodiphenylmethane was synthesized by diazomium coupling reaction. In this reaction an amine (4,4-diaminodiphenylmethane was converted to the diazonium salt and coupled with 4,5-diphenyl imidazole. The bright coloured Cu(II) and Zn(II) complexes with this ligand were synthesized by refluxing the latest with both metals chloride salts. The prepared compounds were characterized by 1H-NMR, 13C-NMR, FTIR, UV-Visible, molar conductivity and atomic absorption. By the infrared data, the coordination between copper and zinc ions and the azo ligand achieved through the nitrogen of the azo group and one of the nitrogen atoms in the imidazole ring. By the molar conductivity test, the non- electrolytic nature of both complexes was also confirmed. The suggested structure for these complexes is octahedral. Using density functional theory (DFT) some theoretical data was obtained for the synthesized complexes. The obtained data include the highest occupied and the lowest unoccupied molecular orbitals energy (HOMO and LUMO), electron density, thermodynamic functions (ΔG°, ΔS°, ΔH°, ΔE°), ionization potential (IP), electron affinity (EA), electrophilicity(ὠ), electronegativity (En), chemical hardness (η) and dipole moment (μ). According to these studied parameters some properties of the two complexes were explained and discussed.
 KEY WORDS: Cu(II) and Zn(II) complexes, Azo ligand, 4,5-Diphenylimidazole, 4,4-Diaminodiphenylmethane, Theoretical study
 Bull. Chem. Soc. Ethiop. 2024, 38(2), 313-323. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i2.4

Coordinated metal complexes with curcumin Schiff base: Synthesis, investigation, antibacterial screening, antioxidant studies, molecular docking and density function theory calculations

Condensation of curcumin with furfuryl amine led to the synthesis of H2L Schiff base in a 1:1 Molar ratio. Subsequently, complexes of this Schiff base with several transition metal ions were prepared also in one‐to‐one molar ratio. Multiple characterization techniques were employed to identify the structure of all compounds. Infrared, UV, proton magnetic resonance spectroscopic tests, elemental analysis, mass spectrometry, thermal analysis, molar conductivity, and density function theory (DFT) calculations were utilized to gain a comprehensive understanding of their structures. Except for the nickel (II) complex, which exhibits non‐electrolyte behavior, all complexes were found to exhibit electrolytic behavior based on molar conductivity studies. Additionally, thermogravimetric analysis was employed to learn more about the complexes' thermal breakdown and the Schiff base ligand's thermal behavior. From DFT studies, some parameters were obtained as bond angles and lengths, chemical hardness, softness, energy levels of highest occupied molecular orbital and lowest unoccupied molecular orbital, electrophilic index, dipole moment, electronegativity, and other variables. Against one or more bacterial species, it was discovered that the antibacterial activity of the metal complexes was superior to that of the free Schiff base. Furthermore, the complexes exhibited notable antioxidant activity according to the results obtained using DPPH scavenging. Overall, a detailed characterization of the synthesized compounds was performed, revealing their structural features, functional properties, and potential applications. Lastly, research on molecular docking was investigated toward all compounds against 3C1L antioxidant protein receptor.

Control list of high-priority chemicals based on 5-HT-RI functionality and the human health interference effects selective CNN-GRU deep learning model

The antidepressant drug known as 5-HT reuptake inhibitor (5-HT-RI) was commonly detected in biological tissues and result in significant adverse health effects. Homology modeling was used to characterize the functionalities (efficacy and resistance), and the adverse outcome pathway was used to characterize its human health interferences (olfactory toxicity, neurotoxicity, and gut microbial interference). The convolutional neural network coupled with the gated recurrent unit (CNN-GRU) deep learning method was used to construct a comprehensive model of 5-HT-RI functionality and human health interference effects selectivity with small sample data. The architecture with 2 SE, 320 neuronal nodes and 6-folds cross-validation showed the best applicability. The results showed that the confidence interval of the constructed model reached 90 % indicating that the model had reliable prediction ability and generalization ability. Based on the CNN-GRU deep learning model, seven high-priority chemicals with a weak comprehensive effect, including D-VEN, (1R,4S)-SER, S-FLX, CTP, S-CTP, NEF, and VEN, were screened. Based on the molecular three-dimensional structure information, a comprehensive-effect three-dimensional quantitative structure-activity relationship (3D-QSAR) model was constructed to confirm the reliability of the constructed control list of 5-HT-RI high-priority chemicals. Analysis with the ranking of calculated values based on the molecular dynamics method and predicted values based on the CNN-GRU deep learning model, we found that the consistency of the three methods was above 85 %. Additionally, by analyzing the sensitivity, molecular electrostatic potential, polar surface area of the comprehensive-effect CNN-GRU deep learning model, and the electrostatic field of the 3D-QSAR models, we found that the significant effects of five key characteristics (DM, Qyy, Qxz, I, and BP), molecular electronegativity, and polarity significantly affected the high-priority degree of 5-HT-RI. In this study, we provided reasonable and reliable prediction tools and discussed theoretical methods for the risk assessment of functionality and human health interference of emerging pollutants such as 5-HT-RI.

SON KULLANMA TARİHİ GEÇMİŞ BİR İLACIN İNHİBİSYON ETKİNLİĞİ ÜZERİNE PROTONASYONUNUN DEĞERLENDİRİLMESİNE YÖNELİK TEORİK BİR YAKLAŞIM

The quantum theoretical calculations were performed to elucidate the corrosion inhibition efficiency of an expired drug. For this purpose, molecular orbital analysis, which is used in the analysis of chemical interactions and gives detailed data about the electronic structure of molecules, was used to gain insight into the electronic properties of the selected drug molecule in neutral and aqueous form. The calculations were carried out at the (B3LYP) 6-311G**(d,p) basis set level utilizing density functional theory (DFT) to examine the relationship between the molecular structure and inhibition efficiency of the corresponding drug molecule. Various quantum chemical descriptors such as highest occupied molecular orbital energy (HOMO), lowest unoccupied molecular orbital energy (LUMO), energy gap (ΔE), dipole moment (μ), ionization potential (I), electron affinity (A), electronegativity (χ), hardness (η), softness (σ), back donation (ΔEback- donation) and fraction of electrons transferred (ΔN) were calculated and correlated to the inhibition efficiency. The most probable nucleophilic and electrophilic reactive sites of studied drug molecule were analyzed through computed Fukui indices. Overall, obtained theoretical data indicate that the quantum chemical parameters correlate well with the inhibition performance.

Synthesis and biological evaluation of novel benzenesulfonamide incorporated thiazole-triazole hybrids as antimicrobial and antioxidant agents.

A library of 20 novel benzenesulfonamide incorporating thiazole tethered 1,2,3-triazoles 1-4a-e was synthesized and screened for their antimicrobial, antioxidant,and cytotoxicity studies. Amoxicillin and fluconazole were used as reference antibacterial and antifungal drugs, respectively. Further, energies of frontier molecular orbitals were calculated for all the synthesized target compounds 1-4a-e to correlate electronic parameters with the observed biological results. Global reactivity descriptors, includinghighest occupied molecular orbitals-lowest unoccupied molecular orbitals energy gap, electronegativity, chemical hardness, chemical softness, and electrophilicity index, were also calculated for the synthesized molecules. All the tested compounds possessed moderate to excellent antibacterial potency; however, 3d and 4d exhibited the overall highest antibacterial effect (minimum inhibitory concentration [MIC] values 5-11 µM) while 2c showed the highest antifungal effect (MIC value 6 µM). Compound 3c exhibited the highest antioxidantactivity with a % radical scavenging activity value of 95.12. The cytotoxicity of the compounds 1-4a-e was also checked against an animal cell line and a plant seed germination cell line, and the compounds were found to be safe against both the tested cell lines.

Study of Tl-based perovskite materials TlZX3 (Z = Ge, Sn, Be, Sr; X = Cl, Br, I) for application in scintillators: DFT and TD-DFT approach

Scintillators are designed significantly for utilization in a broad range of technology fields, notably nuclear physics, healthcare testing, and materials analysis. A number of applications involving scintillators, such as therapeutic image analysis, burglary prevention as well and nuclear investigation, have tempted scientists to establish novel and effective scintillators. In this report, thallium-based perovskite material TlZX3 (Z = Ge, Sn, Be, Sr; X = Cl, Br, I) has been examined by means of DFT and TD-DFT approaches. The structural, electronic, optical, and thermal properties of TlZX3 are calculated and discussed. The HOMO-LUMO energy gap of TlGeX3, TlSnX3, TlBeX3, and TlSrX3 are found in the range of 1.76 eV to 2.12 eV, 1.77 eV to 2.27 eV, 1.56 eV to 2.04 eV and 1.06 eV to 2.81 eV, respectively. Lattice constant, unit cell volume, formation energy, VEA, electrophilicity index, polarizability, refractive index, dielectric constant, entropy, and heat capacity of TlZX3 increase gradually from Cl to Br to I. However, HOMO-LUMO energy gap, tolerance factor, dipole moment, optical electronegativity, thermal energy, ZVPE, and Gibbs energy drop down from Cl to Br to I. Among the studied materials, TlGeI3 shows the maximum value of molecular hardness and electronegativity while TlSrCl3 exhibits the minimum value. The computed HOMO-LUMO energy gap and refractive index of the studied materials are in close agreement with the previously reported findings, it specifies their potential application in scintillator and solar cells.

Ab initio study of molecular properties of l-tyrosine

Contextl-Tyrosine is a naturally occurring agent that acts as a precursor in biosynthesis of monoaminergic neurotransmitters in brain such as dopamine, adrenaline, noradrenaline, and hormones like thyroxine and triiodothyronine. While l-tyrosine in vacuo adopts the canonical aminoacid form with –NH2 and –COOH functional groups, from neutral solutions, is crystallizes in the zwitterionic form possessing –NH3+ and –COO− groups. As l-tyrosine is non-innocent agent with respect to redox processes, redox ability in water expressed by the absolute oxidation and reduction potentials is investigated. The cluster analysis applied to a set of nine related neurotransmitters and trace amines confirms that l-tyrosine is mostly similar to aminoacid forms of phenylalanine, octopamine, and noradrenaline.MethodsThe energetic data at the Hartree–Fock MO-LCAO-SCF method has been conducted using def2-TZVP basis set, and improved by the many-body perturbation theory using the MP2 correction to the correlation energy. For the aminoacid form and the zwitterionic form of l-tyrosine, a set of molecular descriptors has been evaluated (ionization energy, electron affinity, molecular electronegativity, chemical hardness, electrophilicity index, dipole moment, quadrupole moment, and dipole polarizability). The solvent effect (CPCM) is very expressive to the zwitterionic form and alters the sign of the electron affinity from positive to negative values. In parallel, density-functional theory with B3LYP variant in the same basis set has been employed for full geometry optimization of the neutral and ionized forms of l-tyrosine allowing assessing the adiabatic (a) ionization/affinity processes. The complete vibrational analysis enables evaluating thermodynamic functions such as the inner energy, enthalpy, entropy, Gibbs energy, and consequently the absolute oxidation and reduction potentials. Of applied methods, the most reliable are B3LYP(a) results that account to the correlation energy and the electron and nuclear relaxation during the ionization/affinity processes.

A COMPUTATIONAL STUDY OF SUBSTITUENT EFFECT 1, 3, 4-THIADIAZOLE ON CORROSION INHIBITION

A theoretical study of 1, 3, 4-thiadiazole with nine various derivatives in gaseous and aqueous phases was investigated by employing the density functional theory (DFT) at 6-311++(d, p) basis set and Becke’s three parameters hybrid exchange-correlation functional (B3LYP). The molecules are calculated using quantum computational chemistry calculations such as Gaussian09 software. This paper is to determine the chemical reactivity for various heterocyclic organic compounds and to understand the process of corrosion inhibition. The quantum chemical properties such as the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), energy gap (∆E), dipole moment (μ), global hardness (η), global softness (S), electronegativity (χ), electrophilicity (ω), nucleophilicity (ɛ), chemical potential (CP) and electrons transferred from inhibitors to metal surface (ΔN) were calculated. Dynamic simulation approximations to demonstrate the corrosion inhibition performances of studied inhibitors against the corrosion of 1, 3, 4-thiadiazole in the gaseous and aqueous phases can be given as 1<9<8<3<4<5<6<7<2 and1<3<9<8<3<4<5<6<7<2

Correlating theory with experimental data on the effect of symmetry on the electrocatalytic behaviour of Co phthalocyanines

An account on the synthesis of an unsymmetrically substituted cobalt phthalocyanine, 2-(4-carboxyphenoxy)-9,16,23-tri-tert-butyl-phthalocyaninato-cobalt(II) (complex 1) and its symmetric counterpart, 2,9,16,23-tetra-tert-butylphthalocyanine cobalt (II) (complex 2) is provided in this work. The complexes reported were applied in the electrooxidation of hydrazine with a glassy carbon electrode serving as a support for the electrocatalysts. In comparing the two, complex 1 produced the more favourable result with a higher peak current. A further assessment on the reactivity of the complexes was carried out using theoretical calculations. Using the density functional theory method, the electronic parameters including the gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital, electrophilicity (ω), electronegativity (χ), chemical softness (S) and hardness (η) were determined. The theoretical results deemed complex 1 as the more reactive structure as it had higher values for both the electronegativity and electrophilicity. The donor–acceptor hardness (ηDA) values were also found to be in alignment with the experimental results were complex 1 produced the lower oxidation potential as it had the higher ηDA value.

Electronic and optical properties of lead‐free double perovskites A2BCl6 (A = Rb, Cs; B = Si, Ge, Sn) for solar cell applications: A systematic computational study

AbstractIn recent years, lead‐free double perovskite materials have attracted much attention due to their probable applications in photovoltaic and optoelectronic devices. In this work, the electronic and optical properties of lead‐free double perovskites A2BCl6 (A = Rb, Cs; B = Si, Ge, and Sn) are studied using density functional theory (DFT) methodology. The result shows that the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO‐LUMO) energy gaps of these compounds vary between 0.524 and 0.919 eV, which agrees with the previously reported data. HOMO‐LUMO gap for Rb2SiCl6 is observed as 0.919 eV, which falls in the optimal energy gap range, that is, 0.9 to 1.6 eV for double perovskite material. Conceptual DFT‐based descriptors—molecular hardness, softness, electronegativity, electrophilicity index, and dipole moment of these compounds—are studied. The tolerance factor of A2BCl6 is observed in the range of 1.00 to 1.26. Rb2SnCl6 is almost a perfect fit with a value of 1.00. Cs2SiCl6 shows the maximum value of the refractive index and dielectric constant. Optical electronegativity is found between 0.178 and 0.246 eV. The suitable band gap and high value of the refractive index and dielectric constant make double perovskites A2BCl6 effective for solar cells and optoelectronic devices.