Electronegativity Research Articles

Influence of hydrogen bond donor compound type on the properties of betaine based deep eutectic solvents: A computational and experimental approach

Novel deep eutectic solvents (DESs) based on Betaine as a hydrogen bond acceptor and Urea, Lactic acid, Glycerol, 1.2 - Propanediol, Xylitol as a hydrogen bond donor were prepared. Using computational approach, a theoretical analysis of compounds reactivity for hydrogen bond formation was carried out to justify the intermolecular interactions reactivity for hydrogen bond formation among the components. Through frontier molecular orbital theory and HOMO−LUMO values and various quantum chemical parameters, viz., ionization potential, electron affinities, electro negativity, chemical potential, global softness and hardness, electrophilicity and nucleophilicity indexes were calculated for all DESs. The calculated parameter namely charge transfer (ΔN) was used to evaluate the effectiveness of the formation of the DES. The value of charge transfer varies in the range 0.053–0.2836 eV and is higher for systems Betaine – Glycerol and Betaine – 1,2 - Propanediol. Electronegativity of the HBD varies in 4.2465< χ >7.2179 eV. They are promising options for applications that need to contact with water because of their hydrophilic nature. The formation of hydrogen bonds during the formation of DES was confirmed using the nuclear magnetic resonance (NMR) method. Donors of hydrogen bonds are able to ensure the formation of DES with Betaine, but the choice of the donor depends on the specific conditions of use and requirements for the solvent. Thermal behavior, surface tension, viscosity, electrical conductivity, рН of the prepared DES was investigated. Systems of the Betaine based DES with Xylitol and Urea have higher thermal stability (> 150 ºC). The highest values of surface tension are observed for DESs with Glycerol (65.02⋅103 J/m2) and 1.2-Propanediol (54.29⋅103 J/m2). The Betaine-Urea deep eutectic solvents (DES-1) and Betaine-Lactic acid (DES-2) systems have fairly high electrical conductivity (0.0091 and 0.4160 Sm/m). The effect of water on the properties (electrical conductivity, рН and surface tension) of DESs was investigated. The surface tension measurements revealed a broad range of surface tension, with water content being a major factor. This work has the effect of supplying new theoretical approach for a more deliberate comprehension on design of betaine-based DES as novel solvents for use in applications.

Structure, Synthetic Pathway, and Properties of Metastable Phosphorus Carbide, P4C3.

Due to electronegativity (EN) differences, changing from C3N4 to P4C3 is not as trivial as simply replacing nitrogen by phosphorus in the C3N4 structure. Hence, the nonexistent P4C3 phase is nominally the higher-homologue analogue of the well-known C3N4, but its structure and properties are practically unknown for fundamental reasons. Here we predict, by means of an extensive structure search, three energetically favorable yet metastable P4C3 phases adopting space groups P1̅, Cm, and Cmmm, followed by designing their synthetic routes. Different from the planar structural motifs of C3N4, P4C3 is likely to adopt various "puckered" (as regards the P atoms) forms, mainly related to the EN difference between nitrogen and phosphorus, the difference in atomic size, and also less favorable sp orbital mixing for phosphorus related to primogenic repulsion; hence, the P substructures are characterized by single and fractional P-P bonds with rectangular/linear motifs or those resembling simple-cubic P, including multicenter bonding as a function of the large electron count. As regards the carbon substructures, infinite polyacetylene-like motifs, carbon dimers, and infinite chains of cyclopentadienyl-like and polyphenyl-like units are predicted, with C-C bond orders larger than one. Band structure analyses indicate the metallic character of these three phases. The P1̅ polymorph exhibits a Dirac cone, whereas the Cmmm phase, being composed of metallic "phosphorene" units and infinite polyphenyl units, might show potential in applications, e.g., battery electrodes. Moreover, the monolayer of the P1̅ polymorph should be easy to exfoliate and exhibit a large anisotropy with regard to mechanical and electronic properties. The synthesis of P4C3 defining a new class of IV3V4 compounds should be attempted due to its predicted structural and physicochemical properties.

Role of Electronegativity on the Elemental Diversity in High-Entropy Alloys.

High-entropy alloys (HEAs) or multi-principal element alloys (MPEAs) have found extensive applications in high-precision devices. While the increased configurational entropy for HEAs favors more elemental diversity, it also increases the possibility of phase separation into multiple heterogeneous systems. This article reports that these two mutually competing effects are balanced for 3- and 4-component alloys. Analysis of all of the n-component ABCD···-type (∼5 × 105) available compounds in the materials' database shows that more than 70% are either 3- or 4-component ones. Their high propensity is explained on the basis of their optimal average difference of electronegativity (EN) ∼0.5-1.0 and the average sum of electronegativity (EN) ∼5.0-6.5 between the constituent atoms in the Oganov scale. Effectively, these 3- and 4-component alloys lie in the intermediate (centroid) region of the van Arkel-Ketelaar triangle, indicating their metalloid nature.

DFT/TDDFT calculations of geometry optimization, electronic structure and spectral properties of clevudine and telbivudine for treatment of chronic hepatitis B

Chronic hepatitis B remains a worldwide health concern. Presently, many drugs, such as Clevudine and Telbivudine, are recommended for the treatment of chronic hepatitis B disease. For this purpose, the quantum chemical analysis of ELUMO-HOMO (Egap), ionization potential (IP), electron affinity (EA), electronegativity (EN), chemical hardness (η), chemical potential (μ), chemical softness (S), electrophilicity index (ω), electron accepting capability (ω+), electron-donating capability (ω-), Nucleophilicity index (N), additional electronic charge (∆Nmax), Optical softness (σ0) and Dipole Moment, IR and UV–Vis spectra, molecular electrostatic potential (MEP) profile, Mulliken charge analysis, natural bond orbital (NBO) were examined in this study. The dipole moment of the compounds suggests their binding pose and predicted binding affinity. The electrophilic and nucleophilic regions were identified, and techniques such as NBO, UV–Vis, and IR were used to gain insights into the molecular structure, electronic transitions, and potential drug design for Hepatitis B treatment. Calculations for this study were carried out using the Gaussian 09 program package coupled with the DFT/TDDFT technique. The hybrid B3LYP functional method and the 6-311++G(d, p) basis set were used for the calculations.

Exploration of Choline Chloride Based Type II and Type III Deep Eutectic Solvents: A Computational and Experimental Approach

AbstractDeep eutectic solvents (DESs) of choline chloride with citric acid (CACC), Maleic acid (MACC) and Magnesium chloride hexahydrate (MAGCC) were synthesized in 1 : 1 molar ratio and investigated experimentally and computationally. For the computational study, density functional theory (DFT) calculation with B3LYP/6‐31 (+, +) G (d,p) level of theory for MACC and CACC and at B3LYP/SDD basis set for MAGCC was employed and the FT‐IR spectroscopy was used for experimental evaluation. For understanding the orientation of bonds and hydrogen bonding present in DESs geometrically optimized structures were used. Through frontier molecular orbital (FMO) theory and HOMO−LUMO values and various quantum chemical parameters, viz., ionization potential (IP), electron affinities (EA), electro negativity (χ), chemical potential (μ), global softness (σ) and hardness (η), electrophilicity index (ω) were calculated for all DESs. These computational values made it clear that MAGCC is the most stable among the three DESs due to the high value of global hardness (η) (3.291 eV) and HOMO−LUMO energy gap (Egap) (6.582 eV) and lowest value of softness (σ) (0.152 eV), CACC shows the moderate values (η=2.452, Egap=4.905 and σ=0.204 eV). While MACC is found to be the least stable and most reactive among three DESs with values of η, Egap and σ, 1.970, 3.940 and 0.254 eV, respectively. Furthermore, MESP analysis gives an idea about the electrophilic and nucleophilic surface region of DESs. This study will give valuable information for a better understanding of DESs and the applicability of computational calculations in the future.

SIMULTANEOUS ADSORPTION OF Cd (II) AND Pb (II) IONS ON Al-DOPED Mn3O4: VALIDATION BY FAAS and ICP-OES

The one-pot solution combustion method was employed to prepare an Al-doped Mn3O4 nano adsorbent with a tetragonal structure and was characterized by pXRD, FESEM-EDX, and FTIR, instrumental techniques. The synergetic or antagonistic influence of coexisting ion over the other ion was investigated by simultaneous adsorption studies of Cd(II)and Pb(II) ions under the optimized conditions of a pH of 6, 40 mg of Mn3-xAlxO4 adsorbent for 90 minutes. The adsorption of Cd(II)and Pb(II)ions in binary solution was followed by film diffusion with less mass transfer along with the boundary layer effect. The extended Langmuir nonlinear isotherm model revealed the antagonistic effect on the adsorption of each ion in the presence of coexisting ions due to the tremendous interference and competition between both ions on the availability of negatively charged active sites, the positive charge density of the ions, a high affinity on the Mn3-xAlxO4 adsorbent surface, and difference of the electro negativity of Cd (II) and Pb(II) ions. This adsorption of Cd(II) and Pb(II) ions simultaneously was validated by FAAS and ICP-OES.

Green synthesis, molecular structure, spectroscopic, ADME, DFT and molecular docking studies on methyl 10-trans,12-cis-octadecadienoate

The methyl 10-trans, 12-cis-octadecadienoate (MOD) obtained from the methanol extract of Calotropis gigantea flowers was studied using spectroscopic, computational molecular modelling and DFT methods in the current work. The Calotropis gigantea flowers were collected from the surroundings of Tamil Nadu, India's Thiruvallur district. The preparation for extraction of bioactive compound from Plant - based green synthesis of MOD from Calatropis gigantea. The FTIR spectra of MOD have been measured between in 400 and 4000 cm−1. Density functional theory is employed to determine the geometry of the molecules, vibrational frequencies and geometrical parameters by using B3LYP/6–311++G (d, p) basis set. The identification of the modes of vibration depended on the potential energy distributions (PEDs) which have been computed. The HOMO-LUMO energies, chemical hardness, and electro negativity of the molecule have been determined via the DFT/B3LYP/6–311++G (d, p) method. The intra molecular interactions and hydrogen bonding have been interpreted using natural bond orbital analysis by NBO 3.1 program. UV–Visible absorption spectra in the wavelength range of 200–400 nm was noticed, which indicates a molecular exchange of charges inside the molecule. The time dependent density functional theory (TD-DFT) method adopted for this study to determine the excited states of the title molecule. The Argus Lab application was implemented to evaluate the molecular docking tests that were conducted to look at the anti-cancer capabilities of the MOD molecule against Caspase 3.

Rational Design of Graphene-Supported Single Atom Catalysts for High Performance Lithium-Oxygen Batteries

Aprotic lithium-oxygen batteries (LOBs) have been considered as one of the next-generation battery technologies, due to its ultrahigh theoretical energy density (~3600 Wh kg -1), 5-10 times higher than the state-of-the-art lithium-ion batteries (LIBs), supporting the development of electric vehicles (EVs). However, the battery system suffers from poor cyclability, low round-trip efficiency and inferior rate capability, mainly originated from the inertness of oxygen gas and the poor electrical conductivity of lithium peroxide (Li2O2), leading to the sluggish kinetics of oxygen reduction reaction (ORR)/ oxygen evolution reaction (OER). In response to the challenges, developing a highly efficient catalyst at the cathode is vital to boost the reaction rate and reduce the reaction overpotentials, eventually address the problem. Heterogeneous single-atom catalysts (SACs) on solid support are emerging as a new frontier in this research field. Here, we use the density of state (DFT) calculation to determine the catalytic activities of a wide range of transition metal single atoms distributing on the nitrogen doped graphene support and found that Zn-SAC exhibits the highest ORR/OER activities. We discovered that Zn-N4 moieties, functioning as catalytic centers, bind with LiO2 not very strongly, reduce the reaction overpotentials, facilitates the reaction rate and enhance the stability of the catalyst. The catalytic activity of SACs is highly correlated to the Gibbs free energy of the adsorbed LiO2. A descriptor, F of the catalysts determining the catalytic activity was developed from the metal properties of electronegativity (EN), enthalpy of vaporization (EV) and number of electrons in d orbital, by using supervised machine learning (ML) method, providing guidance for designing useful SACs in ORR/OER process. This work systematically provides guidance to design highly efficient SAC for LOBs and provides fundamental insights in choosing the proper metal for the ORR/ OER application.

Wet chemical synthesis and characterization of FeVO4 nanoparticles for super capacitor as energy storage device

Vanadates of transition metal found its potential applications in the fields of lithium ion batteries, gas sensors, photo catalysts, solar cells and so on. Among the metal vanadates, Iron vanadate is vital as an organic pollutant remedying, gas sensor material, and selective catalytic reduction material. This current research focuses on synthesizing iron vanadate nanoparticles by wet chemical synthesis with controlled pH using ammonia solution. The nanostructured FeVO4 particle were characterized structurally with the powder XRD studies. Strong crystal planes were formed at Miller indices (111), (0–12), and (−220) which is confirmed from the intensity of the diffraction peaks. FT- IR and micro Raman studies was taken to identify the molecular vibrations present in the material and it shows that the sharpest apex at 508 cm−1 obtained is attributed to the stretching oscillations of Fe–O and V–O–V modes. The Raman spectrum confirmed the separation of Fe − O, V − O, and different stretching fashions of V − O − Fe. The V–O stretching mode increases the intense bands showing the very high strongest peak of FeVO4 because of electro negativity of iron the metal. The morphology of iron vanadate was confirmed with SEM analysis showing that particles are much isolated and cubical with few polyhedron structures. The electrochemical response of FeVO4 evaluated the specific capacitance at 10 mV/s as 402 Fg−1.Energy density values were calculated as 16.08 Whkg−1, 13.08 Whkg−1, 10.2 Whkg−1, 8.76 Whkg−1, 7.64 Whkg−1 and 6.92 Whkg−1 from the cyclic voltammetry profile at the slow rates varying from 10 −100 mV/s. The magnetic properties were analyzed by measuring the magnetic susceptibility and magnetization using a VSM magnetometer and the results evident that the material exhibits the paramagnetic behavior.

Accelerated design of lead-free high-performance piezoelectric ceramics with high accuracy via machine learning

The piezoelectric performance serves as the basis for the applications of piezoelectric ceramics. The ability to rapidly and accurately predict the piezoelectric coefficient (<i>d</i>₃₃) is of much practical importance for exploring high-performance piezoelectric ceramics. In this work, a data-driven approach combining feature engineering, statistical learning, machine learning (ML), experimental design, and synthesis is trialed to investigate its accuracy in predicting <i>d</i>₃₃ of potassium–sodium–niobate ((K,Na)NbO₃, KNN)-based ceramics. The atomic radius (AR), valence electron distance (DV) (Schubert), Martynov–Batsanov electronegativity (EN-MB), and absolute electronegativity (EN) are summarized as the four most representative features in describing <i>d</i>₃₃ out of all 27 possible features for the piezoelectric ceramics. These four features contribute greatly to regression learning for predicting <i>d</i>₃₃ and classification learning for distinguishing polymorphic phase boundary (PPB). The ML method developed in this work exhibits a high accuracy in predicting <i>d</i>₃₃ of the piezoelectric ceramics. An example of KNN combined with 6 mol% LiNbO₃ demonstrates <i>d</i>₃₃ of 184 pC/N, which is highly consistent with the predicted result. This work proposes a novel feature-oriented guideline for accelerating the design of piezoelectric ceramic systems with large <i>d</i>₃₃, which is expected to be widely used in other functional materials.

Synthesis, spectroscopic elucidation (FT-IR, FT-Raman, UV–vis), quantum chemical computation (PES, FMO, HOMO–LUMO, MEP, NLO, Hirshfeld) and molecular docking studies on 2-thiophenecarboxamide crystal

2TPCA single crystals were grown by slow evaporation technique, vibrational and electronic analyses have been carried out. Density functional (DFT/B3LYP) method with 6-31G** basis set used to calculate infrared intensities and Raman scattering data, vibrational wavenumbers and to study molecular geometry, optimal structure. Inter molecular Interactions, HOMO–LUMO, dipole moment, polarizability, first order hyper polarizability, Molecular electrostatic potential studies on 2TPCAare investigated. The conformational analysis carried out to predict more stable structure of 2TPCA.Intermolecular interactions evaluated using Hirshfeld Surface analysis. The calculated band gap energy of HOMO and LUMO used to study the stability, hardness and softness, electron affinity, electro negativity, chemical potential, ionization potential, electro negativity, electrophilicity of the compound. Molecular Docking analysis of 2TPCA with macromolecule HMG-CoA protein performed to predict the binding orientation, affinity and activity of the compounds.

Controlling the Photocatalytic Activity and Benzylamine Photooxidation Selectivity of Bi2WO6 via Ion Substitution: Effects of Electronegativity

Doping or ion substitution is often used as an effective strategy to improve photocatalytic activities of several semiconductors. Most frequently, the dopants provide extra states to increase light absorption, alter the electronic structure, or lower the carrier recombination. This work focuses on ion substitution in Bi2WO6, where the dopants modify band-edge potentials of the catalysts. Specifically, we investigate how the electronegativity (EN) of the dopant could be used to tune the band-edge potentials and how such changes influence the photocatalytic mechanism. Compared to Te that has a lower EN, I lowers the band-edge potentials. While substitutions with both ions enhance Rh B photodegradation and benzylamine photooxidation, the modified band potentials of I-doped Bi2WO6 influence the benzylamine photooxidation pathway, resulting in higher selectivity. Additionally, substitution of I7+ in the Bi2WO6 lattice improves the morphologies, decreases the band-gap energy, and reduces the carrier recombination. As a result, I-doped Bi2WO6 shows almost 3 times higher %conversion while maintaining 100% selectivity in the oxidative coupling of benzylamine. The findings here signify the importance of the choices of dopants on the photocatalytic reactions and would benefit the design of other related materials for such applications.

Energy Electronegativity and Chemical Bonding

Historical development of the concept of electronegativity (EN) and its significance and prospects for physical and structural chemistry are discussed. The current cutting-edge results are reviewed: new methods of determining the ENs of atoms in solid metals and of bond polarities and effective atomic charges in molecules and crystals. The ENs of nanosized elements are calculated for the first time, enabling us to understand their unusual reactivity, particularly the fixation of N2 by nanodiamond. Bond polarities in fluorides are also determined for the first time, taking into account the peculiarities of the fluorine atom's electronic structure and its electron affinity.

Peculiarities of the dependences of the dielectric properties of solid solutions of multicomponent systems on the electronegativity of their constituent cations

Solid solutions (SS) of 3- and 4-component systems based on lead titanate-zirconate were prepared by the method of solid-phase reactions and uniaxial hot pressing. The dependences of the relative permittivity of polarized samples on the electronegativity (EN) of their constituent cations have been studied. The ferro-hardness of the SS (the stability of the domain structure to external influences) is shown to be directly dependent on the EN of elements B in the corresponding oxidation states, i.e., the degree of covalence of the B–O bond. The deviation from this dependence in SS with Ni and Cd is explained by their individual features, which result in changes in the degree of bond covalence in both cationic sublattices. The conducted crystal-chemical analysis made it possible to choose promising SS when creating ferroelectric materials, including textured piezoelectric ceramic materials for piezoelectric transducers for various purposes: Piezotransformers, piezoelectric motors, ultrasonic emitters, filter devices, ultrasonic flaw detectors, accelerometers, etc.

Achieving tunable luminescence in rare earth free IRMOF-3 through post synthetic modifications by judicious choice of organic linker

Owing to the high cost of rare earth ions/lanthanides, associated health hazard, mining issues and transport constrain, there is an urgent need of designing rare earth free functional materials. Globally lot of thrust has been given on designing cost effective lanthanides free phosphors for light emitting diodes. In addition to cost efficient and environmentally benign, these lanthanide free phosphors are free from doping induced defects, strain and distortions. Herein, two new functionalized Zn based isoreticular metal organic frameworks (IRMOFs) namely; IRMOF-SMA (sulfamic acid) and IRMOF-DPC (diphenyl phosphonic chloride) were synthesized via post synthetic modification (PSM) using IRMOF-3 for investigating the color tunable luminescence. The synthesized materials were characterized using powder X-ray diffraction (powder XRD), thermogravemetric analysis (TGA), fourier transformed infrared (FTIR), and nuclear magnetic resonance spectroscopy (NMR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). For the first time, we have demonstrated tuning of intrinsic violet emission from pristine IRMOF-3 via PSM employing organic ligands viz. SMA and DPC. SMA leads to slight shift in emission hue from violet to blue but DPC leads to giant color shift from violet-blue to white light. The shift is correlated to electro negativity difference between sulfur and phosphorus, respectively, in SMA and DPC. Color correlated temperature evaluated for DPC linked IRMOF-3 was more than 5500 K suggest being bluish white (cool white). Enhancement in luminescence lifetime also observed with PSM MOFs compared to pristine sample owing to lowering of non-radiative transitions. This work opens up new avenues in the field of exploring MOFs for lanthanide optoelectronic devices and light emitting diodes and further tuning the light via PSM strategy.

Investigations on spectroscopic, ADMET properties and drug-likeness, molecular docking, chemical properties of (2E)-3-(biphenyl-4-yl)-1-(2,4-dichlorophenyl)-prop-2-en-1-one by combined density-functional theory

The title compound, (2E)-3-(Biphenyl-4-yl)-1-(2,4-dichlorophenyl)-prop-2-en-1-one (BPDC) has been derived from the compounds namely biphenyl-4-carbaldehyde and 2,4-dichloroacetophenone to perform 3D-Potential energy conformations for molecular stability by DFT calculation of B3LYP/6-311++G(d,p). The geometrical optimization and atoms vibrational spectral data observed FT-IR and FT-Raman spectra values were compared with theoretical values (B3LYP, CAM-B3LYP). The molecule was characterized by absorbed infrared radiation, scattered Raman techniques with the attention on important functional groups (Cl, O, N). Electro negativity difference has been discussed and their biochemical and biomedical properties have been examined. The chemical reactivity of the compound was characterized by MEP-map, NHO, NLMO, and NBO analyses. The frontier molecular orbital (HOMO–LUMO) energy gap, vertical electron truncation of UV–Visible spectrum, and their λ-max value have been compared with CAM-B3LYP and M062X/6-311++G(d,p) approach data. The orbitals arrangements were studied by the density of states (DOS) and the partial density of states (PDOS). BPDC is investigated by Hirshfeld surface analysis that employs three-dimensional contours and two-dimension fingerprint area for intermolecular interactions quantitatively. The biological investigations like drug-likeness and toxicity properties of BPDC molecule were conformed to Lipinski's rule of five and ADMET properties, respectively. The title molecule exhibits a good bioactive score and less toxicity. Antibacterial and also antifungal activities of BPDC were done by docking analysis.

Effect of selected dopants on conductivity and moisture stability of Li3PS4 sulfide solid electrolyte: a first-principles study

The first principle computational screening was performed to investigate the effect of selected dopants for Li3PS4 sulfide solid electrolyte on its ionic conductivity and stability toward moisture. The results suggest that substitution P5+ using isovalent cations whose electronegativity (EN) value is closer to the value of S has more significant effects on the ionic conductivity, whereby W5+ and Sb5+ can improve most. Similarly, aliovalent cation substitutions with compensating changes in the lithium-ion concentration, particularly those with a lower oxidation state and higher EN, such as Cu2+, effectively enhance the lithium-ion conductivity in this structure. For cation dopants, it is found that ionic conductivity improvement of Li3PS4 is the synergetic effect of EN and oxidation number of the dopant as well as the material's lattice parameter change. Oxides of the considered cation dopants can also improve the ionic conductivity of the material but have much lower lithium-ion conductivity than the cases of cation dopants. However, the metal oxide dopants, particularly those derived from soft Lewis' acid cations, show a marginal improvement in moisture stability of the Li3PS4 electrolyte. The effect of halides and metal halide dopants on the lithium-ion conductivity and moisture stability of Li3PS4 electrolyte are also studied. It is found that metal halides are more effective than any other dopants in improving the ionic conductivity of Li3PS4.

Understanding of the bond covalency nature with ionic electronegativity in perovskite cuprates La2CuMO6-x (M = Ti, Mn, Ru)

A bond valence sums (BVS) modified ionic electronegativity (EN) scale was suggested for better accommodating the double perovskite La2CuMO6-x (M ​= ​Ti, Mn, Ru) with mixed bonding nature. Both the M ​− ​O bond covalency fraction (f) and the cooperative B-site sublattice distortion are highlighted to connect structure and physical properties. Particularly, the Ti-based compound hosts the largest M/O ionic EN difference and hence yields the smallest f value while the Ru-based analogue exhibits the opposite result. As the consequence, robust spin disordering accompany with poor dc conductivity is convinced in the Ti-based sample owing to its featuring B-site ionic arrangement and profound suppression of 3d(Ti)-2p(O) orbital hybridization. For the Ru-based sample, strong ferromagnetic spin frustration and low charge carrier hopping potential might be essentially ascribed to its large f value through enhancing orbital degeneracy between 4d(eg)-2p σ and 4d(t2g)-2p π bonding states. The Mn-based sample with the moderate f value exhibits the similar magnetic and electric behaviors as those of Ru-based sample. Both the d(M)-p(O) orbital hybridization and the M ​− ​O bond covalency could be tuned by rationally selecting the M cation with proper ionic EN value. This work provides a deep understanding of the bond covalency nature in perovskite cuprates and might help to develop novel electronic functional materials.

Energetic and Geometric Characteristics of Substituents, Part 3: The Case of NO2 and NH2 Groups in Their Mono-Substituted Derivatives of Six-Membered Heterocycles

Substituted heterocyclic arenes play important roles in biochemistry, catalysis, and in the design of functional materials. Exemplary six-membered heteroaromatic molecules, that differ from benzene by inclusion of one heteroatom, are pyridine, phosphorine, arsabenzene, and borabenzene. This theoretical study concerns the influence of the heteroatom present in these molecules on the properties of substituents of two types: electron-donating (ED) NH2 group and electron-accepting (EA) NO2 group, attached at the 2-, 3-, or 4-position. The effect is evaluated by the energy of interaction (Erel) between the substituent and the substituted system and electronic properties of the substituents described by the charge of the substituent active region (cSAR) index. In addition, several geometric descriptors of the substituent and heteroaromatic ring, as well as changes in the aromaticity, are considered. The latter are assessed using the Electron Density of Delocalized Bonds (EDDBs) property of delocalized π electrons. The obtained results show that the electronegativity (EN) of the heteroatom has a profound effect on the EA/ED properties of the substituents. This effect is also reflected in the geometry of studied molecules. The Erel parameter indicates that the relative stability of the molecules is highly related to the electronic interactions between the substituent and the heteroarene. This especially applies to the enhancement or weakening of π-resonance due to the EN of the heteroatom. Additionally, in the 2-heteroarene derivatives, specific through-space ortho interactions contribute to the heteroatom effects.

Frontier molecular orbital, molecular structure and Thermal properties of 2,4,6,8-tetramethyl-2,3,6,7-tetrahydro-s-indacene-1,5-dione using DFT calculation

The quantum chemical calculations of 2,4,6,8-tetramethyl-2,3,6,7-tetrahydro-s-indacene-1,5-dione molecule were carried out with DFT calculations using DFTB3LYP/6–311++G(d,p) basis set by Gaussian 09 W code. The molecular structure, frontier molecular orbitals (HOMO, LUMO), and thermal properties were explained in this article. From the molecular structural result, we found that the titled molecule more active at O-13 and O-14 oxygen atom. From the frontier molecular orbital study, the HOMO molecular orbital energy is found to be −6.6496 eV and the LUMO molecular orbital energy is found to be −2.2599 eV. The electro negativity and electro positivity and electron density of the titled molecule was calculated from the molecular electrostatic potential maps. The stability, chemical hardness, global softness, and elecrtrophilicity index were also estimated.