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This work establishes the dependences of the biological activity of synthesized dithio- and dithioseleno-containing spatially hindered phenols with α-methylbenzyl groups on the calculated values of the energy parameters of the molecules. For the studied compounds, the values of the electrophilicity index are calculated based on the obtained values of the ionization potentials and electron affinity. Using methods of multiple regression analysis, the dependences of the bactericidal and antifungal properties of the samples on two parameters were established: x1—the energy of the HOMO (highest occupied molecular orbital), and x2—the energy of the LUMO (lowest unoccupied molecular orbital) with a reliability of more than 93%. According to the equations derived based on the antimicrobial properties of bis[n-α-methylbenzyl-m-methyl-2-hydroxyphenyl] disulfides (selenides), three-dimensional graphs of functions were constructed, considering the boundary conditions of the zone of microorganism suppression around the hole on a scale of 0–3 cm. The obtained models show that changes in the energies of the LUMO (x2) have a greater effect on the zone of microorganism suppression than changes in the energies of the HOMO (x1), as indicated by the comparison of the coefficients' values for x2 and x1, respectively. Moreover, the degree of influence of changes in the energies of the boundary molecular orbitals on f antifungal properties is more significant than on bactericidal properties, based on the values of the coefficients of the equations for a mixture of fungi and bacteria at values x1 and x2. [ABSTRACT FROM AUTHOR]

In this study, we introduce a novel definition for the electrophilic descriptor. Following the proposal of other researchers, the foundation of our approach lies in expanding the change in the energy of an electronic system using a third‐order Taylor series, leading to the integration of hyperhardness into the formulation of the electrophilic descriptor. To validate our results, we conducted a comparative analysis of reactivity sequences among 35 electrophilic systems with known reactivities, as reported in external experimental studies. The electrophilic descriptor demonstrated a remarkable ability to accurately replicate the relative reactivities of the compounds under consideration, surpassing predictions based solely on the electrophilicity index. These findings underscore the significance of incorporating hyperhardness as a crucial reactivity descriptor. Additionally, our study provides interesting insights into the interpretation of this concept. [ABSTRACT FROM AUTHOR]

In this manuscript, we postulate a possible relationship of philicity within a molecular ensemble. The philicity has been studied by the Chattaraj et al. (J Phys Chem A 107(25):4973–4975, 2003). This important concept was obtained using the electrophilicity index and Fukui functions. In this work, was related the philicity with Molecular Quantum Similarity framework, to obtain a possible way to relate the philicity between molecules A and B. This methodology, can open a possible way to find systematic relationships in a given molecular ensemble using the selectivity defined in the Density Functional Theory context. [ABSTRACT FROM AUTHOR]

The NLO property of a few designed inorganic–organic hybrid materials based on Nickel dithiolenes end-capped with donor–acceptor groups has been studied theoretically. All the designed molecules possess high first hyperpolarizability values indicating their potential use in optics, photonics, and as photosensitizers. Among the four designed systems, the BODIPY-containing systems significantly reduce the HOMO–LUMO energy gap resulting in a massive trek in the first hyperpolarizability (β) values. To judge their high NLO response, transition dipole moment (TDM) density has been plotted and it has been found that electron dissipation occurs through the molecular network with a large Δr index value. It is to be noted that high Δr index values are quantitative measurements to understand the type of transitions, and we noticed that a charge transfer transition occurs in all of our designed systems. Hence a nice correlation between the first hyperpolarizability, TDM density, and Δr index value has been observed. The global reactivity parameters are also studied and correlated nicely with polarizability and hole-electron transport ability. [ABSTRACT FROM AUTHOR]

The >C=P– or –N=P– functionality in 1,3-azaphospholo[1,5-a]pyridine, named as 2-phosphaindolizine and its 1- and 3-aza derivatives act as dienophiles and undergo Diels–Alder reactions with 1,3-dienes. However, the dienophilic reactivity is affected by the nature of the substituent groups on the two sides of the σ2,λ3-P atom and also by the presence of more nitrogen atom(s) in the five-membered ring. The conceptual density functional theory (DFT) calculations have been used in recent years to predict the reactivity of organic molecules in reactions. We calculated global hardness (η), global softness (S), electronic chemical potential (μ), electrophilicity (ω), and nucleophilicity (N) indices of four classes of 2-phosphaindolizines, on the basis of which their observed relative dienophilic reactivities could be rationalized. Besides, the Fukui functions of the carbon/nitrogen and phosphorus atoms of the >C=P– and –N=P– functionalities were also computed which revealed their hard electrophilic character and accorded well with the dienophilic reactivities observed experimentally. Furthermore, energies and symmetries of the lowest unoccupied molecular orbitals (LUMO) of 2-phosphaindolizines were found to be in conformity with their dienophilic reactivities.

This review aims to be a comprehensive, authoritative, critical, and accessible review of general interest to the chemistry community; because the electrophilicity index is a very useful global reactivity descriptor defined within a conceptual density functional theory framework. Our group has also introduced electrophilicity based new global and local reactivity descriptors and also new associated electronic structure principles, which are important indicators of structure, stability, bonding, reactivity, interactions, and dynamics in a wide variety of physico‐chemical systems and processes. This index along with its local counterpart augmented by the associated electronic structure principles could properly explain molecular vibrations, internal rotations and various types of chemical reactions. The concept of the electrophilicity index has been extended to dynamical processes, excited states, confined environment, spin‐dependent and temperature‐dependent situations, biological activity, site selectivity, aromaticity, charge removal and acceptance, presence of external perturbation through solvents, external electric and magnetic fields, and so forth. Although electrophilicity and its local variant can adequately interpret the behavior of a wide variety of systems and different physico‐chemical processes involving them, their predictive potential remains to be explored. An exhaustive review on all these aspects will set the tone of the future research in that direction. [ABSTRACT FROM AUTHOR]

Electronegativity is an important chemical construct that plays a pivotal role to explain several chemical, biochemical and physicochemical phenomena. The study of this periodic descriptor is still considered an active domain of research, and a number of scientists are involved to propose different scales of electronegativity based on experimental findings and theoretical concepts. In this study, we have proposed a model to compute atomic electronegativity values of 103 elements based on the Floating Spherical Gaussian Orbital approach invoking the atomic electrophilicity index as a descriptor. The computed electronegativity scale observes the periodic trend and justifies many chemical phenomena. Molecular electronegativity values have also been computed using the computed atomic electronegativity data and utilized to justify the Electronegativity Equalization Principle. In order to validate our proposed model, internuclear bond distances for some molecules have been deduced in terms of our computed atomic electronegativity data. A strong correlation with experimental counterparts proves the efficacy of our proposed model. [ABSTRACT FROM AUTHOR]

The preclinical drug discovery stage often requires a large amount of costly and time-consuming experiments using huge sets of chemical compounds. In the last few decades, this process has undergone significant improvements by the introduction of quantitative structure-activity relationship (QSAR) modelling that uses a certain percentage of experimental data to predict the biological activity/property of compounds with similar structural skeleton and/or containing a particular functional group(s). The use of machine learning tools along with it has made life even easier for pharmaceutical researchers. Here, we discuss the toxicity of certain sets of bioactive compounds towards Pimephales promelas and Tetrahymena pyriformis in terms of the global conceptual density functional theory (CDFT)-based descriptor, electrophilicity index (ω). We have compared the results with those obtained by using the commonly used hydrophobicity parameter, logP (where P is the n-octanol/water partition coefficient), considering the greater ease of computing the ω descriptor. The Human African trypanosomiasis (HAT) curing activity of 32 pyridyl benzamide derivatives is also studied against Tryphanosoma brucei. In this review article, we summarize these multiple linear regression (MLR)-based QSAR studies in terms of electrophilicity (ω, ω2) and hydrophobicity (logP, (logP)2) parameters. [ABSTRACT FROM AUTHOR]

[Display omitted] • Importance of DFT calculations along with the mass spectral analysis. • Electrophilicity index is calculated for the metabolites of six oxicams. • Isomeric states of the metabolites should be considered during mass spectrometry. • The electrophilicity index of predicted metabolites is greater than the reported corresponding isomers. Oxicams are important drugs that act as anti-inflammatory agents, of them, piroxicam and its prodrugs are in daily use. The metabolic profiles of oxicams were explored using mass spectrometry methods and, in some cases, NMR. However, there is a noticeable gap in research regarding the in-depth exploration of the electronic structure of their reactive metabolites. The relative energies of the various metabolites of oxicams and the associated possible isomers have not been compared. In this work, the electronic characteristics of the reactive metabolites associated with important oxicams have been evaluated. This comparative analysis helped in identifying additional potential reactive metabolites of several oxicams. For example, the quinonimine metabolite of piroxicam has been suggested as an important possibility. This work highlights that in addition to mass spectrometry analysis, energy comparison of possible isomers needs to be carried out in drug metabolism studies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Higher quantum yield of 4-cyano PM dyes over 4-fluoro PM dyes DFT and TD-DFT method. • Higher electrophilicity index of the excited state leads to stabilization of the 4-cyano BODIPY. • Enhanced QYF owing to lower transition restricted transition from singlet to triplet state. • FMO and MEP plots and the charge transfer involved within the dye. • Solvent effects are studied with both PCM and SMD methods. The modified BODIPY (pyrromethene) dyes with cyano (-CN), substituting usual fluorine (-F), at the 4-position may give enhanced photochemical stability and quantum yield of fluorescence (QYF) when compared to the corresponding fluoro derivative. We have investigated and discussed comparatively the structural parameters of the ground (S 0) and excited (S 1) state geometries of a few widely used BODIPY dyes, both 4-cyano and 4-fluoro pyrromethene (PM), through DFT and TD-DFT studies and established the reasons for improved QYF of the cyano derivatives. The electrophilicity index indicates the stability of the excited geometry of the cyanated BODIPY and the calculated transition dipole moments reveal a longer lifetime of the excited state (S 1) for the cyano BODIPY. The higher singlet and triplet gap in cyanated BODIPY accounts for higher QYF due to restricted transition from singlet to triplet state. This suggests that a population inversion, crucial for laser action, is easier to build up for cyano derivative than for the commonly used fluoro analogue while other gain/loss parameters of the PM dye lasers remain similar. Hence, 4-cyano derivatives of the PM dyes may be useful for more efficient lasing applications. The non-linear optical properties of the PM dyes are also investigated. [ABSTRACT FROM AUTHOR]

An electrochemical study, using cyclic voltammetry of 2-hydroxybenzophenone and related molecules, containing various electron withdrawing and/or electron donating groups, is presented. The CV profiles of the various molecules show one sharp reduction and one small oxidation wave, coupled to the reduction wave. Density functional theory (DFT) calculations shed light on the transmission of charges through the molecule, due to the different substituent groups at the ortho, meta or para positions. Various DFT calculated energies relate linearly to the experimentally measured reduction potential. These obtained linear relationships can be used to predict the reduction potential of similar molecules.

The preclinical drug discovery stage often requires a large amount of costly and time-consuming experiments using huge sets of chemical compounds. In the last few decades, this process has undergone significant improvements by the introduction of quantitative structure-activity relationship (QSAR) modelling that uses a certain percentage of experimental data to predict the biological activity/property of compounds with similar structural skeleton and/or containing a particular functional group(s). The use of machine learning tools along with it has made life even easier for pharmaceutical researchers. Here, we discuss the toxicity of certain sets of bioactive compounds towards Pimephales promelas and Tetrahymena pyriformis in terms of the global conceptual density functional theory (CDFT)-based descriptor, electrophilicity index (ω). We have compared the results with those obtained by using the commonly used hydrophobicity parameter, logP (where P is the n-octanol/water partition coefficient), considering the greater ease of computing the ω descriptor. The Human African trypanosomiasis (HAT) curing activity of 32 pyridyl benzamide derivatives is also studied against Tryphanosoma brucei. In this review article, we summarize these multiple linear regression (MLR)-based QSAR studies in terms of electrophilicity (ω, ω2) and hydrophobicity (logP, (logP)2) parameters.

This theoretical investigation using DFT/B3LYP calculations is dealing with the molecular structures and biological activities of ginger and some of its combinations containing menthol, ascorbic acid, hesperidin, allicin, hydoxycoumarin, or cinnamic aldehyde. The main goal of this theoretical investigation is the prediction of the biological activities of different combinations based on the evaluation of the occurred interactions which are of X-H⋯Y hydrogen bonding types evidenced by the energy decomposition analysis (EDA) and natural bond analysis (NBO) within the natural energy decomposition analysis (NEDA). The antioxidant potency is based on the BDEs (bonding dissociation enthalpies), spin densities, and the stability order between the formed radicals. The O-H bond breaking is related to the H-abstraction. The HOMO-LUMO gaps explain that the possible charge transfer interactions that take place within the molecules are responsible for the molecular reactivity of the studied molecules in the resulting combinations. The chemical hardness, the chemical potential, and the electrophilicity indexes show clearly the improvement of the biological activities of 6-gingerol in different combinations except in the presence of menthol. The spin density distribution for the radicals formed after H-abstraction on each OH of the 6-gingerol displays large value on O(2) of OH(2) group, contrary to that of O(1) showing a delocalization over the C6 ring leading to a significant antioxidant potency, in agreement with low BDE values favoring the H(2)-abstraction in all cases excluding only the H(4')-abstraction from ascorbic acid of the combination (3) giving rise to the most stable formed radical. The calculated dipole moments of 6-gingerol increase in the combinations with allicin and hydroxycoumarin, thus increasing their polarities giving rise to blood thinner combinations. The combination (6) has the highest polarity, so it dissolves in blood more than the others. [ABSTRACT FROM AUTHOR]

In this paper, we introduce new features of silicon in fullerane structures. Silicon, when placed in a fullerane structure, increases its electron affinity and electrophilicity index, compared to placement in a diamondoids structure. These nanoparticles can be used to make optical sensors to detect viral environments. In this work, we theoretically examine the changes in the UV-Visible spectrum of sila-fulleranes by interacting with viral spikes. As a result, we find out how the color of silicon nanoparticles changes when they interact with viruses. We apply N- and O-Links for viral glycoprotein structures, and Si20H20 silicon dodecahedrane, respectively. Our computational method to obtain optimal structures and their energy in the ground and excited states, is density functional theory (DFT). Besides, to get the UV-Visible spectrum, time-dependent density functional theory (TD-DFT) approach has been used. Our results show that the color of sila-dodecahedrane is white, and turns green in the face of viral spikes. We can use the optical sensitivity of silicon nanoparticles, especially to identify environments infected with the novel coronavirus.

Novel β-hydroxy-1,4-disubstituted-1,2,3-triazole-based benzodiazepinedione derivatives were synthesized by a regioselective cascade reaction and were fully characterized by HRMS, FT-IR, 1H NMR, and 13C NMR measurements. The cascade reaction consists of the azidation of epoxides and the Huisgen [3+2] dipolar cycloaddition of the resulted β-hydroxy azides with the N,N′-dipropargyl benzodiazepine to give the wished 1,2,3-triazole-based benzodiazepinedione derivatives. Good yields (60–85%), easily available and inexpensive starting materials, using water as a green solvent, and avoiding the handling of organic azides as they are generated in situ are the advantages of this method. Theoretical calculations were also conducted by the DFT method using the B3LYP functional and 6-31+G(d,p) basis set on structure to characterize structure 3a. For structural and electronic characterization, 1H and 13C chemical shifts were calculated by the computational method and interpreted. The DFT calculated data were in line with the experimental data. [ABSTRACT FROM AUTHOR]

[Display omitted] • Coumarins are a broad and well-studied class of compounds having 1-benzopyran-2-one motif. • Structuaral aspects and charge distribution better understood by computational approach. • Global molecular descriptors give better insight into charge bearing capacity. Fourteen pyranocoumarin (PC) molecules having cis and trans conformations are studied for charge distribution patterns with the help of computational study. To understand the structural characteristics of these molecules, global molecular descriptors, TD-DFT, and NLO studies are employed. On the basis of charge symmetry and MEP plots, it was predicted that trans PC would produce better outcomes. From the findings, it is evident that cis PC had less charge symmetry than trans PC. Although the electrophilicity index suggested the opposite pattern, the values for chemical potential, chemical hardness, and hyperhardness were higher for cis conformation than for trans conformation. Based on the data, it can be concluded that PC with a benzimidazole group exhibits higher intramolecular charge transfer in both its cis and trans forms. Compared to other pyranocoumarins, PC with no substituent clearly displayed weak inference. [ABSTRACT FROM AUTHOR]

Atomic radius plays a key role in the realm of science to understand atomic/molecular physico-chemical properties. Looking at the enormous potential this descriptor has, a model is proposed for absolute radius (r) in terms of electrophilicity index (ω). Atomic radii for 103 elements of the periodic table are reported. Considering the periodic relationship between absolute radius and atomic electrophilicity, this empirical model is proposed invoking regression analysis. The computed radii obey sine qua non of periodic properties. Relativistic effects are also distinct in the newly computed radii. On comparison, the computed data is noted to be in close conformity with the reported radii. Further, some size-dependent properties are calculated by employing the computed absolute radius. These present a substantial periodic behaviour and association with absolute radii. [ABSTRACT FROM AUTHOR]

Ground and excited-state proton transfer and electrical responsive properties along the proton transfer co-ordinate of four donor–acceptor substituted pyrazole derivatives have been investigated using the density function-based range separated hybrid GGA functional ωB97XD with 6-311G(d) basis. Both intrinsic reaction coordinate (IRC) and distinguished co-ordinate (variation of O–H distance of the enol tautomer) have been chosen as a proton transfer co-ordinate of the titled compounds for comparison. Our study reveals that the various electrical responsive parameters like average polarizability (αav), first hyperpolarizability (βav) and global reactivity descriptors e.g., chemical hardness (η), electrophilicity index (ω) along the proton transfer co-ordinate are in conformity with the respective optimum principles. Maximum value of βav is found in the case of nitro substituted pyrazole derivative. Variation of βav along the proton transfer co-ordinate for all compounds have been correlated with the variation of Δµf0/(S1-S0)3 using two-level approximation and electronic special extent () along the proton transfer coordinate. [ABSTRACT FROM AUTHOR]

Electrophilicity index is a well-known Conceptual Density Functional Theory–based reactivity descriptor to explain a wide range of physicochemical behaviours. In the present work, an attempt is made to evaluate a new electrophilicity index scale in terms of nucleophilicity index relying on Gordy's electronegativity scale. The computation is performed for 103 elements of the periodic table invoking regression analysis. The new set of electrophilicity index satisfies the sine qua non of a standard scale. Electrophilicity Equalization Principle is also validated by our computed data. It is put forward that the new scale will be useful in understanding various physicochemical properties and related phenomenon. [ABSTRACT FROM AUTHOR]

Present study deals with synthesis and optical characterizations of several yellow, orange and brown mono azo disperses dyes having built-in UV-absorber stabilizer. Disperse azo dyes have been prepared by the coupling of diazo salts solutions of different aromatic amines with 4-hydroxybenzophenone, 2, 4-dihydroxybenzophenone and 2-hydroxy-4-methoxy benzophenone. Synthesized dyes were well characterized by 1H NMR, 13C NMR, FTIR, Mass spectroscopy and elemental analysis. Dyeing assessments of all the dyes were evaluated on polyester and nylon fibers. Evaluation of UV-protection factor (UPF) of the dyed fabrics suggested that these dyes can be used to make UV-protective fabric. Sustainability of the dyed UV-protective textile substrate tartan using customized based on AATCC 186 method. Dyed fabrics showed very good light fastness and good to excellent washing, rubbing and perspiration fastness. DFT (density functional theory) is carried out to find electrophilicity index of prepared dyes. [ABSTRACT FROM AUTHOR]

Thioguanine is an anti-cancer drug used for the treatment of leukemia. However, thioguanine has weak aqueous solubility and low biocompatibility, which limits its performance in the treatment of cancer. In the present work, these inadequacies were targeted using density functional theory-based simulations. Three stable configurations were obtained for the adsorption of thioguanine molecules on the phosphorene surface, with adsorption energies in the range of −76.99 to −38.69 kJ/mol, indicating physisorption of the drug on the phosphorene surface. The calculated bandgap energies of the individual and combined geometries of phosphorene and thioguanine were 0.97 eV, 2.81 eV and 0.91 eV, respectively. Owing to the physisorption of the drug molecule on the phosphorene surface, the bandgap energy of the material had a direct impact on optical conductivity, which was significantly altered. All parameters that determine the potential ability for drug delivery were calculated, such as the dipole moment, chemical hardness, chemical softness, chemical potential, and electrophilicity index. The higher dipole moment (1.74 D) of the phosphorene–thioguanine complex reflects its higher biodegradability, with no adverse physiological effects.

This paper presented an effective way to select monomers to fabricate active layers for the thin-film composite (TFC) membrane at the molecular level. Five types of diamine monomers and six acid chloride monomers were firstly selected by a conformer search process. Then, the conceptual density functional theory (CDFT) method was adopted to examine the properties of these monomers. A few different molecular properties were calculated, including relative energy, hydrogen bond, global/local/difference local softness, hardness, chemical potential, and electrophilicity index. Similarly, polyamides that were the productions of interfacial polymerization reaction were also analyzed by CDFT. Our results showed that the mixture of trimesoyl chloride (TMC) and m-phenylenediamine (MPD) for the interfacial polymerization was ideal synthetic materials to fabricate the active layer of TFC membranes. [ABSTRACT FROM AUTHOR]

D-π-A chromophore derived coumarins are studied using "DFT and TD-DFT" to compute vertical excitation as well as NLO properties using "global hybrid" (GH) functionals B3LYP and BHandHLYP and "range separated hybrid" (RSH) functionals CAM B3LY', wB97, wB97X, and wB97XD with basis set 6–311++G(d,p) and "correlation consistence polarized valence double and triple zeta" cc-pVDZ and cc-pVTZ respectively in the gas phase and two solvents, N,N-Dimethylformamide (DMF) and ethyl acetate (EA). The trends in absorption and emission values calculated by TD-DFT using all the above mentioned functional and basis sets were studied and it was observed that the trends seen in the computed parameters using B3LYP, BHandHLYP and CAM B3LYP are in good agreement with the trends in experimental values. DFT calculations were performed to determine "static dipole moment" (μ), "linear polarizability" (α), "first order hyperpolarizability" (β0), "second order hyperpolarizability" (γ). We have calculated the mean average errors in dipole moment, linear polarizability, first and second hyperpolarizability and vertical excitation. We have observed large values of 'first order hyperpolarizability' (301–938 × 10^-30 e.s.u) and 'second order hyperpolarizability' (684–2498 × 10^-34) and they can act as good nonlinear optical materials. Also, vibrational contribution indicates the red shifted absorption and emission in 2c. They show higher values of electrophilicity index which indicates the stability and reactivity of molecules. [ABSTRACT FROM AUTHOR]

In the present study, for the first time 1-amide 4-sulfonamide-1,2,3-triazole scaffolds were synthesized by using an azide-alkyne Huisgen cycloaddition reaction. The target products were obtained in moderate to good yields (45–75%) by using catalytic CuI and green system H 2 O/EtOH. The easy availability of the inexpensive starting materials, avoiding isolation and handling of hazardous organic azides and mild reaction conditions make this method a valuable tool for generating functionalized 1,2,3-triazole derivatives. The unambiguous characterization of synthesized compounds was accomplished by using various spectroscopic techniques such as 1H NMR, 13C NMR, and FT-IR. The information regarding optimized geometry, were obtained by applying DFT/B3LYP-6-31G(d) method. The electrophilicity index, 1H and 13C chemical shift values, lithium and sodium ion affinities of the desired product 3b have been also calculated by the mentioned method. As a whole, the calculated results were found in close agreement to that of experimental data. The studies revealed that the compound 3b possesses good Li+ and Na+ affinity and cation π interaction plays a vital role in the complexation of 3b. For the first time, nucleus–independent chemical shift index was used to confirm the cation π interaction of 3b. Image 106 • The novel 1,2,3-triazole derivatives were synthesized in good yields. • To compute physicochemical properties of a product, DFT calculations were used. • NICS index was used to confirm the cation π interaction of 3b. [ABSTRACT FROM AUTHOR]

The prediction of the nature of a reactivity descriptor is of paramount importance to theoretical chemists and thus, much work has been carried out in this area. The electrophilicity index (ω), an important theoretical construct of chemistry, is a measure of the electron acceptor affinity to gain an additional electronic charge from the environment. It is quantified in terms of the maximum energy stabilization in species, which arises due to accepting a charge. The electrophilicity concept is being extensively used in modern chemistry, although the finest measurement scale of the electrophilicity index is yet to be designed. In this study, a new scale of the electrophilicity index invoking the force concept based on the effective nuclear charge (Zeff) and absolute atomic radii (r) is proposed for 97 elements of the periodic table, which is determined through the regression analysis. The computed data follows the periodicity very well satisfying the sine qua non of the standard scale of the electrophilicity index. The electrophilicity equalization principle is also established in terms of the computed data. To test the model in the real field, the internuclear bond distance of some molecules is calculated in terms of the computed electrophilicity index. A comparative study of the theoretical vis-à-vis experimental internuclear bond distance reveals the efficacy of the proposed scale. [ABSTRACT FROM AUTHOR]

Improving biodegradation of pharmaceuticals during wastewater treatment is critical to control the release of emerging micropollutants to natural waters. In this study, biodegradation of six model pharmaceuticals was investigated at different initial concentrations in two discrete activated sludge systems, and moreover, the correlation was explored between the biodegradation rate and key molecular properties of the contaminants. First, the biodegradation rates of the pharmaceuticals were measured fitting a pseudo first−order kinetic model to the experimental kinetic data. The degradation rate constants (k bio) were found to negatively correlate to the initial concentration of the chemicals, indicating an inhibitory effect on the microorganisms by the pharmaceuticals. Further examinations of the rate data against the key molecular properties of the pharmaceuticals revealed, for the first time, that the electrophilicity index (ω), a measure of electrophilic power, served as a better indicator of the biodegradability and predictive parameter for the k bio than the conventional log K OW (a measure of hydrophobicity) in the two discrete aerobic activated sludge systems. However, the correlation strength (goodness‒of‒fit) between ω and k bio deteriorated when the reactor turned from aerobic to anoxic and anaerobic conditions, suggesting that electron transfer from pharmaceutical molecules to enzymes was inhibited when dissolved oxygen was deficit or absent. Our results show that ω can potentially serve as a straightforward and robust indicator for predicting the biodegradability of pharmaceutical in conventional activated sludge processes. Image 1 • Biodegradation of six pharmaceuticals were studied in different activated sludges. • Biodegradation rates (k bio) were negatively related to initial concentrations. • Electrophilicity (ω) was a better indicator than log K OW for predicting k bio. • Predictability of ω for k bio reduces from aerobic to anoxic to anaerobic sludges. [ABSTRACT FROM AUTHOR]

Abstract In this work, the complete structural and vibrational analysis of the bis[4-(3,3-dimethylbut-1-ynyl)-pyrazol-1-yl]methane ligand (L 1) and [ (L 1)PdCl 2 ] complex were carried out by density functional theory (DFT/B3LYP and WB97XD) methods with DGDZVP basis set. Then X-ray crystallography were used to examine the structure of [ (L 1)PdCl 2 ]. The 1H and 13C NMR spectra were computed by using the gauge-invariant atomic orbital (GIAO) method, showing a good agreement with the experimental ones. The calculated vibrational frequencies and chemical shift values were compared with experimental FT-IR and NMR values. The last one UV–vis absorption spectra were analyzed in the presence of three solvent (H 2 O, CCl 4 and C 6 H 5 Cl), saved in the range of 200–400 nm. The hyper-conjugative interaction energy and electron densities of donor and acceptor bonds were calculated using natural bond orbital (NBO) analysis. In addition, frontier molecular orbitals analysis, Non-Linear optical (NLO) activity, electro negativity, ionization energy, global hardness, global softness, and the energy gap between the highest occupied molecular orbital (HOMO) to the Lowest unoccupied molecular orbital (LUMO) were calculated. Graphical abstract Image 1 Highlights • Examining the molecular and spectroscopy structure of complex and ligand. • Analysis of X-ray crystallography, FT IR, NMR, UV‒vis spectra. • Electron transfer was investigated between the atoms which were electron donor and electron acceptor. • Determination of HOMO and LUMO and calculation of energy gap between their orbital levels. • Investigating the effect of different solvents in the analysis of the spectra of UV‒vis, and NMR. [ABSTRACT FROM AUTHOR]

A series of five azo acid dyes were synthesized using different diazotized aromatic amine sulfonic and carboxylic acids followed by coupling with 2H-pyrido[1,2-a]pyrimidine-2,4(3H)-dione. The dyes were characterized by 1H-NMR, 13CNMR, FTIR, and elemental analysis. They were applied on nylon, silk, and wool. Their fastness properties were evaluated and color on the fabric was assessed. Yellow, brown, and crimson dyeings with good fastness properties were obtained. The dyes are water soluble and showed absorption from 380 nm to 550 nm. Acid dyes from diazo component 4- aminonaphthalene-1-sulfonic acid (naphthionic acid) and 4-amino-5-hydroxynaphthalene-2,7-disulfonic acid (H-Acid) were found to be more red shifted as compared to the other dyes. More red shifted absorption maximum was observed in acidic pH than in alkaline pH. The trends in vertical excitations obtained from Time Dependent Density Functional Theory calculations are in good agreement with the experimental absorptions. [ABSTRACT FROM AUTHOR]

Understanding removal mechanisms of emerging organic contaminants in conventional activated sludge systems is of fundamental and engineering importance. In this study, we selected six environmentally relevant pharmaceuticals as target organic contaminants, namely, metronidazole (MTZ), bezafibrate (BZF), ibuprofen (IBP), sulfamethoxazole (SMX), carbamazepine (CBZ), and ciprofloxacin (CIP) for the mechanistic investigation for their removal. We demonstrated that sorption and biodegradation were the dominant pathways for contaminant removal, while volatilization and hydrolysis were negligible. The sorption removal process varied for the selected pharmaceuticals in the batch system. Then, first-order rate model was used to fit the biodegradation kinetics, and their first-order rate constants ( k bio ) were ranged from 3.67 × 10 −3 to 10.2 L g −1  d −1 , in order of CBZ < CIP < SMX < MTZ < BZF < IBP. In order to elucidate the biodegradation mechanism, we calculated a total of twelve geometrical, electrostatic, and quantum chemical descriptors with density functional theory (DFT) approach. Then, correlation analysis was conducted to investigate k bio with these theoretical descriptors. Our results indicate that electrophilicity index ( ω ), a measure of electrophilic power, influences the biodegradation kinetics to the greatest extent. The ω corresponds to the process where the pharmaceutical molecule acts as an electrophile, adding electron density from a nucleophile. The combined experimental and theoretical results provide insight into the intrinsic nature of biodegradation of organic contaminants of emerging concern during conventional activated sludge treatment. [ABSTRACT FROM AUTHOR]

A practically reliable procedure for synthesis of new 1,5-bis( N -substituted 1,2,3‒triazole) benzodiazepinedione derivatives was reported by sequential amidation, propargylation and a click azide‒alkyne [3 + 2] cycloaddition reaction in a one pot fashion. The desired products were characterized by CHN analysis, 1 H and 13 C NMR and ESI-MS spectroscopy. Short reaction time, good yields (55–91%), mild reaction conditions and easily available and less expensive starting materials are advantages of this protocol. Natural bond orbital charge distribution and HOMO-LUMO analysis of the characterized structure of 4e have been also calculated by density functional theory (DFT) calculations. The Li + and Na + ion affinities of 4e have been also investigated by DFT studies to find the applicability of these products as ligand in coordination chemistry. Sodium ion affinity of 4e was determined as 60 kJ mol −1 is less than its lithium ion affinity, indicating that the lithiation of 4e is more exothermic than the sodiation. [ABSTRACT FROM AUTHOR]

The electronic and optoelectronic properties of [A.2AP(w)/A .2AP(WC)/C.2AP(w)/C .2AP(WC)/C.A(w)/ C .A(WC)]–Au8metal-mismatch nucleobase complexes are investigated by means of density functional theory and time-dependent methods. We selected these mispairs as 2-aminopurine (2AP) produces incorporation errors when binding with cytosine (C) into the wobble (w) C·2AP(w) mispair, and is tautomerised into Watson–Crick (WC)-like base mispair C ·2AP(WC) and less effectively produces A.2AP(w)/A .2AP(WC) mispairs. The vertical ionisation potential, vertical electron affinity, hardness and electrophilicity index of these complexes have also been discussed. The modifications of energy levels and charge density distributions of the frontier orbitals are also analysed. The absorption spectra of these complexes lie in the visible region, which suggests their application in fluorescent-bio imaging. The mechanism of cooperativity effect is studied by molecular orbital potential (MEP), atoms-in-molecules (AIM) and natural bond orbital analyses. Most metalated pairs have smaller HOMO–LUMO band gaps than the isolated mismatch nucleobases which suggest interesting consequences for electron transfer through DNA duplexes. [ABSTRACT FROM AUTHOR]

Organic solar cells, especially bulk hetero-junction polymer solar cells (PSCs), are the most successful structures for applications in renewable energy. The dramatic improvement in the performance of PSCs has increased demand for new conjugated polymer donors and fullerene derivative acceptors. In the present study, quantum chemical calculations were performed for several representative fullerene derivatives in order to determine their frontier orbital energy levels and electronic structures, thereby helping to enhance their performance in PSC devices. We found correlations between the theoretical lowest unoccupied molecular orbital levels and electrophilicity index of various fullerenes with the experimental open circuit voltage of photovoltaic devices according to the poly(3-hexylthiophene) (P3HT):fullerene blend. The correlations between the structure and descriptors may facilitate screening of the best fullerene acceptor for the P3HT donor. Thus, we considered fullerenes with new functional groups and we predicted the output factors for the corresponding P3HT:fullerene blend devices. The results showed that fullerene derivatives based on thieno- o -quinodimethane-C 60 with a methoxy group will have enhanced photovoltaic properties. Our results may facilitate the design of new fullerenes and the development of favorable acceptors for use in photovoltaic applications. [ABSTRACT FROM AUTHOR]

Quantitative Structure–Activity Relationship (QSAR) models are useful in understanding how chemical structure relates to the biological activity and the toxicity of natural and synthetic chemicals. The present study shows that Parr’s electrophilicity index ω in combination of two other descriptors, namely, the LUMO energy and the hydrophobicity index logP, prove their utility for the prediction of the toxicity of a series constituted by 50 nitrobenzene derivatives. The QSAR models are developed using the Multiple Linear Regression (MLR) method. It turns out that the best model, which its stability is confirmed using the leave-1/3-of-set-out validation, is able to describe about 87% of the variance of the experimental toxicity. The satisfactory obtained results show that Parr’s electrophilicity index is a useful quantum chemical descriptor for the toxicity modeling of nitrobenzene derivatives. Finally, the elaborated model shows that the most toxic nitrobenzenes are characterized by large hydrophobicities and high electrophilicity powers and could be efficiently applied for the estimation of the toxicity of nitrobenzenes for which the experimental measures are unavailable.

A green, and practically reliable method for the synthesis of novel 1,2,3‒triazole-based sulfonamides via copper (I)‒catalyzed azide‒alkyne [3 + 2] cycloaddition reaction was reported. The desired products were characterized by CHN analysis, FT-IR, 1 H and 13 C NMR, ESI-MS spectroscopy, single crystal X-ray diffraction and density functional theory (DFT) geometry optimization and molecular orbital calculations. Mild and green reaction conditions, atom-economic and high yields (61–91%) make this protocol an attractive option for the synthesis of 1,2,3‒triazoles bearing sulfonamide moiety. Geometrical structures, vibrational frequencies, 1 H and 13 C chemical shift values, Mulliken charge distribution and electrophilicity index (HOMO-LUMO analysis) of the characterized structure of 3f in the ground state have been calculated with the aid of DFT studies. The calculated chemical shifts (NMR) and vibrational frequencies (FT-IR) are in compliance with the experimental findings. The aim of the DFT study was to make a reasonable assignment of vibrational bands and chemical shifts. [ABSTRACT FROM AUTHOR]

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The density functional theory (DFT) based a unique model has been developed to predict the toxicity of ionic liquids using structural-feature based quantum chemical reactivity descriptors. Electrophilic indices (ω), the energy of highest occupied (E HOMO ) and lowest unoccupied molecular orbital, (E LUMO ) and energy gap (∆ E) were selected as the best toxicity descriptors of ILs via Pearson correlation and multiple linear regression analyses. The principle components analysis (PCA) demonstrated the distribution and inter-relation of descriptors of the model. A multiple linear regression (MLR) analysis on selected descriptors derived the model equation for toxicity prediction of ionic liquids. The model predicted toxicity values and mechanism are very consistent with observed toxicity. Cationic and side chains length effect are pronounced to the toxicity of ILs. The model will provide an economic screening method to predict the toxicity of a wide range of ionic liquids and their toxicity mechanism. [ABSTRACT FROM AUTHOR]

The relationship between the electrophilicity ω index and the Hammett constant σp has been studied for the [2+3] cycloaddition reactions of a series of para-substituted phenyl azides towards para-substituted phenyl alkynes. The electrophilicity ω index--a reactivity density functional theory (DFT) descriptor evaluated at the ground state of the molecules--shows a good linear relationship with the Hammett substituent constants σp. The theoretical scale of reactivity correctly explains the electrophilic activation/deactivation effects promoted by electron-withdrawing and electron-releasing substituents in both azide and alkyne components. [ABSTRACT FROM AUTHOR]

Density functional theory was used to investigate the global and local reactivity of some cis-platinum(II) complexes including anticancer drugs, such as cisplatin and carboplatin. Calculated equilibrium geometries at mPW1PW/LANL2DZ* are in close agreement with their available X-ray data. We develop three new local reactivity descriptors: atomic descriptor of philicity, atomic descriptor group and atomic descriptor of philicity group for determining chemical reactivity and selectivity of the studied complexes. This contribution on chemical reactivity allow us to establish qualitative trends, which enable our descriptors for use in rational platinum based anticancer drug design.

Electrophilicity is an intrinsic property of atoms and molecules. It probably originates logistically with the involvement in the physical process of electrostatics of soaked charge in electronic shells and the screened nuclear charge of atoms. Motivated by the existing view of conceptual density functional theory that similar to electronegativity and hardness equalization, there should be a physical process of equalization of electrophilicity during the chemical process of formation of hetero nuclear molecules, we have developed a new theoretical scheme and formula for evaluating the electrophilicity of hetero nuclear molecules. A comparative study with available bench marking reveals that the hypothesis of electrophilicity and equalization, and the present method of evaluating equalized electrophilicity, are scientifically promising.

In the present study, the density functional theory method with various basis sets for optimizing and computing the structural and energetic properties of octasilacubane were performed at 298.15 K and 1 atmosphere. The data from the calculations on this compound show us the internal angles in the structure are 90 degrees. For this reason, the molecule has serious angular pressure. This angular strain is tolerated by a higher percentage of p-orbitals of silicon atoms in the Si-Si σ-bonds formation. According to calculation, σ bonds in the octasilacubane system are formed from an sp d hybrid. Also, IR and NMR spectra of the structure were simulated. The electronic chemical potential, the hardness and electrophilicity power of the molecule were obtained from frontier orbitals energies. The data show the structure has low electrophilicity. Heats of formation and detonation parameters were then calculated at studied levels of B3LYP (Becke, 3 parameter, Lee-Yang-Parr) theory. The simulation results revealed that this compound because for its high molecular weight is not a viable candidate of high energy density materials (HEDMs). [ABSTRACT FROM AUTHOR]

Theoretical descriptions of the molecular nonlinear optical properties of triphenyl borazine (TPB) derivatives are presented by using DFT level theory on employing CAM-B3LYP functional. Based on computational calculation the extent of nonlinear response was account in terms of dipole moment, polarizability ( α ), the first hyperpolarizability ( β ) and the second hyperpolarizability ( γ ) values. The nonlinear optical response of TPB derivatives containing non-metal donor groups display linear relation with increased electron density. The calculated bond length alternation values decrease with increase in the electron density due to electron donating groups, indicating improvement in degree of conjugation. In case of TPB derivatives containing metal donor complexes the NLO properties increases with increase in dipole moment. We have observed that the tensor component along the bond X -axis of all the derivatives dominate the second order hyperpolarizabilities as compared to other components. The developed correlation shows clear dependence of hyperpolarizabilities on highest occupied molecular orbital and electrophilicity of the derivatives. Using time-dependent density functional theory, we investigated the excited-state properties of a series of TPB derivatives. On evaluating two-level model equation we have observed that hyperpolarizability of TPB have contribution both from change in dipole moment and transition dipole moment. Thus, these theoretical calculations predict the possible role of TPB derivatives as nonlinear material for optical devices. [ABSTRACT FROM AUTHOR]

VX and its six other isomers which are potentially nerve agents with molecular weight of 267 were synthesized and their EI and CI MS spectra were studied. Although the major ions in the mass spectra for these isomers are similar, these chemicals could be distinguished based on some low abundance characteristic ions. Structures of fragments were assigned using EI-MS analysis of the deuterated analogs. Density functional theory was also applied to show preferred fragmentation pathways. This study is also focused on calculation of the electrophilicity index of VX and its structural isomers, in order to elucidate their reactive nature. [ABSTRACT FROM AUTHOR]

Due to its large scale applications in the real field, the study of bi-metallic nano-alloy clusters is an active field of research. Though a number of experimental reports are available in this domain, a deep theoretical insight is yet to receive. Among several nano-clusters, the compound formed between Cu-Ag has gained a large importance due to its remarkable optical property. Density Functional Theory (DFT) is one of the most popular approaches of quantum mechanics to study the electronic properties of materials. Conceptually, DFT based descriptors have turned to be indispensable tools for analyzing and correlating the experimental properties of compounds. In this venture, we have analyzed the experimental properties of the (Cu-Ag)n = 1 - 7 nano-alloy clusters invoking DFT methodology. A nice correlation has been found between optical properties of the aforesaid nano-clusters with our evaluated theoretical descriptors. The similar agreement between experimental bond length and computed data is also reflected in this analysis. Beside these, the effect of even-odd alternation behavior of nano compounds on the HOMO-LUMO gap is very important in our computation. It is probably the first attempt to establish such type of correlation. [ABSTRACT FROM AUTHOR]

The structure of all of Lewisite's stereoisomers has been examined by B3LYP/6–311++G(3df,3pd) calculations. The geometry analysis for trans Lewisite L 1–1 shows that the calculated bond angles, bond distances and dipole moment have a satisfactory relation compared with experimental values. HOMO-LUMO analysis of Lewisites reveals that L 1–2 and L 3–7 have the maximum and minimum electrophilicity index, respectively. The calculated chemical shifts were compared with experimental data, showing a very good agreement both for 1 H and 13 C. The vibrational and Raman frequencies of Lewisites have been precisely assigned and theoretical data were compared with the experimental vibrations. The bonding trends and Mulliken and atomic polar tensor charge distribution in Lewisites can be explained by the Bent's rule and the donor–acceptor interaction, respectively. [ABSTRACT FROM AUTHOR]

The structural isomers of cations of xenon trifluoroborazine complexes were investigated by B3LYP method of density functional theory. The aug-cc-PVTZ basis set was applied to H, B, N, and F atoms, and Def2-PVTZ to Xe atom. The DFT results showed that all Xe complexes of trifluoroborazines correspond to real minima in potential energy surface. The calculations also demonstrated the ZPE correction is fairly important to the total electronic energy of Xe complexes. The natural bonding analysis of donor–acceptor interactions indicated remarkably powerful interactions. All donor natural orbitals were core orbitals of Xe atom, and acceptor natural orbitals were post-valence, unoccupied valence, and π* natural orbitals of atoms/bonds of trifluoroborazine. The DFT calculated global reactivity indexes verified xenon trifluoroborazine complexes more electronegative structures with softer nature, and with considerably more electrophilic characteristics than the corresponding trifluoroborazines. [ABSTRACT FROM AUTHOR]