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[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] • 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]

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]

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]

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]

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]

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]

Highlights: [•] Use of polarizability, hardness, electrophilicity as global descriptors for IPT process. [•] Use of IRC as proton transfer co-ordinate supports MPP and MHP principles. [•] Use of O–H distance as PT co-ordinate cannot explain MPP and MHP principle. [•] IRC is the better choice for PT co-ordinate than O–H distance of enol tautomer. [ABSTRACT FROM AUTHOR]

Two oxadiazole derivatives namely 2,5-bis(4-methylphenyl)-1,3,4-oxadiazole (Inh-1) and 2,5-bis(4-methoxyphenyl)-1,3,4-oxadiazole (Inh-II) were investigated as corrosion inhibitors for mild steel using density functional theory (DFT) at B3LYP/6-31G(d,p) level. Quantum chemical parameters most relevant to their potential action as corrosion inhibitors such as EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), the energy gap(ΔE), hardness (η), Softness(S), dipole moment(μ), electron affinity(A), ionization potential(I), the absolute electronegativity (χ), the fraction of electron transferred (ΔN), electrophilicity index(ω) and the back-donation(ΔE Back-donation) have been calculated and discussed. The local reactivity has been analysed through the Fukui and condensed softness indices inorder to predict both the reactive centres and to know the possible sites of nucleophilic and electrophilic attacks. The theoretical conclusions were found to be consistent with the experimental data reported. [ABSTRACT FROM AUTHOR]

Endohedral derivatives of BN nanocage (M@BN, M = Li, Na, K, Mg, Ne, O, S, F, Cl) and its iso-electronic fullerne M@C have been employed to investigate the relation between the trapped atom/ion and electrophilicity of the BN and C nanocages. The electrophilicity index, ω, of these endohedral nanocages has been evaluated from the ionization potential and the electron affinity computed by vertical ionization/affinity at the B3LYP/6-311++G(df,pd) level. Obtained results illustrate that the nature of trapped atom/ion affects HOMO-LUMO band gap, global electrophilicity indices and reactivity of BN and C nanocages. Encapsulation BN with different atom/ions may be a possible method for modifying HOMO-LUMO energy gap, electrophilicity and so chemical characteristics of and C nanocages. [ABSTRACT FROM AUTHOR]

In this present paper, we have made an attempt to explain the adsorption mechanism and inhibition performance of two triazole derivatives, ie., 4-(benzylideneamino)-3-propyl-5-mercapto-1,2,4-triazole(BIPMT) and 4-(salicylidene amino)-3-propyl-5-mercapto-1,2,4-triazole (SIPMT), on mild steel using density functional theory (DFT) at the B3LYP/6-31G(d,p) level. Quantum chemical parameters such as EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), the energy gap(?E), hardness(?), Softness(S), dipole moment(µ), electron affinity(EA), ionization potential(IE), the absolute electronegativity (?), the fraction of electron transferred (?N), electrophilicity index(?) and the back-donation (?E Back-donation) have been calculated. The local reactivity has been studied through the Fukui and condensed softness indices in order to predict both the reactive centres and to know the possible sites of nucleophilic and electrophilic attacks. The obtained correlations and theoretical conclusions agree well with the experimental data. [ABSTRACT FROM AUTHOR]

The corrosion inhibition characteristics of two vinyl imidazole derivatives, ie., 2,4,5-triphenyl-1-vinyl-1H-imidazole (C1) and 2-(4-methoxyphenyl)-4,5-diphenyl-1-vinyl-1H-imidazole(C2), on mild steel has been studied using Density functional theory (DFT).Quantum chemical parameters such as EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), the energy gap(ΔE), hardness(η), Softness(S), dipole moment(μ), electron affinity(EA), ionization potential(IE), the absolute electronegativity (χ), electrophilicity index(μ) and the fraction of electron transferred (ΔN) have been calculated using B3LYP/6-31G(d,p) basis set. The local reactivity has been studied through the Fukui and condensed softness indices in order to predict both the reactive centres and to know the possible sites of nucleophilic and electrophilic attacks. The obtained correlations and theoretical conclusions agree well with the experimental data. [ABSTRACT FROM AUTHOR]