B3LYP Level Of Theory Research Articles

Synthesis, spectroscopic characterizations, enzyme inhibition, molecular docking study and DFT calculations of new Schiff bases of sulfa drugs

New Schiff bases were synthesized (Z)-4-((4-(diethylamino)benzylidene)amino)-N-(3,4-dimethylisoxazol-5-yl)benzenesulfonamide (L1) and (Z)-4-((4-(dimethylamino)benzylidene) amino)-N-(5-methylisoxazol-3-yl)benzenesulfonamide (L2) derived from sulfamethoxazole (S1)/sulfisoxazole (S2) and substituted salicylaldehyde. The synthesized compounds were characterized by FT-IR, 1H-13C NMR, LC-MS. We evaluated the effects of compounds on eight enzyme activities by spectrophotometric assays at final concentrations of 0.5–5 μg. L1 acted as an inhibitor on cholesterol esterase, tyrosinase and α-amylase activities with IC50 values 38, 38 and 173 μM. Tyrosinase, α-glucosidase, cholesterol esterase, and α-amylase enzymes were inhibited by L2 with IC50 values 24, 46, 63, and 231 μM. To comprehend the binding interactions between the inhibitors and enzymes with low IC50 values, molecular docking studies of compounds were performed for cholesterol esterase and tyrosinase. Finally, molecular docking was performed to determine the probable binding mode of the designed compounds into the active site of enzymes. DFT calculations were carried out at the B3LYP levels of theory with 6-311G ++ (d, p) basis set for compounds.

Computational study of the C[sbnd]I bimetallic oxidative addition at Pt[sbnd]M (M = Ni, Pd and Pt) reaction centers

Three bimetallic complexes of the type [Me2Pt(μ-bipym)MMe2] (M = Ni, Pd, Pt) in which bipym = 2,2′-bipyrimidine, with a systematic variation in the metals, are chosen to investigate CI bond activation of MeI through SN2-type oxidative addition reactions by using the B3LYP levels of theory. The non-identical dual-core complexes (when M = Pd and Ni) containing two potential nucleophilic centers are theoretically studied to elucidate which center (M or Pt) is the stronger nucleophile toward MeI. The reasons for these two pathways (first attack on Pt, path A, or first attack on M, path B) are discussed based on the energy barrier needed for path A versus path B. On the basis of DFT calculations, in the reaction of complexes Pt–Ni and Pt–Pd with MeI, it is found that these complexes react through Pt(II) at the first step, following by M(II) attacking on carbon atom of MeI to give final Pt(IV)–M(IV) complexes. Also complex [Me2Pt(μ-bipym)NiMe2] is predicted reacting with MeI faster than the others with a lower free energy barrier. Qualitative frontier molecular orbitals for the complexes, energies and main compositions of the relevant frontier orbitals of complexes are also studied.

A DFT study on N-6-amino-hexylamide functionalized single-walled carbon nanotubes in interaction with silver ion in a gaseous environment

In this study, quantum mechanical calculations, such as density functional theory (DFT), have been employed to determine the active positions of nanosensor and thermodynamics functions of interaction between Ag+ and nanosensor have been calculated. HOMO and LUMO energies and energy difference between donor atoms (i) and acceptor atoms (j) have been evaluated. In addition, the effect of the number of substitution agents on the reactivity of the functional carbon nanotubes and the charge on the interacting atoms and Ag+ before and after interaction have been investigated. The geometry optimization and theoretical calculations have been carried out using B3LYP level of theory. Results show that the interaction of Ag+ with nanosensor is in terms of thermodynamically possible. The negative values of ΔG° denote a spontaneous reaction and the negative values of ΔH° represent an exothermic reaction. In addition, the nanosensor has two active positions and the product obtained through the interaction between Ag+ and oxygen of the carbonyl group is the most stable state. The interaction of Ag+ with the nanosensor is accompanied by a reduction in the energy gap (Eg) which increases the stability of the complex, causes indicating that a charge transfer occurred between the nanosensor and Ag+.

Conformations of diethyl ether and its interaction with pyrrole at low temperatures.

Conformations of diethyl ether (DEE) were studied at low temperatures in N2 and Ar matrixes. Computations performed at B3LYP/aug-cc-pVDZ level of theory yielded three minima corresponding to tt, tg± and g±g± conformers of DEE. Of the three, the tt and tg± conformers of DEE were experimentally identified in N2 and Ar matrixes. Furthermore, hydrogen bonded complexes of pyrrole (py) with DEE have been investigated using Density Functional Theory (DFT) and matrix isolation infrared spectroscopy. Computations performed at B3LYP level of theory using aug-cc-pVDZ basis set on pyrrole with tt and tg± conformers of DEE gave py-DEE-tt and py-DEE-tg± complexes, both characterized by NH⋯O interaction. Experimental evidence for the formation of py-DEE-tt and py-DEE-tg± complexes was affirmed from the shifts in the NH stretching, NH bending regions of pyrrole and COC and CH stretching regions of DEE. NBO analysis was carried out to understand the charge-transfer delocalization interactions in the conformers of DEE and its hydrogen bonded complexes.

Energetic vs structural study of two biomass degradation derivatives: 2-Cyclopentenone and 3-methyl-2-cyclopentenone

The standard molar enthalpies of formation in the gaseous state, at T = 298.15 K, of the 2-cyclopentenone and 3-methyl-2-cyclopentenone were derived from their standard molar energies of combustion and from their standard molar enthalpies of vaporization, obtained from static-bomb combustion calorimetry measurements and high-temperature Calvet microcalorimetry, respectively. The enthalpies of hydrogenation of the two cyclopentenones were derived from their gas-phase enthalpies of formation and the gas-phase enthalpies of formation of the corresponding cycloalkanones. The gas-phase standard molar enthalpy of formation of the compounds studied were also obtained using high level ab initio calculations and are in very good agreement with the experimental ones. In addition, thermochemical parameters associated to 2-cyclopentenone and 3-methyl-2-cyclopentenone transformations were investigated using the G3(MP2)//B3LYP level of theory. The conversions of both compounds to longer chain alkanes were found to be thermodynamically favourable.

Photolysis of PCl3/POCl3 with Oxygen Dopant Using 193 nm ArF Excimer at Low Temperatures: Oxygen Insertion through ‘Phosphadioxirane’ Pathway

AbstractPhotolysis was performed on PCl3 and POCl3 in the presence of oxygen dopant in Ar matrix at low temperatures using 193 nm ArF excimer laser. The photo irradiation initially facilitated the formation of ozone in situ in the low temperature matrix. For PCl3+O2 photolysis with 193 nm ArF excimer, initially POCl3 was produced and subsequent oxygen atom insertion on POCl3 generated PO2Cl3. Furthermore, secondary reaction channel opens up in PCl3+O2 photolysis to form a variety of photoproducts such as POCl, PIIIO2Cl, PVO2Cl and PO3Cl. The insertion of oxygen atom on POCl through phosphadioxirane intermediate generated PIIIO2Cl and the direct oxygen atom addition resulted in PVO2Cl. A successive oxygen insertion on PVO2Cl triggered the PO3Cl generation. The identification of all the photoproducts was confirmed through 18O2 isotopic experiments and quantum chemical computations performed using density functional theory (DFT). Computations carried out at B3LYP level of theory with 6–311++G(d,p) basis set were used to correlate the structure of photo products obtained experimentally. Interestingly, photo irradiation of POCl3 with oxygen dopant in Ar matrix @193 nm ArF excimer resulted in the generation of PO2Cl3, PO3Cl3 and PO4Cl3 photo products by a sequential insertion of oxygen atoms through phosphadioxirane intermediate. A compelling evidence for the passage of the reaction through phosphadioxirane intermediate is established through 18O2 isotopic substitution experiments.

Toward of Safer Phenylbutazone Derivatives by Exploration of Toxicity Mechanism.

A drug design for safer phenylbutazone was been explored by reactivity and docking studies involving single electron transfer mechanism, as well as toxicological predictions. Several approaches about its structural properties were performed through quantum chemistry calculations at the B3LYP level of theory, together with the 6-31+G(d,p) basis sets. Molecular orbital and ionization potential were associated to electron donation capacity. The spin densities contribution showed a preferential hydroxylation at the para-positions of phenyl ring when compared to other positions. In addition, on electron abstractions the aromatic hydroxylation has more impact than alkyl hydroxylation. Docking studies indicate that six structures 1, 7, 8 and 13–15 have potential for inhibiting human as well as murine COX-2, due to regions showing similar intermolecular interactions to the observed for the control compounds (indomethacin and refecoxib). Toxicity can be related to aromatic hydroxylation. In accordance to our calculations, the derivatives here proposed are potentially more active as well safer than phenylbutazone and only structures 8 and 13–15 were the most promising. Such results can explain the biological properties of phenylbutazone and support the design of potentially safer candidates.

Quantum Chemical Studies on the Molecular Structure and Electronic Properties of Rhenium Metal Complexes

HOMO and LUMO energies and thermodynamics of Rhenium metal complexes have been evaluated based on Density Functional Theory (DFT) at B3LYP level of theory at SDD biases set in the Gaussian program.. The electron charge density allowed to find out different molecular properties such us the electrostatic potential and the dipole moment, which were finally subject to a comparison leading to a good match obtained between studied molecules. The optimized structures, total energies, electronic states (HOMO-LUMO), energy gap, and dipole moment were measured.

Ligand- and structure-based virtual screening from 16-((diisobutylamino)methyl)-6α-hydroxyivouacapane-7β,17β-lactone a compound with potential anti-prostate cancer activity

Prostate cancer is one of the leading causes of disease and death on the planet. The probable bioactive pose of 16-((diisobutylamino)methyl)- -6?-hydroxyvouacapane-7?,17?-lactone (N,N-DHL), a pivot compound with prostatic anti-cancer activity, was investigated via a semi-empirical method (PM3) and refined with the base set 6-31+G(d,p) calculated in the DFT method at the B3LYP level of theory. This structure was used in ligand-based virtual screening for five commercial compound bases using the software ROCS and EON that selected 2000 per base and another that resulted in 100 per base, respectively. This set was used for pharmacokinetic and toxicological predictions. The molecular overlap index at 50 % steric/electrostatic provided 68 structures that were used for a molecular docking study. The results showed that of 238,922 structures, only eight, 7 (?10.9 kcal mol-1) as the best in the series and 1 (?8.1 kcal mol-1) as less favorable, with others in this range (?2.8 kcal mol-1) with their respective binding affinity: 8 (?8.2 kcal mol-1), 5 (?8.2 kcal mol-1), 4 (?8.3 kcal mol-1), 2 (?8.5 kcal mol-1), 3 (?8.6 kcal mol-1) and 6 (?8.8 kcal mol-1) remaining in the final selection. The predictions for 21 pharmacokinetic properties were within the recommended range, similar to 95 % of the drugs available on the market, with no toxicity warning. The structures showed similarity greater than 75 % to the pivot based on binding affinity and predictions but only the structures 6 and 7 were considered more promising for their potential anti-prostate cancer activity (PC-3).

First principles investigations of vibrational properties of titania and zirconia clusters

Clusters are considered as ultrafine particles at microscopic scale and present the distinctive chemical and physical characteristics. In this paper, we described the structural and vibrational characteristics of titania and zirconia clusters calculated using density functional theory. The investigated clusters include monomers TiO2 and ZrO2, dimmers Ti2O4 and Zr2O4; and the hybrid TiZrO4 clusters. The hybrid cluster was prepared from two routes: first from titania and second from zirconia as starting material. The hybrid clusters are structural isomers of the same cluster and are named as trans − TiZrO4 and cis − TiZrO4, respectively. The geometries of the clusters were optimized at B3LYP level of theory and the structural properties including bond length, bond angle, and dipole moment, and Hirshfeld charges were studied. The vibrational properties of the clusters were predicted by calculating the Raman and infrared spectra. In case of monomers, the results indicated the presence of 3 Raman and 3 IR active modes. Whereas for dimmers, 12 modes of vibration were found which were simultaneously Raman and IR active. The hybrid clusters exhibited 12 Raman and IR active modes which are described in details. The formation of the trans − TiZrO4 is energetically cheaper than that of cis − TiZrO4 by an amount of 0.25 eV. The various parameters such as intensities, linear depolarization factors, and vibrations in route for preparation of the hybrid clusters are discussed. The studied Raman and IR properties shed light on the characteristics of the clusters which will be helpful to explore the applications of the materials. The calculated thermodynamic properties of the clusters are also given and discussed in detail.

Experimental and theoretical investigations of infrared multiple photon dissociation spectra of lysine complexes with Zn2+ and Cd2.

The gas-phase structures of zinc and cadmium complexes of lysine (Lys) are investigated via a combination of infrared multiple photon dissociation action spectroscopy and ab initio quantum chemical calculations. In order to unambiguously identify the experimentally observed species, [Zn(Lys-H)]+ and CdCl+(Lys), the action spectra were compared to linear absorption spectra calculated at the B3LYP level of theory, using 6-311+G(d,p) and def2-TVZP basis sets for the zinc and cadmium systems, respectively. Single point energies were also calculated at the B3LYP, B3P86, MP2, and B3LYP-GD3BJ (accounting for empirical dispersion) levels of theory using larger basis sets. Identification of the experimentally formed isomers is possible through good agreement between infrared multiple photon dissociation action spectra and the theoretically predicted spectra. The [Zn(Lys-H)]+ complex adopts a tridentate orientation involving the amino acid backbone amine and deprotonated carboxylic acid groups as well as the side-chain amine group, [Nα,CO-,Nɛ]. The CdCl+(Lys) complex similarly adopts a tridentate chelation involving the amino acid backbone amine and carbonyl groups, as well as the side-chain amine group, [Nα,CO,Nɛ]. In both cases, the identified complexes are the lowest energy gas-phase structures at all levels of theory.

Fourier transform infrared spectroscopy of 13C2D4 in the 2000–4800 cm−1 region: Revisit of the [formula omitted] and [formula omitted] bands

A low resolution (0.5 cm−1) Fourier transform infrared (FTIR) spectrum of 13C2D4 in the 2000–4800 cm−1 region was recorded to re-analyze the two fundamental bands (ν9 and ν11) and to identify the combination bands in this region. The combination bands ν2+ν12, ν6+ν11, ν6+ν9, ν1+ν12, ν5+ν12, ν2+ν11, ν2+ν9, ν5+ν11 and ν5+ν9 were identified and their band centers (with an uncertainty of ± 0.1 cm−1) and band types were determined. In addition, the high-resolution FTIR spectrum of the fundamental ν11 band (2120–2250 cm−1) was recorded at an unapodized resolution of 0.0019 cm−1 and its infrared (IR) lines were analyzed. Rovibrational constants up to five quartic terms and band center of 2193.75943(22) cm−1 were derived with improved precision for the ν11=1 state, with an rms deviation of 0.0019 cm−1. Three rotational constants and the band center of the ν2=ν7=1 state together with the b-Coriolis resonance parameter were derived with improved precision from the study of the Coriolis interactions between the two states (ν11=1 and ν2=ν7=1). Also in this work, the FTIR spectrum of the ν9 band of 13C2D4 was measured between 2230 and 2450 cm−1 at an unapodized resolution of 0.0019 cm−1. For the first time, 2069 perturbed and unperturbed IR transitions of the ν9 band, centered at 2324.358484(46) cm−1, were fitted to obtain the a-Coriolis resonance parameter from its interaction with the ν4=ν10=ν12=1 state. The IR lines of the ν4+ν10+ν12 band were too weak for detection. Two rotational constants (A and B), the band center of the ν4+ν10+ν12 band and the a-type Coriolis resonance parameter were derived for the first time in this work. All the rotational constants A, B and C for the ν11, ν9 and ν2+ν7 bands are in close agreement with theoretically calculated values using the cc-pVQZ basis set at MP2 and B3LYP levels of theory. Ground state rovibrational constants of 13C2D4 up to three sextic terms were also derived from a fit of 3153 ground state combination differences (GSCDs) with an rms deviation of 0.00037 cm−1 from the IR transitions of the present analyses.

Theoretical study on the isomerization process of retinal in gas and aqueous phase

B3LYP/6-311++G(d,p) level of theory was carried out to explain the isomerization process of retinal stereoisomer based on the structural and molecular properties in gas phase and implicit aqueous environment. Frequency calculations on the fully optimized molecular geometries of the retinal isomers confirmed them to be true minima. The relative energies, dipole moments, bond orders, theoretically predicted vibrational frequencies, and HOMO–LUMO energy gaps of the retinal isomers were analyzed. The influence of the explicit aqueous environment on the geometrical parameters associated with the geometry of polyene chain and the vibrational spectra of retinal isomers were evident. The geometries of 11-cis and all-trans retinal isomers exhibited delocalized bonds along the polyene chain in the aqueous phase with a pattern of longer double bonds and shorter single bonds. The vibrational frequencies of the retinal isomers calculated at the B3LYP level of theory were in better agreement with the experimental values in the gas phase. The method and results presented in this study may help to better understand the effects of environment on its isomerization process.

Noble gas inserted compounds of borazine and its derivative B3N3R6: structures and bonding.

Quantum chemistry computations were performed at the MP2 and B3LYP levels of theory using the basis sets aug-cc-pVDZ and def2-TZVPPD to study the noble gas (Ng) compounds formed by insertion of a Ng atom (Kr, Xe, Rn) into the B-H/F and N-H/F bonds of inorganic benzene B3N3H6 and its fluorine derivative B3N3F6. The geometrical structures were optimized and vibrational analysis was carried out to demonstrate these structures being local minima on the potential energy surface. The thermodynamic properties of the formation process of Ng compounds were calculated. A series of theoretical methods based on the wavefunction analysis, including NBO, AIM and ELF methods and energy decomposition analysis, was used to investigate the bonding nature of the noble gas atoms and the properties of the Ng compounds. The N-Ng bond was found to be stronger than the B-Ng bond, but the B-Ng bond is of typical covalent character and σ-donation from the Ng atom to the ring B atom makes the predominant contribution towards stability of the B-Ng bond. NICS calculation shows that these Ng-containing compounds are of weak π-aromaticity.

Role of Ligand Straining in Complexation of Eu3+-Am3+ Ions by TPEN and PPDEN, Scalar Relativistic DFT Exploration in Conjunction with COSMO-RS.

To search for new ligands suitable for the separation of minor actinides (MA) from lanthanides (Ln) in nuclear waste reprocessing, theoretical (density functional theory) studies were carried out on the complexation (structures, bonding, and thermodynamics) of La3+, Sm3+, Eu3+, and Am3+ complexes with moderately soft donor ligands TPEN [N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine] and PPDEN [N,N,N′,N″,N″-pentakis(2-pyridylmethyl) diethylenetriamine] in aqueous and nitrobenzene solutions. B3LYP level of theory was used in conjunction with the conductor-like screening model for real systems (COSMO-RS). The metal ions in [M(NO3)2(TPEN)]NO3 and [M(NO3)(PPDEN)](NO3)2 complexes were deca-coordinated with both TPEN and PPDEN. The enthalpy of the complexation with TPEN in an aqueous solution was found to be negative, indicating the exothermic nature of the reaction as observed in the experiments. The calculated values of free energy of complexation follow the experimental trend: Am3+ > Sm3+ > La3+. Furthermore, the calculated free energy with PPDEN is reduced compared to that with TPEN, which may be attributed to the ligand straining during complex formation, which is also reflected in greater residual charges on both the Eu3+ and Am3+ central ions in the complexes of octadentate PPDEN compared to hexadentate TPEN. The experimental complexation selectivity of Am3+ over Eu3+ with TPEN is established by employing COSMO-RS. Furthermore, TPEN is Am3+-selective, whereas PPDEN is Eu3+-selective, which could be exploited for the efficient separation of MA from Ln.

Synthesis, crystal structure analysis, spectral IR, UV–Vis, NMR assessments, electronic and nonlinear optical properties of potent quinoline based derivatives: Interplay of experimental and DFT study

Quinoline and its derivatives are widely studied by both synthetic and computational chemists due to their exciting perspectives in biological and nonlinear optical (NLO) research. Herein, three novel arylated quinolines: 3-(4-acetylphenyl)quinoline (1), 3-(4-(methylthio)phenyl)-quinoline (2) and 3-(4-phenoxyphenyl)quinoline (3) were synthesized employing Pd catalyzed Suzuki–Miyaura cross-coupling reaction. The chemical structures of all compounds were resolved employing different analytical techniques like 1H-NMR, FT-IR, UV–Vis, EIMS, elemental analysis and finally confirmed by single crystal X-ray diffraction analysis. Synthesized compounds were further subjected to density functional theory (DFT) calculations at B3LYP level of theory in conjunction with 6-311 + G(2d,p) basis set to explore optimized geometry, natural bond orbital (NBO) analysis, FT-IR spectroscopic data, frontier molecular orbitals (FMOs) and NLO properties. Overall, a good agreement was found between DFT computed results and corresponding experimental findings. Vertical electronic transition states were computationally calculated using time-dependent DFT (TDDFT) at same B3LYP level of theory and 6-311 + G(2d,p) basis set combination. NBO calculations indicated the occurrence of intra-molecular charge transfer in synthesized compounds, hence enormous molecular stability owing to hyperconjugative interactions. Energy of FMOs was used to calculate the global reactivity descriptors which indicated that synthesized molecules are chemically hard compounds with greater kinetic stability and electron donating capability. NLO properties were found to be in the range 1830–2960 a.u and order of 2 > 1 > 3. Urea molecule comparative analysis and two-state model confirmed that synthesized molecules are excellent NLO candidates and may have prospective uses in the technology related applications.

Effective degradation of Reactive Red 195 via heterogeneous electro-Fenton treatment: theoretical study and optimization

The magnetite (Fe3O4) nanoparticles were synthesized and supported on the reduced graphene oxide. The characterization of the catalyst was performed by FT-IR, VSM, SEM, XRD, and BET techniques. The obtained results indicated that the in situ synthesis of Fe3O4 using coprecipitation method caused the homogenous formation of magnetite nanoparticles on the surface of reduced graphene oxide (average particle size ~ 71.032 nm) with high stability and catalytic activity toward electro-Fenton removal of Reactive Red 195. The effect of various factors (current intensity, initial pollutant concentration, catalyst weight, and pH) was evaluated by response surface methodology using central composite design. The analysis of variance exhibited that the experimental data are in accordance with the quadratic model. At the optimized operation condition (current intensity of 194.96 mA, initial RR195 concentration of 168.43 mg L−1, 2.0 mg catalyst at pH 3.04), the RR195 and COD removals reached 93.34% and 75.27% in 60 min, respectively. The DFT simulation was performed at B3LYP level of theory. The HOMO–LUMO energy gap was reduced from 2.536 to 2.514 eV after supporting of Fe3O4 on the reduced graphene oxide, which demonstrated the higher electrical conductivity. The RR195 removal followed pseudo-first-order kinetics model (k = 0.044 min−1, R2 = 0.9938). The stability of the catalyst against leaching was evaluated, and only 2.4% of iron was leached. The catalyst almost remained efficient after six cycles.

Synthesis, spectroscopic investigation and biological activities of copper(II) complex of 2-(2,4-difluorophenyl)pyridine: A combined theoretical and experimental study

This paper reports the synthesis, crystal structure determination and spectroscopic characterization of a new copper (II) complex, [CuCl2(dfpy)2] [dfpy: 2-(2,4-difluorophenyl)pyridine]. The Cu(II) complex crystallizes in triclinic space group P1¯ and the Cu(II) ion lies on a crystallographic inversion center. The Cu(II) ion is four-coordinated in a square planar geometry in which Cu(II) atom bound to the dfpy ligands’ nitrogen atoms and chloride ions. Density Functional Theory (DFT) method with the B3LYP/6-31 + G (d, p) level has been used to obtain ground state geometry for the title complex. The experimental FT-IR spectrum of the Cu(II) complex has been analyzed and compared with theoretical data obtained by the B3LYP level of theory. The electronic transitions, HOMO-LUMO energies, chemical hardness, softness, and electronegativity have been explained using the time-dependent DFT (TD-DFT) method. The second-order interaction energies of the Cu(II) complex have been obtained from Natural Bond Orbital (NBO) analysis. The antimicrobial activities have been tested by using minimal inhibitory concentration method (MIC).

Influence of Branching on the Conformational Space: Case Study of Tri- sec-butyl Phosphate Using Matrix Isolation Infrared Spectroscopy and DFT Computations.

The conformational analysis of long chain phosphates poses a serious challenge due to the presence of rotationally flexible multiple alkyl groups. Tri- sec-butyl phosphate (TsBP) is an interesting example, in which branching can be expected to influence the conformational landscape. To solve the conformational problem of TsBP systematically, the conformations of model dimethyl- sec-butyl phosphate (DMsBP), a molecule possessing a single secondary butyl strand, were analyzed. On the basis of the analysis of the energy profile of DMsBP, a few conformational bunches were eliminated. The presence of branched methyl group appears to completely influence the conformational space of TsBP and as a result, the number of conformations is drastically reduced in comparison to its structural isomer, tri- n-butyl phosphate (TBP). B3LYP level of theory in association with 6-311++G(d,p) basis set was used for computing all the conformer geometries. Experimentally, the conformations of TsBP were studied using infrared spectroscopy by trapping the molecule in N2 and Ar matrixes at low temperatures, which were correlated well with the computational results.

Synthesis, crystal structure, DFT, molecular dynamics simulation and evaluation of the anticorrosion performance of a new pyrazolotriazole derivative

A new pyrazolotriazole derivative, namely, 1-acetyl-6-methyl-1H-pyrazolo [3,2-c][1,2,4]triazole (APT) was synthesized. The corrosion inhibition performance of APT on carbon steel in 1 M hydrochloric acid solution was investigated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) methods. The results showed that the inhibition efficiency of APT increases with concentration and attains its maximum of 93% at 10−3 M. The potentiodynamic polarization study suggests that APT acts as mixed type inhibitor. The EIS studies show that APT produces a covering layer at the metal/electrolyte interface. The adsorption of this compound on steel surfaces followed a Langmuir adsorption isotherm. DFT calculations at the B3LYP level of theory and the analyses of frontier orbitals allow the determination of the active adsorbed sites of APT on the metal surface, and molecular dynamics simulations further illustrate the most reasonable adsorption configuration.