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In this paper, we report the synthesis of new unsymmetrical azines Schiff bases. These compounds were prepared by condensation of hydrazine with different aldehydes and ketones to give (E) -2-hydroxynaphthalene-1-carbaldehyde [(1E...
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In this paper, we report the synthesis of new unsymmetrical azines Schiff bases. These compounds were prepared by condensation of hydrazine with different aldehydes and ketones to give (E) -2-hydroxynaphthalene-1-carbaldehyde [(1E) -2-thienylmethylene] hydrazone compound (I) and (Z) - 2 - [(E) -1- (2-hydroxyphenyl) ethylidenehydrazin-1-ylidene] -1,2-diphenylethanone compound (II). The method adopted consists in reacting the two different carbonyl compounds simultaneously in one step in a stepwise manner reported which is practical and cost-effective. The reaction with a minor modification in operating conditions proceeded efficiently and with excellent performance. The structure of each of the two compounds (I) and (II) was determined by the X-ray diffraction technique performed on single crystals. The asymmetric unity of the two molecules consists of one asymmetry-independent molecule. In addition, hydrogen bonds C-H center dot center dot center dot pi are observed in the compound (II). We then present a detailed DFT study based on B3LYP/6-31G (d, p) geometric structures of compounds (I); (II) and another compound (III) also another asymmetric azine (Z) -2- [(E) -2-benzylidenehydrazine-1-ylidenel -1,2-diphenylethanone whose crystal structure is reported. The fundamental vibration wave numbers are calculated and a good agreement between the observed and calculated wave numbers is obtained. The study was extended to the HOMO-LUMO analysis to calculate the energy gap. The calculated HOMO and LUMO energy reveals that the charge is transferred into the molecule. (C) 2018 Elsevier B.V. All rights reserved.
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A systematic spectroscopic study of (R)-2-Amino-1-Phenylethanol was carried out using FT-IR, FT Raman, NMR and UV analysis. FT-IR (4000-400 cm-1) and FT-Raman (4000-100 cm-1) spectrum of the title molecule were recorded in solid p...
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A systematic spectroscopic study of (R)-2-Amino-1-Phenylethanol was carried out using FT-IR, FT Raman, NMR and UV analysis. FT-IR (4000-400 cm-1) and FT-Raman (4000-100 cm-1) spectrum of the title molecule were recorded in solid phase, the H-1 and C-13 NMR spectra were recorded in CDCI3 (deuterated chloroform) solution phase and the UV Vis (200-800 nm) spectrum was recorded in gas phase and ethanol solution phase. Potential energy surface (PES) scan was performed using B3LYP functional with 6-311++G (d, p) basis set. The geometrical parameters (such as bond length, bond angle, dihedral angles) and theoretical frequencies of the title compound were studied from density functional theory (OFT) using B3LYP and B3PW91 functionals with 6-311++G (d, p) basis sets. The computed frequencies were scaled and compared with the experimental values and potential energy distribution (PED) has been tabulated. A comparative study of atomic charges was made by calculating Mulliken, Natural Population Analysis (NPA) and Electrostatic Potential (ESP) simultaneously, with B3LYP/6311++G (d, p) basis set. H-1 and C-13 NMR spectra were recorded and chemical shifts were compared to TMS by Gauge-Independent Atomic Orbital (GIAO) method. Electronic properties such as excitation energy, energy gap between HOMO and LUMO was calculated using time dependent OFT technique. NBO analysis, which predicts the different possibilities of electronic transition in the molecule, was computed using B3PW91 functional with 6-311++G (d, p) basis set. The thermodynamic properties such as heat capacity, entropy and enthalpy at different temperatures were computed and analyzed. Molecular docking study shows that the secondary hydroxyl group and the primary amino group in the aliphatic chain attached to the benzene ring are crucial for binding and the title compound might exhibit inhibitory activity against Bacteroides fragilis (3P24) and may act as anti-bacterial agent. (C) 2016 Elsevier B.V. All rights reserved.
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The chemical and physicochemical properties of the purine derivative hypoxanthine have been the subject of study for several year from different points of view. In this article, the density functional theory study of the hypoxanth...
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The chemical and physicochemical properties of the purine derivative hypoxanthine have been the subject of study for several year from different points of view. In this article, the density functional theory study of the hypoxanthine monocationic state was carried out; the relative energetic stabilities, the structural parameters, several electronic structure properties, the tautomeric equilibrium constants and the IR vibrational spectra of the first five energetically most stable hypoxanthine tautomers were calculated. Additionally, we obtained the #DELTA#G for certain heterocylic protonic transfer processes. The theoretical properties of the comparatively most stable 179 ketonic tautomer are discussed and successfully employed to analyze some features of the experimental physicochemical and chemical behavior of this hypoxanthine~(1+) predominant tautomer, as inferred from the studies on hypoxanthine-Lewis acid chemical interactions both in solution and in solid state.
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The study of the chemical and physicochemical properties of purine derivatives and isomers has received heightened attention for several years. Accordingly, the Density Functional Theory study of the dicationic state of purine der...
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The study of the chemical and physicochemical properties of purine derivatives and isomers has received heightened attention for several years. Accordingly, the Density Functional Theory study of the dicationic state of purine derivative hypoxanthine was performed. In this study, the relative energetic stabilities, several molecular and electronic structure properties and the IR vibrational spectra of the four energetically most stable dicationic hypoxanthine tautomers were calculated. Additionally, we calculated #DELTA#G for the heterocyclic protonic transfer processes and the constants of the tautomeric equilibria. The theoretical properties of the comparatively most stable K 1379 ketonic form are discussed and compared with those for the energetically most stable hypoxanthine tautomers and isomers in different protonation levels. The results obtained are employed to analyze some features of the experimental physicochemical and chemical behavior of both the predominantly dicationic tautomer and hypoxanthine in diverse heterocyclic protonation states.
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Charges on hydrogen atoms of proton-donor groups (OH, COH, COOH, H) modifying the surface of nanodiamond particles have been simulated by DFT quantum chemical calculations. The highest charge has been found on the OH hydrogen atom.
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Charge transfer (CT) complexes, consisting of three substituted N-aryl-N'-4-(-p-anisyl-5-arylazothiazolyl)thiourea as electron-donor molecules and four benzoquinone derivatives as electron-acceptor molecules, were investigated at ...
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Charge transfer (CT) complexes, consisting of three substituted N-aryl-N'-4-(-p-anisyl-5-arylazothiazolyl)thiourea as electron-donor molecules and four benzoquinone derivatives as electron-acceptor molecules, were investigated at the DFT/B3LYP/6-31G(d,p) level of theory. The geometric structures, orbital energies, energy gaps and normal vibrational modes were determined. Quantum chemical parameters, including dipole moment, electronegativity, hardness, softness, electrophilicity index and number of electrons transferred, were calculated. The transition energies of the charge transfer complexes were calculated at the TD-DFT/B3LYP/6-31G(d,p) level of theory. The calculated parameters were comparable to the corresponding experimental parameters and the computational results facilitated the experimental interpretation. The calculated first hyperpolarizabilities demonstrate that those complexes are notably promising candidates as non-linear optical materials.
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Spectral characteristics study of meso-tetraphenylporphyrin derivatives (TPP1 and TPP2) used as photosensitizers for utilization in photodynamic therapy (PDT) has been performed by density functional theory (DFT) and time dependen...
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Spectral characteristics study of meso-tetraphenylporphyrin derivatives (TPP1 and TPP2) used as photosensitizers for utilization in photodynamic therapy (PDT) has been performed by density functional theory (DFT) and time dependent DFT (TD-DFT) calculations at B3LYP/6-31G(d) level of theory using PCM solvation model. The geometrical parameters of porphyrins have been studied for ground and excited-state geometry to deduce the influence of various substituents as well as solvent effect on the deformation of porphyrin ring. Two theoretical approaches-linear response (LR) and external iteration (EI)-have been performed to replicate absorption and fluorescence emission spectra. Experimental and theoretical investigations have shown that EI method reproduces the absorption energies very well for both singlet-singlet and triplet-triplet transitions, whereas the LR approach is more coherent with experimental fluorescence emission spectra. Spectral features and HOMO-LUMO band gap analysis have shown that TPP1 can be more useful in PDT. Calculations have revealed that two the highest occupied and two the lowest unoccupied molecular orbitals are responsible for the Q-band absorption and are located mainly on the porphyrin ring. In order to verify the substituent effect on the activity of tested compounds in their ground and excited states, the molecular electrostatic potential surfaces have been analyzed.
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This work presents the results of DFT and classical mechanics' calculations and theoretical analysis of geopolymer structure. The calculations were carried out using a bottom-up approach (from small oligomers to clusters with incr...
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This work presents the results of DFT and classical mechanics' calculations and theoretical analysis of geopolymer structure. The calculations were carried out using a bottom-up approach (from small oligomers to clusters with increasing size) for various Si:Al ratio.
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Semiempirical molecular orbital treatment at the level of AM1(RHF)and single point DFT level calculations has been performed on dicyano(-CN)derivatives of[22](1,4)-cyclophanes(para-cyclophane derivatives)at different po-sitions[th...
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Semiempirical molecular orbital treatment at the level of AM1(RHF)and single point DFT level calculations has been performed on dicyano(-CN)derivatives of[22](1,4)-cyclophanes(para-cyclophane derivatives)at different po-sitions[the bridge positions and phane-deck(s)].All the isomeric structures studied here found are stable and endothermic as well.The effect of-CN group on the stability of the para-cyclophane derivatives is found.The frontier molecular orbital energies are calculated and the energy gap between HOMO and LUMO is reported.
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We present a theoretical study on the point defects in ZrO_2–silicon interfaces using molecular dynamics (MD) calculations. A super-cell model that contains 9 atomic layers of silicon and 9 atomic layers of ZrO_2 was used for the...
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We present a theoretical study on the point defects in ZrO_2–silicon interfaces using molecular dynamics (MD) calculations. A super-cell model that contains 9 atomic layers of silicon and 9 atomic layers of ZrO_2 was used for the simulation. Three atomic layers containing 17 oxygen atoms, eight silicon atoms, and nine Zr atoms were used to simulate the ZrO_2–silicon interface. We then performed density functional theory (DFT) with plane-wave basis to calculate the interface band structure. Results demonstrate that the stretched Zr–O bonds at the interface would produce some defect levels in the band gap. Particularly, the defect levels originated from the interstitial oxygen atoms are located close to the bottom of the ZrO_2 conduction band and hence it will affect the electrical properties of the gate dielectrics.
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