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1.
《Tetrahedron letters》2014,55(50):6827-6830
A series of push–pull benzothiazoles were designed and synthesized by the Pd-catalyzed Sonogashira cross-coupling and [2+2] cycloaddition–retroelectrocyclization reactions. The photonic and electrochemical properties of these systems exhibit strong donor–acceptor interaction. The BTs 5–8 show strong intramolecular charge-transfer in the near-infrared (NIR) region. The absorption studies indicate systematic lowering of the optical HOMO–LUMO gap with increase in acceptor strength. The computational studies reveal that incorporation of strong acceptors TCNE and TCNQ results in substantial stabilization of the LUMO level compared to the HOMO level, leading to the low HOMO–LUMO gap and bathochromic shift of the absorption spectrum. The TCBD and DCNQ linked BTs 5–8 exhibit multi-step redox waves and improved thermal stability. 相似文献
2.
《Solid State Sciences》2012,14(4):476-487
The Fourier transform infrared (FT-IR) and Fourier transform Raman (FTR) spectra of 4-amino-3(4-chlorophenyl) butanoic acid were recorded in the regions 4000–400 cm−1 and 4000–100 cm−1, respectively, in the solid phase. Molecular electronic energy, geometrical structure, harmonic vibrational spectra, infrared intensities and Raman scattering activities, highest occupied molecular orbital, lowest unoccupied molecular orbital energy, energy gaps and thermodynamical properties such as zero-point vibrational energies, rotational constants, entropies and dipole moment were computed at the Hartree–Fock/6-31G(d,p) and three parameter hybrid functional Lee–Yang–Parr/6-31G(d,p) levels of theory. The vibrational studies were interpreted in terms of potential energy distribution (PED). The results were compared with experimental values with the help of scaling procedures. Most of the modes have wave numbers in the expected range and are in good agreement with computed values. The first order hyperpolarizability (βtotal) of this molecular system and related properties (β, μ, 〈α〉 and Δα) are calculated using HF/6-31G(d,p) and B3LYP/6-31G(d,p) methods based on the finite-field approach. Stability of the molecule arising from hyperconjugative interactions, charge delocalization and intramolecular hydrogen bond-like weak interaction has been analyzed using natural bond orbital (NBO) analysis by using B3LYP/6-31G(d,p) method. The results show that electron density (ED) in the σ1 and π1 antibonding orbitals and second-order delocalization energies E(2) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule. 相似文献
3.
This paper presents, a theoretical study of the structural, 13C and 1H NMR chemical shifts, electronic transitions, vibrational analysis, and first hyperpolarizability for Ru(NHC)2Cl2(=CH-p-C6H5) complex in gas phase and different solvents. The solvent effect on structural parameters, frontier orbital energies, Ru=Ccarbene and Ccarbene-H stretching frequencies, and chemical shifts of Ccarbene, CNHC and Hcarbene of complex was explored based on Polarizable Continuum Model (PCM). The wavenumbers of υ(Ru=Ccarbene) and υ(Ccarbene-H) of complex in different solvents were correlated with the Kirkwood–Bauer–Magat equation (KBM). As well as, the polarizability and the first order hyperpolarizability values of the investigated compound were computed in various solvents. 相似文献
4.
Density functional theory (DFT) has been employed to study the geometric and electronic structures, band gap, thermodynamic
properties, density, and performance properties of a series of polynitrotriazoles at the B3LYP/aug-cc-pVDZ level. The detonation
performances were evaluated by the Kamlet–Jacobs semi-empirical equations based on the calculated densities and heats of reaction.
It has been found that the model compounds with the predicted densities of 1.8 g/cm3, detonation velocities of 8.8 km/s, and detonation pressures of 35 GPa may be novel potential candidates of high energy density
materials. The discrepancies in the performance properties, stabilities or sensitivities among isomers are caused by the relative
position of NH2 and NO2 groups. 相似文献
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Sebastian S Sundaraganesan N Karthikeiyan B Srinivasan V 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(2):590-600
The Fourier transform infrared (FT-IR) and FT-Raman of 4-methyl-2-cyanobiphenyl (4M2CBP) have been recorded and analyzed. The equilibrium geometry, bonding features and harmonic vibrational frequencies have been investigated with the help of density functional theory (DFT) method. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFF). The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the Gauge including atomic orbital (GIAO) method. The first order hyperpolarizability (β0) of this novel molecular system and related properties (β, α0 and Δα) of 4M2CBP are calculated using HF/6-311G(d,p) method on the finite-field approach. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ* and π* antibonding orbitals and second order delocalization energies (E2) confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. UV-vis spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent density functional theory (TD-DFT) approach. Finally the calculations results were applied to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra. 相似文献
7.
VineetKumar Choudhary ArvindKumar Bhatt Dibyajit Dash Neeraj Sharma 《Journal of computational chemistry》2019,40(27):2354-2363
8.
《The Journal of chemical thermodynamics》2004,36(2):107-113
The standard (p∘=0.1 MPa) molar enthalpy of formation of crystalline 2-hydroxypyridine N-oxide was measured, at T=298.15 K, by static bomb calorimetry and the standard molar enthalpy of sublimation, at T=298.15 K, was obtained using Calvet microcalorimetry. These values were used to derive the standard molar enthalpy of formation of 2-hydroxypyridine N-oxide in gaseous phase, and to evaluate the dissociation enthalpy of the N–O bond. Additionally, high-level density functional theory calculations using the B3LYP hybrid exchange-correlation energy functional have been performed for the three isomers of hydroxypyridine N-oxide in order to confirm the experimental trend for the dissociation enthalpy of the (N–O) bond. 相似文献
9.
First‐principles calculations were carried out on recently synthesized Re2 and Re3 as well as hypothetical Tc and Mn nitrides. It is found that structure and covalent bonds play an important role in determining mechanical properties. Under a large strain along (0001)〈101 0〉direction, Re2N undergoes a phase transformation with a slight increase in ideal shear strength. On the other hand, it is transformed into a phase with weaker mechanical properties, if the strain is along Re2〈1 21 0〉 direction. Mn2N can be synthesized under moderate conditions due to its more negative formation energy. Re2N, Re3N, and Mn2N show structure‐related mechanical property under larger strains to ReB2 but exhibit much lower ideal strengths, which is attributed to the larger ionicity of cation–anion bond. Three‐dimensional framework of strong covalent bonds is thus highly recommended to design superhard materials. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011 相似文献
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Mina Ghiasi Majid M. Heravi Elham Hatami 《Journal of the Iranian Chemical Society》2013,10(2):257-263
Ab initio quantum mechanical calculations using density functional (B3LYP) method and 6-311G** basis set have been performed on two cis and trans conformers of 2,4-diphenyl thietane dioxide (DPTD), 2,4-diphenyl thietane (DPT), 2,4-diphenyl azetidine (DPA) and 2,4-diphenyl oxetane (DPO). The calculated stability energy for cis–trans isomerization in gas phase and in different solvents such as benzene, DMSO, water and methanol indicated that the cis conformer is more stable than trans in all above-mentioned compounds about 11–2 kcal mol?1. In the next step, a transition states for cis–trans inter-conversion for all four-membered heterocycles (DPTD, DPT, DPA and DPO) were proposed in methanol as solvent. Thermodynamic functions such as standard enthalpies of isomerization (?Hºiso), standard entropy of isomerization (?Sºiso) and standard Gibbs free energy of isomerization (?Gºiso) for all studied compounds were also evaluated. The calculation showed that the conversion of trans to cis isomer is exothermic and spontaneous. In all calculations, solvent effects were considered using a polarized continuum model. 相似文献
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Suman Mitra Santanu Chattopadhyay Sunil Sabharwal Anil K. Bhowmick 《Radiation Physics and Chemistry》2010,79(3):289-296
Electron beam (EB) crosslinked natural rubber (NR) gels were prepared by curing NR latex with EB irradiation over a range of doses from 2.5 to 20 kGy using butyl acrylate as sensitizer. The NR gels were systematically characterized by solvent swelling, dynamic light scattering, mechanical and dynamic mechanical properties. These gels were introduced in virgin NR and styrene butadiene rubber (SBR) matrices at 2, 4, 8 and 16 phr concentration. Addition of the gels improved the mechanical and dynamic mechanical properties of NR and SBR considerably. For example, 16 phr of 20 kGy EB-irradiated gel-filled NR showed a tensile strength of 3.53 MPa compared to 1.85 MPa of virgin NR. Introduction of gels in NR shifted the glass transition temperature to a higher temperature. A similar effect was observed in the case of NR gel-filled SBR systems. Morphology of the gel-filled systems was studied with atomic force microscopy. The NR gels also improved the processability of the virgin rubbers greatly. Both the shear viscosity and the die swell values of EB-irradiated gel-filled NR and SBR were lower than their virgin counterparts as investigated by capillary rheometer. 相似文献
15.
Ljubica Andjelković Marko Perić Matija Zlatar Sonja Grubišić Maja Gruden-Pavlović 《Tetrahedron letters》2012,53(7):794-799
The aromatic/antiaromatic behavior of the Jahn–Teller (JT) active benzene cation and anion has been investigated using Density Functional Theory (DFT) calculations of Nuclear Independent Chemical Shifts (NICS) and magnetic susceptibility. NICS parameters have been scanned along the Intrinsic Distortion Path (IDP) for the benzene cation showing antiaromaticity which decreases with increasing deviation from D6h to D2h symmetry. Changes in NICS values along the IDP from D6h to C2v in the benzene anion revealed non-aromatic character. 相似文献
16.
Krzysztof K. Zborowski Ibon Alkorta Jose Elguero Leonard M. Proniewicz 《Structural chemistry》2013,24(2):543-548
An extension of the harmonic oscillator model of aromaticity (HOMA) model for systems with boron–boron bonds is presented. For the first time, the parameters of the HOMA model are estimated using only theoretically calculated bond lengths. The HOMA parameters obtained make geometric aromaticity studies possible for a large number of compounds containing the boron–boron bond. The derived HOMA parameters have been used to investigate how the introduction of the boron–boron moiety in the structure of selected hydrocarbons modifies their aromaticity. The conclusion is that the insertion of a boron–boron bond usually strongly decreases the aromaticity of the boron-containing compounds in comparison to their parent hydrocarbons. 相似文献
17.
LI Yong-Hong HONG San-GuoDepartment of Chemistry Jiangxi Normal University Nanchang Jiangxi China 《中国化学》1996,14(2):105-108
MINDO/3 molecular orbital theory has been used to study the thermal rearrangements of HNCRCR'CO.The results obtained show that the activation energy of this rearrangement depends on the migrating group R and the group R'. 相似文献
18.
E. F. Zhilina P. A. Slepukhin N. S. Boltacheva M. G. Pervova D. L. Chizhov V. I. Filyakova V. N. Charushin 《Russian Journal of General Chemistry》2012,82(12):1962-1969
The reaction of fluorinated lithium 1,3-diketonates with propargylamine hydrochloride and 1,1,1-trifluorpentane-2,4-dione or 1,1,1-trifluoro-4-methoxypent-3-en-2-one with propargylamine and 3-aminophenylacetylene were performed to obtain fluorinated 1,3-enaminones containing at a nitrogen atom substituents with terminal C≡C bonds: (Z)-1,1,1-trifluoro-4-(2-propynylamino)-3-pentene-2-one, (Z)-1,1,2,2-tetrafluoro-5-(2-propynylamino)-4-hexen-3-one, and 4-(3-ethynylphenylamino)-1,1,1-trifluoropentyl-3-en-2-one. Reactions of 4-(3-ethynyl-phenylamino)-1,1,1-trifluoro-pentyl-3-en-2-one with Cu(II) acetate or nanosized powder of copper or its oxides led to the respective chelate complex. The structure of (Z)-1,1,2,2-tetrafluoro-5-(2-propynylamino)-4-hexen-3-one and a copper complex of 4-(3-etinilphenylamino)-1,1,1-trifluoropenta-3-en-2-one was determined by XRD. 相似文献
19.
LI Yong-Hong HONG San-Guo WANG Shen PENG Yi-YuanDepartment of Chemistry Jiangxi Normal University Nanchang Jiangxi China 《中国化学》1997,15(1):21-24
AM1 molecular orbital method using the unrestricted Hartree-Fock(UHF) calculations has been applied to investigate the thermal reaction of cyclohexadiene and methyl crotonate. The calculated results indicate that the thermal Diels-Alder reaction proceeds to product through the concerted path and two radical pathways. 相似文献
20.
Geng ZhiYuan Yao Kun Wang YongCheng Fang Ran Zhang XingHui Jia BaoLi 《中国科学B辑(英文版)》2007,50(3):335-344
The mechanisms of theion reaction of alkylidenegermylene with oxirane and thiirane have been characterized detail in using density functional theory, as well as ab initio method, including geometry optimization and vibrational analysis for the involved stationary points on the potential energy surface. Energies were calculated by CCSD(T)/6-311G(d)//B3LYP/6-311G(d,p) method for the involved conformations. The results show that the reaction pathways for both reactions consist of two ways: (1) the reactants can yield bent products (P1; P4) by syn-isomers; (2) the reactants can also yield three-membered products (P2; P5) by anti-isomers, which then further react with oxirane and thiirane to form the ultimate products (P3-1, P3-2; P6). Furthermore, a comparison with alkylidenecarbene, oxirane, and thiirane was done. 相似文献