Crystal structure,spectroscopic properties and density functional theory study of (Z)-1-[(2,4-dimethoxyphenylamino)methylene]naphthalen-2(1H)-one

The Schiff base (Z)-1-[(2,4-dimethoxyphenylamino)methylene]naphthalen-2(1H)-one was synthesized from the reaction of 2-hydroxy-1-naphthaldehyde with 2,4-dimethoxyaniline. The title compound has been characterized by FT-IR, UV-Vis and, X-ray single-crystal techniques. The present X-ray investigation shows that the compound exists in the keto-amine tautomeric form. Molecular geometry and vibrational frequencies of the compound in the ground state have been calculated using the density functional theory (DFT) with 6–311G(d, p) basis set and compared with the experimental data. The calculated results show that the optimized geometry is compatible with the crystal structure and the theoretical vibrational frequencies are in good agreement with the experimental values. Besides, molecular electrostatic potential (MEP), frontier molecular orbital analysis (HOMO-LUMO) and non-linear optical (NLO) properties of the compound were investigated using the same theoretical calculations.     

Molecular structure,spectroscopic (FT-IR and UV-Vis) and DFT quantum-chemical studies on 2-[(2,4-Dimethylphenyl)iminomethyl]-6-methylphenol

Density functional calculations of the structure, vibrational spectra, molecular electrostatic potential and thermodynamic functions have been performed at the B3LYP/6-311++G(d,p) level of theory for the Schiff base compound 2-[(2,4-Dimethylphenyl)iminomethyl]-6-methylphenol. Experimental and theoretical Fourier transform infrared (FT-IR) studies of the title compound show the preference of enol form, as supported by X-ray analysis results. Using the time-dependent density functional theory (TD-DFT) method, electronic absorption spectra of the compound have been predicted and a good agreement is determined with the experimental ones. To investigate the tautomeric stability, optimisation calculations at B3LYP/6-311++G(d,p) level were performed for the enol and keto forms of the title compound. Calculated results show that its enol form is more stable than that of the keto form. The predicted non-linear optical properties of the title compound are much greater than those of urea. The changes in thermodynamic properties for the formation of the title compound with the temperature ranging from 200 K to 500 K have been obtained using the statistical thermodynamic method. At 298.15 K the change of Gibbs free energy for the formation reaction of the title compound is 37.03 kJ/mol. The title compound cannot be spontaneously produced from the isolated monomers at room temperature. The tautomeric equilibrium constant is also computed as 1.23×10^?3 at 298.15 K for enol ? keto tautomerisation of the title compound.     

Quantum-chemical calculation on 5-phenyl-2-(4-pyridyl)pyrimidine

The molecular geometry and vibrational frequencies of 5-phenyl-2-(4-pyridyl)pyrimidine in the ground state have been calculated by the density functional theory with B3LYP/6-311G(d) as the basis set. The observed frequencies of 5-phenyl-2-(4-pyridyl)pyrimidine and those calculated are nearly the same. The form of the modes for all fundamentals is based on potential energy distribution calculations.     

Synthesis,spectroscopic properties and DFT study of (E)-1-[(3-(trifluoromethyl)phenylimino)methyl]naphthalen-2-olate

The Schiff base (E)-1-[(3-(trifluoromethyl)phenylimino)methyl]naphthalen-2-olate was synthesized from the reaction of 2-hydroxy-1-naphthaldehyde with 3-trifluoromethylaniline. The title compound has been characterized by FT-IR, UV-vis and X-ray single-crystal techniques. The present X-ray investigation shows that the compound exists in the zwitterionic form. Molecular geometry of the compound in the ground state have been calculated using the density functional method (DFT) with 6-31G(d,p) basis set and compared with the experimental data. The calculated results show that the optimized geometry can well reproduce the crystal structural parameters. By using TD-DFT method electronic absorption spectra of the compound have been predicted and a good agreement with the TD-DFT method and experimental one is determined. In addition DFT calculations of the compound, molecular electrostatic potential (MEP), frontier molecular orbital analysis (HOMO-LUMO) and non-linear optical (NLO) properties were performed at B3LYP/6-31G(d,p).     

Synthesis of chalcone (3-(4-fluorophenyl)-1-(4-methoxyphenyl)prop-2-en-1-one): advantage of sonochemical method over conventional method

In this work, an attempt was made to synthesize chalcone (3-(4-fluorophenyl)-1-(4-methoxyphenyl)prop-2-en-1-one) by condensation of 4-fluorobenzaldehyde with 1-(4-methoxyphenyl)ethanone under basic conditions by using both conventional (NUS) and sonochemical (US) methods. A simple condensation reaction of 4-fluorobenzaldehyde and 1-(4-methoxyphenyl)ethanone using potassium hydroxide as a base was carried out for the study. The synthesized chalcone derivative was characterized for FTIR, NMR, elemental analyses and studied for XRD, PSM, TGA and SEM properties to evaluate its performance obtained under ultrasonic energy. It was observed that complete conversion to chalcone occurred in 10 min by sonochemical method and in 4h by conventional method. Also it was found that crystallinity of the US synthesized chalcone was found to be increased by 63% than that of NUS synthesized chalcone. Finally, it has been observed that chalcone synthesis using sonochemical method is an energy efficient technique over conventional method (almost 90% of energy saving).     

2-对二甲氨基苯基-5-氟-6-吗啉苯并咪唑的合成及其光谱学性质研究

合成了一种新的取代苯并咪唑化合物 ,2 对二甲氨基苯基 5 氟 6 吗啉苯并咪唑 ,采用紫外 可见光谱、荧光光谱及荧光寿命等方法探讨了溶液pH值对该化合物吸收光谱的影响及其与 β 环糊精的作用。结果表明 ,pH >7 0时 ,该化合物在溶液中主要以中性分子状态存在 ,当 3 8相似文献   

The role of N dopant in inducing ferromagnetism in (ZnO)n clusters (n = 1-16)

The effect of nitrogen doping on the magnetic properties of (ZnO)(n) clusters (n = 1-16) has been investigated using spin polarized density functional theory. The total energy calculations suggest that N is more stable at the O site than at the Zn site in (ZnO)(n) clusters and induces a magnetic moment of 1 μ(B)/N atom. The N-Zn-N configuration is more stable than isolated N for 3D structures. The N dopants do not show any tendency for clustering. The binding energy is found to decrease with the increase in the number of N dopants. The magnetic moment increases gradually with the increase in the number of atoms with 1 μ(B)/N atom for n ≤ 4 and less than 1 μ(B)/N for n > 4. The local magnetic moment is mainly localized at the N site with a small magnetic moment induced at the O site. The presence of a Zn vacancy (V(Zn)) induced an additional magnetic moment of 2 μ(B) on the nearest O atoms. The N dopant prefers to form a N-V(Zn) pair. The combination of N and V(Zn) in 3D structures leads to a total magnetic moment of 3 μB. The Mulliken charge transfers from Zn to N and O in all N doped (ZnO)(n) clusters. The calculated results are consistent with existing experimental and theoretical results.     

Synthesis,experimental and theoretical analysis,and antiproliferative activity of 2-(4-methoxyphenylamino)-2-oxoethyl methacrylate

In this study 2-(4-methoxyphenylamino)-2-oxoethyl methacrylate (MPAEMA) has been synthesized and characterized experimentally (FTIR, NMR). Theoretically, physical, electronic and vibrational properties of MPAEMA molecule have been investigated using density functional theory (DFT) calculations at B3LYP/6-311++G(d,p) basis set. Bond distance, FTIR spectrum, NMR spectra and vibrational frequencies have been carried out. The calculated FTIR and NMR spectra of the headline molecule from the DFT have been compared with the measured ones, and good results have been obtained. UV spectrum characteristics and the electronic properties, like frontier orbitals, and band gap energy of MPAEMA have also been recorded by time-dependent (TD-DFT) method based on optimized structure with different solvent. The experimental results have been compared with theoretical values. Both experimental and theoretical methods have shown that the compound has successfully been synthesized. Cytotoxicity of MPAEMA has been investigated by XTT cell proliferation assay. IC50 values of MPAEMA have been identified as 1.8 mM on HeLa cell line.     

Excited State Lactim to Lactam Type Tautomerization Reaction in 5-(4-Fluorophenyl)-2-Hydroxypyridine: Spectroscopic Study and Quantum Chemical Calculation

The photophysical properties of 5-(4-fluorophenyl)-2-hydroxypyridine (FP2HP) have been studied by steady state and time resolved spectroscopy in combination with quantum chemical calculations. The molecule FP2HP exists as lactim and lactam form in the ground state due to small stability difference but does not undergo lactim to lactam isomerisation due to high barrier energy. Whereas in the excited state the lactim form undergoes tautomerization producing red shifted emission of the lactam tautomer along with the local emission of the lactim form. In polar protic solvents, the barrier for lactim-lactam tautomerization rapidly decreases forming the lactam tautomer only. Temperature has pronounced effect on the excited state tautomerization equilibrium and is clearly reflected in the measured equilibrium constant (K _tau ⁰ ) and free energy change (??G⁰). Structural calculations at Hartree Fock and Density Functional Theory levels, calculated stability of the isomers in different solvents using Polarized Continuum Model and the theoretical potential energy surfaces for the ground and excited states along the proton transfer coordinate are reported for the tautomeric equilibrium of FP2HP.     

FT-IR, FT-Raman, NMR spectra and DFT simulations of 4-(4-fluoro-phenyl)-1H-imidazole

The FT-IR, FT-Raman and FT-NMR spectra of the compound 4-(4-Fluoro-phenyl)-1H-imidazole (4-FPI) were recorded and analyzed. Density functional method (B3LYP level with the 6–311G(d, p) and 6–311++G(d, p) and cc-pVQZ as basis sets) has been used to compute optimized geometry, vibrational wavenumbers of the 4-FPI. Only one tautomeric form was found most stable by using DFT/B3LYP. The detailed interpretation of the vibrational spectra was carried out with the aid of total energy distribution following the scaled quantum mechanical force field methodology. Potential Energy Surface scan studies has also been carried out by ab initio calculations with the same basis sets.     

(E)-3-(4一羟苯基)-1-(哌啶-1-基)丙-2-烯-1-酮衍生物核磁共振特征与构象分析

设计并合成了一系列(E)-3-(4-羟苯基)-1-(哌啶-1-基)丙-2-烯-1-酮衍生物. 通过一维和二维核磁共振实验完成了¹H和¹³C信号的指认. 通过ROESY、变温实验和分子模拟技术对这类化合物的构象进行了分析.     

2,3-二取代喹唑啉-4(3H)-酮化合物结构和活性的密度泛函理论研究

采用密度泛函理论中的广义梯度近似(DFT/GGA)方法,在PW91/DNP水平上研究了21种2,3-二取代喹唑啉-4(3H)-酮化合物的结构、化学活性和前线轨道.结果表明:此类化合物的能隙E_g大部分都在3.50~3.60 e V之间,其中在喹唑啉环3位上取代甲氧基苄基,或是在8位上取代甲基,化合物的能隙降低,而且甲氧基在苄基的间位比对位降低得更厉害.通过比较还发现,2,3-二取代喹唑啉-4(3H)-酮化合物对水稻纹枯菌(Rhizoctonia solani bacteria)的杀菌活性与哌啶并噻吩并嘧啶酮衍生物对水稻纹枯菌的杀菌活性相当,而哌啶并噻吩并嘧啶酮衍生物比2,3-二取代喹唑啉-4(3H)-酮化合物对苹果轮纹病(Botryospuaeria gregaria bacteria)杀菌活性好.     

Vibrational characterization of the oxidation products on Si(111)-(7 x 7)

The oxidation products on Si(111)-(7x7) are investigated at 82 K by means of high-resolution electron energy loss spectroscopy. The isotope-labeled vibrational spectra with 16O2, 18O2, and 16O 18O show that, in the initial stage of the oxidation, an O2 molecule dissociates to form a metastable product with an O atom bonding on top of the Si adatom and the other inserted into the backbond. The metastable product is observed as a dark site in the topographic scanning tunneling microscopy (STM) image and can be transformed to a stable product by the STM manipulation. Our results are in good agreement with recent theoretical calculations.     

Ta4Cn^-/0(n=0-4)团簇的电子结构、成键性质及稳定性

本文采用尺寸选择的负离子光电子能谱技术,结合密度泛函理论,对Ta4Cn^-/0(n=0-4)团簇电子结构、成键性质以及稳定性进行了研究.实验测得Ta4Cn-(n=0—4)团簇负离子基态结构的垂直脱附能分别为(1.16±0.08),(1.35±0.08),(1.51±0.08),(1.30±0.08)和(1.86±0.08)eV.中性Ta4Cn(n=0—4)团簇的电子亲和能分别为(1.10±0.08),(1.31±0.08),(1.44±0.08),(1.21±0.08)和(1.80±0.08)eV.研究发现Ta4^-/0团簇为四面体结构,Ta4C1-/0团簇中碳原子覆盖在Ta4四面体的一个面上方,Ta4C2^-/0团簇则是两个碳原子分别覆盖在Ta4四面体中的两个面上方.Ta4C3^-/0团簇是一个缺角立方体结构.Ta4C4^-/0团簇则是近似立方体结构,可以看成是α-TaC面心立方晶体的最小晶胞单元.分子轨道分析结果显示Ta4C3团簇的单电子最高占据轨道主要布居在单个钽原子周围,导致Ta4C3^-团簇的垂直脱附能明显低于其相邻团簇.理论研究显示随着碳原子数目的增加,Ta4Cn^-/0(n=0—4)团簇中的钽-钽金属键逐渐被钽-碳共价键取代,单原子结合能逐渐增加且明显高于Ta4+n^-/0(n=0-4)团簇.中性Ta4C4的单原子结合能高达7.13 eV,这说明钽-碳共价键的形成有利于提高材料的熔点,这与碳化钽作为高温陶瓷材料的特性密切相关.     

Structure of 2-(2-(anthracen-9-ylmethylene)hydrazinyl)-4-(3-methyl-3-phenylcyclobutyl)thiazole by combined X-Ray crystallographic and molecular modelling studies

A single crystal of 2-(2-(anthracen-9-ylmethylene)hydrazinyl)-4-(3-methyl-3-phenylcyclobutyl)thiazole (C₂₉H₂₅N₃S) containing anthracene, thiazole and cyclobutane rings has been synthesised. The synthesised crystal structure was characterised using IR, ¹H-NMR and ¹³C-NMR spectroscopic and X-Ray analysis techniques. In the crystal, neighbouring molecules formed chains along [110] by interconnecting with N–H···N hydrogen bonding and π–π interactions. The geometrical parameters of the title compound were optimised by Gaussian 09 software in the gas phase and Quantum-Espresso software under Periodic Boundary Conditions (PBC) in the solid phase. Theoretically, IR, NMR spectra, Mulliken, NPA and AIM atomic charges, Hirshfeld surface and frontier molecular orbitals (FMOs) of the title compound were examined. Using the Hirshfeld surface and two-dimensional (2D) fingerprint graphics, the presence of intermolecular interactions in the crystal packing were analysed. The energies of these interactions and their distribution on the crystal structure were shown graphically. In general, it was seen that theoretical calculations were consistent with X-Ray results.     

Synthesis,structure, spectroscopic (FT-IR) and density functional modelling studies of 1-[(4-ethoxyphenylimino)methyl]napthalene-2-ol

Synthesis, crystallographic characterisation, spectroscopic (Fourier transform infrared spectroscopy [FT-IR]) and density functional modelling studies of the Schiff base 1-[(4-ethoxyphenylimino)methyl]napthalene-2-ol (C₁₉H₁₇NO₂) have been reported. The molecular structure obtained from X-ray single-crystal analysis of the investigated compound in the ground state has been compared using Hartree–Fock and density functional theory (DFT) with the 6-311++G(d,p) basis set. In addition to the optimised geometrical structures, atomic charges, molecular electrostatic potential, natural bond orbital, non-linear optical (NLO) effects and thermodynamic properties of the compound have been investigated by using DFT. The experimental (FT-IR) and calculated vibrational frequencies (using DFT) of the title compound have been compared. The solvent effect was also investigated for obtained molecular energies and the atomic charge distributions of the compound. There exists a good correlation between experimental and theoretical data for enol-imine form of the compound. The total molecular dipole moment (µ), linear polarisability (α), and the first-order hyperpolarisability (β) were predicted by the B3LYP method with different basis sets 6-31G(d), 6-31+G(d,p), 6-31++G(d,p), 6-311+G(d) 150 and 6-311++G(d,p) for investigating the effects of basis sets on the NLO properties. Our computational results yield that β_tot for the title compound is greater than those of urea.     

Predissociation linewidths and oscillator strengths for the (2-0) to (13-0) Schumann-Runge bands of O2

Analysis of the absorption spectrum of O₂ in the Schumann-Runge bands (B³Σ_u^?-X³Σ_g^?) from the 2-0 to the 13-0 band yields oscillator strengths which are in good agreement with past theoretical calculations. Predissociation linewidths deduced from the data tend to be larger than theoretical predictions for v′ ≤ 5 and are reasonably near theory for v′ > 5. The qualitative dependence of the linewidths on vibrational level is in accord with that expected for a repulsive potential intersecting the B³Σ state near v′ = 4. For a given band the predissociation linewidth deduced from the spectra tends to increase as the total angular momentum increases. The new linewidths are smaller than some past experimental results, and this will have an impact on future calculations of the photodissociation rates of O₂, NO, and H₂O in the earth's upper atmosphere.     

Experimental and quantum chemical calculational studies on 2-[(4-propylphenylimino)methyl]-4-nitrophenol

The Schiff base compound 2-[(4-propylphenylimino)methyl]-4-nitrophenol has been synthesized and characterized by IR, UV–Vis, and X-ray single-crystal determination. The molecular geometry from X-ray determination of the title compound in the ground state has been compared using the Hartree–Fock (HF) and density functional theory (DFT) with the 6-31G(d) basis set. The calculated results show that the DFT and HF can well reproduce the structure of the title compound. The energetic behaviour of the title compound in solvent media was examined using the B3LYP method with the 6-31G(d) basis set by applying the Onsager and the polarizable continuum model (PCM). The results obtained with these methods reveal that the PCM method provides a more stable structure than Onsager's method. Using the TD-DFT method, electronic absorption spectra of the title compound have been predicted and good agreement with the TD-DFT method and the experimental determination was found. The predicted nonlinear optical properties of the title compound are much greater than those of urea. In addition, DFT calculations of the molecular electrostatic potential and NBO analysis of the title compound were carried out at the B3LYP/6-31G(d) level of theory.