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substituent effect on the molecular stability,group interaction,detonation performance,and thermolysis mechanism of nitroamino-substituted cyclopentanes and cyclohexanes

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Science China Chemistry 2008年第12期51卷 1231-1245页

作者： QIU Ling GONG XueDong JU XueHai XIAO HeMing Institute for Computation in Molecular and Material Science School of Chemical EngineeringNanjing University of Science and TechnologyNanjing 210094China Key Laboratory of Nuclear Medicine Ministry of HealthJiangsu Institute of Nuclear MedicineWuxi 214063China

Density functional theory (DFT) method has been employed to study the effect of nitroamino group as a substituent in cyclopentane and cyclohexane, which usually construct the polycyclic or caged nitra-mines. Molecular structures were investigated at the B3LYP/6-31G** level, and isodesmic reactions were designed for calculating the group interactions. The results show that the group interactions ac-cord with the group additivity, increasing with the increasing number of nitroamino groups. The dis-tance between substituents influences the interactions. Detonation performances were evaluated by the Kamlet-Jacobs equations based on the predicted densities and heats of formation, while thermal stability and pyrolysis mechanism were studied by the computations of bond dissociation energy (BDE). It is found that the contributions of nitroamino groups to the detonation heat, detonation velocity, detonation pressure, and stability all deviate from the group additivity. Only 3a, 3b, and 9a-9c may be novel potential candidates of high energy density materials (HEDMs) according to the quantitative cri-teria of HEDM (ρ≈ 1.9 g/cm3, D ≈ 9.0 km/s, P ≈ 40.0 GPa). Stability decreases with the increasing number of N-NO2 groups, and homolysis of N-NO2 bond is the initial step in the thermolysis of the title com-pounds. Coupled with the demand of thermal stability (BDE > 20 kcal/mol), only 1,2,4-trinitrotriazacy-clohexane and 1,2,4,5-tetranitrotetraazacyclohexane are suggested as feasible energetic materials. These results may provide basic information for the molecular design of HEDMs.

关键词： density functional theory (DFT) substituent effect monocyclic nitramine high energy density material (HEDM) group interaction detonation performance thermal stability bond dissociation energy (BDE)

Effects of N-1 substituent on the phototoxicity of fluoroquinolone antibiotics: comparison of pefloxacin and difloxacin

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Nuclear Science and Techniques 2020年第7期31卷 34-45页

作者： Jian-Feng Zhao Yan-Cheng Liu Yu-Lie Xu Wen-Feng Wang Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Science Beijing 100049China

The photophysics and photochemistry of pefloxacin(PEF),a 1-ethyl-substituted fluoroquinolone(FQ)antibiotic,were studied using transient,steady-state experimental methods and computational methods.The fundamental photoproperties of PEF and its phototoxicity toward lysozyme,a single-chain protein,were compared with those of a 1-fluorophenyl-substituted FQ antibiotic,difloxacin(DIF).The results showed that the phototoxicity was significantly decreased by the insertion of the bulky1-fluorophenyl substituent(the phototoxicity of DIF was approximately one-quarter of that observed for PEF).This trend was attributed to the lowest lying singlet state with sizeable oscillator strength(f C 0.1)being shifted from319 nm in PEF to 266 nm in DIF upon the insertion of the bulky substituent at the 1-position,as investigated by using computational methods.In addition,95%of the solar UV irradiation that reaches the earth’s surface has wavelength[315 nm.Therefore,reducing the most effective excitation wavelength by optimizing the substituent at the1-position may be a promising strategy to alleviate the phototoxicity of FQ antibiotics.These findings may be applied to other FQ antibiotics because a large number of phototoxicity studies on FQ antibiotics with different substituents at the 1-position can prove these finding’s effectiveness.Delafloxacin,an FQ antibiotic bearing a chlorine and bulky substituent at the 8-and 1-positions,respectively,exhibits no phototoxicity is the most recent example reported to date.To the best of our knowledge,this is the first transient and steady-state study of the effect of the N-1 substituent on the photochemistry and phototoxicity of FQ antibiotics.These findings will be beneficial to the development of novel FQ antibiotics without phototoxicity.

关键词： substituent transient photochemistry

Electron structure and substituent effects in o-,m-,p-IC_6H_4OCH_3 iodoanisoles

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Science China Chemistry 2009年第11期52卷 1932-1937页

作者： TONG ShengRui,WANG WeiGang,MA ChunPing,GE MaoFa & WANG DianXun Beijing National Laboratory for Molecular Sciences(BNLMS),State Key Laboratory for Structural Chemistry of Unstable and Stable Species,Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,China Beijing National Laboratory for Molecular Sciences (BNLMS) State Key Laboratory for Structural Chemistry of Unstable and Stable Species Institute of Chemistry Chinese Academy of Sciences Beijing China

The electronic structures and substituent effects in o-,m-,and p-iodoanisoles have been investigated by ultraviolet photoelectron spectroscopy(UPS).The observed UPS bands were analyzed by combining empirical arguments and theoretical methods.Owing to the electron-donating nature of both iodoand methoxy substituents,the first ionization potentials of the three iodoanisoles are lower than those of iodobenzene and anisole.The presence of the two substituents in iodoanisoles leads to an electronrich structure,which might contribute to the observed high reactivity of iodoanisoles in a number of organic reactions.

关键词： electronic structures substituent effects ultraviolet photoelectron spectroscopy reactivity

Theoretical Studies on the Aminolysis of Ester: Effects of the Catalysis and substituent to the Reaction of Methyl Indole-3-acetate with Ammonia

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Chinese Journal of Structural Chemistry 2019年第6期38卷 855-866页

作者：张亮陈容梁国明 College of Chemistry Chongqing Normal University

A comprehensive exploration of the aminolysis mechanism for methyl indole-3-acetate with ammonia is carried out by employing the B3 LYP/6-311++G(d,p), M06-2 X/6-311++G(d,p) and MP2/6-311++G(d,p)//M06-2 X/6-311++G(d,p) levels. Two alterative reaction channels of the concerted and addition/elimination stepwise processes including the uncatalyzed, base-catalyzed reactions are taken into consideration. Subsequently, the substituent effects and solvent effects in methanol are also evaluated at the M06-2 X/6-311++G(d,p) level. The calculated results indicate that the calculated values of M06-2 X level are quite close to those of MP2, the stepwise pathway has more advantages to the concerted one for all of the reaction processes and the catalyst facilitates the proton migration and decreases the energy barriers as well. It is shown that the most preferred mechanism is the based-catalyzed stepwise process, the substituent of NH2 group slightly accelerates all the aminolysis reaction processes, and the solvent effect does not remarkably change the mechanism of the reaction.

关键词： aminolysis methyl indole-3-acetate mechanism catalytic effect substituent effect

Theoretical studies on the spectroscopic properties and the substituent effects of pyridyl triazole Os(Ⅱ) complexes

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Science China Chemistry 2009年第3期52卷 261-265页

作者： WU YuHui, ZHOU Xin & ZHANG HongXing State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China State Key Laboratory of Theoretical and Computational Chemistry Institute of Theoretical Chemistry Jilin University Changchun China

To explore the spectroscopic properties of pyridyl triazole Os(Ⅱ) complexes and how the substituent effects affect the spectroscopic properties of [Os(ptz)2L2] (L=PH3; ptzH=(2-pyridyl)-1,2,4-triazole) (1), [Os(bptz)2L2] (bptzH=3-tert-butyl-5-(2-pyridyl)-1,2,4-triazole) (2), [Os(fptz)2L2] (fptzH=3- (trifluoreomethyl)- 5-(2-pyridyl)-1,2,4-triazole) (3), and [Os(fbtz)2L2] (fbtzH=3-(trifluoreomethyl)-5-(4-tert-butyl- 2-pyridyl)-1,2, 4-triazole) (4), the density functional theory (DFT) method at the B3LYP level was used to optimize the geometrical structures in the ground and excited state. The absorption and emission properties of the dichloromethane solution were predicted at the time-dependent density functional theory (TD-DFT, B3LYP) level associated with the PCM solvent effect model, the transitions characters of them were assigned. Important correlations between substituent effects and emission spectra and the quantum yield have been obtained by comparing and analyzing the calculated results.

关键词： pyridyl triazole Os(Ⅱ) complexes excited state density functional theory TD-DFT substituent effects

Theoretical Insights into the substituent Effects on the Fluorescence of Boron Complexes of 2-(Benzothiazol-2-yl)phenols: a Quantum Mechanics Study

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Chinese Journal of Structural Chemistry 2020年第2期39卷 243-254,184页

作者：李会学王晓峰朱元成袁焜吕玲玲李志锋 School of Chemical Engineering and Technology Tianshui Normal UniversityTianshui 741001China

The performance of organic fluorescent materials can be improved by chemical substitutions with auxochrome groups such as amino to increase solubility, alter emitting color, or modify film quality. The complex 6,6-difluoro-6-bora-5-oxa-11-thia-6 a-aza-benzo[a]fluorine(BOBTP) and its derivatives, which possess excellent luminescent property at room temperature, were theoretically simulated by density functional theory. The geometries of the ground state and the first excited state of BOBTPs complexes were investigated and their bond parameters were obtained. Further, these bond parameters are compared with each other, and the computational wavelengths of maximum absorption and emission of studied complexes match up with the experimental values. It was found that amino substituent bonding to appropriate positions of BOBTP can reduce the reorganization energy significantly, which is ascribed to electron-donating effect of the amino group. The reorganization energy also plays an important role in the fluorescence quantum yield of all the BOBTPs. In particular, the radiative decay of complexes 3 and 4 is dominant due to the smaller reorganization energies, so their fluorescence quantum yield is almost 1, on the contrary the non-radiative decay and intersystem crossing rate of both the 1 and 2 can not be ignored for the larger reorganization energies, and the corresponding fluorescence quantum yields were calculated when the radiative decay rate(kr) and nonradiative decay rate(k(nr)) were taken into account.

关键词： theoretical study fluorescence spectrum BOBTPs substituent effects

Structure-property relationships of fluoroolefins 7.substituent effects on the kinetic parameters of the thermal dimerization of trifluorostyrenes

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化学学报(英文版) 1985年第4期3卷 369-375页

作者： JIANG Xi-Kui JI Guo-Zhen YU Chong-Xi Shanghai Institute of Organic Chemistry,Academia Sinica,345 Lingling Lu,Shanghai,China Shanghai Institute of Organic Chemistry Academia Sinica 345 Lingling Lu Shanghai China

The rate constants（k2）of the thermal dimerization of seven substituted trifluorostyrenesin n-hexane solution have been determined in the temperature range 110°—160℃.In general,nogood correlation can be obtained with various Hammett type substituent parameters,e.g.,σ,σ+,σ-,σ0,σR,σR+,σR-,and σR0 etc.These results accord with the view that in addition to the polar effects,theabilities of the substituent to delocalize the spin also play important roles in affecting the rates ofdimerizations.Rationalizations for previously reported successful correlations of polar substituentconstants with radical reactions are presented.

关键词： substituent hexane substituted constants polar affecting stabilize rings thermally bonds

Derivatization based on tetrazine scaffolds:synthesis of tetrazine derivatives and their biomedical applications

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Organic Chemistry Frontiers 2022年第2期9卷 481-498页

作者： Hongbao Sun Qinghe Xue Chang Zhang Haoxing Wu Ping Feng Huaxi MR Research Center(HMRRC) Department of RadiologyFrontiers Science Center for Disease-related Molecular NetworkNational Clinical Research Center for GeriatricsFunctional and Molecular Imaging Key Laboratory of Sichuan ProvinceWest China HospitalSichuan UniversityChengdu 610041China Clinical Trial Center West China Hospital of Sichuan UniversityChengdu 610041China

Bioorthogonal chemistry is widely used in biological systems and has been trialed in patients,attracting a lot of attention in this century.Tetrazine-based bioorthogonal reactions are essential in chemical biology applications,including cellular labeling,live-cell imaging,diagnosis,drug release,and oncotherapy,due to their tunable rapid reaction kinetics and unique fluorogenic characteristics.However,the scope of de novo tetrazine synthesis is restricted due to the limited supply of commercial starting materials.Therefore,derivatization based on tetrazine scaffolds has been used to synthesize various tetrazine derivatives to enhance the applications of tetrazine bioorthogonal reactions.Herein,the recent advances in tetrazine scaffold-based derivatizations,including tetrazine skeletons,aromatic substituents and alkyl substituents of tetrazines,have been summarized.The advantages and limitations of the derivatization methods and applications of the developed tetrazine derivatives in bioorthogonal chemistry have also been highlighted.

关键词： materials. synthesis substituent

Molecular rotor based on an oxidized resorcinarene

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Organic Chemistry Frontiers 2022年第1期9卷 39-50页

作者： Daniel T.Payne Jan Labuta Zdeněk Futera Václav Březina Lenka Hanyková Mandeep K.Chahal Jonathan P.Hill International Center for Materials Nanoarchitectonics National Institute for Materials ScienceNamiki 1-1TsukubaIbaraki 305-0044Japan bInternational Center for Young Scientists National Institute for Materials ScienceNamiki 1-1TsukubaIbaraki 305-0044Japan Institute of Physics Faculty of ScienceUniversity of South BohemiaBranišovská1760ČeskéBudějovice 37005Czech Republic Faculty of Mathematics and Physics Charles UniversityV Holešovičkách 218000 Prague 8Czech Republic

Molecular rotors are an important class of dynamic molecules which have been studied not only for their possible uses as components of molecular machines but also because of potential applications as probes of local viscosity in biological media,especially self-assembled membranes.For the former,factors affecting rotational motility are critical while for the latter the rotor activity must be complexed with an output signal(often fluorescence)for reporting of local conditions.Molecular single stator-double rotor activity of an oxidized resorcinarene(fuchsonarene)macrocycle containing unsaturated hemiquinonoid groups at its meso positions was investigated.Fuchsonarenes contain two hemiquinonoid substituents at diagonally-opposed meso-positions with two electron rich phenol groups at the remaining meso-positions between the hemiquinonoid groups.All meso-substituents are in proximity at one side of the resorcinarene macrocycle(so-called rccc-type isomer)with rotational activity of the phenol meso-substituents.Rotation rates of the phenol moieties can be controlled by varying temperature,solvent polarity and acidity of the medium of study with rotation being thermally activated in neutral and acidic media and tunable in the range from 2 s^(−1) to 20000 s^(−1).Experimental and computational data indicate that rotation of the mobile phenol meso-substituents is remotely affected by interactions with acidic solvents at the carbonyl CvO groups of macrocyclic acetyloxy groups,which occurs with the emergence of a lower energy electronic absorption band whose intensity is correlated with both the acidity of the medium and the rotation rate of the phenol substituents.Time-dependent DFT calculations suggest that the low energy band is due to a molecular conformational adjustment affecting electronic conjugation caused by strong interaction of macrocyclic acetyloxy carbonyl groups with the acid medium.The work presents a molecular mechanical model for estimating solution acidity and also gives insight into a possible method for

关键词： substituent rotation oxidized