Pyrrole and Pyrimidine Derivatives as Possible Electron Donors for Colored Charge-Transfer Complexes with a Weakly Electrophilic Energetic Material,FOX-7:A Theoretical Study

A number of electron-rich heterocycles are studied as potential reagents for visual colorimetric detection of FOX-7 due to colored charge-transfer complexes formation.The obtained results suggest that pyrrole and pyrimidine derivatives can form such complexes playing the role of electron donors despite a low electrophilicity of FOX-7.Density functional theory calculations,as well as quantum theory of atoms in molecules analysis,suggest stacking binding mode as the most preferable one with the binding energy of about 21-36 kJ/mol.All the complexes demonstrate a clear single charge-transfer absorption band in the visible region and the expected colors of the complexes are varying from violet and blue to red and orange.The calculations of the crystalline state of the studied complexes indicate high lattice energies,which are higher than that of pure FOX-7 and are close to the recently reported hydrogen-bonded complex of FOX-7 with 1,10-phenanthroline.Additional analysis of the studied charge-transfer complexes using properties based on density difference grids clearly suggests the acceptor role of FOX-7 in the complexes.This analysis can be effectively applied to identify the nature of other possible complexes of FOX-7,in which its role is unclear because of the specific reactivity,namely,both weak electrophilic and nucleophilic properties at the same time.

Charge-Transfer and SERS Coupling on TiO2

We report the SERS enhancements of Raman forbidden surface modes of TiO2 in different sized TiO2 crystals. This current study utilizes the relationship between the vibronic coupling and the degree of charge-transfer to explain the differences of Surface Enhanced Raman Scattering (SERS) enhancements. Our study shows a direct correlation between the degree of charge-transfer and vibronic coupling. This relationship suggests that charge-transfer between the N-719 dye and TiO2 due to vibronic coupling plays a fundamental role in SERS enhancements. Furthermore, this study shows a strong dependence of the enhancements of the N-719 dye molecular modes to that of the surface modes. This indicates that the mechanism that governs the enhancements of the surface modes in TiO2 crystals most likely also dictates the enhancements of the N-719 dyes.

Sensitive Spectrofluorimetric Method for Determination of Fluoroquinolones through Charge-Transfer Complex Formation

A sensitive spectrofluorimetric method was developed for determination of ciprofloxacin (CPFX), levofloxacin (LEV), gatifloxacin (GAT) and moxifloxacin (MOX) in pure, commercial formulations, human urine and plasma. The method is based on charge-transfer (CT) complex with chloranilic acid. Fluorescence intensity of the complexes was measured at emission wavelength ranging from 445-492 nm with excitation wavelengths from 285-330 nm. At optimum experimental conditions, a linear calibration plot was obtained in the concentration range of 20-1000 ng·mL-1, 60-320 ng·mL-1, 20-800 ng·mL-1 and 20 -00 ng·mL-1 for CPFX, LEV, MOX and GAT, respectively with good correlation coefficient in the range of 0.9929-1.0 in methanolic medium. The limit of detection and limit of quantification were found to be 5 ng·mL-1 and 18 ng·mL-1 for CPFX, 12 ng·mL-1 and 40 ng·mL-1 for LEV, 8 ng·mL-1 and 19 ng·mL-1 for MOX, 6 ng·mL-1 and 19 ng·mL-1 for GAT, respectively. The method was found free of interferences from excipients used as additive in pharmaceutical preparations, some common cations and compounds present in urine and plasma as well as co-administered analgesic, vitamins and other drugs. The method was successfully applied for quantification of selected fluoroquinolones in commercial formulations and also in spiked human urine and plasma samples with percent recoveries of 100.0 ± 1.56 and 100.2 ± 1.29 respectively.

REACTIVITY RATIOS FOR COPOLYMERIZATION WITH THE PARTICIPATION OF A CHARGE-TRANSFER COMPLEX

The complexation between styrene (St) and N-phenylmaleimide (PMI) was investigated by H-1-NMR spectroscopy, and the existence of a complex was proved. The equilibrium constant of St/PMI in chloroform at 50 degrees C was determined to be 0.27. New elementary propagation reactions were proposed. On the basis of the propagation elementary reactions for copolymerization with the participation of a charge-transfer complex (CTC), a method for measuring the reactivity ratios is presented. Four reactivity ratios and relative reactivities of free monomer and CTC were obtained. They are r(12) = 0.034, r(21) = 0.012, r(1C) = 0.0030, r(2C) = 0.0034, and k(1C)/k(12) = 11.34, k(2C)/k(21) = 3.42.

Anisotropic electrical conductivity, phase transition and thermal hysteresis of a charge-transfer salt dibutylammonium bis-7,7,8,8-tetracyanoquinodimethane DBA(TCNQ)_2

This paper reports that a charge-transfer salt dibutylammonium bis-7,7,8,8-tetraeyanoquinodimethane [DBA （TCNQ）2] has been prepared. The temperature dependences of the DC electrical conductivity of the DBA （TCNQ）2 single crystal measured along the crystallographic a, b, and c axes are reported. The crystal shows semicondueting behaviour and the room-temperature conductivities are highly anisotropic （σa = 3.63× 10^-4S/cm, σb = 2.84× 10^-6S/cm, and （σe = 1.82 × 10^-5S/cm）. Particularly, a sharp semiconductor to semiconductor transition has been observed around 270 K on the resistivity curves measured under cooling and heating. In addition, thermal hysteresis phenomena on conductivity and differential scanning calorimetry curves are also reported.

^(19)F NMR Study on the Charge-Transfer Process between Ground-State Acceptor Fluoranil (or Pentafluorophenyl Carboxylate) and Some N-Alkylphenothiazine Donors

The line positions of 19F NMR absorption of fluoranil (TFQ) or pentafluorophenylcarboxylate (PFE-16) in the presence of N-alkylphenothiazine donors have been measured. By comparing the 19F chemical shift in C6D6 of TFQ or PFE-16 in the absence of the donor with thosein the presence of the donor. the difference of these chemical shifts was found to be large. In thepresence of the donor. 19F upheld shifts of TFQ or PFE-16 have been observed. The experimentalresults showed that there is a charge-transfer process between TFQ or PFE-16 and the donor .When TFQ or PFE-16 accepts the charge from the donor. its 19F resonance moves upfield.

Highly efficient H-bonding charge-transfer complex for microsupercapacitors under extreme conditions of low temperatures

Owing to sluggish ionic mobility at low temperatures, supercapacitors, as well as other energy-storage devices, always suffer from severe capacity decay and even failure under extreme low-temperature circumstances. Solar-thermal-enabled self-heating promises an attractive approach to overcome this issue.Here, we report a unique H-bonding charge-transfer complex with a high photothermal conversion efficiency of 79.5% at 405 nm based on chloranilic acid and albendazole. Integrated with a microsupercapacitor, the chloranilic acid-albendazole complex(CAC) film prompts an apparent temperature increase of 22.7 °C under 1 sun illumination at-32.6 °C, effectively elevating the working temperature of devices.As a result, the rate capability of the microsupercapacitor has been significantly improved with a 17-fold increase in capacitance at a current density of 60 μA cm^(-2), leading to outstanding low-temperature performances. Importantly, the integrated device is capable of working at a low temperature of-30 °C in the open air, which demonstrates the potential of CAC in practical applications for low-temperature ultracapacitive energy-storage devices.

Preparation and Crystal Structure of a Charge-transfer Complex between an Organic Substrate and Molybdosilicic Acid [(CH_3)_2NH(CH_2)C_6H_5]_4SiMo_(12)O_(40)·2CH_3CN·H_2O

The charge transfer complex N,N-dimethylbenzylamine which is between the molybdosilicic acid and organic substrate has been prepared. Yellow crystals of the title compound ([(CH3)2NH(CH2)C6H5]4SiMo12O402CH3CNH2O) were synthesized from the mixture of water and acetonitrile. The single-crystal X-ray analysis reveals that the crystal crystallizes in triclinic system, space group P1 with a = 13.313(2), b = 14.673(2), c = 19.736(3) ? a = 86.22(1), b = 88.76(1), g = 66.97(1), V = 3540.2(9) 3 and Z = 2. The anion has the Keggin structure. The MoO bond distances range from 1.675(3) to 1.691(3) ?for the terminal oxygen atoms, 1.798(3) to 2.045(3) ?for the bridging ones, and 2.328(3) to 2.361(3) ?for those in the SiO4 tetrahedron. The SiO bond distances fall in the range of 1.623(3)～1.630(3) ?

Charge-transfer interaction of drug quinidine with quinol,picric acid and DDQ: Spectroscopic characterization and biological activity studies towards understanding the drug–receptor mechanism

Investigation of charge-transfer （CT） complexes of drugs has been recognized as an important phenomenon in understanding of the drug-receptor binding mechanism. Structural, thermal, morpholo-gical and biological behavior of CT complexes formed between drug quinidine （Qui） as a donor and quinol （QL）, picric acid （PA） or dichlorodicyanobenzoquinone （DDQ） as acceptors were reported. The newly synthesized CT complexes have been spectroscopically characterized via elemental analysis;infrared （IR）, Raman, 1H NMR and electronic absorption spectroscopy; powder X-ray diffraction （PXRD）;thermogravimetric （TG） analysis and scanning electron microscopy （SEM）. It was found that the obtained complexes are nanoscale, semi-crystalline particles, thermally stable and spontaneous. The molecular composition of the obtained complexes was determined using spectrophotometric titration method and was found to be 1：1 ratios （donor：acceptor）. Finally, the biological activities of the obtained CT complexes were tested for their antibacterial activities. The results obtained herein are satisfactory for estimation of drug Qui in the pharmaceutical form

CHARGE-TRANSFER AND ENERGY-TRANSFER IN THE PHOTO-INDUCED COPOLYMERIZATION OF 2-VINYLNAPHTHALENE WITH MALEIC ANHYDRIDE

The initiation mechanism of the copolymerization of 2-vinylnaphthalene with maleic anhydride was studied under irradiation of 365 nm. The excited complex was formed from (1) the local excitation of 2-vinylnaphthalene followed by the charge-transfer interaction with maleic anhydride and (2) the excitation of the ground state charge-transfer complex, and then it collapsed to 1,4-tetramethylene biradical for initiation. A1: 1 alternating copolymer was formed in different monomer feeds. Addition of benzophenone could greatly enhance the rate of copolymerization through energy-transfer mechanism.

SPECTROPHOTOMETRIC STUDY OF DDQ CHARGE-TRANSFER COMPLEXES WITH 1,10-PHENANTHROLINE AND ITS DERIVATIVES

1,10-phenanthroline and its derivatives can form charge-transfer complexes with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone(DDQ).The absorption spectra and conditions of complex formation,such as the reaction time,the quantity of DDQ, and the solvents, have been studied.After the HMO calculation of phenanthrolines,the molar absorptivities were found to depend on the substituents on the phenanthroline rings.

Study on Alternating LB Films of Charge-Transfer Complex of Octadecyl-TCNQ and Copper Phthalocyanine Derivative

Infrared spectra of alternating LB films of octadecyl-TCNQ/CuPc are studied. Charge-transfer complexes are formed in LB films and conductance increases about three orders than that of pure CuPc LB films.

美国高等教育国际化发展动向及中国的应对策略

当前,在全球化迅猛发展的大背景下,高等教育正面临全新的机遇与挑战。高等教育国际化作为应对全球化的重要利器,成为美国在高等教育领域制胜的重要工具。通过分析美国高等教育国际化的政策框架,探明其高等教育国际化政策机制,分析其高等教育国际化当前政策和计划,为我国应对高等教育全球化提出可行性战略举措。我国高等教育国际化发展需要构建国际化运行体系、鼓励跨文化交流活动、探索在地国际化活动、搭建国际合作交流平台、加强国际协作与沟通。只有立足当前、放眼长远,在国际化大环境中寻找全新定位,才能为培养全球化创新人才提供内生动力和战略转机。

上消化道出血SATE诊断及介入栓塞止血的临床观察

目的分析超选择性血管造影(SATE)在上消化道出血中的诊断价值及经导管栓塞治疗消化道出血的有效性。方法选取我院收治的67例上消化道出血患者作为研究对象,均接受超选择性血管造影检查,其中26例有手术病理结果,比较SATE与手术病理符合度,明确其定性、定位价值;对符合栓塞适应证的血管造影阳性者,行经导管栓塞止血,评估止血效果。结果本组67例中,SATE明确出血灶及出血血管50例,阳性率为74.63%;26例有明确手术病理结果且SATE诊断阳性者中,SATE与手术病理定性、定位符合率分别为76.92%、84.62%。本研究50例SATE阳性者中,37例行经导管插管栓塞治疗,止血成功率为86.49%。结论 SATE对上消化道出血患者出血灶定位、定性均有较高的准确性,配合经导管栓塞治疗,可提高即刻止血成功率。

基于OBE与系统韧性分析的城市管理专业建设研究

城市管理的客体是“物理+人理+事理”巨系统,具有综合性、专业性、复杂性和动态性特点。本文在充分分析城市的系统特征基础上,深度剖析多技术环节与多场景组合的城市常态监管与应急管理多维度内涵,以新时代城市管理的要求倒推对应的专业建设要求,一是应用OBE思路建立三层级城市管理专业教育教学目标体系。二是引入生态系统韧性保持的思路,结合城市管理技术复合型特点,提出并设计了包含辨识、预测、控制与评估等四环节以及工程、信息、安全与应急等四模块的专业建设框架,并对框架内部逻辑关系进行了阐释。三是应用课程地图方法,以城市安全与应急为典型建立了能力模型,并在此基础上提出了对应的多映射课程框架。

Organic stoichiometric cocrystals with a subtle balance of charge-transfer degree and molecular stacking towards high-efficiency NIR photothermal conversion

Charge-transfer(CT)stoichiometric cocrystals are promising choice of organic materials for unveiling the structure-property relationship.However,due to the contradiction between large CT degree required for strong NIR absorption and flexible molecular stacking,construction of stoichiomorphism-based cocystals with near-infrared(NIR)photothermal property remains challenging.Herein,the first example of stoichiomorphism-based photothermal cocrystals were accomplished through the adaptive assembly of 3,3,5,5-tetramethylbenzidine(TMB)donor and 1,2,4,5-tetracyanobenzene(TCNB)acceptor.The selective cocrystallization could be controlled by varying the donor-acceptor stoichiometries via a surfactantassisted method,resulting in two cocrystals with 1:1(T1C1)and 1:2(T2C1)stoichiometries.The absorbance intensity of T1C1 at 808 nm was nearly twice that of T2C1,while the photothermal conversion efficiency(PCE)of the former was 60.3%±0.6%,approximately 80%of that for the latter(75.5%±2.6%),which might be caused by the different intermolecular interactions in distinct molecular stacking patterns.Notably,both excellent PCEs of stoichiometric cocrystals were attributed to the nonradiative transition process,including internal conversion and charge dissociation processes,as elucidated by femtosecond transient absorption spectroscopy measurements.Furthermore,T1C1 was used as an NIR heater for preparing agarose-based photothermal hydrogel,showing great potential for light-controlled in-situ gelation.This strategy of balancing the CT degree and molecular packing orientation not only uncovered the relationship between stoichiometric stacking and photothermal property,but also provided an opportunity to develop advanced organic optoelectronic materials.

Cation-Anion Redox Active Organic Complex for High Performance Aqueous Zinc Ion Battery

Organic redox compounds are attractive cathode materials in aqueous zinc-ion batteries owing to their low cost,environmental friendliness,multiple-electron-transfer reactions,and resource sustainability.However,the realized energy density is constrained by the limited capacity and low voltage.Herein,copper-tetracyanoquinodimethane(CuTCNQ),an organic charge-transfer complex is evaluated as a zinc-ion battery cathode owing to the good electron acceptation ability in the cyano groups that improves the voltage output.Through electrochemical activation,electrolyte optimization,and adoption of graphene-based separator,CuTCNQ-based aqueous zinc-ion batteries deliver much improved rate performance and cycling stability with anti-self-discharge properties.The structural evolution of CuTCNQ during discharge/charge are investigated by ex situ Fourier transform infra-red(FT-IR)spectra,ex situ X-ray photoelectron spectroscopy(XPS),and in situ ultraviolet visible spectroscopy(UV-vis),revealing reversible redox reactions in both cuprous cations(Cu^(+))and organic anions(TCNQ^(x-1)),thus delivering a high voltage output of 1.0 V and excellent discharge capacity of 158 mAh g^(-1).The remarkable electrochemical performance in Zn//CuTCNQ is ascribed to the strong inductive effect of cyano groups in CuTCNQ that elevated the voltage output and the graphene-modified separator that inhibited CuTCNQ dissolution and shuttle effect in aqueous electrolytes.

Photoluminescent nickel(Ⅱ)carbene complexes with ligand-to-ligand charge-transfer excited states

While nickel(II)complexes have been widely used as catalysts for carbon-carbon coupling reactions,the exploration of their photophysical and photochemical properties is still in the infancy.Here,a series of square-planar Ni(II)complexes[(diNHC)NiX2]bearing chelating benzimidazole-based bis(N-heterocyclic carbene)ligands and varying anionic coligands(1,X=Cl;2,X=Br;3,X=I)are synthesized and structurally characterized.In solid state,both 1 and 2 exhibit orange-red photoluminescence under ambient conditions.The photophysical and electrochemical measurements along with density functional theory(DFT)calculations reveal that the low-energy emissions can be attributed to singlet excited states with ligand-to-ligand charge-transfer(LLCT)character.This work suggests that strong-field N-heterocyclic carbene ligands play a crucial role to achieve the luminescence of Ni(II)complexes.

气固两相湍流非定常压力脉动特性数值模拟研究

与发动机振荡燃烧相关的气固两相流中的压力脉动现象长期以来备受关注。为了解发动机气固两相流动中的非定常压力脉动特性,以典型的后台阶气固两相流动为研究对象,使用发展的自适应湍流模拟(Self-adaptive turbulence eddy simulation,SATES)和离散相模型(Discrete phase model,DPM)相结合的方法,对两相流场进行了三维非定常高精度数值计算。以实验数据作为参考验证了计算方法的精度和可靠性。通过将两相流场的压力脉动信号与纯气相流场进行对比,发现加入颗粒后流场压力脉动主导频率略有变化,无量纲压力脉动幅值明显减小;进一步研究了固体颗粒直径和质量分数对脉动特性的影响规律,发现随着颗粒直径变大,流场振幅先减小后增大。颗粒直径为10μm时,振幅最小;随着质量分数的增大,流场振幅呈现出下降趋势。研究表明气固两相流中颗粒的参数变化对振荡主频影响较小,对脉动振幅影响显著。

SATE培训管理模式

D公司是一家专门提供移动通信网络整体解决方案的高科技公司，多年来，其凭借领先的科技实力，取得了良好的效益．目前已是通信产业的领航人。