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 pyri...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.展开更多
We report the SERS enhancements of Raman forbidden surface modes of TiO<sub>2</sub> in different sized TiO<sub>2</sub> crystals. This current study utilizes the relationship between the vibroni...We report the SERS enhancements of Raman forbidden surface modes of TiO<sub>2</sub> in different sized TiO<sub>2</sub> 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 TiO<sub>2</sub> 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 TiO<sub>2</sub> crystals most likely also dictates the enhancements of the N-719 dyes.展开更多
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. T...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.展开更多
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 re...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.展开更多
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 w...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.展开更多
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. So...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.展开更多
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...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) ?展开更多
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 q...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.展开更多
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.
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-pla...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.展开更多
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...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.展开更多
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 TF...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.展开更多
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 beh...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展开更多
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 ...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.展开更多
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...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.展开更多
The main task of this article was to prepared of new pigment model in situ solar cells accordance to charge-transfer complexes of rhodamine C(RhC) donor as dye laser gain media with iodine(σ-acceptor) and chloranilic...The main task of this article was to prepared of new pigment model in situ solar cells accordance to charge-transfer complexes of rhodamine C(RhC) donor as dye laser gain media with iodine(σ-acceptor) and chloranilic acid, CLA(π-acceptor). The synthesis stoichiometry of these complexes were of 1∶2(donor∶acceptor) with general formulas [(RhC)]I·I3 and [(RhC)(CLA)2]. The discussed data of elemental analysis, conductivity measurements, FT-IR, UV-Vis spectroscopy and photometric titration data visualized the stoichiometry, formula and complexity of the complexes. The physicochemical and spectroscopic analyses obtained suggested that the electron transfer occurred through nitrogen atom in a tertiary amine —N(C2H5)2 of RhC donor with acceptor. The synthesized solid complexes were under go to thermogravimetric analyses to investigate their thermal stability and decomposition steps. The molar conductance measurements revealed that RhC complexes have an electrolytic statement. The thermal stability of rhodamine C complexes was enhanced in comparable with RhC itself. The polymer membranes of poly-methyl methacrylate)(PMMA) combined with the RhC charge(transfer complexes in chloroform solvent have been prepared and characterized by(infrared & electronic) spectroscopy and scanning electron microscopy(SEM) morphological examination. The photo-stability properties of the RhC complexes have been investigated.展开更多
UV-Vis absorption spectra of the molecular complex formed by imidazole （Ira） and chloranil （CA） were measured in chloroform. The stoichiometry of the imidazole-chloranil （hn-CA） complex was determined as 1：1 by...UV-Vis absorption spectra of the molecular complex formed by imidazole （Ira） and chloranil （CA） were measured in chloroform. The stoichiometry of the imidazole-chloranil （hn-CA） complex was determined as 1：1 by applying Benesi-Hildebrand＇s equation and Job＇s continuous variation method. Density function theory （DFT） and MP2 calculations were performed to study the structures and the binding energies of the Im-CA complex. The calculations located four conformations （denoted as S1-S4） for the Ira-CA complex, two edge（Im）-to-face（CA） linked and two edge（Im）-to-edge（CA） linked. It was found that the edge-to-face conformers are more stable than the edge-to-edge ones. The bonding characteristics of these conformers were investigated with natural population analysis （NPA）, topological analysis of electron density, and natural bond orbital （NBO） analysis. It was revealed that the edge-to-face conformers are charge-transfer （CT） complexes whereas the edge-to-edge conformers are the hydrogen bond complexes. For the most stable conformation of the Ira-CA complex （S1）, the charge transfer interaction of the imidazole n（N15） lone pair orbital with the chloranil π＊ （C1=O7） orbital plays a crucial role in the Ira-CA binding, and the binding is further strengthened by the O7… H2O hydrogen bond. The electronic excitation energies of the complex （S1） were calculated with time-dependent DFT （TDDFT）, and the observed UV-Visible spectrum of the complex was analyzed based on the computed results.展开更多
Purpose: Tenofovir disoproxil fumarate (TEN) and emtricitabine (EMT) are both second generation ant-retroviral drugs used in the “treatment” of HIV/AIDS. The aim of this study is to establish the physic-chemical pro...Purpose: Tenofovir disoproxil fumarate (TEN) and emtricitabine (EMT) are both second generation ant-retroviral drugs used in the “treatment” of HIV/AIDS. The aim of this study is to establish the physic-chemical properties of their reaction with chloranilic acid in different solvent systems and to justify the chemical basis for simultaneous quantitative determination of these drugs in their combined formulation. Method: TEN and EMT were individually isolated from their single formulations and purified by chromatography to obtain secondary standard. Purity of the isolates were tested for by comparison with literature values. Stock solution of chloranilic acid (CA) [3.0 × 10﹣3 M] was prepared in the following solvents of different polarities: ethanol, acetonitrile, ethylacetate, chloroform and hexane. Equal volumes of CA and TEN [3.0 × 10﹣2 M] and EMT [3.0 × 10﹣2 M] dissolved in different solvents were mixed whereby colored products were observed. Absorption maxima were determined. Calibration curves were generated and validated. Quantitative simultaneous determination of TEN and EMT was determined by standard protocol. Stoichiometric relationships between the drugs and CA were established. Equilibrium constants were determined at different temperatures from which the Gibb’s free energies were calculated. Arrhenius equation was used to calculate the enthalpy, entropy was similarly calculated. Results: Absorption maxima of CA in different solvents are as follows: Ethanol 310 nm;Acetonitrile 330 nm;Ethyl acetate 340 nm;Chloroform 350 nm and hexane 310 nm. The complex of CA and TEN in the different solvents are: Alcohol 525 nm, Acetonitrile 500 nm;Ethyl acetate 505 nm;Chloroform 510 nm and hexane 515 nm. For EMT complex absorption maxima are: Alcohol 510 nm;Acetonitrile 515 nm’ Ethyl acetate 520 nm’ Chloroform 505 nm and hexane 530 nm. Simultaneous quantitative recovery values for TEN are: Ethanol;97.89% ± 1.21;Acetonitrile 101.17 V 1.51%;Ethyl acetate 96.55% ± 0.71%;Chloroform 99.11% ± 0.34% and hexane 98.03% ± 0.15%. For EMT the values are also: Ethanol: 98.92% ± 1.45%;Acetonitrile 100.471 ± 13;Ethyl acetate 97.06% ± 0.87%;Chloroform 99.31% ± 0.94% and Hexane 99.97% ± 1.63%. Stoichiometry of complexation showed a 1:1 ratio for both drugs. Equilibrium constants for TEN were highest in acetonitrile and least for Ethanol while for EMT, equilibrium constant was least for acetonitrile and highest in chloroform. Gibb’s free energy for TEN was least in ethanol and highest in acetonitrile. Gibb’s free energy for EMT was least in acetonitrile and highest in chloroform. Enthalpy for TEN was least in chloroform and highest in hexane. Similarly, the enthalpy for EMT was highest in chloroform and lowest in hexane. Conclusion: These results shows that solvent polarity influence charge transfer complexes in a non consistent fashion. The structure of the donor might have contributed to thermodynamics of complexation since orbital overlap may vary from solvent to solvent. For quantitative analysis hexane appears to be the most suitable solvent because it has the highest molar absorptivity and higher enthalpy of interactions. Molecules that can donate electrons and their stereochemistry could contribute to intensity of absorption maxima of the electronic transitions.展开更多
基金supported by the Ministry of Education and Science of Ukraine(No.0122U000760)。
文摘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.
文摘We report the SERS enhancements of Raman forbidden surface modes of TiO<sub>2</sub> in different sized TiO<sub>2</sub> 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 TiO<sub>2</sub> 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 TiO<sub>2</sub> crystals most likely also dictates the enhancements of the N-719 dyes.
文摘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.
基金financially supported by the National Natural Science Foundation of China(Nos.52102117,51173170,and 21773216)the joint project from the Henan-Provincial and the China-National Natural Science Foundations(No.U2004208)Key Science and Technology Program of Henan Province(No.202102310212)
文摘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.
文摘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.
基金supported by the National Natural Science Foundation of China (Nos. 51772116 and 51972132)Program for HUST Academic Frontier Youth Team (2016QYTD04)。
文摘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.
基金This work was supported by the Natural Science Foundation of Henan Province (20011500024)
文摘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) ?
基金Supported by the National Natural Science Funds.
文摘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.
文摘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.
基金the Natural Science Foundation of China(No.22175191)Y.C.thanks the financial support from CAS-Croucher Funding Scheme for Joint Laboratories and Beijing Municipal Science&Technology Commission(No.Z211100007921020).
文摘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.
基金Project supported by the National Natural Science Foundation of China (Grant No 10604038)the Program for New Century Excellent Talents in University (NCET-2007)
文摘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.
文摘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.
文摘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
基金Project Supported by the National Natural Science Foundation of China.
文摘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.
基金supported by the National Natural Science Foundation of China(Nos.22001006,22375002,22273057,22225401)the Anhui Provincial Natural Science Foundation(No.2308085Y10)+4 种基金the Open Project of Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Anhui University,Ministry of EducationThe National Key Research and Development Program of China(Nos.2022YFC_(2)403500,2020YFA0210800)The Universities Joint Laboratory of Guangdong,Hong Kong and Macao(No.130/07422011)the Natural Science Foundation of Guangdong Province(No.2022A1515011661)the China Postdoctoral Science Foundation(Nos.2023M730760,2023M740010)。
文摘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.
基金the Deanship of Scientific Research at Imam Abdulrahman Bin Faisal University(2017-143-CED)
文摘The main task of this article was to prepared of new pigment model in situ solar cells accordance to charge-transfer complexes of rhodamine C(RhC) donor as dye laser gain media with iodine(σ-acceptor) and chloranilic acid, CLA(π-acceptor). The synthesis stoichiometry of these complexes were of 1∶2(donor∶acceptor) with general formulas [(RhC)]I·I3 and [(RhC)(CLA)2]. The discussed data of elemental analysis, conductivity measurements, FT-IR, UV-Vis spectroscopy and photometric titration data visualized the stoichiometry, formula and complexity of the complexes. The physicochemical and spectroscopic analyses obtained suggested that the electron transfer occurred through nitrogen atom in a tertiary amine —N(C2H5)2 of RhC donor with acceptor. The synthesized solid complexes were under go to thermogravimetric analyses to investigate their thermal stability and decomposition steps. The molar conductance measurements revealed that RhC complexes have an electrolytic statement. The thermal stability of rhodamine C complexes was enhanced in comparable with RhC itself. The polymer membranes of poly-methyl methacrylate)(PMMA) combined with the RhC charge(transfer complexes in chloroform solvent have been prepared and characterized by(infrared & electronic) spectroscopy and scanning electron microscopy(SEM) morphological examination. The photo-stability properties of the RhC complexes have been investigated.
基金ACKNOWLEDGMENT This work was supported Science Foundation of China by the National Natural （No.20473078）.
文摘UV-Vis absorption spectra of the molecular complex formed by imidazole （Ira） and chloranil （CA） were measured in chloroform. The stoichiometry of the imidazole-chloranil （hn-CA） complex was determined as 1：1 by applying Benesi-Hildebrand＇s equation and Job＇s continuous variation method. Density function theory （DFT） and MP2 calculations were performed to study the structures and the binding energies of the Im-CA complex. The calculations located four conformations （denoted as S1-S4） for the Ira-CA complex, two edge（Im）-to-face（CA） linked and two edge（Im）-to-edge（CA） linked. It was found that the edge-to-face conformers are more stable than the edge-to-edge ones. The bonding characteristics of these conformers were investigated with natural population analysis （NPA）, topological analysis of electron density, and natural bond orbital （NBO） analysis. It was revealed that the edge-to-face conformers are charge-transfer （CT） complexes whereas the edge-to-edge conformers are the hydrogen bond complexes. For the most stable conformation of the Ira-CA complex （S1）, the charge transfer interaction of the imidazole n（N15） lone pair orbital with the chloranil π＊ （C1=O7） orbital plays a crucial role in the Ira-CA binding, and the binding is further strengthened by the O7… H2O hydrogen bond. The electronic excitation energies of the complex （S1） were calculated with time-dependent DFT （TDDFT）, and the observed UV-Visible spectrum of the complex was analyzed based on the computed results.
文摘Purpose: Tenofovir disoproxil fumarate (TEN) and emtricitabine (EMT) are both second generation ant-retroviral drugs used in the “treatment” of HIV/AIDS. The aim of this study is to establish the physic-chemical properties of their reaction with chloranilic acid in different solvent systems and to justify the chemical basis for simultaneous quantitative determination of these drugs in their combined formulation. Method: TEN and EMT were individually isolated from their single formulations and purified by chromatography to obtain secondary standard. Purity of the isolates were tested for by comparison with literature values. Stock solution of chloranilic acid (CA) [3.0 × 10﹣3 M] was prepared in the following solvents of different polarities: ethanol, acetonitrile, ethylacetate, chloroform and hexane. Equal volumes of CA and TEN [3.0 × 10﹣2 M] and EMT [3.0 × 10﹣2 M] dissolved in different solvents were mixed whereby colored products were observed. Absorption maxima were determined. Calibration curves were generated and validated. Quantitative simultaneous determination of TEN and EMT was determined by standard protocol. Stoichiometric relationships between the drugs and CA were established. Equilibrium constants were determined at different temperatures from which the Gibb’s free energies were calculated. Arrhenius equation was used to calculate the enthalpy, entropy was similarly calculated. Results: Absorption maxima of CA in different solvents are as follows: Ethanol 310 nm;Acetonitrile 330 nm;Ethyl acetate 340 nm;Chloroform 350 nm and hexane 310 nm. The complex of CA and TEN in the different solvents are: Alcohol 525 nm, Acetonitrile 500 nm;Ethyl acetate 505 nm;Chloroform 510 nm and hexane 515 nm. For EMT complex absorption maxima are: Alcohol 510 nm;Acetonitrile 515 nm’ Ethyl acetate 520 nm’ Chloroform 505 nm and hexane 530 nm. Simultaneous quantitative recovery values for TEN are: Ethanol;97.89% ± 1.21;Acetonitrile 101.17 V 1.51%;Ethyl acetate 96.55% ± 0.71%;Chloroform 99.11% ± 0.34% and hexane 98.03% ± 0.15%. For EMT the values are also: Ethanol: 98.92% ± 1.45%;Acetonitrile 100.471 ± 13;Ethyl acetate 97.06% ± 0.87%;Chloroform 99.31% ± 0.94% and Hexane 99.97% ± 1.63%. Stoichiometry of complexation showed a 1:1 ratio for both drugs. Equilibrium constants for TEN were highest in acetonitrile and least for Ethanol while for EMT, equilibrium constant was least for acetonitrile and highest in chloroform. Gibb’s free energy for TEN was least in ethanol and highest in acetonitrile. Gibb’s free energy for EMT was least in acetonitrile and highest in chloroform. Enthalpy for TEN was least in chloroform and highest in hexane. Similarly, the enthalpy for EMT was highest in chloroform and lowest in hexane. Conclusion: These results shows that solvent polarity influence charge transfer complexes in a non consistent fashion. The structure of the donor might have contributed to thermodynamics of complexation since orbital overlap may vary from solvent to solvent. For quantitative analysis hexane appears to be the most suitable solvent because it has the highest molar absorptivity and higher enthalpy of interactions. Molecules that can donate electrons and their stereochemistry could contribute to intensity of absorption maxima of the electronic transitions.
