The inclusion complexation behavior of 2,5-Bis(5-tert-butyl-benzoxazol-2yl)-thiophene (UVOB) with native β-cyclodextrin (βCD) and βCD-monochlorotriazinyl (βCD-MCT) was evaluated by fluorescence spectroscopy. The a...The inclusion complexation behavior of 2,5-Bis(5-tert-butyl-benzoxazol-2yl)-thiophene (UVOB) with native β-cyclodextrin (βCD) and βCD-monochlorotriazinyl (βCD-MCT) was evaluated by fluorescence spectroscopy. The association constant (K<sub>s</sub>), stoichiometry, , and were evaluated at 25℃ ± 0.1℃ in phosphate buffer solution (pH = 10.5, 0.1 mo•dm<sup>–3</sup>) in order to find out the complex formation ability and stability. Fluorescence enhancement for UVOB and UVBNB with both CDs has been observed as a result of the complex formation. A stoichiometry 1:1 for UVOB in both CDs was observed;a stoichiometry 3:1 for UVBNB in both CDs has been observed. The K<sub>s</sub>values for UVOB were 4916 ± 137 M<sup>–1</sup> and 655 ± 19 M<sup>–1</sup> (acetone: water 90/10, v/v) with βCD and βCD-MCT, respectively. The value obtained indicates a spontaneous and stable complex formation, but the complex βCD-UVOB showed high K<sub>s </sub>value as an indicative of a high concentration of complex formed. Additionally, K<sub>s </sub>and thermodynamic parameters and were evaluated in a commercial product UVBNB (UVOB, 13%, v/v). In aqueous solution, the values obtained were 2552 ± 115 and 1787 ± 75 M<sup>–1</sup> respectively. Complexation of UVOB with CDs is an interesting approach for utilization of UVOB in aqueous systems without the need of solvents and or surfactants used in commercial product (UVBNB).展开更多
The intramolecular charge transfer dual fluorescence of p-dibutylaminobenzoic acid-b-cyclodextrin inclusion complex showed a substantially higher sensitivity toward aqueous solution pH variation when compared with tha...The intramolecular charge transfer dual fluorescence of p-dibutylaminobenzoic acid-b-cyclodextrin inclusion complex showed a substantially higher sensitivity toward aqueous solution pH variation when compared with that of p-dibutylaminobenzoic acid alone, which established a new principle for direct CT fluorescence sensing in aqueous solution by using the CT fluorophore-cyclodextrin inclusion complex.展开更多
The inclusion complex reaction condition and the mechanism of β cyclodextrin with hymecromone have been studied by fluorescent spectrum. The fluorescent intensity and the stability of the system can be qreatly i...The inclusion complex reaction condition and the mechanism of β cyclodextrin with hymecromone have been studied by fluorescent spectrum. The fluorescent intensity and the stability of the system can be qreatly increased in qiven condition, and the formation constant of the inclusion complex reaction has been determined too. The system can be applied to the determination of trace amounts of hymecromone, the maximum fluorescent intensity is obtained with excitation and emission wavelength at 362 nm and 452 nm, respectively. The linear range for hymecromone is 8.0×10 -9 mol·L -1 to 1.0×10 -5 mol·L -1 . The detection limit is 1.8×10 -9 mol·L -1 . A simple, rapid and highly sensitive fluorimetric method is proposed for the determination of hymecromone. The results obtained are in agreement with those given by an official method.展开更多
An equation for determining the equilibrium association constant (KA) of cyclodextrin inclusion complex with fluorescence anisotropy is derived and used to determine KA of pyrene-B-cyclodextrin inclusion complex. The ...An equation for determining the equilibrium association constant (KA) of cyclodextrin inclusion complex with fluorescence anisotropy is derived and used to determine KA of pyrene-B-cyclodextrin inclusion complex. The existing forms of cyclodextrin inclusion complex in solution, the interaction type of host with guest, and the possibility of application of B-cyclodextrin in the analysis of metal ions using naphthalene derivative as a ligand are discussed based on the equation derived along with the curve of fluorescence anisotropy versus cyclodextrin concentration of guest/cyclodextrin system.展开更多
A simple sensitive spectrofluorimetric method was developed for the determination of amoxicillin. Amoxicillin in the presence of formaldehyde produces a fluorescent pyrazine derivative, whose fluorescence intensity ca...A simple sensitive spectrofluorimetric method was developed for the determination of amoxicillin. Amoxicillin in the presence of formaldehyde produces a fluorescent pyrazine derivative, whose fluorescence intensity can be enhanced by forming an inclusion complex with β-cyclodextrin. Optimum conditions for the determination of amoxicillin were also investigated. Fluorimetric detection was carried out at λex=365 nm and λem=445 nm. The linear range of this method for the determination of amoxicillin is 0.1―10 mg/L and the limit of detection is 0.03 mg/L （IF=102.16ρ-9.6, r=0.9994）. The developed method is practical and can be successfully applied to determine the content of amoxicillin in capsules and tablets with satisfactory results.展开更多
A comparative study on the fluorescence behavior of the chemical modified β-cyclodextrin appended a N,N-dimethylamino-chalcone group (DMAC-CD) and the non-modified β-CD mixed with free dimethylamino-chalcone (DMAC+C...A comparative study on the fluorescence behavior of the chemical modified β-cyclodextrin appended a N,N-dimethylamino-chalcone group (DMAC-CD) and the non-modified β-CD mixed with free dimethylamino-chalcone (DMAC+CD) in alcohol/water mixed solvents have been carried out in this work.The fluorescence data obtained——maximum peak wavelength and emission intensity——indicates that the inclusion behavior of the above-mentioned systems is obviously different in mixed alcohol/water solvents.The solvent-induced multi-component complex formation and dissociation and the effect of polarity and size of alcohol used have been also studied carefully by variation of the fluorescence spectroscopic characters.The result indicates that the self-inclusion complex of DMAC-CD has a higher stability in mixed alcohol/water solvents than that in the DMAC +β-CD system.The obtained results and the observed phenomena have been discussed in details.展开更多
The fluorescence spectra have been studied in phosphate buffer aqueous solution(pH=7.20) to give the stability constants( K s) for the supramolecular system formed by L Pro β CD(1), L Leu β CD(2), and L Ileu β CD(3...The fluorescence spectra have been studied in phosphate buffer aqueous solution(pH=7.20) to give the stability constants( K s) for the supramolecular system formed by L Pro β CD(1), L Leu β CD(2), and L Ileu β CD(3) with TNS. The results obtained indicate that the binding ability of modified β cyclodextrins(1) with TNS is larger than that of 2 and 3. One possible explanation is that there are different substitutes among the three modified β cyclodextrins.The molecular binding ability is discussed from the size fit concept between the host and the guest molecules. The results indicate that the substitute on the side arm attached to the edge of β CD plays a crucial role in guest inclusion.展开更多
Spectrofluorometric titration and continuous variation were used to study supramolecular inclusion complexes of β-CD and its derivatives with 2-p-toluidinglnaphthalene-6-sulfonate(TNS).The stoichiometry,stability con...Spectrofluorometric titration and continuous variation were used to study supramolecular inclusion complexes of β-CD and its derivatives with 2-p-toluidinglnaphthalene-6-sulfonate(TNS).The stoichiometry,stability constants and configuration of supramolecular inclusion complexes were discussed.The results suggest that β-CD and its derivatives form 1∶1 supramolecular inclusion complexes with TNS in aqueous solutions.The hydrophobic interactions and van der Waals forces determine the stability of supramolecular inclusion complexes.The size fit between the hosts and the guest plays important roles in the formation of the supramolecular inclusion complexes.展开更多
文摘The inclusion complexation behavior of 2,5-Bis(5-tert-butyl-benzoxazol-2yl)-thiophene (UVOB) with native β-cyclodextrin (βCD) and βCD-monochlorotriazinyl (βCD-MCT) was evaluated by fluorescence spectroscopy. The association constant (K<sub>s</sub>), stoichiometry, , and were evaluated at 25℃ ± 0.1℃ in phosphate buffer solution (pH = 10.5, 0.1 mo•dm<sup>–3</sup>) in order to find out the complex formation ability and stability. Fluorescence enhancement for UVOB and UVBNB with both CDs has been observed as a result of the complex formation. A stoichiometry 1:1 for UVOB in both CDs was observed;a stoichiometry 3:1 for UVBNB in both CDs has been observed. The K<sub>s</sub>values for UVOB were 4916 ± 137 M<sup>–1</sup> and 655 ± 19 M<sup>–1</sup> (acetone: water 90/10, v/v) with βCD and βCD-MCT, respectively. The value obtained indicates a spontaneous and stable complex formation, but the complex βCD-UVOB showed high K<sub>s </sub>value as an indicative of a high concentration of complex formed. Additionally, K<sub>s </sub>and thermodynamic parameters and were evaluated in a commercial product UVBNB (UVOB, 13%, v/v). In aqueous solution, the values obtained were 2552 ± 115 and 1787 ± 75 M<sup>–1</sup> respectively. Complexation of UVOB with CDs is an interesting approach for utilization of UVOB in aqueous systems without the need of solvents and or surfactants used in commercial product (UVBNB).
基金This work was support by NNSF of China through grants No.29975023 and No.20175020.
文摘The intramolecular charge transfer dual fluorescence of p-dibutylaminobenzoic acid-b-cyclodextrin inclusion complex showed a substantially higher sensitivity toward aqueous solution pH variation when compared with that of p-dibutylaminobenzoic acid alone, which established a new principle for direct CT fluorescence sensing in aqueous solution by using the CT fluorophore-cyclodextrin inclusion complex.
文摘The inclusion complex reaction condition and the mechanism of β cyclodextrin with hymecromone have been studied by fluorescent spectrum. The fluorescent intensity and the stability of the system can be qreatly increased in qiven condition, and the formation constant of the inclusion complex reaction has been determined too. The system can be applied to the determination of trace amounts of hymecromone, the maximum fluorescent intensity is obtained with excitation and emission wavelength at 362 nm and 452 nm, respectively. The linear range for hymecromone is 8.0×10 -9 mol·L -1 to 1.0×10 -5 mol·L -1 . The detection limit is 1.8×10 -9 mol·L -1 . A simple, rapid and highly sensitive fluorimetric method is proposed for the determination of hymecromone. The results obtained are in agreement with those given by an official method.
文摘An equation for determining the equilibrium association constant (KA) of cyclodextrin inclusion complex with fluorescence anisotropy is derived and used to determine KA of pyrene-B-cyclodextrin inclusion complex. The existing forms of cyclodextrin inclusion complex in solution, the interaction type of host with guest, and the possibility of application of B-cyclodextrin in the analysis of metal ions using naphthalene derivative as a ligand are discussed based on the equation derived along with the curve of fluorescence anisotropy versus cyclodextrin concentration of guest/cyclodextrin system.
基金Supported by the National Natural Science Foundation of China(No.40973081)the Foundation for Analysis and Measurement of Kunming University of Science and Technology+2 种基金 China(No.2009092)the Innovation Fund for Small Technology Based Firms China (No.10C26215305131)
文摘A simple sensitive spectrofluorimetric method was developed for the determination of amoxicillin. Amoxicillin in the presence of formaldehyde produces a fluorescent pyrazine derivative, whose fluorescence intensity can be enhanced by forming an inclusion complex with β-cyclodextrin. Optimum conditions for the determination of amoxicillin were also investigated. Fluorimetric detection was carried out at λex=365 nm and λem=445 nm. The linear range of this method for the determination of amoxicillin is 0.1―10 mg/L and the limit of detection is 0.03 mg/L （IF=102.16ρ-9.6, r=0.9994）. The developed method is practical and can be successfully applied to determine the content of amoxicillin in capsules and tablets with satisfactory results.
文摘A comparative study on the fluorescence behavior of the chemical modified β-cyclodextrin appended a N,N-dimethylamino-chalcone group (DMAC-CD) and the non-modified β-CD mixed with free dimethylamino-chalcone (DMAC+CD) in alcohol/water mixed solvents have been carried out in this work.The fluorescence data obtained——maximum peak wavelength and emission intensity——indicates that the inclusion behavior of the above-mentioned systems is obviously different in mixed alcohol/water solvents.The solvent-induced multi-component complex formation and dissociation and the effect of polarity and size of alcohol used have been also studied carefully by variation of the fluorescence spectroscopic characters.The result indicates that the self-inclusion complex of DMAC-CD has a higher stability in mixed alcohol/water solvents than that in the DMAC +β-CD system.The obtained results and the observed phenomena have been discussed in details.
文摘The fluorescence spectra have been studied in phosphate buffer aqueous solution(pH=7.20) to give the stability constants( K s) for the supramolecular system formed by L Pro β CD(1), L Leu β CD(2), and L Ileu β CD(3) with TNS. The results obtained indicate that the binding ability of modified β cyclodextrins(1) with TNS is larger than that of 2 and 3. One possible explanation is that there are different substitutes among the three modified β cyclodextrins.The molecular binding ability is discussed from the size fit concept between the host and the guest molecules. The results indicate that the substitute on the side arm attached to the edge of β CD plays a crucial role in guest inclusion.
文摘Spectrofluorometric titration and continuous variation were used to study supramolecular inclusion complexes of β-CD and its derivatives with 2-p-toluidinglnaphthalene-6-sulfonate(TNS).The stoichiometry,stability constants and configuration of supramolecular inclusion complexes were discussed.The results suggest that β-CD and its derivatives form 1∶1 supramolecular inclusion complexes with TNS in aqueous solutions.The hydrophobic interactions and van der Waals forces determine the stability of supramolecular inclusion complexes.The size fit between the hosts and the guest plays important roles in the formation of the supramolecular inclusion complexes.
