Two new chiral oxazaborolidine derivated from L-cystine have been used to catalyze the enantioselective reduction of prochiral ketones and the secondary alcohols are obtained with good to excellent opitical yields.
In the presence of cucurbit[7]uril （CB[7]）, the CB[7] could react with palmatine, which served as a sensitive fluorescence probe, to form host-guest stable complexes and the fluorescence intensity of the complexes w...In the presence of cucurbit[7]uril （CB[7]）, the CB[7] could react with palmatine, which served as a sensitive fluorescence probe, to form host-guest stable complexes and the fluorescence intensity of the complexes was greatly enhanced. The fluorescence intensity decreased linearly with an increasing number of L-cystine in the inclusion system. The experimental results show that there exists a competition between L-cystine and palmatine for the CB[7] hydrophobic cavity and L-cystine occupies the space of CB[7] cavity, leading palmatine molecules to be forced to reside in the aqueous environment. Based on the fluorescence quenching of the CB[7]/palmatine complexes resulting from complex formation between CB[7] and L-cystine, a spectrofluorimetric method for the determination of L-cystine in aqueous solution in the presence of CB[7] was developed. The linear relationship between the corresponding values of the fluorescence quenching AF and L-cystine concentration was obtained in the range of 6.0 to 1.5 × 10^3 ngomL l, with a correlation coefficient （r） of 0.9996. The detection limit was 2.0 ng·mL -1. The application of the present method to the determination of L-cystine in tablets gave satisfactory results. This paper also discussed the mechanism of the fluorescence indicator probe.展开更多
A simple biomolecule-assisted synthetic route has been successfully developed to prepare bismuth sulfide（Bi 2 S 3 ） nanorods under solvothermal conditions.In the synthetic system,pentahydrate bismuth nitrate was emp...A simple biomolecule-assisted synthetic route has been successfully developed to prepare bismuth sulfide（Bi 2 S 3 ） nanorods under solvothermal conditions.In the synthetic system,pentahydrate bismuth nitrate was employed to supply Bi source and L-cystine was used as sulfide source and complexing agent.The morphology,structure,and phase composition of the as-prepared Bi 2 S 3 products were characterized by X-ray diffraction（XRD）,energy dispersion spectroscopy（EDS）,X-ray photoelectron spectroscopy（XPS）,field-emission scanning electron microscopy（FESEM）,transmission electron microscopy（TEM）,selected area electron diffraction（SAED）,and high-resolution transmission electron microscopy（HRTEM）.The experimental results show that the nanorods have uniform diameter of 100-200 nm and length of 2-4 μm.The possible formation mechanism for the bismuth sulfide nanorods was discussed.展开更多
Recently,many efforts have been dedicated to creating enzyme-mimicking catalysts to replace natural enzymes in practical fields.Inspired by the pathological biomineralization behaviour of L-cystine,in this study,we co...Recently,many efforts have been dedicated to creating enzyme-mimicking catalysts to replace natural enzymes in practical fields.Inspired by the pathological biomineralization behaviour of L-cystine,in this study,we constructed a laccase-like catalyst through the co-assembly of L-cystine with Cu ions.Structural analysis revealed that the formed catalytic Cu-cystine nanoleaves(Cu-Cys NLs)possess a Cu(I)-Cu(II)electron transfer system similar to that in natural laccase.Reaction kinetic studies demonstrated that the catalyst follows the typical Michaelis-Menten model.Compared with natural laccase,the Cu-Cys NLs exhibit superior stability during long-term incubation under extreme pH,high-temperature or high-salt conditions.Remarkably,the Cu-Cys NLs could be easily recovered and still maintained 76%of their activity after 8 cycles.Finally,this laccase mimic was employed to develop a colorimetric method for epinephrine detection,which achieved a wider linear range(9–455μmol·L^(−1))and lower limit of detection(2.7μmol·L^(−1)).The Cu-Cys NLs also displayed excellent specificity and sensitivity towards epinephrine in a test based on urine samples.展开更多
文摘Two new chiral oxazaborolidine derivated from L-cystine have been used to catalyze the enantioselective reduction of prochiral ketones and the secondary alcohols are obtained with good to excellent opitical yields.
文摘In the presence of cucurbit[7]uril （CB[7]）, the CB[7] could react with palmatine, which served as a sensitive fluorescence probe, to form host-guest stable complexes and the fluorescence intensity of the complexes was greatly enhanced. The fluorescence intensity decreased linearly with an increasing number of L-cystine in the inclusion system. The experimental results show that there exists a competition between L-cystine and palmatine for the CB[7] hydrophobic cavity and L-cystine occupies the space of CB[7] cavity, leading palmatine molecules to be forced to reside in the aqueous environment. Based on the fluorescence quenching of the CB[7]/palmatine complexes resulting from complex formation between CB[7] and L-cystine, a spectrofluorimetric method for the determination of L-cystine in aqueous solution in the presence of CB[7] was developed. The linear relationship between the corresponding values of the fluorescence quenching AF and L-cystine concentration was obtained in the range of 6.0 to 1.5 × 10^3 ngomL l, with a correlation coefficient （r） of 0.9996. The detection limit was 2.0 ng·mL -1. The application of the present method to the determination of L-cystine in tablets gave satisfactory results. This paper also discussed the mechanism of the fluorescence indicator probe.
基金support from National Natural Sciences Foundation of China (GrantNos. 50772075 and 50972107)
文摘A simple biomolecule-assisted synthetic route has been successfully developed to prepare bismuth sulfide（Bi 2 S 3 ） nanorods under solvothermal conditions.In the synthetic system,pentahydrate bismuth nitrate was employed to supply Bi source and L-cystine was used as sulfide source and complexing agent.The morphology,structure,and phase composition of the as-prepared Bi 2 S 3 products were characterized by X-ray diffraction（XRD）,energy dispersion spectroscopy（EDS）,X-ray photoelectron spectroscopy（XPS）,field-emission scanning electron microscopy（FESEM）,transmission electron microscopy（TEM）,selected area electron diffraction（SAED）,and high-resolution transmission electron microscopy（HRTEM）.The experimental results show that the nanorods have uniform diameter of 100-200 nm and length of 2-4 μm.The possible formation mechanism for the bismuth sulfide nanorods was discussed.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.21621004 and 21676191).
文摘Recently,many efforts have been dedicated to creating enzyme-mimicking catalysts to replace natural enzymes in practical fields.Inspired by the pathological biomineralization behaviour of L-cystine,in this study,we constructed a laccase-like catalyst through the co-assembly of L-cystine with Cu ions.Structural analysis revealed that the formed catalytic Cu-cystine nanoleaves(Cu-Cys NLs)possess a Cu(I)-Cu(II)electron transfer system similar to that in natural laccase.Reaction kinetic studies demonstrated that the catalyst follows the typical Michaelis-Menten model.Compared with natural laccase,the Cu-Cys NLs exhibit superior stability during long-term incubation under extreme pH,high-temperature or high-salt conditions.Remarkably,the Cu-Cys NLs could be easily recovered and still maintained 76%of their activity after 8 cycles.Finally,this laccase mimic was employed to develop a colorimetric method for epinephrine detection,which achieved a wider linear range(9–455μmol·L^(−1))and lower limit of detection(2.7μmol·L^(−1)).The Cu-Cys NLs also displayed excellent specificity and sensitivity towards epinephrine in a test based on urine samples.
