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991.
The synthesis and absorption/fluorescence properties of two novel intramolecular charge transfer (ICT) compounds of (fluorene-2-yl)-(9-ethylcarbazole-3-yl) ketene and 1-phenyl-3-(fluorenone-2-yl)-5-(9-ethylcarbazole-3-yl)-2-pyrazoline were reported. The primary structure of the target compounds was characterized by IR and 1H NMR. The systems contained a fluorenone or a propenon group as an electron acceptor (A) and an N-ethylcarbazole and a pyrazoline group as electron donors (D). From the emissive properties it was concluded that the electronic coupling between D and A was sufficient to allow charge transfer in these molecules. The ICT maximal emission displayed a large wavelength shift and Stokes shifts increased in response to the increase of the solvent polarity. The highly solvatochromic properties made the two compounds of great interest as new classes of fluorescent probes, electroluminescent and electrofax materials. 相似文献
992.
An aqueous solution containing sodium polyacrylate (PA, 0.0030 M) was used in diffusive gradients in thin-films technique (DGT) to measure DGT-labile Cu2+ and Cd2+ concentrations. The DGT devices (PA DGT) were validated in four types of solutions, including synthetic river waters containing metal ions with or without complexing EDTA, natural river water (Hun River, Shenyang, China) spiked with Cu2+ and Cd2+, and an industrial wastewater (Shenyang, China). Results showed that only free metal ions were measured by PA DGT, recovery = 98.79% for Cu2+ and recovery = 97.80% for Cd2+ in solutions containing only free metal ions, recovery = 51.02% for Cu2+ and recovery = 51.92% for Cd2+ in solution with metal/EDTA molar ratio of 2:1 and recovery = 0 in solutions with metal/EDTA molar ratio of 1:1 and 1:2. These indicated that the complexes of Cu-EDTA and Cd-EDTA were DGT-inert or not DGT-labile. The DGT performance in spiked river water (recovery = 8.47% for Cu2+ and recovery = 27.48% for Cd2+) and in industrial wastewater (recovery = 14.16% for Cd2+) were also investigated. Conditional stability constants (log K) of PA-Cu and PA-Cd complexes were determined as 6.98 and 5.61, respectively, indicating strong interaction between PA and the metals. 相似文献
993.
高通量微孔板DAMBO-P~H荧光检测一氧化氮 总被引:1,自引:0,他引:1
一氧化氮(NO)是生物体内的一种重要生物信号传导分子,广泛参与生物体内多种生理及病理过程.为建立快速高效、准确检测生物体释放NO的分析方法,本文选用高灵敏度、高选择性的NO特异性荧光探针8-(3,4-diaminophenyl)-2,6-bis(2-carboxyethyl)-4,4-difluoro-1,3,5,7-tetramethyl-4- bora-3a,4a-diaza-s-indacene (DAMBO-P~H),激发波长和发射波长分别为520 nm和535 nm,以高通量微孔板(384孔)作为实验工具载体.该方法荧光强度与NO浓度在8.0×10~(-10)~8.0×10~(-7) mol·~(-1)范围内呈良好线性关系,R=0.9989,检出限为0.18 nmol·~(-1),回收率为98%~102%.该方法应用于多种生物样品中释放NO的分析检测,结果令人满意. 相似文献
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997.
W. Z. Zhang Ma Shuang M. C. Zhu Liu Lei E. J. Gao 《Russian Journal of Coordination Chemistry》2009,35(12):874-878
A novel complex [Zn(Qina)2(DMSO)2] · 2DMSO (I) (Qina = quinaldic acid, DMSO = dimethyl sulfoxide) has been synthesized and characterized by X-ray diffraction, elementary analysis, and IR spectrum. The unit cell parameters for complex I: a = 8.2884(11), b = 22.015(3), c = 9.0685(12) Å, β = 100.61(0)°, V = 1626.41(40) Å3, Z = 2, space group, P21/n. In the complex I, the Zn(II) atom was six-coordinated to form a distorted octahedral geometry by two Qina ligands and two dimethyl sulfoxide molecules. The crystal structure is stabilized by hydrogen bonds, C - H... π, π-π stacking interaction between adjacent complexes. The binding of the complex I with calf thymus DNA has been investigated by fluorescence spectroscopic studies. The result suggested that the complex intercalates into DNA base pairs. 相似文献
998.
A growing number of peptides are being used today in bioanalytical laboratories. Because of this, there is an increasing interest in the development of highly sensitive, specific and robust liquid chromatography/tandem mass spectrometry (LC/MS/MS) assays for the quantitative analysis of peptides in biological samples. Among the mass spectrometers previously used for peptide quantification, triple quadrupole mass spectrometers are generally not considered the instrument of choice. With this instrumentation, collision cascades or multiple fragmentations tend to generate multiple peaks that have weak intensities. This leads to a loss in detection sensitivity. However, in cases where immonium product ions were formed in abundance, it was found that peptide quantification succeeded. A common feature of these peptides is their intra-loop structure. To elucidate the usefulness of this feature in fragmentation, several peptide analytes with intra-chain disulfide bonds were investigated in this study, including a newly synthesized analog having a single amino acid substitution. The results presented here indicate that abrupt bond cleavage from the intra-loop structure of peptides could be one of the premises for intense immonium ion generation. In contrast, any preferential cleavage of peptide bonds (e.g., proline effect) that gives rise to a linearized sequence would break the intactness of the loop and prevent it from completely dissociating. In addition, the utilization of immonium product ions in LC/MS/MS was demonstrated for the determination of peptides with intra-chain disulfide bonds in biological fluids. 相似文献
999.
Hao Luo Ying‐Kun Nie Yu‐Jie Fu Yuan‐Gang Zu Shuang‐Ming Li Wei Liu Lin Zhang Meng Luo Yu Kong Zheng‐Nan Li 《Journal of separation science》2009,32(2):192-201
A method based on microwave‐assisted extraction (MAE) has been developed for the determination of paclitaxel and five related taxoids, namely 10‐deacetylbaccatin III (10‐DAB III), cephalomannine, 10‐deacetylpaclitaxel (10‐DAT), 7‐xyl‐10‐ deacetylpaclitaxel (7‐xyl‐10‐DAT), and 7‐epi‐10‐deacetylpaclitaxel (7‐epi‐10‐DAT) in Taxus species in this study. The influential parameters of the MAE procedure were optimized, and the optimal conditions were as follows: extraction solvent 80% ethanol solution, solid/liquid ratio 1:10 (g/mL), temperature 50°C, and three extraction cycles, each cycle 10 min. The method validation for LC‐MS/MS analysis was performed. The LOD and LOQ were 3.16–9.20 and 12.20–30.45 ng/mL, respectively. Repeatability and reproducibility for the six taxiods with RSD ranged from 2.78 to 3.85% and from 5.26 to 6.60%. The recoveries of the method for the six taxoids were 92.6–105.6%. The developed MAE‐LC‐MS/MS method was also successfully applied to determine the contents of six taxoids in different Taxus species. 相似文献
1000.
Quan‐Bin Han Lina Wong Fanny Lai Nian‐Yun Yang Jing‐Zheng Song Chun‐Feng Qiao Hong‐Xi Xu 《Journal of separation science》2009,32(2):309-313
In order to provide the chemical markers for the quality control of herbal medicines, four diterpenoids, pseudolaric acids A and B (PAA and PAB), and their glucosides were isolated from the methanol extract of the Chinese herb Pseudolarix kaempferi using high‐speed counter‐current chromatography (HSCCC). The diphase solvent system was n‐hexane/EtOAc/MeOH/H2O which was used at two ratios (5:5:5:5 and 1:9:4:6 by volume) in the separation of pseudolaric acids and their glycosides, respectively. As a result, PAA (14 mg), PAB (129 mg), PAA‐O‐β‐D ‐glucopyranoside (8 mg, PAAG), and PAB‐O‐β‐D ‐glucopyranoside (42 mg, PABG) were obtained from 0.5 g of the crude extract. Their purities were determined to be above 97% by HPLC analysis. Their chemical structures were confirmed by 1H and 13C NMR analysis or HPLC comparison with the reference compounds. 相似文献