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Now showing items 1 - 9 of 9

  • A Colorimetric and Fluorescent pH Probe for Extremely Acidic Conditions and its Application in pH Test Paper

    You, Qihua   Shen, Jinhai   Shen, Ganping   Peng, Liyun   Lu, Yuanqin   Fu, Qi   Xu, Yuqing   Zhang, Lei  

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  • A ratiometric fluorescent and colorimetric probe for selective detection of hydrazine

    Tse, Hoyin   Li, Qinghua   Chan, Singming   You, Qihua   Lee, Albert W. M.   Chan, Winghong  

    A colorimetric and ratiometric fluorescent hydrazine reactive probe COUMA2 has been developed. In aqueous solution, hydrazinolysis of COUMA2 results in deacetylation affording fluorescent products displaying dual emissive peaks at 500 and 655 nm. 50 mu M NH2NH2 can induce a ratiometric change of fluorescent signal from COUMA2 by a factor of 4.89.
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  • Superbase‐Promoted N ‐α‐sp 3 C‐H Functionalization of Tertiary Enaminones: Synthesis of Polysubstituted Pyrroles

    Xu, Limei   Wu, Longqiao   Chen, Ting   Xu, Shuang   Huang, Chuiting   Wang, Yanyun   You, Qihua   Shen, Jinhai  

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  • Selective tracking of lysosomal Cu2+ ions using simultaneous target- and location-activated fluorescent nanoprobes.

    Li, Yinhui   Zhao, Yirong   Chan, Winghong   Wang, Yijun   You, Qihua   Liu, Changhui   Zheng, Jing   Li, Jishan   Yang, Sheng   Yang, Ronghua  

    Levels of lysosomal copper are tightly regulated in the human body. However, few methods for monitoring dynamic changes in copper pools are available, thus limiting the ability to diagnostically assess the influence of copper accumulation on health status. We herein report the development of a dual target and location-activated rhodamine-spiropyran probe, termed Rhod-SP, activated by the presence of lysosomal Cu(2+). Rhod-SP contains a proton recognition unit of spiropyran, which provides molecular switching capability, and a latent rhodamine fluorophore for signal transduction. Upon activation by lysosomal acidic pH, Rhod-SP binds with Cu(2+) by spiropyran-based proton activation, promoting, in turn, rhodamine ring opening, which shows a "switched on" fluorescence signal. However, to protect Rhod-SP from degradation and interference by the physiological environment, it is engineered on mesoporous silica nanoparticles (MSNs), and the surface of Rhod-SP@MSNs is further anchored with beta-cyclodextrin (beta-CD) to enhance the solubility and bioavailability of Rhod-SP@MSN-CD. Next, to enhance cell specificity, a guiding unit of c(RGDyK) peptide conjugated adamantane (Ad-RGD) as prototypical system, is incorporated on the surface of Rhod-SP@MSN-CD to target integrin alphavbeta3 and alphavbeta5 overexpressed on cancer cells. Fluorescence imaging showed that both Rhod-SP@MSN-CD and Rhod-SP@MSN-CD-RGD were suitable for visualizing exogenous and endogenous Cu(2+) in lysosomes of living cells. This strategy addresses some common challenges of chemical probes in biosensing, such as spatial resolution in cell imaging, the solubility and stability in biological system, and the interference from intracellular species. The newly designed nanoprobe, which allows one to track, on a location-specific basis, and visualize lysosomal Cu(2+), offers a potentially rich opportunity to examine copper physiology in both healthy and diseased states. =20
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  • Facile synthesis of 2-(2-aminobenzoyl)benzoic acid via a base-promoted aerobic cascade reaction

    Shen, Jinhai   Chen, Yangxin   Chen, Ting   Zou, Zhongai   Feng, Yadong   You, Qihua  

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  • Base-Promoted Cascade C-C Coupling/N-alpha-sp(3)C-H Hydroxylation for the Regiospecific Synthesis of 3-Hydroxyisoindolinones

    Shen, Jinhai   You, Qihua   Fu, Qi   Kuai, Changsheng   Huang, Huabin   Zhao, Li   Zhuang, Zhixia  

    A base-promoted cascade reaction for the regiospecific synthesis of substituted 3-hydroxyisoindolinones under transition-metal-free conditions is developed. The base-mediated C-C bond coupling and N-alpha-sp(3)C-H bond hydroxylation are involved in this procedure, which features high regioselectivity, efficiency, and environmental friendliness. Various substituted 3-hydroxyisoindolinones, including some bioactive molecules, were provided in up to 93% yield for 28 examples.
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  • Organosulfates in atmospheric aerosol:synthesis and quantitative analysis of PM2.5 from Xi'an,northwestern China

    Huang, Ru-Jin   Cao, Junji   Chen, Yang   Yang, Lu   Shen, Jincan   You, Qihua   Wang, Kai   Lin, Chunshui   Xu, Wei   Gao, Bo   Li, Yongjie   Chen, Qi   Hoffmann, Thorsten   O'Dowd, Colin D.   Bilde, Merete   Glasius, Marianne  

    The sources, formation mechanism and amount of organosulfates (OS) in atmospheric aerosol are not yet well understood, partly due to the lack of authentic standards for quantification. In this study, we report an improved robust procedure for the synthesis of organosulfates with different functional groups. Nine authentic organosulfate standards were synthesized and four standards (benzyl sulfate, phenyl sulfate, glycolic acid sulfate, and hydroxyacetone sulfate) were used to quantify their ambient concentrations. The authentic standards and ambient aerosol samples were analyzed using an optimized ultra performance liquid chromatography-electrospray ionization-tandem mass spectrometric method (UPLC-ESI-MS/MS). The recovery ranged from 80.4 to 93.2 %, the limits of detection and limits of quantification obtained were 1.1-16.7 and 3.4-55.6 pg m(-3), respectively. Measurements of ambient aerosol particle samples collected in winter 2013/2014 in urban Xi'an, northwestern China, show that glycolic acid sulfate (77.3 +/- 49.2 ng m(-3)) is the most abundant species of the identified organosulfates followed by hydroxyacetone sulfate (1.3 +/- 0.5 ng m(-3)), phenyl sulfate (0.14 +/- 0.09 ng m(-3)), and benzyl sulfate (0.04 +/- 0.01 ng m(-3)). Except for hydroxyacetone sulfate, which seems to form mainly from biogenic emissions in this region, the organosulfates quantified during winter in Xi'an show an increasing trend with an increase in the mass concentrations of organic carbon indicating their anthropogenic origin.
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  • A Colorimetric and Fluorescent pH Probe for Extremely Acidic Conditions and its Application in pH Test Paper

    You, Qihua   Shen, Jinhai   Shen, Ganping   Peng, Liyun   Lu, Yuanqin   Fu, Qi   Xu, Yuqing   Zhang, Lei  

    Here, we report a highly water-soluble colorimetric and fluorescent pH probe that works in the pH range 0.2-3.0. The probe showed a rapid response, high stability, and excellent reversibility to acidity. Moreover, the fluorescence of probe was not influenced by the existence of high concentration of cations. The pK(a) of probe was calculated to be 2.25 +/- 0.06. Furthermore, the pH test papers coated with the probe exhibited a distinct color change in acidic conditions.
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  • Base-catalysed [3+2] cycloaddition of propargylamines and aldehydes to substituted furans

    Shen, Jinhai   Zhao, Jing   Hu, Bing   Chen, Yangxin   Wu, Longqiao   You, Qihua   Zhao, Li  

    A base-catalysed [3 + 2] cycloaddition reaction of propargylamines and aldehydes for the regiospecific synthesis of substituted furans under metal-free conditions is developed. Propargylamines are used as allenyl anion equivalents and applied in [3 + 2] cycloaddition reactions with aldehydes. Various substituted furans are provided up to 91% yield for 28 examples.
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