- Preparation of a novel bridged bis(β-cyclodextrin) chiral stationary phase by thiol-ene click chemistry for enhanced enantioseparation in HPLC
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A bridged bis(β-cyclodextrin) ligand was firstly synthesized via a thiol-ene click chemistry reaction between allyl-ureido-β-cyclodextrin and 4-4′-thiobisthiophenol, which was then bonded onto a 5 μm spherical silica gel to obtain a novel bridged bis(β-cyclodextrin) chiral stationary phase (HTCDP). The structures of HTCDP and the bridged bis(β-cyclodextrin) ligand were characterized by the 1H nuclear magnetic resonance (1H NMR), solid state 13C nuclear magnetic resonance (13C NMR) spectra spectrum, scanning electron microscope, elemental analysis, mass spectrometry, infrared spectrometry and thermogravimetric analysis. The performance of HTCDP in enantioseparation was systematically examined by separating 21 chiral compounds, including 8 flavanones, 8 triazole pesticides and 5 other common chiral drugs (benzoin, praziquantel, 1-1′-bi-2-naphthol, Tr?ger's base and bicalutamide) in the reversed-phase chromatographic mode. By optimizing the chromatographic conditions such as formic acid content, mobile phase composition, pH values and column temperature, 19 analytes were completely separated with high resolution (1.50-4.48), in which the enantiomeric resolution of silymarin, 4-hydroxyflavanone, 2-hydroxyflavanone and flavanone were up to 4.34, 4.48, 3.89 and 3.06 within 35 min, respectively. Compared to the native β-CD chiral stationary phase (CDCSP), HTCDP had superior enantiomer separation and chiral recognition abilities. For example, HTCDP completely separated 5 other common chiral drugs, 2 flavanones and 3 triazole pesticides that CDCSP failed to separate. Unlike CDCSP, which has a small cavity (0.65 nm), the two cavities in HTCDP joined by the aryl connector could synergistically accommodate relatively bulky chiral analytes. Thus, HTCDP may have a broader prospect in enantiomeric separation, analysis and detection. This journal is
- Gong, Bolin,Guo, Siyu,Zhang, Ning
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p. 35754 - 35764
(2021/12/02)
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- Preparation and evaluation of a triazole-bridged bis(β-cyclodextrin)–bonded chiral stationary phase for HPLC
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A triazole-bridged bis(β-cyclodextrin) was synthesized via a high-yield Click Chemistry reaction between 6-azido-β-cyclodextrin and 6-propynylamino-β-cyclodextrin, and then it was bonded onto ordered silica gel SBA-15 to obtain a novel triazole-bridged bis (β-cyclodextrin)–bonded chiral stationary phase (TBCDP). The structures of the bridged cyclodextrin and TBCDP were characterized by the infrared spectroscopy, mass spectrometry, elemental analysis, and thermogravimetric analysis. The chiral performance of TBCDP was evaluated by using chiral pesticides and drugs as probes including triazoles, flavanones, dansyl amino acids and β-blockers. Some effects of the composition in mobile phase and pH value on the enantioseparations were investigated in different modes. The nine triazoles, eight flavanones, and eight dansyl amino acids were successfully resolved on TBCDP under the reversed phase with the resolutions of hexaconazole, 2′-hydroxyflavanone, and dansyl-DL-tyrosine, which were 2.49, 5.40, and 3.25 within 30 minutes, respectively. The ten β-blockers were also separated under the polar organic mode with the resolution of arotinolol reached 1.71. Some related separation mechanisms were discussed preliminary. Compared with the native cyclodextrin stationary phase (CDSP), TBCDP has higher enantioselectivity to separate more analytes, which benefited from the synergistic inclusion ability of the two adjacent cavities and bridging linker of TBCDP, thereby enabling it a promising prospect in chiral drugs and food analysis.
- Shuang, Yazhou,Liao, Yuqin,Wang, Hui,Wang, Yuanxing,Li, Laisheng
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p. 168 - 184
(2019/11/25)
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- Structure-activity relationship of uniconazole, a potent inhibitor of ABA 8′-hydroxylase, with a focus on hydrophilic functional groups and conformation
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The plant growth retardant S-(+)-uniconazole (UNI-OH) is a strong inhibitor of abscisic acid (ABA) 8′-hydroxylase, a key enzyme in the catabolism of ABA, a plant hormone involved in stress tolerance, stomatal closure, flowering, seed dormancy, and other physiological events. In the present study, we focused on the two polar sites of UNI-OH and synthesized 3- and 2″-modified analogs. Conformational analysis and an in vitro enzyme inhibition assay yielded new findings on the structure-activity relationship of UNI-OH: (1) by substituting imidazole for triazole, which increases affinity to heme iron, we identified a more potent compound, IMI-OH; (2) the polar group at the 3-position increases affinity for the active site by electrostatic or hydrogen-bonding interactions; (3) the conformer preference for a polar environment partially contributes to affinity for the active site. These findings should be useful for designing potent azole-containing specific inhibitors of ABA 8′-hydroxylase.
- Todoroki, Yasushi,Kobayashi, Kyotaro,Yoneyama, Hidetaka,Hiramatsu, Saori,Jin, Mei-Hong,Watanabe, Bunta,Mizutani, Masaharu,Hirai, Nobuhiro
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p. 3141 - 3152
(2008/09/19)
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- Synthesis of Optically Active α,β-Unsaturated Triazolyl Alcohols via Chiral Auxiliary-Modified NaBH4 Reduction of the Corresponding Ketones
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α-Disubstituted pyrrolidine-2-methanols were synthesized starting from L-proline and their application as chiral auxiliary in the asymmetric NaBH4 reduction of α,β-unsaturated triazolyl ketones was investigated. The corresponding α,β-unsaturated triazolyl alcohol derivatives (Uniconazole and Diniconazole) were obtained in good chemical yields with high ee values (up to 93%).
- Zhenghong, Zhou,Yilong, Tang,Lixin, Wang,Guofeng, Zhao,Qilin, Zhou,Chuchi, Tang
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p. 217 - 220
(2007/10/03)
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- Synthesis of optically active α,β-unsaturated triazolyl alcohols via asymmetric NaBH4 reduction of the corresponding ketones
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Chiral ligands 5a-d were synthesized starting from L-proline and their application in the asymmetric NaBH4 reduction of α,β -unsaturated triazolyl ketones 2 was investigated. The corresponding α,β-unsaturated triazolyl alcohol derivatives (1a,
- Zhou, Zhenghong,Tang, Yilong,Wang, Lixin,Zhao, Guofeng,Zhou, Qilin,Tang, Chuchi
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p. 1359 - 1365
(2007/10/03)
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- Plant growth regulating formulations
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Plant growth regulating preparations comprising: (a) 0.1-20 wt. % of a 16,17-dihydro gibberellin of formula (Ia) or (Ib); (b) up to 99.9 wt. % of a formulation additive selected from: (b1) the reaction products of triglycerides based on carboxylic acids having 2-30C and ethylene oxide and/or propylene oxide in the presence of a base, and/or (b2) fatty acid alcohol polyethoxylates; (c) up to 50 wt. % of an organic solvent; (d) 0.1-50 wt. % of a formulation auxiliary different from (b1) and (b2); (e) up to 50 wt. % of additional plant growth regulating compounds can be used in agriculture and horticulture to induce the desired effects on, for example, seed germination and seedling growth, rooting, dormancy, juvenility, maturity and senescence, flowering, abscission of leaves, flowers and fruit, fruit set and development, tuber formation, growth of shoot and root, photoassimilation, control of unwanted plants and senescence of whole plants or single organs. The 16,17-dihydroGA's are used to synergize the biological activity of exogenously supplied gibberellins. Particularly in graminaceous species, the compounds synergize the action of exogenous GA's and can, thus, be used to increase the yield of malt and decrease the amount of time required for the malting process, increase the yield of sugar cane and stimulate germination and seedling development in rice, wheat, barley, oats, rye, maize, sorghum, turf grasses and other plant species.
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- Patch preparations for treating plants
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The following invention introduces a patch preparation for treating plants, whereas the patch preparations comprise a chemical layer composed of at least one agrochemically active compound, at least one adhesive and optionally, one or more additives. The components are dispersed in a matrix state on a substrate which are then introduced on the roots of the plant to be treated.
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- Method for the treatment of plants with agrochemical tablet compositions
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Novel method for applying agrochemicals to plants, which method consists in attaching to the surface of the plants tablets comprising at least one agrochemically active compound and at least one adjuvant, which is solid, liquid of pasty at room temperature, and optionally, one or more excipients optionally in admixture with one or more other additives and/or water.
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