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Effective assignment of positional isomers in dimeric shikonin and its analogs by ^(1)H NMR spectroscopy

Chinese Chemical Letters 2024年第5期35卷 223-226页

作者： Ling-Hao Zhao Hai-Wei Yan Jian-Shuang Jiang Xu Zhang Xiang Yuan Ya-Nan Yang Pei-Cheng Zhang State Key Laboratory of Bioactive Substance and Function of Natural Medicines Institute of Materia MedicaChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100050China

An approach for distinguishing two types of positional isomers of dimeric shikonin and its analogs was explored with ^(4)JC,H long-range correlation by prolonging the acquisition time at ^(2,3)JC,H values of 2.0 and ***,the ^(1)H(proton)nuclear magnetic resonance(NMR)pattern of phenolic hydroxyl protons was developed as a“diagnosis signal”to ascertain the relative location of each side chain in DMSO-d_(6) at sample concentrations of 0.022-0.034 mol/*** chemical shift differences of 0.6ppm between OH-5' and OH-1 and between OH-8'and OH-4 are assigned to Type A and Type B,*** reported ambiguous structures were corrected by this ***,the steric structures of isolated compounds were elucidated by quantum chemical calculations of electronic circular dichroism(ECD)spectra.

关键词： Arnebia euchroma Dimeric hydroxyl naphthoquinones positional isomers ^(1)H NMR spectroscopy Chemical shift difference

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Selectivity of New β-Cyclodextrin Derivatives as CGC Stationary Phases and Application for the Analysis of Volatile Compounds in Traditional Chinese Medicines

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Journal of Beijing Institute of Technology 2009年第2期18卷 224-228页

作者：齐美玲郭彦妮方良华张聪 School of Sciences Beijing Institute of Technology

New cyclodextrin derivatives （CDs）, heptakis（2, 6-di- O-methyl-3- O-methoxymethyl）-β-CD （ Ⅰ ） and heptakis（2, 3, 6-tri-O-methoxymethyl）-β-CD （ Ⅱ ）, were investigated for their chromatographic performance as stationary phases for capillary gas chromatography （CGC）. Both of the CDs exhibited good selectivity and satisfactory separation for test mixtures and aromatic positional isomers, and volatile compounds from Ligusticurn chuanxiong Hort. Additionally, the selectivity and elution orders of major compounds were compared with a well-recognized commercial column on the basis of the results by gas chromatography-mass spectrometry （GC-MS）. The present work demonstrates the good selectivity of the two new CDs and can be used as GC stationary phases for the separation of positional isomers and analytes in complex samples.

关键词： cyclodextrin derivatives stationary phase positional isomers traditional Chinese medicines

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positional Isomeric Thiophene-Based π-Conjugated Chromophores:Synthesis,Structure,and Optical Properties

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Precision Chemistry 2023年第9期1卷 548-554页

作者： Huan Yi Xi Qin Lei Zhai Huiyuan Duan Huafeng Chen Yulan Zuo Xin Lian Kui Tian Jinling Zhang Zhengli Liu Peng Xu Department of Chemistry and Chemical Engineering Chongqing University of Science and TechnologyChongqing 401331P.R.China School of Pharmaceutical Sciences Chongqing UniversityChongqing 401331P.R.China

A series of positional isomeric chromophores o-TC,m-TC,and p-TC,in which electron-rich thiophene moieties were connected byπ-conjugated bridges,were divergently synthesized and ***-crystal X-ray diffraction analysis revealed an intriguing zipper-like packing mode which was adopted by m-TC in the solid ***,UV−vis absorption spectra and fluorescence spectra in a series of solvents were *** nearly coplanar para isomer p-TC was found to have the most intense UV−vis absorption,fluorescence emission,and the highest photoluminescence quantum *** molecule structure,electronic nature,and origination of the absorption of p-TC were revealed through density functional theory ***,all three positional isomers exhibited strong and stable electrochemiluminescence emission,which enriched the existing knowledge on the optical properties of thiophene-based oligomers.

关键词： positional isomers Single-crystal structure UV−vis absorption Fluorescence emission ECL properties DFT simulations

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