共查询到20条相似文献,搜索用时 187 毫秒
1.
设计合成了含噻二唑的间苯二甲酰基硫脲受体,并用紫外光谱研究了其对阴离子客体的识别性能.主体1a与F-和CH3COO-相互作用,主体吸收光谱发生一定变化,且主体溶液的颜色也有明显变化.而与Cl-,Br-,I-,HSO4-,H2PO4-和ClO4-作用,吸收光谱几乎没有变化.Job工作曲线表明1a与F-和CH3COO-形成1∶1络合物,紫外滴定光谱的结果经非线性拟合,计算出主客体结合的稳定常数.1 H NMR滴定实验进一步证明了受体分子与阴离子之间以氢键作用方式相结合. 相似文献
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设计合成了一系列基于羟基和氨基的酰腙类受体分子.利用紫外-可见吸收光谱及1HNMR考察了其与F-,Cl-,Br-,I-,CH3COO-,H2PO4?,HSO4?,ClO?4等阴离子的作用.结果表明,该类受体分子在DMSO溶液中能较好地比色识别F-,CH3COO-,H2PO4?,其中受体2在含水介质中[V(DMSO)∶V(H2O)=7∶3]能选择性比色识别CH3COO-.1HNMR滴定实验研究了受体分子与阴离子之间的作用,结果表明受体分子与阴离子之间以氢键作用方式相结合. 相似文献
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通过6-氨基嘧啶、取代苯甲醛与丙二腈的三组分反应合成了4种吡啶并[2,3-d]嘧啶受体分子,利用紫外-可见吸收光谱考察了其与F-,Cl-,Br-,AcO-,4HSO-,2 4H PO-等阴离子的作用.结果表明该类受体分子与阴离子形成氢键配合物,导致吡啶并[2,3-d]嘧啶受体的光谱发生变化.测定了配合物的结合比和稳定常数,发现受体化合物对AcO-离子具有良好的选择性,对其它多种阴离子无影响.Job曲线表明受体分子与阴离子间形成1∶1型的配合物.1H NMR滴定进一步证实了氢键作用的存在及参与类型. 相似文献
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设计合成了一个新型的含1,8-萘酰亚胺信号单元的咔唑磺酰肼类阴离子受体1,荧光和UV-vis光谱滴定实验表明,1在DMSO中能选择性识别具有重要生物学意义的F-,Ac O-和2 4H PO-;受体1与这些阴离子形成1∶1的配合物,且它们的结合常数均大于103 L?mol-1.有趣的是,在含水10%(V/V)的DMSO中1对F-表现出了专一性识别.DMSO-d6中的核磁滴定表明,在F-浓度较低时,受体1通过五重分子间氢键作用与其产生了有效结合. 相似文献
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间苯二甲醛缩双芳氨基硫脲的合成及阴离子识别研究 总被引:5,自引:0,他引:5
设计合成了5种间苯二甲醛缩双芳氨基硫脲受体分子, 利用紫外-可见吸收光谱及1H NMR, 考察了其与F-, Cl-, Br-, I-, CH3COO-, HSO-4, NO-3和H2PO-4等8种阴离子的作用. 当在受体分子S0, S1, S2, S3和S4的DMSO溶液中加入F-和CH3COO-四丁基铵盐的DMSO溶液时, 吸收光谱发生显著红移, 溶液颜色由无色变为深黄色, 而加入其它阴离子则无显著变化, 可以实现对这两种阴离子的裸眼检测及光谱分析. 计算结果表明, 随着苯环上取代基的变化, 此5种受体分子对F-和CH3COO-的识别作用呈现规律性变化. 1H NMR 及质子溶剂效应进一步证明了受体分子与阴离子之间以氢键作用方式相结合. Job工作曲线表明, 该类受体分子与阴离子形成1∶1的氢键配合物. 相似文献
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以间三苯酚为原料与不同的二溴代烷反应得到不同链长的三溴中间体1a~1c,再与二茂铁甲基咪唑反应得到不同臂长的三核茂铁咪唑阴离子受体2a~2c.利用循环伏安法(CV)、差分脉冲伏安法(DPV)和核磁共振氢谱(1H NMR)研究了受体与阴离子的结合特性.电化学滴定实验结果表明,受体2a~2c在乙腈溶液中均能很好地识别F-;核磁滴定结果表明,受体2a~2c在DMSO-d6中与阴离子通过(C—H)+…anion氢键作用形成1∶1络合物,F-的滴加同时对受体产生去质子化效应;阴离子识别实验结果表明,三核茂铁咪唑受体能很好地选择性识别F-. 相似文献
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《理化检验(化学分册)》2016,(10)
合成了3种含缩氨基硫脲席夫碱侧链的苯并菲阴离子受体R1、R2和R3,通过核磁共振氢谱法和红外光谱法对合成的阴离子受体进行结构表征。采用比色法、紫外-可见吸收光谱法和荧光光谱法研究所合成的阴离子受体的阴离子识别能力。识别试验表明:受体R1,R2和R3均能有效识别F-,其中R3还可以对Ac-和H2PO4-的存在给予响应。在R3紫外-可见吸收光谱中,随着3种阴离子的加入,原345nm处吸收峰逐渐减弱,同时在455nm处出现新的吸收峰。合成的3种阴离子受体,通过氢键作用来实现对阴离子的结合与识别,F-因电负性最强,最易与受体硫脲部形成氢键,因而识别效果最佳。 相似文献
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《有机化学》2015,(10)
以β-萘酚为原料,经过多步反应合成了5种不同电子效应的1-(5,6-苯并香豆素-3-甲酰基)-4-芳基氨基硫脲衍生物,并通过1H NMR,13C NMR,IR及元素分析等测试手段对受体分子进行表征.利用紫外-可见吸收光谱和荧光光谱考察了这类受体分子与F-,Ac O-,C1-,Br-,I-,HSO4-等阴离子的作用,发现受体分子对其它阴离子无响应;而对F-和Ac O-离子具有良好的选择性检,检测限分别为5.45与7.00μg/L,响应时间分别为5与10 min.实验结果表明该类受体分子与阴离子通过氢键形成配位物,从而导致光谱信号的变化.通过主客体间结合比和稳定常数的计算,证实了受体分子对F-和Ac O-选择性好,形成稳定化合物.Job’s曲线可知受体分子与阴离子形成1∶2的配合物,并利用核磁滴定与理论计算[B3LYP/6-31G(d,p)]进一步证实了受体分子与阴离子的氢键作用. 相似文献
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Alexsandro E. Ferreira Ana Carolina F. Soares Julian C. S. Pavan Pedro Y. Kovatch Humberto T. Sakamoto João L. Callegari Lopes Vinícius Palaretti Vladimir C. G. Heleno 《Magnetic resonance in chemistry : MRC》2020,58(10):975-980
A complete 1H and 13C NMR analysis for a group of four sesquiterpene lactones isolated from Eremanthus elaeagnus (Asteraceae) is described in this work. 1H NMR, 13C {1H} NMR, gCOSY, gHMQC, and gHMBC experiments were performed to provide sufficient structural information to allow an unequivocal assignment. All hydrogen coupling constants were measured, clarifying all hydrogen signal multiplicities. 相似文献
13.
Benzoxazine oligomers: evidence for a helical structure from solid-state NMR spectroscopy and DFT-based dynamics and chemical shift calculations 总被引:1,自引:0,他引:1
Goward GR Sebastiani D Schnell I Spiess HW Kim HD Ishida H 《Journal of the American Chemical Society》2003,125(19):5792-5800
A combination of molecular modeling, DFT calculations, and advanced solid-state NMR experiments is used to elucidate the supramolecular structure of a series of benzoxazine oligomers. Intramolecular hydrogen bonds are characterized and identified as the driving forces for ring-shape and helical conformations of trimeric and tetrameric units. In fast MAS (1)H NMR spectra, the resonances of the protons forming the hydrogen bonds can be assigned and used for validating and refining the structure by means of DFT-based geometry optimizations and (1)H chemical-shift calculations. Also supporting these proposed structures are homonuclear (1)H[bond](1)H double-quantum NMR spectra, which identify the local proton-proton proximities in each material. Additionally, quantitative (15)N[bond](1)H distance measurements obtained by analysis of dipolar spinning sideband patterns confirm the optimized geometry of the tetramer. These results clearly support the predicted helical geometry of the benzoxazine polymer. This geometry, in which the N...H...O and O...H...O hydrogen bonds are protected on the inside of the helix, can account for many of the exemplary chemical properties of the polybenzoxazine materials. The combination of advanced experimental solid-state NMR spectroscopy with computational geometry optimizations, total energy, and NMR spectra calculations is a powerful tool for structural analysis. Its results provide significantly more confidence than the individual measurements or calculations alone, in particular, because the microscopic structure of many disordered systems cannot be elucidated by means of conventional methods due to lack of long-range order. 相似文献
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In this contribution, we first found the novel clathrate hydrate containing two gaseous guests of hydrogen and carbon dioxide by spectroscopic analysis. X-ray powder diffraction and NMR spectroscopy were used to identify structure and guest distribution of the mixed H2 + CO2 hydrate. X-ray diffraction result confirmed that the unit cell parameter was 11.8602 +/- 0.0010 A, and the formed hydrate was identified as structure I hydrate. 1H magic angle spinning (MAS) NMR and 13C cross-polarization (CP) NMR spectroscopy were used to examine the distribution of hydrogen and carbon dioxide molecules in the cages of structure I, respectively. These NMR spectra showed that carbon dioxide molecules occupied both small 512 cages and large 51262 cages, and hydrogen molecules only were occluded in small 512 cages of structure I. The new finding of the mixed hydrogen hydrate is expected to contribute toward the development of hydrogen production technology and, particularly, inclusion chemistry. 相似文献
16.
Pedro Y. Kovatch Alexsandro E. Ferreira Guilherme M. L. Ghizonni Sérgio R. Ambrósio Antônio E. M. Crotti Vladimir C. G. Heleno 《Magnetic resonance in chemistry : MRC》2022,60(2):255-260
In this paper, a complete 1H and 13C NMR data assignment of ent-polyalthic acid, a biologically active labdane-type diterpene, is presented. The assignments were carried on the basis of spectroscopic data from 1H NMR, 13C{1H} NMR, gCOSY, gHMQC, and gHMBC experiments. Furthermore, a software-assisted methodology, using FOMSC3_rm_NB and NMR_MultSim programs, supported the detailed and unequivocal assignment of 1H and 13C signals, allowing all hydrogen coupling constants to be determined and thus clarifying all hydrogen signal multiplicities. 相似文献
17.
The aromatic C-H...O hydrogen bonding within the series of the structurally relative indenone derivatives has been studied. The presence of the hydrogen bonds is corroborated by the large low-field chemical shifts of the protons involved in the hydrogen bond observed experimentally and reproduced by quantum mechanical calculations. Further confirmation is provided by analysis of the orbital overlap coefficients, (13)C NMR chemical shifts, and one-bond spin-spin coupling constants J((13)C-(1)H). The relationship between molecular geometry and (1)H NMR chemical shifts of involved protons has a complex nature, but the C-H...O distance is the principal factor. 相似文献
18.
Okamura TA Taniuchi K Lee K Yamamoto H Ueyama N Nakamura A 《Inorganic chemistry》2006,45(23):9374-9380
Salts of the monooxomolybdenum(IV,V) areneselenolates having intramolecular NH...Se hydrogen bonds, [Mo(IV)O(Se-2-RCONHC6H4)4]2- (R = t-Bu, CH3, CF3) and [Mo(V)O(Se-2-t-BuCONHC6H4)4]-, were synthesized and characterized by 1H nuclear magnetic resonance (NMR), 77Se NMR, electron spin resonance (ESR), UV-visible spectra, X-ray analysis, and electrochemical measurements. 77Se-1H correlated spectroscopy (COSY) indicated a significant correlation between amide 1H and selenolate 77Se atoms through an NH...Se hydrogen bond with 1J(77Se-1H) = 5.4 Hz coupling. The hydrogen bonds contribute to the positive shift in the Mo(V)/Mo(IV) redox potential. In the crystal structure of (PPh4)2[Mo(IV)O(Se-2-CH3CONHC6H4)4], an NH...O=Mo hydrogen bond was found. Ab inito calculations support the presence of intramolecular NH...O=Mo and NH...Se hydrogen bonds. 相似文献
19.
Torres-Valencia JM Meléndez-Rodríguez M Alvarez-García R Cerda-García-Rojas CM Joseph-Nathan P 《Magnetic resonance in chemistry : MRC》2004,42(10):898-902
A Monte Carlo random search using molecular mechanics, followed by geometry optimization of each minimum energy structure employing density functional theory (DFT) calculations at the B3LYP/6-31G* level and a Boltzmann analysis of the total energies, generated accurate molecular models which describe the conformational behavior of the antispasmodic bicyclic sesquiterpene valeranone (1). The theoretical H-C-C-H dihedral angles gave the corresponding 1H, 1H vicinal coupling constants using a generalized Karplus-type equation. In turn, the 3J(H,H) values were used as initial input data for the spectral simulation of 1, which after iteration provided an excellent correlation with the experimental 1H NMR spectrum. The calculated 3J(H,H) values closely predicted the experimental values, excepting the coupling constant between the axial hydrogen alpha to the carbonyl group and the equatorial hydrogen beta to the carbonyl group (J(2beta, 3beta)). The difference is explained in terms of the electron density distribution found in the highest occupied molecular orbital (HOMO) of 1. The simulated spectrum, together with 2D NMR experiments, allowed the total assignment of the 1H and 13C NMR spectra of 1. 相似文献
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da Silva R Pedersoli S Lacerda V Donate PM de Albuquerque S Bastos JK de Matos Araújo AL Andrade e Silva ML 《Magnetic resonance in chemistry : MRC》2005,43(11):966-969
The structures of three benzylidenebenzyl butyrolactone lignans (gossypifan, carthamogenin, and savinin) have been established on basis of 1H NMR and 13C NMR spectroscopic data. The 1H NMR and 13C NMR spectra of these lignans have been fully assigned by the use of techniques such as gCOSY, non-edited gHSQC, and gHMBC. Complete assignment and most homonuclear hydrogen coupling constant measurements were performed, also providing enough data for the determination of the relative stereochemistry. 相似文献