~(13)C-NMR对油脂的定量测定

本工作用外加驰豫试剂及反转门控去偶方式对菜籽油和“营养”油进行了~(13)C-NMR谱的定量测定。在归属各峰基础上,认为该两油脂都以甘油酯形式存在。提出了①多烯类结合脂肪酸占烯类总量的摩尔分数P;②烯碳数与饱和碳数之比R;③包括同种油脂及不同油脂间的油脂分子各类功能团的相对含量的测定计算表达式。     

C~3~6的结构及其张力的理论研究

在SCF-HF/6-31G水平上,对C~3~6分子进行了非对称性限制下的全优化,对优化的结构使用B3LYP/6-31G计算了1^3^CNMR谱,并分析了它们的电子结构,同时,使用POAV方法,对不同结构异构体的不同碳原子以及不同键型分别进行了张力、再次杂化及π-π轨道夹角分析。     

柴乌定及其类似物^13C核磁共振谱的研究

本文报道了十一种紫乌定及其似物的^13C核磁共振谱,有助于此类二萜生物碱的结构测定.     

谷胱甘肽与衡土离子作用的13^C NMR研究

本文利用顺磁稀土离子的诱导化学位移变化的性质, 研究了多官能团配体谷胱甘肽(GSH)与稀土的配位作用。在水溶液中GSH通过分子两端的羧基负离子与稀土形成遥爪配位结构。谷氨酸和甘氨酸羧基与Eu^3+的配位稳定常数分别为12.5±0.1L.mol和100.0±0.5L/mol。从13^C化学位移的pH变化曲线求得谷氨酸和甘氨酸羧基解离的pK~a值分别为2.20±0.02和3.50±0.04。对Dy^3+、Ho^3+、Er^3+、Tm^3+和Yb^3+作用下, GSH的13^C位移数据分析表明, 配体与这些离子形成同构的配合物, 分子两端羧基均可能以双齿形式与稀土配位。     

用~1H-和~(13)C-NMR方法研究聚对苯二甲酸乙二酯/聚一氧基苯甲酸酯共聚酯的序列分布

测定了PET/30PHB和PET/60PHB共聚酯的高分辨~1H和~(13)C谱,并采用INEPT方法和部分弛豫FT技术确定了季碳吸收峰,对NMR谱进行了归属.应用我们先前提出的方法对共聚酯的序列分布进行了表征.结果表明,两种共聚酯的无规度B_q值均小于1,序列分布不象Jackson等认为的那样为完全无规的.此外,文中还指出,某些研究者套用Flory公式判别PET/PHB共聚酯是否为无规的不妥之处.     

谷胱甘肽与衡土离子作用的13^C NMR研究

本文利用顺磁稀土离子的诱导化学位移变化的性质, 研究了多官能团配体谷胱甘肽(GSH)与稀土的配位作用。在水溶液中GSH通过分子两端的羧基负离子与稀土形成遥爪配位结构。谷氨酸和甘氨酸羧基与Eu^3+的配位稳定常数分别为12.5±0.1L.mol和100.0±0.5L/mol。从13^C化学位移的pH变化曲线求得谷氨酸和甘氨酸羧基解离的pK~a值分别为2.20±0.02和3.50±0.04。对Dy^3+、Ho^3+、Er^3+、Tm^3+和Yb^3+作用下, GSH的13^C位移数据分析表明, 配体与这些离子形成同构的配合物, 分子两端羧基均可能以双齿形式与稀土配位。     

南海软珊瑚Sarcophyton molle化学成分的研究

从中国南海软肉芝软珊瑚(Sarcophyton molle)中分离到七个化合物, 经紫外光谱(UV), 红外光谱(IR), 质谱(MS)和核磁共振光谱(1H NMR, 13C NMR)分析, 确定了其化学结构。它们是: 异新西松烯(1), (E, E, E)-7, 8-环氧-1-异丙基-4, 8, 12-三甲基-十四环-1,3, 11-三烯(2), 正十八烷酸(3), 鲨肝醇(4), 神经酰胺(5), 胸腺嘧啶(6), 胸腺嘧啶脱氧核苷(7)。其中化合物(2)为新化合物。本文是第一次报道软珊瑚Sarcophyton molle的化学成分。     

中国乌头的研究 XXII: 赣烷乌头生物碱的研究

从赣皖乌头(Aconitum finetianum Hand-Mazz)中又分得五个生物碱, 其中三个为新的二萜类生物碱, 分别命名为去氧刺乌头碱(deoxylappaconitine), 赣乌新碱(neofinaconitine)和异刺乌状碱(isolappaconitine), 经IR、MS、^1H和^1^3C NMR推定了它们的化学结构, 另两个为已知生物碱ajacine和inuline.     

核磁共振法研究固体表面上的吸附

应用JEOL FX-90Q NMR谱仪测定了吸附在NaY分子筛,氧化铝,二氧化硅上的四甲基硅烷和正己烷的核磁氢谱和碳谱.结果表明,在一些吸附体系的研究中,现有仪器适用于液体样品,以氢谱和碳谱比较发现碳谱在分辨率分方面较之氢谱有几个优点,顺磁杂质对谱线宽度有明显影响.在NaY分子筛上预先吸附氢以后再吸附乙烯,其吸附速率低于未吸附氢的样品.     

Assignment of the 1H and 13C NMR signals of some benzofurocoumarins

The complete 1H and 13C NMR assignment of four 6,7-benzo-fused furocoumarins (1-4) and three 3,4-benzo-fused furocoumarins (5-7) has been performed using 1D and 2D NMR techniques, including COSY, HMQC and HMBC experiments.     

Assignment of the 1H and 13C NMR signals of some hydroxyphenylcoumarins

The complete 1H and 13C NMR assignments of six hydroxyphenylcoumarins have been made using 1D and 2D NMR techniques, including COSY, HMQC and HMBC experiments.     

(13)C NMR spectral assignment of 1,4-diarylpiperazinones

The piperazinone derivatives have potential application in the pharmaceutical, polymer and textile fields. The present work describes the preparation of a series of new 1,4-diarylsubstituted-2-piperazinones by condensation of substituted N,N'-bis-(2-hydroxyphenyl)-ethylenediamines with glyoxal and the complete (13)C NMR spectral assignment accomplished using APT, HMQC and HMBC techniques. Substituent chemical-shift effects (SCS) were calculated, which showed different values for the lactam- and amine-substituted aromatic rings. The results show that predictions based on SCS effects are not simple for these molecules due to electronic and steric effects. Moreover, in the case of the ortho-substituted derivative 2 g, the NMR spectra reveal a dynamic behavior related to restricted rotation of the phenyl groups (atropisomerism).     

Complete 1H and 13C NMR assignment for aryl diisoprenes

The characterization of four aryl diisoprenes was carried out by 1D‐ and 2D‐NMR methods, which permitted the assignment of the signals of all protons and all carbon atoms. Copyright © 2003 John Wiley & Sons, Ltd.     

1H and 13C NMR studies of 2-functionalized 5-(methylsulfonyl)-1-phenyl-1H-indoles

The 1H and 13C NMR resonances of thirty 2-functionalized 5-(methylsulfonyl)-1-phenyl-1H-indoles were assigned completely and unequivocally using the concerted application of one- and two-dimensional experiments (DEPT, gs-HMQC and gs-HMBC). Finally, the influence of the 2-substituent of 5-(methylsufonyl)-1-phenyl-1H-indoles on the carbon atoms of the indole moiety was estimated.     

热塑性酚醛树脂的13C NMR表征

采用一种新型环保工艺合成了热塑性酚醛(phenol novolac,PN)树脂,并采用13C NMR方法对其分子结构进行了分析,由谱图中各峰积分值定量计算出了o-o、o-p、p-p结构、支化结构、游离苯酚和醚键等其它结构所占比例分别约为19.42%、46.21%、22.32%、3.13%、4.24%和4.69%。与常规工艺生产的PN相比并无大的变化,但新型工艺从根本上解决了常规工艺带来的高浓度含苯酚废水污染的问题。研究发现催化剂浓度的提高可以减少支化结构的产生,反应温度的提高有利于o-o结构的生成,随着反应时间的延长,o-o、o-p、p-p3种结构增多。     

Analysis of the 1H and 13C NMR spectra of bicyclo[6.2.1]undecane ring systems

A detailed NMR analysis with full assignment of the ¹H and ¹³C spectral data for two polycyclic compounds is described. These compounds are derivatives of the product obtained from the pericyclic reaction between cyclopentadiene and tropone. Peculiar intriguing conformational features of these molecules are discussed. Copyright © 2003 John Wiley & Sons, Ltd.     

1H and 13C NMR assignments of new methoxylated furanoflavonoids from Lonchocarpus araripensis

Two new polymethoxylated flavonoids, 2',5',6'-trimethoxy-[2',3' : 3',4']furano dihydrochalcone and 2,4',4,5-tetramethoxy-[2',3' : 6,7]-furanodihydroaurone, were isolated from the root barks of Lonchocarpus araripensis, along with the known compounds 3,4,5,6-tetramethoxy-[2',3' : 7,8]-furanoflavan, 3,6-dimethoxy-1',1'-dimethylcromene-[2',3' : 7,8]-flavone, 3',4'-methylenodioxy-5,6-dimethoxy-[2',3' : 7,8]-furanoflavone, 3,5,6-trimethoxy-[2',3' : 7,8]-furanoflavanone, 3,5,6-trimethoxy-[2',3' : 7,8]-furanoflavone, and 6alpha-hydroxy-medicarpin. The complete (1)H and (13)C NMR assignments of the new furan flavonoids were performed using 1D and 2D pulse sequences, including COSY, HSQC, and HMBC experiments, and comparison with spectral data for analog compounds from the literature, particularly for the new furanodihydroaurone because of several inconsistencies on the carbonyl chemical shifts from the literature.     

1H and 13C NMR spectral assignments of novel chromenylchalcones

Several types of chalcones containing 2H‐chromen group were synthesized. Claisen–Schmidt condensation of 2H‐chromen‐3‐carbaldehydes (I) with methoxy substituted acetophenones afforded (E)‐3‐(2H‐chromen‐3‐yl)‐1‐(methoxyphenyl)prop‐2‐en‐1‐ones (chromenylchalcones, 1–7). Other types of chromenylchalcone, (E)‐1‐(6‐methoxy‐2H‐chromen‐3‐yl)‐3‐(methoxyphenyl)prop‐2‐en‐1‐ones (8–13) were also obtained between reaction of methoxy substituted benzaldehydes and 1‐(6‐methoxy‐2H‐chromen‐3‐yl)ethanone (II). Dichromenylchalcones (14–16) were also synthesized through the same reaction between aldehydes (I) and ketone (II). Their complete ¹H‐NMR and ¹³C‐NMR assignments are reported here and more polysubstituted chromenylchalcones synthesized or isolated from the natural sources in the future can be identified on the basis of the NMR data reported here. Copyright © 2012 John Wiley & Sons, Ltd.     

Complete assignments of NMR data of 13 hydroxymethoxyflavones

Diosmetin, 5,7,3'-trihydroxy-4'-methoxyflavone shows chemopreventive, antimutagenic, and antiallergic effects. On the other hand, chrysoeriol, 5,7,4'-trihydroxy-3'-methoxyflavone induced nodABC-lacZ in Rhizobium meliloti. Both of them belong to hydroxymethoxy- flavones. One major difference between diosmetin and chrysoeriol is the substituted position of hydroxyl and methoxyl groups. In order to elucidate the relationships between their structures and activity, one of the first things to be done is the determination of their structures. However, most flavones occur widely in nature, and thus it is difficult to obtain in sufficient amounts from natural sources to identify their structures. Assignments of NMR data of several hydroxymethoxyflavones may help us to identify novel flavonoid compounds isolated from natural sources based on their NMR experiments. Therefore, we report here the complete assignments of 1H and 13C NMR data of 13 hydroxymethoxyflavones.