氮杂菲及其10-取代衍生物的~1H及~(13)C核磁共振谱

本文测定并研究了氮杂菲和它的10-羟基,7,9-二溴-10-羟基,7,9-二氯-10-羟基,10-乙酰基,10-甲氧基衍生物的~1H及~(13)C NMR谱。在XL-200型仪器上使用标准的FT技术、分辨率增强和自旋模拟法,识别了~1H和~(13)C谱峰,测得J_(HH)。氮杂菲的10-H显著去屏蔽。当忽略10-H时,δ_O和δ_H相关很好。还测得氮杂菲~(13)C的T_1值。     

含氮配体铂配合物—宁辛铂的~1H~,~(13)C和~(195)PtNMR研究

本文测定了具有抗癌活性的含氮配体铂配合物——宁辛铂Pt(C_8H_(18)N_2)(CICH_2COO)_2的~1H,~(13)C及~(195)Pt NMR谱,用DEPT及选择去偶等技术对~1H,~(13)C谱线进行了归属,并用位移理论和经验规律对~(195)Pt NMR化学位移进行了初步探讨,从而进一步确证了该化合物双齿配位的平面正方形结构。     

有机钛化学——Ⅳ.二氯二取代茂钛衍生物的~(13)C核磁共振谱

本文报道了烷基,烯基,四氢呋喃甲基等取代的二氯二茂钛的(13)~C 核磁共振谱,并鉴别了非对映异构体的不同化学位移。     

紫乌定及其类似物~(13)C核磁共振谱的研究

本文报道了十一种紫乌定及其类似物的~(13)C核磁共振谱,有助于此类二萜生物碱的结构测定。     

~(13)C核磁共振研究稀土催化剂聚合双烯的机理

用~(13)C-NMR 方法测定了稀土顺丁二烯和聚异戊二烯链端结构及序列结构,从链端结构推测的聚合活性链端结构与前文是一致的。在聚异戊二烯中存在着“头-头”和“尾-尾”结构,这种结构引起活性链端甲基位置的改变,从而解释了稀土异戊二烯中3,4-链节的形成。测定了不同聚合温度对聚合物中顺、反结构含量的影响,可用活性链端的 anti-syn异构化加以解释。     

含氟不饱和酯的~(13)C核磁共振谱

本文报道了含氟不饱和酯的~(13)C化学位移和偶合常数。并根据碳上电荷转移、杂化程度以及邻接基团的电荷密度,解释了炔碳的化学位移和氟碳偶合常数。     

双标记~(13)C,~(15)N_3-呋喃妥因的制备

以双标记13 C,15 N3-氨基脲为原料,先与苯甲醛缩合,继而与氯乙酸乙酯取代、环化,再经盐酸水解反应后与5-硝基糠醛二乙酯反应,最终制得双标记13 C,15 N3-呋喃妥因.产物经红外光谱、高效液相色谱及质谱表征.结果表明,所选用的合成路线反应条件温和,产物总收率高于60%,且同位素丰度不下降;目标产物的化学纯度>99.0%,13 C同位素丰度>98%,15 N同位素丰度>99%.     

DNA的~(13)C化学位移与其链间嘌呤-嘌呤碰撞的相关性

本文发现并间接证实了DNA的~(13)C化学位移与其结构参数(主轴螺旋扭曲角Ω,碱基平面滚动角ρ,主链扭曲角δ和螺旋浆式扭曲角ω)之间存在着相关性,文中阐明了与这些结构参数相关的碳及其理论上的解释。这些碳的化学位移相对变化明显地反映出DNA链间嘌呤-嘌呤碰撞(立体障碍)所引起的DNA双螺旋局部结构的变化,并与Calladine-Dickerson加和函数Σ作了比较。从DNA的~(13)C NMR谱可以得到有关其构象的信息,从而有可能通过~(13)C谱观测DNA在溶液中的Ω,ρ,δ和ω等结构参数。     

乙烯-α-烯烃共聚物序列结构的~(13)C NMR研究——Ⅳ.氯化聚乙烯(CPE)

本文应用取代基效应方法研究了氯化聚乙烯~(13)C NMR谱的归属。讨论了它的链结构并指出中氯含量氯化聚乙烯的结构特征是分子链中出现1,2-二氯乙烷式的结构,从氯化聚乙烯的~(13)C谱中归纳出取代基参数,发现氯含量和温度的改变对取代基参数没有明显的影响。而在溶剂ODCB中加入C_2Cl_4后,取代基参数S_1减小0.48ppm。文章最后研究了氯化聚乙烯的序列分布,讨论了氯含量对序列结构的影响。     

二萜生物碱的~(13)C核磁共振谱

本文通过对186个二萜生物碱及其衍生物的~(13)C NMR谱数据的分析比较,就以下几方面作了归纳总结:①信号归属的方法;②常见取代基OCH_3、NCH_3、、NCH_2CH_3、OCOCH_3、的化学位移范围;③季碳和某些特定碳的化学位移规律。某些特定结构,如C_(20)二萜生物碱中的噁唑烷环以及C_(20)差向异构体等的~(13)C NMR谱特征;④C_(19)二萜生物碱中不同位置上取代基(H→OH、H→OMe、OH→OAc、OH→OMe、OH→C=O)效应和立体化学效应。这些归纳总结有助于此类化合物结构的阐明。     

LC-MS测定C13-尿素同位素丰度方法的建立

13C-尿素呼气试验(13C-UBT)是采用C13尿素在临床上诊断幽门螺杆菌(Hp)的一种无创性方法,具有高效、灵敏度高、特异性强和使用安全等特点,被认为是除组织培养以外的诊断Hp的"金标准",在临床上已被广泛应用。美国药典使用GC-MS方法检测C13尿素同位素丰度,检测浓度达到12mg／mL,这种方法容易达到饱和状态,也有人用衍生化结合GC-MS方法对尿素进行检测,但衍生化步骤繁琐,且由于尿素的不稳定性易在衍生化过程中发生降解,不适合检测标准的建立。由于国内尚无C13尿素的同位素丰度定量检测方法,所以在选择C13尿素片时缺乏依据,为了更好的开展13C-UBT试验,有必要建立一个能够对高13C-尿素同位素丰度定量的方法。本实验室建立了一种快速、高效地检测13C-尿素同位素丰度的LC-MS方法。     

Statistical analysis of (13)C and (15)N NMR chemical shifts from GIAO/B3LYP/6-311 + + G** calculated absolute shieldings

The (13)C and (15)N absolute shieldings of 28 compounds have been calculated at the GIAO/B3LYP/6-311 + + G** level to complete a collection of data already published. This has allowed us to devise new equations relating delta and sigma for these nuclei based on 461 points ((13)C) and 70(72) points ((15)N).     

双氢埃托啡的^1H, ^1^3C NMR和立体化学

双氢埃托啡(1)为合成的高效镇痛剂。药理实验结果表示,其镇痛作用优于吗啡。该化合物的~1H和~(13)C NMR谱都较为复杂,尚未见报道,并且多数谱峰采用一般方法难以指定。     

Polymeric adducts of rhodium(II) tetraacetate with aliphatic diamines: natural abundance 13C and 15N CPMAS NMR investigations

Complexation properties of dimeric rhodium(II) tetracarboxylates have been utilised in chemistry, spectroscopy and organic synthesis. Particularly, the combination of these rhodium salts with multifunctional ligands results in the formation of coordination polymers, and these are of interest because of their gas‐occlusion properties. In the present work, the polymeric adducts of rhodium(II) tetraacetate with flexible ligands exhibiting conformational variety, ethane‐1,2‐diamine, propane‐1,3‐diamine and their N,N′‐dimethyl‐ and N,N,N′,N′‐tetramethyl derivatives, have been investigated by means of elemental analysis, ¹³C CPMAS NMR, ¹⁵N CPMAS NMR and density functional theory modelling. Elemental analysis and NMR spectra indicated the axial coordination mode and regular structures of (1 : 1)_n oligomeric chains in the case of adducts of ethane‐1,2‐diamine, N,N′‐dimethylethane‐1,2‐diamine N,N,N′,N′‐tetramethylethane‐1,2‐diamine and N,N,N′,N′‐tetramethylpropane‐1,3‐diamine. Propane‐1,3‐diamine and N,N′‐dimethylpropane‐1,3‐diamine tended to form heterogeneous materials, composed of oligomeric (1 : 1)_n chains and the additive of dirhodium units containing equatorially bonded ligands. Experimental findings have been supported by density functional theory modelling of some hypothetical structures and gauge‐invariant atomic orbital calculations of NMR chemical shifts. Copyright © 2013 John Wiley & Sons, Ltd.     

Co-acquisition of hyperpolarised 13C and 15N NMR spectra

Recent developments in dynamic nuclear polarisation now allow significant enhancements to be generated in the cryo solid state and transferred to the liquid state for detection at high resolution. We demonstrate that the Ardenkjaer-Larsen method can be extended by taking advantage of the properties of the trityl radicals used. It is possible to hyperpolarise 13C and 15N simultaneously in the solid state, and to maintain these hyperpolarisations through rapid dissolution into the liquid state. We demonstrate the almost simultaneous measurement of hyperpolarised 13C and hyperpolarised 15N NMR spectra. The prospects for further improvement of the method using contemporary technology are also discussed.     

1H, 13C and 15N NMR spectra of ciprofloxacin

1H NMR assignment, including the values of delta(H) and J(H,H) for the cyclopropane moiety, and 13C NMR and 15N NMR spectral data for ciprofloxacin are presented.     

Derivatives of pyrazinecarboxylic acid: 1H, 13C and 15N NMR spectroscopic investigations

NMR spectroscopic studies are undertaken with derivatives of 2‐pyrazinecarboxylic acid. Complete and unambiguous assignment of chemical shifts (¹H, ¹³C, ¹⁵N) and coupling constants (¹H,¹H; ¹³C,¹H; ¹⁵N,¹H) is achieved by combined application of various 1D and 2D NMR spectroscopic techniques. Unequivocal mapping of ¹³C,¹H spin coupling constants is accomplished by 2D (δ,J) long‐range INEPT spectra with selective excitation. Phenomena such as the tautomerism of 3‐hydroxy‐2‐pyrazinecarboxylic acid are discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

13C and 15N NMR chemical shifts of 1-(2',4'-dinitrophenyl) and 1-(2',4',6'-trinitrophenyl) pyrazoles in the solid state and in solution

The (13)C and (15)N CPMAS NMR spectra of 18 pyrazoles substituted at position 1 by dinitrophenyl and trinitrophenyl (picryl) groups have been recorded. To help in the assignments, some of these compounds were studied in DMSO-d(6) solution. Phenomena such as the conformation of the N-aryl groups and broadening of splittings due to quadrupolar nuclei are discussed.     

无环醇~(13)C NMR化学位移与其结构参数的定量关系

用新颖的原子拓扑矢量Y_C、原子平衡电负性q_e、结构信息参数[N_H~i(i=α,β)]和γ校正参数对63个无环饱和脂肪醇的局部化学微环境进行了结构表征,并对化合物~(13)C NMR化学位移进行了QSSR研究.采用偏最小二乘回归得到模型的复相关系数R和标准偏差S分别为0.9915和2.4827;对353个碳原子~(13)C NMR化学位移的实验值与计算值的平均绝对误差仅为2.01×10~(-6).同时,采用留分法(Leave-molecule-out)和外检验方法测试模型的内部稳定性和外部预测能力.与文献结果比较,本研究所用参数少,且计算简便.