2-甲基-6-(2-甲苯基)-2-庚烯的波谱学研究

采用色谱法从蒲儿根花部位中分离得到2-甲基-6-(2-甲苯基)-2-庚烯,该化合物第一次以单体的形式得到,通过测定氢-氢相关谱(1H-1H COSY)、DEPT谱、异核单量子相关谱(HSQC)及异核多键相关谱(HMBC)等二维谱确定了该化合物的结构,并对该化合物的1H NMR和13C NMR谱进行了归属.     

四氢β-咔啉类化合物的1H NMR及立体化学研究

本文提供了三类(六个)代表性四氢β-咔啉化合物的2D-NMR的同核二维相关谱(cosy)和同核NOE谱(NOESY)。根据实验测得的分子中有关基团间显示的NOE关系,指定了所有化合物的构型。借助分子模型,讨论了它们的构象。     

呋喃阿洛糖衍生物水解产物的结构确定

1,2;5,6-双-O-异丙叉基-3-C-硝甲基-α-D-呋喃阿洛糖（化合物1）在酸性条件下选择性脱除5,6-异丙叉基得到C-3位构型保持的水解产物1,2-O-异丙叉基-3-C-硝甲基-α-D-呋喃阿洛糖（化合物2）;化合物1先经过Moffatt脱水生成C-3硝基烯产物1,2;5,6-双-O-异丙叉基-3-脱氧-亚甲基硝基-α-D-呋喃木糖（化合物3）,然后在酸性条件下选择性脱除5,6-异丙叉基过程中协同发生氧杂-Michael加成反应得到C-3位构型反转的水解产物1,2-O-异丙叉基-3-C-硝甲基-α-D-呋喃葡萄糖（化合物2′）,两种产物化合物2和2′互为C-3差向异构体.通过¹H NMR、¹³C NMR、DEPT-135、¹H-¹H COSY、gHSQC和gHMBC等核磁共振（NMR）技术,对化合物2′的¹H和¹³C NMR数据进行了全归属．     

没药中一呋喃倍半萜的核磁共振研究

从没药氯仿提取物中分离得到一呋喃倍半萜类化合物：2-甲氧基-5-乙酰氧基呋喃吉马-1(10)E-烯-6-酮．通过1D NMR和2D NMR（¹H-¹H COSY,HSQC和HMBC）等技术确定了该化合物的结构,利用2D NMR技术对其核磁共振信号进行了全归属,修正了文献中的归属错误. 通过NOESY实验以及偶合常数的分析,确定了其结构中1,10位双键和甲氧基、乙酰氧基、 甲基等基团的相对构型.     

四氢β—咔啉类化合物的~1H NMR及立体化学研究

本文提供了三类(六个)代表性四氢β-咔啉化合物的2D-NMR的同核二维相关谱(cosy)和同核NOE谱(NOESY)。根据实验测得的分子中有关基团间显示的NOE关系,指定了所有化合物的构型。借助分子模型,讨论了它们的构象。     

手性薄荷酮腙与一氧化氮反应产物的NMR谱研究

在温和条件下手性薄荷酮腙(1)与NO在痕量O₂存在下发生偶氮-硝化反应,高选择性的生成α-硝基偶氮化合物. 通过DEPT谱、1D NOE差谱和¹H- ¹H COSY,HSQC等2D NMR技术对目标化合物2（2,4-二硝基苯基-1-硝基-(2-异丙基-5-甲基)环己基-二氮烯）的¹H,¹³C NMR 谱的信号进行了全归属和较详细的解析,确定了目标化合物2的结构.     

外型和内型C-2位单取代降冰片烯衍生物的核磁共振波谱研究

C-2位单取代降冰片烯衍生物中降冰片烯环存在各向异性,且多数为外型和内型异构体的混合物,导致其结构解析困难.针对这一问题,本文在制备了单一构型的C-2位羧基和羟甲基取代的降冰片烯衍生物的基础上,利用¹H NMR、DEPT135、¹H-¹H COSY、¹H-¹³C HMQC、¹H-¹H NOESY谱和相应的耦合裂分信息,对外型-5-降冰片烯-2-羧酸、内型-5-降冰片烯-2-羧酸、外型-5-降冰片烯-2-甲醇和内型-5-降冰片烯-2-甲醇的¹H和¹³C NMR信号进行归属,并探讨了降冰片烯衍生物的取代基种类及空间构型对¹H NMR化学位移的影响.     

N,N-二(8-羟基-5-喹啉甲基)甘氨酸乙酯的量子化学研揪

运用分子轨道理论中的半经验AM1、PM3方法和Hartree-Fock从头算方法,通过能量梯度全优化率先计算了新近合成的化合物N,N-二(8-羟基-5-喹啉甲基)甘氨酸乙酯的平衡几何构型、电子结构以及生成热、偶极矩等分子基本性质,并联系经典有机电子结构理论进行讨论.三种方法得到的结构参数基本一致,和实验测量的晶体结构符合较好.在稳定构型基础上,用AM1方法进行正则振动频率分析,得到C-C双键、C-N单双键、C-O单双键和羟基OH的振动基频,和实验测得的红外光谱特征峰吻合较好.     

运用分子模拟计算和NMR研究确定化合物3-(3,5-二甲基-2-吡咯亚甲基)-5-溴-吲哚酮的绝对构型

用MM2和半经验AM1方法对化合物进行计算,获得化合物两种构型的原子间距离参数,依据¹H NMR产生NOE效应所需条件预报分子中可能存在的NOE.通过与实验测得的核磁共振NOE效应结果对比,确定化合物构型.     

运用分子模拟计算和NMR研究确定化合物3-(3,5-二甲基-2-吡咯亚甲基)-5-溴-吲哚酮的绝对构型

用MM2和半经验AM1方法对化合物进行计算,获得化合物两种构型的原子间距离参数,依据¹H NMR产生NOE效应所需条件预报分子中可能存在的NOE.通过与实验测得的核磁共振NOE效应结果对比,确定化合物构型.     

1,2-取代乙烯衍生物结构的核磁共振研究

该文对1,2-取代乙烯衍生物的化学结构的NMR测定方法进行了研究. 结果表明,多频率位移激发双梯度自旋回波1D NOE新方法用于阐明这类化合物的化学结构具有独到之处. 强偶合自旋体系信号的选择性粒子数转移 (SPT)影响可得到有效抑制,NOE信号为吸收型,微小(约0.8%)的NOE信号也可明确测定,重叠复杂的谱峰可分离和辨认,测定顺反异构体不需要标准样品对照,结果准确、可靠. 该文以2-甲氧基-4-(2-苯基-2-环己基氨基甲酰基-乙烯基)-乙酸苯酯为例,阐明1D NOE方法在1,2-取代乙烯衍生物的化学结构和立体化学研究中的应用.     

532nm激光作用下甲基异丙基酮的电离解离研究

在532 nm激光波长下,利用时间飞行质谱（TOF-MS）对甲基异丙基酮的多光子电离解离机制进行了研究。实验结果显示,母体分子首先发生 断裂并且吸收（2+2）个光子到达离子态。主要的质谱峰 , , 等在质谱图中清晰可见。结合Guassian03,运用HF/ 3-21G 、CIS/ 3-21G对基态和激发态的构型进行了优化和频率计算,发现激发态的碳氧键变为介于碳氧单键和双键之间特殊键,并用QST2方法找到了其中的过渡态,对三个状态的几何结构参数进行了分析得出了其解离过程是 键断裂和基团构象转化协同进行的结论。     

532nm激光作用下甲基异丙基酮的电离解离研究

在532 nm激光波长下,利用时间飞行质谱(TOF-MS)对甲基异丙基酮的多光子电离解离机制进行了研究.实验结果显示,母体分子首先发生α断裂并且吸收(2+2)个光子到达离子态.主要的质谱峰C_2H_3~+,CH_3COC_3H_7~+,CH_3~+等在质谱图中清晰可见.结合Guassian03,运用HF/3-21G、CIS/3-21G对基态和激发态的构型进行了优化和频率计算,发现激发态的碳氧键变为介于碳氧单键和双键之间特殊键,并用QST2方法找到了其中的过渡态,对三个状态的几何结构参数进行了分析得出了其解离过程是α键断裂和基团构象转化协同进行的结论.     

NMR and inelastic incoherent neutron scattering (IINS) studies of monohydroxy-17 and -21-substituted derivatives of progesterone

Internal dynamics of 17- and 21-substituted progesterone derivatives was studied by the methods NMR, inelastic incoherent neutron scattering (IINS) and quantum chemical calculations. Comparison of the computer simulation of the phonon density of states (PDS) spectrum performed by the density functional theory (DFT) method with the spectrum obtained after a transformation of the experimental results permits an interpretation of subsequent modes. Only for 17OH prg the second moment of NMR line decreases to 10 G2 near room temperature, most probably because of the oscillations about direction of inter-molecular hydrogen bond. Significant mobility of protons in this compound is also confirmed by a low intensity of the elastic peak in INS and broadening of this spectrum.     

低聚壳聚糖衍生物与BSA的作用研究

研究了具有生物相容性的低聚壳聚糖衍生物与活性药物牛血清白蛋白(BSA)之间的作用。合成了聚合度为20的窄分子量分布低聚壳聚糖 (NLCS₂₀)的3种衍生物：N-马来酰化低聚壳聚糖(MNLCS)、N-羧甲基低聚壳聚糖(CNLCS)和N-琥珀酰化低聚壳聚糖(SNLCS)。通过紫外光谱(UV)、荧光光谱和等温滴定微量热仪(ITC)研究了NLCS₂₀衍生物与BSA之间的相互作用。结果表明,BSA的构象在NLCS₂₀衍生物溶液微环境中没有发生变化,活性也没有受到影响。NLCS₂₀衍生物与BSA的作用过程是放热的且是自发进行的,主要作用力是氢键和疏水作用。说明低聚壳聚糖衍生物能够作为潜在的亲水药物如活性医药蛋白或氨基酸的运输载体。     

Definitive Carbon-13 Chemical Shift Assignments in 2-Substituted Adamantane Derivatives by Deuterium Isotope Effects

Deuterium isotope effects on carbon-13 chemical shifts in 5-[²H]-isotopomeres of ten 2-substituted adamantane derivatives were determined and used for complete assignment of their carbon-13 NMR spectra.

The carbon-13 NMR spectra of ten 2-substituted adamantane derivatives have been assignated by consideration of deuterium isotope effects. Some four- and five-bond downfield deuterium effects on certain chemical shifts have been measured and attributed to remote hyperconjugative interactions.     

d^10组态金属离子与邻菲罗啉衍生物配位反应的^1H NMR研究

通过研究ｄ＾１０组态金属离子Ｚｎ＾２＋，Ｃｄ＾２＋，Ｈｇ＾２＋与邻菲罗啉及其衍生物发生配位时配体的＾１Ｈ ＮＭＲ谱的变化，对配离子的种类进行了讨论，给出了配离子中配键稳定性的比较，提出了一种通过实验直接研究溶液中的ｄ＾１０组态离子为中心离子的配合物的方法。     

Efficient, highly selective laser isotope separation of carbon-13

We recently demonstrated an original approach to highly selective laser isotope separation of carbon-13 that employs vibrational overtone pre-excitation of CF₃H together with infrared multiphoton dissociation [O.V. Boyarkin, M. Kowalczyk, T.R. Rizzo, J. Chem. Phys. 118, 93 (2003)]. The practical implementation of this approach was complicated by the long absorption path length needed for the overtone excitation laser beam. In the present work, we employ a low overtone level for the pre-excitation that shortens this pathway, facilitating engineering of the process. We propose an optimal configuration of the isotope separation scheme and consider a realistic example of a separation unit for isotopic enrichment of carbon-13 to 94–98%. The photon energy expenditure of 97 eV per separated atom is much lower than that of the current commercial laser technology, making this process economically feasible.PACS 82.30.Lp; 89.90.+n     

Experimental determination of orientations for the 17 O electric-field-gradient and chemical shielding tensors in L-alanine

We have presented a solid-state 17 O NMR study of [13C, 17 O]-L-alanine. Using the experimental results for the 13C-17 O dipolar vector and Euler angles, the absolute orientations of 17 O chemical shielding (CS) and electric-field-gradient (EFG) tensors with respect to the molecular frame can be determined for L-alanine. The present results suggest that the intermediate EFG tensor components, VYY, lie in the carboxylate plane and parallel to the C-O bond directions, while the least shielded components, delta11, and the intermediate CS tensor components, delta22, roughly lie in the molecular plane and the direction of delta22 components are approximately 38 degrees and 25 degrees off the C-O bonds for O1 and O2, respectively. These results are in reasonable agreement with those of our quantum chemical calculations reported previously.     

Both experimental and theoretical investigations of solid-state 17O NMR for L-valine and L-isoleucine

We have presented an experimental investigation of the carboxyl oxygen NMR parameters for four distinct sites in l-valine and l-isoleucine. The carboxyl (17)O quadrupolar coupling constant, C(Q), and isotropic chemical shift, delta(iso), for these compounds are obtained by analyzing two-dimensional (17)O multiple-quantum magic-angle spinning (MQMAS) and/or 1D MAS spectra. The values of C(Q) and delta(iso) found to be in the range of 7.00-7.85 MHz, and 264-314 ppm, respectively. Extensive quantum chemical calculations at the density functional levels have been performed for a full cluster of l-valine molecules and a few theoretical models. The calculated results indicated that there was a correlation between the (17)O NMR parameters and C-O bond lengths, which was helpful for the spectral assignment. They also demonstrated that the torsion angle of l-valine plays an important role in determining the magnitudes of (17)O NMR parameters.