Low-temperature relaxation of polymers around doped dyes studied by persistent spectral hole burning

Persistent spectral hole burning spectroscopy is applied to evaluate the low-temperature relaxation around the dye molecules doped in several types of polymers. The doped dye is tetraphenylporphine, and the measured polymers are vinyl polymers and main chain aromatic polymers. The changes of microscopic environments around the dye are evaluated from the changes in the hole profiles during temperature cycling experiments. The relaxation behavior of the polymers is discussed in relation to their chemical structures. (C) 1999 John Wiley & Sons, Inc.

配合物Ru(dcbpy)(phen)_2(PF_6)_2的2D-NMR分析

用一维ＮＭＲ方法研究了新型电化学发光探针Ru(dcbpy)(phen)2(PF6)2的立体结构，借助二维1H-1HCOSY和1H-13ccosy实验技术对其氢谱和碳谱进行了完全的归属，并给出了其氢谱和碳谱的化学位移值。

Gd(DTPA-BIN)的热力学性质及与牛血清白蛋白作用的NMR研究

报道了一种新合成的DTPA酰胺类衍生物DTPA－BIN的质子解离过程，其质子化常数总和与稳定性大于DTPA－BMA并采用核磁共振弛豫分析法研究了Gd（DTPA、BIN）在水溶液和牛血清白蛋白溶液中的诱导弛豫增强性质．Gd（DTPA－BIN）配合物在水溶液中弛豫效率为3.28mmol－1·L-1。牛血清白蛋白分子可以与Gd（DTP－BIN）配合物非共价地结合，这种非共价结合体的旋转相关时间明显长于自由配合物，使Gd（DTPA－BIN）在蛋白质溶液中弛豫效率增高．本文结果表明弛豫增强方法可以用来研究顺磁性金属配合物与蛋白质之间的相互作用情况.

联萘衍生物的NMR表征Ⅱ.2,2′-(3,4-四酸二酐)二苯甲酰氧基-1,1′联萘

用一维 1HNMR、13CNMR方法研究了2,2′-(3,4 -四酸二酐)二苯甲酰氧基 -1,1′联萘的结构 ,并通过二维1H - 1H同核相关、13C - 1H异核相关及13C - 1H异核远程相关谱进一步地确定其1H谱和13C谱中各谱峰的归属 ,为同类化合物的表征提供了依据。

利用~1H-NMR计算环化氯丁橡胶的环化度和溶剂参与量

对环化氯丁橡胶的1H -NMR谱进行了归属 ,并推导出计算环化氯丁橡胶 (CR)的环化度和溶剂参与量的公式。

Probing lanthanide ions binding on tRNA(Phe) by H-1 NMR

The structure of phenylalanine transfer ribonucleic acid (tRNA(Phe)) in solution was explored by H-1 NMR spectroscopy to evaluate the effect of lanthanide ion on the structural and conformational change. It was found that La3+ ions possess specific effects on the imino proton region of the H-1 NMR spectra for yeast tRNA(Phe). The dependence of the imino proton spectra of yeast tRNA(Phe) as a function of La3+ concentration was examined, and the results suggest that the tertiary base pair G(15). C-48, which is located in the terminal in the augmented dihydrouridine helix (D-helix), was markedly affected by La3+ (shifted to downfield by as much as 0.35). Base pair U-8. A(14) in yeast tRNA(Phe), which are stacked on G(15). C-48, was also affected by added La3+ when 1 similar to 2 Mg2+ were also present. Another imino proton that may be affected by La3+ in yeast tRNA(Phe) is that of the tertiary base pair G(19). C-56. The assignment of this resonance in yeast tRNA(Phe) is tentative since it is located in the region of highly overlapping resonances beween 12.6 and 12.2. This base pair helps to anchor the D-loop to the T Psi C loop. The binding of La3+ caused conformational change of tRNA, which is responsible for shifts to upfield or downfield in H-1 NMR spectra.

NMR titration and molecular model MOPAC calculation of protonation processes of two MRI ligands

The protonation process of two DTPA bis(amide) derivatives, DTPA-BDMA and DTPA-BDEA, was studied by using H-1 NMR titration and MOPAC calculation. Their protonation process was proposed in the order of the central amine, the terminal amines, the central carboxyl, the terminal carboxyl, the other terminal carboxyl and central amine. During the protonation of the terminal amine, there existed a large fraction of proton transfer from the central amine to the other terminal amine.

A phenomenological study of the structural relaxation of an inorganic glass (Li(2)O2SiO(2))

The structural relaxation process of an inorganic glass (Li(2)O2SiO(2)) has been studied by differential scanning calorimetry. The sample is subjected to different thermal ageing histories with isothermal stages at an ageing temperature of T-g - 30 degrees C for different ageing times and at an ageing time of 16 h for different ageing temperatures. A four-parameter Tool-Narayanaswamy-Moynihan (TNM) model, is applied to simulate the normalized specific-heat curves measured. The ageing-temperature and ageing-time dependence of the structural relaxation parameters in the TNM model is obtained. (C) 1998 Elsevier Science S.A. All rights reserved.

Effect of lanthanum ions on tRNA(Phe) structure: Imino proton NMR spectroscopy

The effect of lanthanum ions on the structural and conformational change of yeast tRNA(Phe) was studied by H-1 NMR. The results suggest that the tertiary base pair (G-15)(C-48), which was located in the terminal in the augmented dihydrouridine helix (D-helix), was markedly affected by adding La3+ and shifted 0.33 downfield. Based pair (U-8)(A-14), which is associated with a tertiary interaction, links the base of the acceptor stem to the D-stem and anchors the elbow of the L structure, shifted 0.20 upfield. Another imino proton that may be affected by La3+ in tRNA(Phe) is the tertiary base pair (G-19)(C-56). The assignment of this resonance is tentative since it is located in the region of highly overlapping resonances between 12.6 and 12.2. This base pair helps to anchor the D-loop to the T psi C loop.

Structural relaxation of an inorganic glass Li2O center dot 2SiO(2) - (I) - Tool-Narayanaswamy-Moynihan (TNM) model

The main characteristics of structural relaxation and the associated Tool-Narayanaswamy-Moynihan (TNM) model are thoroughly introduced, The structural relaxation of an inorganic glass (Li2O . 2SiO(2)) at different aging temperatures and aging times is found to be well modeled by the TNM model.

High resolution solid-state NMR and DSC study of poly(ethylene glycol) silicate hybrid materials via sol-gel process

Hybrid materials incorporating poly(ethylene glycol) (PEG) with tetraethoxysilane (TEOS) via a sol-gel process were studied for a wide range of compositions of PEG by DSC and high resolution solid-state C-13- and Si-29-NMR spectroscopy. The results indicate that the microstructure of the hybrid materials and the crystallization behavior of PEG in hybrids strongly depend on the relative content of PEG. With an increasing content of PEG, the microstructure of hybrid materials changes a lot, from intimate mixing to macrophase separation. It is found that the glass transition temperatures (T-g) (around 373 K) of PEG homogeneously embedded in a silica network are much higher than that (about 223 K) of pure PEG and also much higher in melting temperatures T-m (around 323 K) than PEG crystallites in heterogeneous hybrids. Meanwhile, the lower the PEG content, the more perfect the silica network, and the higher the T-g of PEG embedded in hybrids. An extended-chain structure of PEG was supposed to be responsible for the unusually high T-g of PEG. Homogeneous PEG-TEOS hybrids on a molecular level can be obtained provided that the PEG. content in the hybrids is less than 30% by weight. (C) 1998 John Wiley & Sons, Inc.

镧离子对tRNA~(Phe)结构的影响:亚胺质子NMR谱

采用1HNMR方法研究了镧离子对酵母tRNAPhe分子结构和构象变化的影响 .结果表明位于扩大二氢尿嘧啶螺旋 (D 螺旋 )的端梢三级碱基对 (G_15) (C_4 8)明显受加入La3+ 的影响 ,向低场位移 0 33;与三级相互作用相关 ,连接D 茎和接受茎起固定L结构转折的 (U_8) (A_14)碱基对向高场位移 0 2 0 ;另一可能受La3+影响的亚胺质子碱基对为 (G_19) (C_56 ) ,由于该碱基对位于高度叠加的 12 6和 12 2之间 ,其归属仅供参考 ,该碱基对有助于D 环对TΨC环的连接.

铕离子对tRNA~(Phe)结构影响的NMR研究

采用ＮＭＲ波谱方法研究了溶液中铕离子对酵母苯丙氨酸转移核糖核酸（ｐｈｅｎｙｌａｌａ－ｎｉｎｅｔｒａｎｓｆｅｒｒｉｂｏｎｕｃｌｅｉｃａｃｉｄ，简称ｔＲＮＡＰｈｅ）结构和构象变化的影响．Ｅｕ３＋离子对ｔＲＮＡＰｈｅ亚胺质子范围的１ＨＮＭＲ谱具有特殊的影响，酵母ｔＲＮＡＰｈｅ亚胺质子谱作为Ｅｕ３＋浓度函数的研究表明位于扩大二氢尿嘧啶螺旋（Ｄ－螺旋）的端梢三级碱基对Ｇ１５·Ｃ４８明显地受加入Ｅｕ３＋的影响（向低场位移０．８５）；堆积在Ｇ１５·Ｃ４８上的Ｕ８·Ａ１４碱基对在存有１～２个Ｍｇ２＋离子下亦受加入Ｅｕ３＋的影响．酵母ｔＲＮＡＰｈｅ中可能受到Ｅｕ３＋影响的另一亚胺质子为Ｇ１９·Ｃ５６三级碱基对，由于Ｇ１９·Ｃ５６的亚胺质子共振位于高度叠加的１２．６与１２．２之间，其归属仅供参考．该碱基对有助于Ｄ－环对ＴΨＣ环的联接．配位Ｅｕ３＋引起ｔＲＮＡ分子构象的变化并且导致一些谱峰向高场或低场位移.

NMR方法表征联萘衍生物 I2,2′-二(对氨苯氧基)-1,1′-联萘

用１Ｈ－ＮＭＲ、１３Ｃ－ＮＭＲ和二维核磁共振技术研究了２，２′－二（对氨苯氧基）－１，１′－联萘的结构，并通过１Ｈ－１Ｈ质子同核相关及１３Ｃ－１Ｈ异核相关谱提供的信息确定了其１Ｈ谱和１３Ｃ谱中各谱峰的归属，为聚合物的表征提供了依据。

NMR探测苯丙氨酸转移核糖核酸中镧离子的键合

用ＮＭＲ谱研究了溶液中镧离子对苯丙氨酸转移核糖核酸（简称ｔＲＮＡＰｈｅ）结构和构象变化的影响。研究表明Ｌａ３＋对ｔＲＮＡＰｈｅ亚胺质子范围的１ＨＮＭＲ谱具有特殊的影响，位于扩大二氢尿嘧啶螺旋（Ｄ螺旋）的端梢三级碱基对Ｇ１５·Ｃ４８明显受Ｌａ３＋的影响（向低场位移０３５）；堆积在Ｇ１５·Ｇ４８上的Ｕ８·Ａ１４碱基对在存有１～２个Ｍｇ２＋时亦受Ｌａ３＋的影响。酵母ｔＲＮＡＰｈｅ中可能受到Ｌａ３＋影响的另一亚胺质子为Ｇ１９·Ｃ５６三级碱基对，由于Ｇ１９·Ｃ５６的亚胺质子共振位于高度叠加的１２６～１２２之间。该碱基对有助于Ｄ环对ＴΨＣ环的联接。Ｌａ３＋引起ｔＲＮＡ分子构象的变化并且导致一些谱峰向高场或低场位移。