稀土离子与二棕榈酰磷脂酰胆碱脂质体相互作用的分子机制

用傅里叶变换红外光谱法研究了稀土离子Ｎｄ＾３＋，Ｇｄ＾３＋和Ｙｂ＾３＋与二棕榈酰磷脂酰胆碱脂质体的相互作用。结果表明这三种稀土离子的掺入都使磷脂的凝胶－液晶相转变温度明显升高，同时相变的协同隆降低。稀土离子与磷脂极性头部的ＰＯ２＾－基团产生了键合作用，这种键合稳定，不受磷脂质体相态的影响。无论在凝胶相或液晶相，稀土离子的掺入都增加了磷脂双分子层的构象有序度。     

铈离子与银表面NAD自组装单分子层作用的SERS光谱研究

本文采用表面增强拉曼光谱,观察了稀土三价铈离子与银表面NAD自组装单层膜的相互作用。实验结果和PM3理论计算表明,三价铈离子是与NAD+分子中磷酸酯及核糖部分发生配位,从而影响单分子层的吸附结构。     

硬脂酸稀土对PVC热稳定性的作用机理研究

采用FTIR及XRD对硬脂酸稀土稳定剂进行结构表征 ,可知硬脂酸稀土中硬脂酸酸根与稀土离子间的作用主要是离子键性质的 ,且硬脂酸稀土具有层状晶体结构 ,晶层中稀土离子倾斜于基面。刚果红法测定结果表明 ,随着硬脂酸稀土用量增加 ,PVC的热稳定时间呈现增加的趋势 ,4种不同稀土硬脂酸盐稳定能力大小顺序为Last>Ndst>Yst>Dyst。通过FTIR对PVC稀土稳定体系稳定机理进行预测 ,结果表明Last和Ndst两种稀土稳定剂能取代不稳定的Cl原子 ,阻止PVC分子链上脱HCl反应 ,改变构象使其达到稳定的效果。Yst和Dyst在改变构象方面贡献较不明显。     

团簇分子[Zn-(CH_3CH_2OH)_n]~(2+)的荧光光谱研究及理论光谱验证

通过荧光光谱实验和理论计算对金属离子在乙醇溶液中的微团簇结构进行了研究。荧光光谱实验发现在275~330 nm范围存在较强的乙醇分子荧光峰,当加入盐离子(Zn~(2+))后该处荧光强度逐渐变弱,说明盐的加入对乙醇体系的荧光效率产生了影响,破坏了原有乙醇分子之间的作用,使得其刚性结构发生改变,荧光效率降低,同时Zn~(2+)与乙醇分子通过溶剂化作用形成了新的微团簇,在350~380 nm之间出现了新峰。通过对团簇结构[Zn-(H_2O)_n]~(2+)(n=1~3)进行优化比较,得到了相对精确及运算成本较低的密度泛函理论B3LYP方法,并应用于Zn~(2+)在乙醇溶液中团簇结构计算。结果表明体系的第一溶剂化层存在着n=1~6的微团簇分子,且最多为6。比较理论计算荧光光谱与实验荧光光谱,进一步说明了Zn~(2+)与乙醇形成了新的微团簇及计算方法的可行性。     

低能离子对酪氨酸溶液损伤作用的光谱研究初报

利用气体我放电产生低能离子,其在放电间隙的电场加速下撞击水溶液样品。了低能离子作用后酪氨酸溶液的紫外及红外吸收光谱的变化。结果表明,气体放电产生的离子对Ｔｙｒ造成了多种损伤。不仅使化学键断裂,分子解体,而且外来的活性离子会与溶液中的元素形成新的化学基团,妆在受损伤分子碎片上组成新的损伤物质,充分体现了低能离子与物质相互作用的“离子沉积”效应。     

协同发光效应及机理探讨

在研究共存离子对稀土配合物荧光强度影响时发现,许多稀土和非稀土离子在一定浓度范围内可对配合物的荧光产生增强效应.这种现象与协同萃取类似,我们将其命名为“协同发光效应”.本文采用激光诱导荧光光谱法,研究了十四种稀土离子对Eu、Sm-TTA-Phen-Triton X-100体系和Eu、Sm-DBM-CPB体系的协同发光效应.并从稀土离子的化学性质,光谱能级和所形成配合物的化学结构和空间结构等方面综合考虑,提出协同发光机理.拟定出用于痕量铕和钐测定的薪的超高灵敏度分析方法.     

[C2MIM]+在碳纳米管中结构和性质的理论研究

采用密度泛函理论方法,系统研究了1-乙基-3-甲基咪唑离子 ( [C2MIM]+ ) 在三种不同管径的碳纳米管中的稳定结构、相互作用能和分子轨道性质. 研究表明,随着碳纳米管管径的增加,[C2MIM]+在碳纳米管内的稳定结构从居中的位置越发靠近碳纳米管的管壁,其与碳纳米管的结合能也从-45.52 kcal/mol降低到-39.45 kcal/mol. 通过分析[C2MIM]+在不同尺寸碳纳米管中的分子轨道排布,发现研究体系的HOMO轨道和LUMO轨道主要是局域在碳纳米管上,电子跃迁表现为π→π*,表明[C2MIM]+与碳纳米管之间为弱的范德华作用. 本研究为理解离子液体与碳纳米管之间的相互作用提供了重要的理论基础.     

利用同步辐射与离子阱研究高电离态离子

近年来,各种形式的离子阱作为“清洁”的离子存储器被应用于低能高电离态离子的碰撞和光谱学的研究.同步辐射作为一种新型光源,其能量范围宽,产生的光子能量高,是高电离态产生、电离和激发的有力手段.把二者的优点结合起来,可开辟新的科学生长点.[1] 研究低能高电离态离子,对于实验室等离子体和天体等离子体中的光电离和碰撞过程;对于量子电动力学的精密检验; 对于研究高电离态离子的能极结构和谱线;对于检验和发展光电离以及其他光与离子相互作用理论,都具有非常重要的意义,是当前原子、分子物理学的重要研究前沿. 利用同步辐射光产生离子…     

高浓度NaBF4/DMF溶液中的离子溶剂化和离子缔合

利用振动光谱技术和量子化学方法研究了NaBF4／DMF溶液中的离子缔合和离子溶剂化现象。DMF分子的谱带变化表明,Na^ 与DMF分子的相互作用是通过DMF分子羰基上的氧原子进行的。Na^ 的溶剂化层内含有4个DMF分子,呈近似的四面体结构。而BF4^-谱带的变化表明,溶液中存在着离子缔合,有直接接触离子对生成。直接接触离子对的含量随溶液浓度增加而增大。     

自极化效应对稀土掺杂聚合物激发和发射光谱的影响

合成并用FT IR和元素分析方法表征了Eu(DBM) 3·Phen .对不同浓度的稀土络合物溶液和掺杂聚合物的激发光谱和发射光谱进行了测定和研究 ,结果发现在溶液和固体介质中都存在着溶质间的相互作用 .这种自极化相互作用影响包括两个方面 :有机配体的吸收光谱出现红移现象 ;稀土离子的对称性的变化 .自极化相互作用导致分子内的电荷分布变化 ,改变了激发态和基态间的能量 ,激发光谱出现红移 .在低浓度时 ,介质的性质对红移影响较大 ,高浓度时 ,介质的影响变小 .还讨论了各种因素对稀土掺杂体系的荧光性质的影响     

二维相关光谱探测荧光能量转移现象

以EuCl₃和NdCl₃混合水溶液为研究对象,按正交浓度序列以浓度为外部扰动构建紫外可见-荧光二维相关光谱。在混合溶液的二维相关光谱中,观察到了Eu3+的荧光发射谱峰与Nd^{3+的吸收谱峰之间存在交叉峰。交叉峰的出现表明Eu3+和Nd3+的荧光发射与吸收之间存在能量传递。二维相关光谱中交叉峰的产生并非由于溶剂水分子与溶质(Eu3+或Nd3+)之间相互作用;若以单一溶质的EuCl₃和NdCl₃的水溶液构造模拟的“混合溶液”的拟合光谱构建二维紫外可见-荧光相关光谱,由于Eu3+和Nd3+在空间上相互分离,无相互作用发生,交叉峰并不存在。二维相关光谱的交叉峰可为从光谱学角度探测复杂体系能量传递及其相关机制提供一条新思路。}     

Thermal and Thermo-Oxidative Degradation of Biodegradable Poly(Ester Urethane) Containing Poly(L-Lactic Acid) and Poly(Butylene Succinate) Blocks

A novel biodegradable poly(ester urethane; PEU) was synthesized by chain extension reaction of dihydroxylated poly(L-lactic acid; PLLA) and poly(butylene succinate; PBS) using diisocyanate as a chain extender. The kinetics of thermal and thermo-oxidative degradation of PEU containing PLLA and PBS blocks were studied by thermogravimetric analysis (TGA). TGA results indicated that PEU was more stable in air than in nitrogen and went through a two-stage degradation process irrespective of the experimental atmosphere. Activation energy of each stage was calculated by means of Kissinger, Kim-Park, Friedman, Flynn-Wall-Ozawa, and Kissinger-Akahira-Sunose methods. For the first stage, the activation energy value obtained in air was slightly higher than the corresponding value obtained in nitrogen; and for the second stage, the activation energy showed a much higher value in air than in nitrogen. The Coats-Redfern method was employed to study the degradation mechanism of each stage. The results indicated that the degradation of the first stage follows the P3/4 mechanism irrespective of the experimental atmosphere; the degradation of the second stage of PEU obeys the P1 mechanism in nitrogen while P3/2 in air.     

脱氧胆酸钇络合物的EXAFS和FTIR表征

用ＥＸＡＦＳ，ＦＴＩＲ以及ＩＣＰ等实验方法，对脱氧胆酸钇的结构进行了初步探讨。实验结果证实，钇与脱氧胆酸配位，生成稀土络合物，其中钇周围有八个氧原子，配位数为八，Ｙ－Ｏ平均距离为０．２３４ｎｍ。脱氧胆酸中羧基氧原子，羟基氧原子均与钇发生配位作用。     

The effect of hard segment content on ionic conductivity of poly(ether urethane)-based solid polymer electrolytes

To investigate the effect of hard segment content on ionic conductivities of poly(ether urethane) (PEU)-based solid polymer electrolytes (SPEs), PEUs containing 20, 40, 60, 80, and 100 wt.% of hard segment content were synthesized. Also we introduced polymer-in-salt system with ion-hopping mechanism contrary to traditional salt-in-polymer system with segmental motion mechanism and investigated the effect of hard segment of PEU on ionic conductivities by A.C. impedance, FT-IR, DSC, and SEM. And it could be known that hydrogen bonding of urethane group influenced the ionic conductivities of PEU-based SPE. PEU-based SPE containing 70 wt.% of salt and 20 wt.% of hard segment showed the highest ionic conductivity of 2.95 × 10⁻⁵ S/cm at room temperature.     

One-step reverse precipitation synthesis of water-dispersible superparamagnetic magnetite nanoparticles

A convenient method for preparation of pure and doped yttrium oxide was developed, which is based on irradiation of solutions containing yttrium nitrate and ammonium formate with UV light or accelerated electrons. Solid phase formed under irradiation was consequently calcined at 500?°C or higher temperatures to obtain nanocrystalline yttrium oxide. Addition of small amount of cerium(III) or europium(III) nitrates to irradiated solutions resulted in doping of yttrium oxide with Ce(III) or Eu(III) ions. Under both types of irradiation, the method yields material with high specific surface area, consisting of spherical nanoparticles 25?C100?nm in diameter depending on preparative conditions and post-radiation treatment and with narrow size distribution. In the doped oxides (Y₂O₃:Ce or Y₂O₃:Eu), radioluminescence spectra typical for Ce³⁺ or Eu³⁺ doped oxide structures were observed.     

Lanthanide ions bind specifically to an added "EF-hand" and orient a membrane protein in micelles for solution NMR spectroscopy

Twelve amino acid residues corresponding to an "EF-hand" calcium-binding site were added to the N-terminus of a protein, providing a specific lanthanide ion binding that weakly orients the protein in solution. A comparison of spectra of the protein with and without the EF-hand residues demonstrates that the structure of the native protein is not perturbed by this modification, since there are minimal chemical shift changes. With a lanthanide but not calcium bound to the EF-hand, the protein is weakly oriented by the magnetic field, since residual dipolar couplings can be measured. Since the signs and magnitudes of the couplings varied with the type of lanthanide, this demonstrated the ability to obtain multiple orientations of the protein in solution. The sample is a membrane protein in lipid micelles that disrupted the commonly employed bicelle and filamentous phage solutions; therefore, the addition of a specific metal binding site in the form of an EF-hand may provide a general approach to orienting proteins where the addition of external agents is problematic. An additional benefit is that the lanthanide ions perturb the protein resonances in ways that provide unique orientational and distance constraints.     

Lanthanide ion induced formation of stripes domain structure in phospholipid Langmuir-Blodgett monolayer film observed by atomic force microscopy

Long-range ordered stripes domain structures were observed in Dipalmitoylphosphatidylcholine (DPPC) Langmuir-Blodgett monolayer film which was spread on the subphase of lanthanide ion (Eu³⁺) solution and transferred to a freshly cleaved mica substrate by vertical deposition. This novel phenomenon was discussed in terms of the competitive interaction of dipole-dipole and electrostatic interactions of the DPPC molecules combined with lanthanide ions with those DPPC molecules free of lanthanide ions.     

The effect of tetramethylammonium ions on the distribution of silicate species in the methanolic solutions

The effect of the addition of tetramethylammonium ions on the distribution of silicate species in the methanolic solutions was studied by the trimethylsilylation technique. Tetramethylammonium ions affected silicate species formed in the hydrolysis of tetraethoxysilane, causing the singular formation of the cubic octameric silicate species in the methanolic solution. The recovery was higher in the methanolic solution than in the aqueous system. It was found that the presence of water was necessary for the singular formation, suggesting an interaction among silicate species, tetramethylammonium ions and water. It was also found that the formation of the cubic octamer started immediately after preparation of the solution.     

氯柱硼镁石在氯化镁水溶液中相转化平衡液相的红外光谱分析

采用差示FTIR光谱技术,研究了氯柱硼镁石在30℃下浓度为0.5,12和18％MgCl_2水溶液中溶解及相转化平衡饱和水溶液中硼氧配阴离子的FTIR光谱。给出了溶液中硼氧配阴离子的FTIR光谱振动频率的归属,515cm~(-1)为单和二硼氧配阴离子特征峰,630cm~(-1)为三硼氧配阴离子特征峰,550cm~(-1)为四硼氧配阴离子特征峰。对饱和水溶液中硼氧配阴离子的存在形式及其相互作用以及与相转化析出固相的关系进行了讨论。     

聚己内酰胺-锌盐相互作用的研究

本文用X 射线衍射和傅里叶变换红外光谱法研究了聚己内酰胺与氯化锌的相互作用。实验结果表明 ,当把聚己内酰胺的甲酸溶液加入饱和氯化锌水溶液 ,沉淀析出物与在纯水中析出的聚己内酰胺有明显的不同。X 射线衍射结果表明在纯水中沉淀析出的聚己内酰胺分子链发生结晶而在饱和氯化锌水溶液中析出的聚己内酰胺却未观察到尖锐衍射峰。红外光谱研究证明 ,在饱和氯化锌水溶液中析出的聚己内酰胺中所含的锌离子与酰胺基团发生相互作用 ,致使酰胺Ⅰ ,Ⅱ带发生巨大变化。酰胺Ⅰ带发生红移证明锌离子与酰胺基团上的羰基发生络合配位 ,这种作用抑制尼龙分子链之间通过CO和N—H基团形成氢键 ,阻碍聚己内酰胺分子的自由运动和整齐堆砌 ,从而使尼龙无法结晶。尼龙与锌盐之间的这种相互作用可能为发展一种尼龙加工制造新方法提供种新的机会。