细胞内游离离子及离子通道的核磁共振研究

生物细胞内游离离子及离：子通道(Ca^2 、Mg^2 、Na^ 、K^ 以及Na^ ／Ca^2 和Na^ ／Li^ 交换等)在生理病理过程中起着重要作用。用于这些方面研究的生物核磁共振方法主要包括有：^31PNMR、^19NMR、^7Li NMR及^23Na NMR等。^31P NMR主要用于对细胞内小分子代谢物、pH及游离Mg^2 的分析测定；^19F NMR是利用氟代指示剂间接地测定细胞内游离Mg^2 和Ca^2 的浓度，进而对钙镁离子通道进行分析研究；^7Li NMR、^23Na NMR等方法分别用于研究Li^ 、Na^ ／Li^ 交换、Mg^2 ／Li^ 交换、Na^ 及K^ 等。为了更好地理解和阐释细胞内离子的调控机制，本文对近几年核磁共振技术在这些方面的应用进行了综述。     

新型氮杂大环化合物的研究3: 取代不对称多齿氮 杂大环化合物的合成、表征 与配位性能

合成了四种以Nsp^2和Nsp^3为配位原子的取代不对称多齿氮杂大环化合物,制备了它们与不同金属离子的配合物,通过元素分析和光谱表征,研究了配体的结构与其配位性能的关系。以吡啶环为侧链功能基的配体L^1和L^2可根据其环大小选择性地识别Na^+或K^+离子,与过渡金属离子形成1:1型配合物,而与Hg^2^+,Cd^2^+等离子则形成1:2型配合物。大环配体L^3与Co^2^+和Na^+离子形成的双核配合物中两个冠醚环和一个Na^+离子形成夹心配位结构。L^5环中有两个配位中心,因而可同时与两个Ru^2^+离子配位。L^1和L^2均表现出对不同金属离子良好的液膜传输性能和传输选择性。     

新型氮杂大环化合物的研究3: 取代不对称多齿氮 杂大环化合物的合成、表征 与配位性能

合成了四种以Nsp^2和Nsp^3为配位原子的取代不对称多齿氮杂大环化合物,制备了它们与不同金属离子的配合物,通过元素分析和光谱表征,研究了配体的结构与其配位性能的关系。以吡啶环为侧链功能基的配体L^1和L^2可根据其环大小选择性地识别Na^+或K^+离子,与过渡金属离子形成1:1型配合物,而与Hg^2^+,Cd^2^+等离子则形成1:2型配合物。大环配体L^3与Co^2^+和Na^+离子形成的双核配合物中两个冠醚环和一个Na^+离子形成夹心配位结构。L^5环中有两个配位中心,因而可同时与两个Ru^2^+离子配位。L^1和L^2均表现出对不同金属离子良好的液膜传输性能和传输选择性。     

中性载体ETH129推动金属离子在水/硝基苯界面的转移

本文用循环伏安法发现了中性载体ETH129(N, N, N', N'-四环己基-3-氧杂-戊二酰胺)在水/硝基苯界面推动H^+, Li^+, Na^+, Zn^2^+, Mg^2^+, Cu^2^+的离子转移,对推动离子转移过程的机理进行了探讨, 测定了相应离子的扩散系数和其配合物的稳定常数。     

离子色谱法测定酸雨中的阳离子

用离子色谱法测定酸雨中的Na^ 、NH4^ 、K^ 、Mg^2 、Ca^2 等阳离子，并同时用原子吸收分光光度法进行了对比实验。结果表明，利用离子色谱法测定阳离子，方法简便、快捷，能一次同时测定多种离子，测定结果和原子吸收法相符。     

离子色谱法同时测定水中六种阳离子

研究了用抑制电导离子色谱法一次进样同时测定水中Li^ ,Na^ , NH4^ ,Mg^2 ,Ca^2 的色谱法条件，相对标准偏差小于0．5％，加标回收率在97．5％－104．0％。在水质分析中运用t检验法，比较了用钙、镁离子浓度计算和传统方法测定的总硬度之间是否存在显著性差异。     

四足配体铽配合物-蒙脱土超分子复合发光材料的插层组装、表征和性质研究

用两种方法分别将四足配体铽配合物[TbL（NO3）]^2＋和[TbL]^3＋插层组装到了蒙脱土（MT）层板间，制备出超分子复合发光材料[TbL（NO3）^2＋-MT和[TbL]^3＋-MT。方法一：通过离子交换反应让配离子[TbL（NO3）]^2＋取代钠＋基蒙脱土（Na-MT）中的Na^＋离子，插层组装到蒙脱土层板间。方法二：用配体L与铽基蒙脱土（Tb-MT）反应，使配体插入蒙脱土层板间与Tb^3＋离子配位。用元素分析、XRD，FT-IR,UV-vis和热分析对材料进行了表征，并对其荧光性质进行了研究。结果表明，复合材料保持了蒙脱土良好的层柱结构特征，其层间距d001值与插层配离予的直径吻合较好，配离子以单层形式分布于蒙脱土层板间，复合材料中配合物的热稳定性有明显提高。在紫外光激发下，复合材料发出较强的Tb^3＋特征荧光，其发射光谱与相应配合物的发射光谱很相似；复合材料中配合物的相对荧光强度较相应纯配合物有明显提高。荧光寿命较长；配合物的激发波长向可见光区发生位移，说明插层组装实现了对配合物激发波长的调制作用。     

Eu3+掺杂SiO2-Al2O3-B2O3玻璃制备及光谱性能研究

高温溶制了Eu^3＋掺杂SiO2-Al2O3-B2O3-MxOy（M=Li^＋,Na^＋,K^＋,Mg^2＋,Ca^2＋,Sr^2＋,RE^3＋）硼硅酸盐玻璃,测试了玻璃样品的发射光谱、激发光谱和透射光谱,研究了不同碱金属离子、碱土金属离子对该系统荧光性能的影响。利用发射光谱计算了Ω2,Ω4以及^5D0到^7F2,^7F4的自发辐射几率和振子强度f（^5D0→^7F2）,f（^5D0→^7F4）。结果表明,材料的发射能级为^5D0→^7F1（590nm）,^5D0→^7F2（617nm）,^5D0→^7F4（698nm）,而且材料的结构对称性越差,跃迁戒律打破地越彻底,荧光发射越强。     

NaBF4/DMSO溶液微观结构的研究

利用红外、拉曼光谱技术和密度泛函理论研究了高浓度四氟硼酸钠／二甲基亚砜(DMSO)溶液中的离子溶剂化和离子缔合现象。红外和拉曼光谱分析表明，Na^ 与DMSO分子间有较强的相互作用．这种相互作用破坏了DMSO分子间的缔合，改变了DMSO分子的微观结构，使DMSO分子的谱带发生了明显的变化．对Na^ 与DMSO分子相互作用的溶剂化构型的量子化学计算表明，Na^ 与DMSO分子的相互作用是通过S-O基团上的氧原子进行的，钠离子的溶剂化数为4．另外，BF4^-离子的v1谱带的分裂表明，溶液中存在着直接接触离子对，形成的Na^ BF4^-离子对具有Cs构型．     

稀土离子及其配合物对二棕榈酰磷脂酰乙醇胺相变性质的影响

用差示扫描量热研究了金属离子和稀土配合物对二棕榈酰磷脂酰乙醇胺(DPPE)脂双层由凝胶态向液晶态相转变的影响T~m的影响。发现加入金属离子提高了DPPE脂双层的相转变温度。其中, Na^+＜Ca^2^+＜Ln^3^+。Pr^3^+的影响较La^3^+强。在pH 7.4时, 柠檬酸镧对T~m影响很小, 相反在pH 2.0时, 则降低相变温度T~m。乳酸稀土在pH 2.0和pH 7.4时都显著提高T~m, 在中性条件下, 对T~m影响更大。同时, 乳酸稀土较相同浓度下的稀土离子影响大, 说明乳酸稀土中稀土离子和乳酸根配体存在协同作用。我们初步探讨了金属离子以及稀土配合物对DPPE脂双层相变温度影响的原因。     

NH4Cl和HCl溶液浸取电石渣制备多晶型CaCO3

以电石渣为原料,分别以NH4Cl溶液和HCl溶液为浸取剂提取电石渣中的钙,以NH4HCO3为碳化剂制备CaCO3。研究了两种浸取工艺对电石渣中Ca^2+离子提取率的影响,并对两种体系浸取得到的Ca^2+离子提取率、二次残渣量和滤液中的杂质情况,以及制得的CaCO3的产率和性状进行了比较。结果表明,在浸取时间为30 min,浸取剂浓度为2.5 mol·L^-1,pH为8的条件下,以NH4Cl溶液浸取电石渣,加入量按Cl^-/Ca^2+物质的量比为2.0,得到Ca^2+离子提取率为92.87%;以HCl溶液浸取电石渣,加入量按Cl-/Ca^2+物质的量比为2.2,得到Ca^2+离子提取率为98.65%。Ca^2+离子滤液中的主要杂质通过调节pH均可以得到有效控制。NH4Cl溶液浸取电石渣Ca^2+离子提取率略低,二次残渣量高(22.39%),制得CaCO3的产率为1.065 g·g^-1电石渣;HCl溶液浸取电石渣Ca^2+离子提取率高,二次残渣量小(8.87%),制得CaCO3的产率为1.203 g·g^-1电石渣。两种浸取液碳化后制得的CaCO3产品纯度都在99%以上,白度在92.2-97.1%之间,通过控制碳化条件均可制得方解石型、球霰石型和文石型三种晶型的CaCO3。     

2001年全国高中学生化学竞赛（决赛）理论试题答案

第 1题1- 1　Ａ :ＮＨ4 ＨＣＯ3[或 (ＮＨ4 ) 2 ＣＯ3]　Ｂ :ＫＣｌ　Ｃ :Ｋ2 ＳＯ4 　Ｄ :ＮＨ4 Ｃｌ　Ｅ :Ｆｅ2 Ｏ3　Ｆ :ＣＯ21- 2　反应 (1) :(ｍ +ｎ)ＦｅＳＯ4 + 2 (ｍ +ｎ)ＮＨ4 ＨＣＯ3=Ｆｅｍ +ｎ(ＯＨ) 2ｎ(ＣＯ3) ｍ↓ + (ｎ +ｍ) (ＮＨ4 ) 2 ＳＯ4 + (2ｎ +ｍ)ＣＯ2 ↑ +ｍＨ2 ＯＮＨ4 ＨＣＯ3 写成 (ＮＨ4 ) 2 ＣＯ3,Ｆｅｍ +ｎ(ＯＨ) 2ｎ(ＣＯ3) ｍ 写成 (1)Ｆｅ2 (ＯＨ) 4-2ｍ(ＣＯ3) ｍ,(2 )Ｆｅ2 (ＯＨ) 2 ＣＯ3,(3)Ｆｅ(ＯＨ) 2 和ＦｅＣＯ3 且配平的 ,也给分。反应 (2 ) :2Ｆｅｍ +ｎ(ＯＨ) 2ｎ(ＣＯ3) ｍ+ ｍ +ｎ2 Ｏ2…     

Flash photolytic generation of o-quinone alpha-phenylmethide and o-quinone alpha-(p-anisyl)methide in aqueous solution and investigation of their reactions in that medium. Saturation of acid-catalyzed hydration.

o-quinone alpha-phenylmethide was generated as a short-lived transient species in aqueous solution by flash photolysis of o-hydroxy-alpha-phenylbenzyl alcohol, and its rate of decay was measured in HClO4 and NaOH solutions as well as in CH3CO2H, H2PO4-, and HCO3- buffers. These data show that hydration of this quinone methide back to its benzyl alcohol precursor occurs by acid-, base-, and uncatalyzed routes. The acid-catalyzed reaction gives the solvent isotope effect kH+/kD+ = 0.34, whose inverse nature indicates that this reaction occurs via rapid preequilibrium protonation of the quinone methide on its carbonyl oxygen atom followed by rate-determining capture of the ensuing carbocationic intermediate by water, a conclusion supported by the saturation of acid catalysis in concentrated HClO4 solution. o-quinone alpha-(p-anisyl)methide was also generated by flash photolysis of the corresponding benzyl alcohol and of the p-cyanophenol ether of this alcohol as well, and its rate of decay was measured in HClO4 and NaOH solutions and in HCO2H, CH3CO2H, HN3, CF3CH2NH3+, imidazolium ion, H2PO4-, (CH2OH)3CNH3+, (CH3)3CPO3H-, and HCO3- buffers. Acid-, base-, and uncatalyzed hydration reaction routes were again found, and solvent isotope effects as well as saturation of acid catalysis, this time in dilute HClO4, confirmed a preequilibrium mechanism for the acid-catalyzed reaction. Analysis of the buffer data gave buffer-base rate constants that did not conform to the Br?nsted relation, consistent with the expected nucleophilic nature of the buffer reactions.     

Chemical properties of the Pd4(dppm)4(H)2(2+) cluster and the homogeneous electrocatalytical behavior of hydrogen evolution and formate decomposition

Two new reductive electrochemical (CO2 + H2O + 2e-; HCO2H + 2e-) and two new chemical methods (Al(CH3)3 + proton donor; NaO2CH) to prepare the title compound from Pd2(dppm)2Cl2 are reported. For the latter method, an intermediate species formulated as Pd2(dppm)4(O2CH)2(2+) is identified spectroscopically (1H NMR, 31P NMR, IR, and FAB-MS). Limited stability of the title compound in the presence of Cl- and Br- as counteranions is noticed and is due to sensitivity of the cluster toward nucleophilic attack of the halide ions. This result is corroborated by the rapid decomposition of these clusters in the presence of CN- to form the binuclear species Pd2(dppm)2(CN)4 and by the preparation of the stable salts [Pd4(dppm)4(H)2](X)2(X- = BF4-, PF6-, BPh4-). Upon a two-electron electrochemical reduction of this cluster to the neutral species (E1/2 = -1.42 V vs SCE in DMF) in the presence of 1 equiv of HCO2H, a highly reactive species formulated as [Pd4(dppm)4(H)3]+ is generated and characterized by 1H NMR, 31P NMR, and cyclic voltammetry. Subsequent addition of H+ (via RCO2H; R = H, CH3, CF3, C6H5) under the same reducing conditions, induces the homogeneous catalysis of H2 evolution. The turnover number is found to be 134 in 2 h, with no evidence for catalyst decomposition. This same species also exhibits a one-electron oxidation process (E1/2 = -0.61 V vs SCE in DMF) that induces the catalytical decomposition of formate (HCO2- --> CO2 + 1/2H2 + 1e-). This double catalysis from the same cluster intermediate is unprecedented.     

Exchange equilibria between bicarbonate, carbonate, chloride and bromide on dowex 1 x 8

The exchange reaction 2R(+)HCO(3)(2-) + CO(3)(2-) right harpoon over left harpoon R(2)(+) CO(3)(2-) + 2HCO(3)(2-) has been studied on Dowex 1 x 8 in the presence of bicarbonate solution in equilibrium with atmospheric carbon dioxide (open system). The experiments showed, as theory predicts, that the composition of the resin phase is independent of the concentration of the bicarbonate solution. The mole fraction of carbonate at equilibrium is about 0.4 and the equilibrium constant is 0.15M at 20 degrees . With this value of the constant, the composition of the ion-exchanger for various bicarbonate concentrations has been calculated for a closed system. At [HCO(3)(-)] < 0.01M a substantial part of the resin is in the carbonate form, whereas for [HCO(3)(-)] 0.05M the resin is present almost exclusively in bicarbonate form. The exchange constants of bromide at trace level have been determined for the bicarbonate and mixed carbonate forms of the ion-exchanger. The exchange constant K(Cl)(HCO(3)) has been determined over the whole composition range and the results can be represented by K(Cl)(HCO(3))= 0.428 -0.063x(Cl) -0.115x(Cl)(2), where X(Cl) is the mole fraction of chloride in the resin. The constants are used to discuss the conditions for the Chromatographie enrichment of bromide from fresh water.     

堆积模型在萃取中的应用I: 水相介质协同效应

根据推积模型提出一种新的协萃体系,即:(简单阴离子)1+(简单阴离子)2+萃取剂,并以实验证实了水相混合介质的协同效应.研究了UO2/OAc,C1/TBP-二甲苯体系的协萃效应,测定了萃合物的组成以及各种影响分配比的因素.     

碳酸钇铵复盐结晶的形成及影响因素

对碳酸氢铵沉淀钇时碳酸钇铵复盐结晶的形成条件与ｐＨ变化特征进行了研究,发现其结晶过程与平衡溶液ｐＨ有对应关系。溶液ｐＨ由碳酸钇铵结晶化反应和碳酸氢铵的水解反应所控制。根据溶液ｐＨ的变化可以判断结晶反应是否发生或完成,以及结晶速度的快慢和结晶的程度。Ｘ－射线衍射及差热－热重分析结果表明,产物为复盐结晶２,加料方式对结晶的形成有很大影响。     

Reaction Channels of HCO with NO Study by Time-resolved TR-FTIR Spectroscope

The gaseous reaction of CH+NO2 has been investigated experimentally. CH radical was generated by multiple photon photolysis of CHBr3 at 248 nm. Vibrationally excited species of HCO (ν3), CO(v), CO2(ν3), HNO (ν1), OH(v) were detected as emitters of CH+NO2 reaction by time-resolved Fourier transform spectroscope. Three exothermic reaction channels leading to HCO+NO, NH+CO2, CO+HNO, are identified. The minor reaction leading to OH+NCO may also occur.     

Characteristic negative ion fragmentations of deprotonated peptides containing post-translational modifications: mono-phosphorylated Ser, Thr and Tyr. A joint experimental and theoretical study

Peptides and proteins may contain post-translationally modified phosphorylated amino acid residues, in particular phosphorylated serine (pSer), threonine (pThr) and tyrosine (pTyr). Following earlier work by Lehmann et al., the [M-H]- anions of peptides containing pSer and pThr functionality show loss of the elements of H3PO4. This process, illustrated for Ser (and using a model system), is CH3CONH-C(CH2OPO3H2)CONHCH(3) --> [CH3CONHC(==CH2)CONHCH3 (-OPO3H2)] (a) --> [CH3CONHC(==CH2)CONHCH3-H]- + H3PO4, a process endothermic by 83 kJ mol(-1) at the MP2/6-31++G(d,p)//HF/6-31++G(d,p) level of theory. In addition, intermediate (a) may decompose to yield CH3CONHC(==CH2)CONHCH3 + H2PO4 - in a process exothermic by 3 kJ mol(-1). The barrier to the transition state for these two processes is 49 kJ mol(-1). Characteristic cleavages of pSer and pThr are more energetically favourable than the negative ion backbone cleavages of peptides described previously. In contrast, loss of HPO3 from [M-H]- is characteristic of pTyr. The cleavage [NH2CH(CH2-C6H4-OPO3H-)CO2H] --> [NH2C(CH2-C6H4-O-)CO2H (HPO3)] (b) --> NH2CH(CH2-C6H4-O-)CO2H + HPO3 is endothermic by 318 kJ mol(-1) at the HF/6-31+G(d)//AM1 level of theory. In addition, intermediate (b) also yields NH2CH(CH2-C6H4-OH)CO2H + PO3 - (reaction endothermic by 137 kJ mol(-1)). The two negative ion cleavages of pTyr have a barrier to the transition state of 198 kJ mol(-1) (at the HF/6-31+G(d)//AM1 level of theory) comparable with those already reported for negative ion backbone cleavages.     

Backbone cleavages and sequential loss of carbon monoxide and ammonia from protonated AGG: A combined tandem mass spectrometry,isotope labeling,and theoretical study

The fragmentation characteristics of protonated alanylglycylglycine, [AGG + H](+), were investigated by tandem mass spectrometry in MALDI-TOF/TOF, ion trap, and hybrid sector instruments. b(2) is the most abundant fragment ion in MALDI-TOF/TOF, ion trap, and hybrid sector metastable ion (MI) experiments, while y(2) is slightly more abundant than b(2) in collision activated dissociation (CAD) performed in the sector instrument. The A-G amide bond is cleaved on the a(1)-y(2) pathway resulting in a proton-bound dimer of GG and MeCH=NH. Depending on the fragmentation conditions employed, this dimer can then (1) be detected as [AGG + H - CO](+), (2) dissociate to produce y(2) ions, [GG + H](+), (3) dissociate to produce a(1) ions, [MeCH=NH + H](+), or (4) rearrange to expel NH(3) forming a [AGG + H - CO - NH(3)](+) ion. The activation method and the experimental timescale employed largely dictate which of, and to what extent, these processes occur. These effects are qualitatively rationalized with the help of quantum chemical and RRKM calculations. Two mechanisms for formation of the [AGG + H - CO - NH(3)](+) ion were evaluated through nitrogen-15 labeling experiments and quantum chemical calculations. A mechanism involving intermolecular nucleophilic attack and association of the GG and imine fragments followed by ammonia loss was found to be more energetically favorable than expulsion of ammonia in an S(N)2-type reaction.