An introduction to molecular spintronics

We review the progress and future possibilities in the emerging area of molecular spintronics. We first provide an overview of the different transport regimes in which electronic nanodevices can operate, then briefly overview the important characteristics of molecular magnetic materials that can be useful for application in spintronics and we eventually present several schemes to include such systems into spintronic nanodevices. We hightlight the importance of a chemical approach to the area, and in the last section we showcase some approaches to the creation of hybrids made of carbon nanostructures and molecular magnets, which are gaining increasing attention.     

Kinetic Carbon Isotope Effects in the Decarbonylation of Lactic Acid of Natural Isotopic Composition and of [1-14C] Lactic Acid

Studies of carbon-13 and carbon-14 kinetic isotope effects (K. I. E.) in the decarbonylation of lactic acid (L. A.) in sulphuric acid and in phosphoric acids media have been summarized and compared with earlier studies of ¹⁴C and ¹³C K. I. E. in the decarbonylation of formic and oxalic acids in concentrated sulphuric acid. Supplementary data concerning the decarbonylation of L. A. in sulphuric acid diluted with water and in pyrophosphoric acid are presented and discussed. The observed temperature dependences of ¹³C and ¹⁴C K. I. E. in concentrated H₂SO₄ and in concentrated phosphoric acids media have been rationalized by invoking a change of the mechanism of decarbonylation of L. A. in concentrated sulphuric and phosphoric acids with temperature. Preliminary calculational results concerning ¹³C and ^1??C K. I. E. in decarbonylation processes are also presented. In H₂SO₄ diluted with water and in H₃PO₄ diluted with water the temperature dependence of ¹³C and ¹⁴C K. I. E. is normal and well reproduced by one frequency approximation. In concentrated sulphuric acid and in concentrated phosphoric acids besides the C—OH bond rupture the rupture of a C—C bond had to be considered also to reproduce the observed ¹³C K. I. E. in selected temperature regions.     

Mechanical properties and deformation morphologies of covalently bridged multi-walled carbon nanotubes: Multiscale modeling

We formulate a multiscale modeling framework to investigate the deformation morphologies and energetics of covalently bridged multi-walled carbon nanotubes (MWCNTs). The formulation involves extending a previously established quasi-continuum model by incorporating the inter-wall bridging energy density function into the constitutive relations via message passing from fully atomistic simulations. Using the extended numerical model, we studied the mechanical responses of the 10-walled MWCNT with varying inter-wall bridge densities under torsion, bending, and uniaxial compression. Our simulation results show that the presence of inter-wall covalent bridges not only enhances the post-buckling rigidities of the MWCNTs, but also modifies the deformation morphologies and morphology pathways. For bending and uniaxial compression, we constructed in the space of bridge density and applied strain the deformation morphology phase diagram, where three phases, uniformly deformed phase, rippling pattern, and diamond-shaped pattern, are identified and separated by linear phase boundaries. We attribute the deformation phase transitions to the interplay of inter-wall and intra-wall interaction energies. The multiple shape transitions of MWCNTs and the elastic nature of the deformation suggest that MWCNTs can be designed as shape-memory nanodevices with tunable stabilities.     

Scission of Carbon Monoxide Using TaR3, R=(N(tBu)Ph) or OSi(tBu)3: A DFT Investigation

The experimentally known reduction of carbon monoxide using a 3‐coordinate [Ta(silox)₃] (silox=OSi(tBu)₃) complex initially forms a ketenylidene [(silox)₃Ta? CCO], followed by a dicarbide [(silox)₃Ta? CC? Ta(silox)₃] structure. The mechanism for this intricate reaction has finally been revealed by using density functional theory, and importantly a likely structure for the previously unknown intermediate [(silox)₃Ta? CO]₂ has been identified. The analysis of the reaction pathway and the numerous intermediates has also uncovered an interesting pattern that results in CO cleavage, that being scission from a structure of the general form [(silox)₃Ta? C_nO] in which n is even. When n is odd, cleavage cannot occur. The mechanism has been extended to consider the effect of altering both the metal species and the ligand environment. Specifically, we predict that introducing electron‐rich metals to the right of Ta in the periodic table to create mixed‐metal dinuclear intermediates shows great promise, as does the ligand environment of the Cummins‐style 3‐coordinate amide structure. This latter environment has the added complexity of improved electron donation from amide rotation that can significantly increase the reaction exothermicity.     

Sm2O3对Ni／sepiolite甲烷化催化剂的影响

采用浸渍法制备了Ni/sepiolite及Ni-Sm/sepiolite催化剂并测定了催化剂的CO甲烷化活性，采用抗热实验，XPS及CS2中毒等手段研究了钐对Ni/sepiolite催化剂的影响，结果表明，加入Sm2O3提高了Ni/sepiolite催化剂的甲烷化活性，催化剂热稳定性及抗毒能力，降低了镍原子的电子结合能。     

二苯并噻吩在分散型钼催化剂和原位产生的氢存在下的加氢脱硫Ⅲ. 催化剂前身物、硫化氢、一氧化碳和水对反应的影响(英)

研究了水／ 甲苯乳化液中二苯并噻吩（ 硫芴） 在分散型钼酸、磷钼酸和四硫钼酸铵催化剂存在下的加氢脱硫反应． 反应在高压釜中于３４０ ℃及三种不同的气氛即Ｈ２ ，Ｈ２／Ｈ２ Ｏ和ＣＯ／Ｈ２Ｏ（ＣＯ 和Ｈ２Ｏ 经水煤气转换反应（ ＷＧＳＲ） 产生原位氢） 的存在下进行． 用ＧＣ和ＧＣＭＳ鉴定、分析了气体和液体产物的组成． 结果表明： 对硫芴的加氢脱硫反应，在分散型四硫钼酸铵催化剂存在下，原位产生的氢的效果仅比加入的氢气稍好，而在分散型钼酸和磷钼酸催化剂存在下，原位产生的氢远比加入的氢气有效． 实验结果还表明： 硫化氢能显著提高分散型钼酸和磷钼酸催化剂的加氢脱硫活性，但在分散型四硫钼酸铵催化剂存在下，硫化氢能促进加氢反应而抑制氢解反应． 一氧化碳和水均选择性地抑制氢解反应．     

槲皮素化学修饰碳糊电极吸附溶出伏安法测定痕量铅

建立了用槲皮素修饰碳糊电极测定痕量铅的新方法 ,在 0 .1 0mol L甲酸盐缓冲液 (pH 4.3 )中 ,于 -0 .1 0V(vs.SCE)搅拌富集 ,再在 -0 .70V静止还原 40s后 ,阳极化扫描 ,于 -0 .42V左右获得一灵敏的铅阳极溶出峰。在最佳条件下 ,富集不同时间 ,其二次导数峰电流与Pb2 + 在 1 .0× 1 0 - 8～ 8.0× 1 0 - 7mol L和 2 .0× 1 0 - 9～ 6.0× 1 0 - 8mol L两个范围内呈线性关系 ,检出限为 8.0× 1 0 - 1 0 mol L(S N =3 )。同时初步探讨了电极反应机理。