Intercalation and exchange reactions of clay minerals and non-clay layer compounds

Presently, a large variety of layered materials are synthesized that are able to intercalate neutral guest molecules or to exchange inorganic and organic ions for interlayer ions. Several of these materials are also found as minerals.The intracrystalline reactivity of a few selected compounds will be described and compared to clay minerals:

Raman spectra and structural features of ClOF2 + cation in a solution of anhydrous HF

The Raman spectra of ClOF₂ ⁺ cation in solutions of anhydrous HF were studied. In the ClOF₂ ⁺HF₂ ⁻ and ClOF₂ ⁺BF₄ ⁻−HF systems, this cation exists as a pyramidal structure (C _s symmetry), while in the ClOF₂ ⁺AuF₆ ⁻−HF system, it exists as a planar structure (C _2v symmetry). Based on nonempirical calculations by the Hartree-Fock-Roothaan method, an explanation for the dependence of the structure of the ClOF₂ ⁺ cation on the nature of the anion was proposed. For the Cl−O bond vibrations, the correlation functions of vibrational and rotational relaxations were calculated, and the characteristic times of these processes were determined. The main contribution to the formation of the band contours corresponding to the above-mentioned modes is made by the vibrational dephasing. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 432–437, March, 1998.     

A model for cation adsorption to clays and membranes

A cation adsorption model is presented and its recent applications are discussed. The model combines electrostatic equations with specific binding, and considers neutral and positively charged complexes between the negative surface sites and organic cations in a closed system. Extensions in the model account for dye aggregation in solution, and for the formation of solution complexes of inorganic cations, such as [M⁺⁺ Cl^–]⁺. The amounts of 45Ca²⁺ adsorbed to vesicles extracted from the plasma membranes of melon root cells could be adequately simulated and predicted. The binding coefficients determined for Ca²⁺, Na⁺, and Mg²⁺ are in the range of values previously deduced for binding to phospholipid components. Model calculations were applied to the test of hypotheses on the effect of salt stress on the growth of roots. The adsorption of monovalent organic cations to montmorillonite is characterized by binding coefficients that are at least six orders of magnitude larger than those of Na⁺, Mg²⁺, Ca²⁺, and Cd²⁺, or those of CdCl⁺ or CaCl⁺. Monovalent organic cations were found to adsorb 140–200% of the cation exchange capacity of the clay and to cause charge reversal. Deductions from adsorption results of acriflavin are consistent with those drawn from the application of other experimental methods. Preliminary results on the adsorption of divalent organic cations are presented. Agro-environmental applications of organo-clays are discussed.     

Total synthesis of (+)-cylindricine C

A stereoselective total synthesis of (+)-cylindricine C has been achieved starting with (S)-N-Boc-2-pyrrolidinone. The key elements of this synthesis involve the sequence of reactions including BF₃-mediated addition of the allyl Grignard reagent to the cyclic imine, spirocyclization via enamine formation, and intramolecular Michael addition to form the tricyclic core.     

β-D-核糖（ RI）与一价、二价金属离子相互作用的理论研究

在HF和MP2水平用全电子(AE)和相对论有效芯势(RECP)方法研究了Ⅰa、Ⅰb、Ⅱa和Ⅱb族金属离子与β D 核糖(RI)的相互作用. 结果表明, RECP能可靠地用于重金属离子;二价金属离子(M2＋)比一价金属离子(M＋)更易使β D 核糖(RI)变形;二价金属离子络合物(RI M2＋)比一价金属离子络合物(RI M＋)稳定. 电荷布居分析的结果支持上述结论.     

OH-Induced shift from carbon to oxygen acidity in the side-chain deprotonation of 2-, 3- and 4-methoxybenzyl alcohol radical cations in aqueous solution: results from pulse radiolysis and DFT calculations

DFT calculations have been carried out for 2-, 3- and 4-methoxybenzyl alcohol radical cations (1⁺, 3⁺ and 4⁺, respectively) and the α-methyl derivatives 2⁺ and 5⁺ using the UB3LYP/6-31G(d) method. The theoretical results have been compared with the experimental rate constants for deprotonation of 1⁺-5⁺ under acidic and basic conditions. In acidic solution, the decay of 1⁺-5⁺ proceeds by cleavage of the C-H bond, while in the presence of ⁻OH all the radical cations undergo deprotonation from the α-OH group. This pH-dependent change in mechanism has been interpreted qualitatively in terms of simple frontier molecular orbital theory. The ⁻OH induced α-O-H deprotonation is consistent with a charge controlled reaction, whereas the C-H deprotonation, observed when the base is H₂O, appears to be affected by frontier orbital interactions.     

Proton-ionizable crown compounds. 12. Proton-Coupled selective membrane transport of Li+ using a proton-ionizable pyridono macrocycle

The macrocycle-mediated fluxes of several alkali metal cations have been determined in a H₂O-CH₂Cl₂-H₂O liquid membrane system. Water-insoluble proton-ionizable macrocycles of the pyridono type were used. The proton-ionizable feature allows the coupling of cation transport to reverse H⁺ transport. This feature offers promise for the effective separation and/or concentration of alkali metal ions with the metal transport being driven by a pH gradient. A counter anion in the source phase is not co-transported. The desired separation of a particular metal ion involves its selective complexation with the macrocycle, subsequent extraction from the aqueous phase to the organic phase, and exchange for H⁺ at the organic phase-receiving phase interface. Factors affecting transport which were studied include ring size, source phase pH, and receiving phase pH. Lithium was transported at a rate higher than that of the other alkali metals in both single and competitive systems using a 15-crown-5 pyridono carrier.     

Synthesis, Characterization, and X-Ray Diffraction Analysis of Triethylenetetraammonium Tetrathiomolybdate

The reaction of gaseous H₂S with aqueous ammonium heptamolybdate in the presence of triethylenetetramine (trien) gave a red complex. The complex was recrystallized in hot water and characterized by element analysis and UV, visible, IR, and ¹H NMR spectroscopy. PMR has revealed accidental magnetic equivalence, resulting from the proximity of [MoS₄]^2- species in one complex molecule to the open triethylenetetramine ligand of another molecule. (TrienH₂)[MoS₄] crystallizes in the orthorhombic crystal system, space group Pca2₁, a=13.045(2), b=16.461(3), c=13.754(2) , =90, =90, =90°, V=2953.5(9) ³, Z=8, R₁=0.0323, wR₂=0.0730. The structure consists of the tetrahedral tetrathiomolybdate anions, forming an extended 3D framework in solids due to the interactions with triene cations via Mo-S...H-N hydrogen bonds.     

高效阳离子交换法分离纯化蛋清中的溶菌酶

 建立了用高效阳离子交换分离纯化蛋清中溶菌酶的新方法 ,讨论了纯化的工艺条件。蛋清样品匀浆后 ,用氯化钠初步纯化 ,然后用弱阳离子交换柱XIDACE WCX分离。结果表明 ,被纯化的溶菌酶和杂蛋白得到很好分离。经活性检测 ,溶菌酶过柱后的活性回收率为 10 7% ,蛋白的比活为 15 4 6 7U/mg ,纯化倍数提高了 5 6倍。用尺寸排阻 (SEC)鉴定 ,得到的溶菌酶呈均一性。该法较传统软基质低压离子交换分离速度快 ,纯化效率高。     

Nitrosation of β′-hydroxylamino-α,β-unsaturated oximes: synthesis of 1,7-dioxa-2,6-diaza-spiro[4,4]nona-2,8-diene ring system

Nitrosation of bis arylidene acetone oximes with nitrous acid in glacial acetic acid gives 3-vinyl pyrazolone-N,N′-dioxides in 32-37% yield. Similar reactions of 2-arylidene-6-(hydroxylamino-aryl-methyl)-cyclohexanone oximes give tricyclic compounds with dioxa-2,6-diaza-spiro[4,4]nona-2,8-diene ring systems in 77-84% yield.