Twining Poly(polyoxometalate) Chains into Nanoropes

Organic polymers and inorganic clusters belong to two different disciplines and have completely different properties and structures. When a cluster is attached to the backbone of a polymer as a pendant, the resultant hybrid polymers (polyclusters) exhibit unique behaviours totally different from those of conventional polymers owing to the nanoscale size of the cluster and its particular interactions. Herein, the aggregation of a poly(polyoxometalate)—a polynorbornene backbone with inorganic polyoxometalate cluster pendants—upon addition of a non-solvent to its dilute solution is reported. A three-dimensional network of tangled and snake-like nanothreads was observed. Direct visualisation of individual nanoscale clusters enabled identification of single chains within the nanothreads. These observations suggest that during the process of aggregation, the hybrid polymer forms curved or extended chains as a consequence of an armouring effect in which the collapsed cluster pendants wrap around the backbone. The collapse occurs because they become less soluble in the solvent/non-solvent mixture. The extended chains then become entwined and form nanoropes consisting of multiple chains wound around each other. This study provides a deeper understanding of the nature of polyclusters and should also prove useful for their future development and application.     

Solid-state Electrochemistry of Gadolinium Hexacyanoferrate Modified Electrode and Electrocatalytic Properties of Gadolinium Hexacyanoferrate

A new electroactive polynuclear inorganic compound of rare earth metal, gadolinium hexacyanoferrate (GdHCF), was prepared and characterized using the techniques of FTIR spectroscopy, thermogravimetric analysis (TG), UV-Vis spectrometry, X-ray photoelectron spectroscopy (XPS), ICP atomic emission spectroscopy, and EDX. The results of ICP atomic emission spectroscopy, EDX, and TGA indicated that the prepared GdHCF sample had a stoichiometry of NaGdFe(CN)₆·12H₂O (when GdHCF was prepared in NaCl solution). The FTIR spectrum of GdHCF showed that there were two types of water molecules in the structure of GdHCF: one was the interstitial water (5 H₂O), which resulted from the association of water due to H-bonding, and the other was water coordinated with Gd (7 H₂O). The results obtained using XPS showed that the oxidation state of Fe and Gd in the GdHCF sample was +2 and +3, respectively. GdHCF was immobilized on the surface of spectroscopically pure graphite (SG) electrode forming the GdHCF/SG electrode, and the solid-state electrochemistry of the resultant electrode was studied using cyclic voltammetry. The cyclic voltammetric results indicated that the GdHCF/SG electrode exhibited a pair of well-defined and stable redox peaks with the formal potential of E^0′=(197±3) mV. The effects of the concentration of the supporting electrolyte on the electrochemical characteristics of GdHCF were studied, and the results showed that the value of E^0′ increased linearly with the activity of the cationic ion of the supporting electrolyte (lga_Na⁺), with a slope of 54.1 mV, which may become a novel method for determining the activity of Na⁺ in solution. Further experimental results indicated that GdHCF had electrocatalytic activities toward the oxidation of dopamine (DA) and ascorbic acid (AA), and the electrocatalytic current increased linearly with the concentration of DA (or AA) in the range of 1.0–10.0 mmol·L^?1 (for DA) or 0.5–20.0 mmol·L^?1 (for AA).     

五种氨基酸钆络合物的ESR波谱

迄今未见任何稀土氨基酸络合物的ESR波谱报道,本文在合成Gd³⁺分别与甘氨酸、β-丙氨酸、谷氨酸、天冬氨酸和天冬酰胺五种氨基酸络合物的基础上,测定了不同温度下,水溶液、粉末及分子筛吸附样品的ESR谱,讨论了络合物中晶体场强,对称性及成键特性。     

Rational synthesis of covalently bonded organic-inorganic hybrids

Hybrid materials based on covalently linked inorganic polyoxometalates (POMs) and organic species containing a delocalized pi system have drawn increasing attention. These hybrids, traditionally prepared by cluster assembly approaches that lack predictability and controllability, can now be synthesized through common organic reactions by using organically functionalized POM clusters as building blocks. This minireview highlights some of the most recent advances on a particular type of hybrids where the organic and inorganic components are connected by an imido linkage.     

Linking Chiral Clusters with Molybdate Building Blocks: From Homochiral Helical Supramolecular Arrays to Coordination Helices

The synthesis of four new oxo‐centered Fe clusters ( 1 a – c , 2 ) of the form [Fe^III₃(μ₃‐O)(CH₂=CHCOO)₆] with acrylate as the bridging ligand gives rise to potentially intrinsically chiral oxo‐centered {M₃} trimers that show a tendency to spontaneously resolve upon crystallization. For instance, 1 a , [Fe^III₃(μ₃‐O)(CH₂=CHCOO)₆‐(H₂O)₃]⁺, crystallizes in the chiral space group P3₁ as a chloride salt. Crystallization of 1 b , [Fe₃(μ₃‐O)(C₂H₃CO₂)₆(H₂O)₃]NO₃?4.5H₂O, from aqueous solution followed by recrystallization from acetonitrile also gives rise to spontaneous resolution to yield the homochiral salt [Fe₃(μ₃‐O)(C₂H₃CO₂)₆‐(H₂O)₃]NO₃?CH₃CN of 1 c (space group P2₁2₁2₁). Furthermore, the reaction of 1 a with hexamolybdate in acetonitrile gives the helical coordination polymer {[(Fe₃(μ₃‐O)L₆(H₂O))(MoO₄)‐(Fe₃(μ₃‐O)L₆(H₂O)₂)]?2CH₃CN?H₂O}_∞ 2 (L: H₂C?CHCOO), which crystallizes in the space group P2₁. The nature of the ligand geometry allows the formation of atropisomers in both the discrete ( 1 a – c ) and linked {Fe₃} clusters ( 2 ), which is described along with a magnetic analysis of 1 a and 2 .     

High purity gadolinium by the electrolysis of GdF3

The anodic overvoltage on carbon and platinum electrodes in the electrochemical production of high purity gadolinium from molten 75 LiF-25 mol% GdF₃ solutions is discussed. At the cell temperature of 840°C calciumimpregnated anodes led to the reduction of inert electrode films and to a current yield of nearly 100%.The deposited gadolinium contained 75, 22, 54 and less than 100 ppm of the interstitial elements H, N, O and C respectively; the concentrations of the highest other analysed impurities were: Si (89), Fe (15), Y (5), Zr (3), Nd (3), Tb (71), Ta (49), W (23) and Re (<3 ppm).Partly performed at the Ames Laboratory—U.S. Department of Energy.     

一缩二甘醇酸体系荧光分析法同时测定钆和铽

本文研究了Ｇｄ＾３＾＋，Ｔｂ＾３＾＋与一缩二甘醇酸形成络合物的荧光性能及发光机理，探讨了Ｇｄ＾３＾＋，Ｔｂ＾３＾＋同时测定的最佳条件和共存离子的影响。Ｇｄ＾３＾＋，Ｔｂ＾３＾＋的检测限分别为１６０和３ｎｇ／ｍｌ。并将该法成功地应用于稀土氧化物中Ｇｄ＾３＾＋，Ｔｂ＾３＾＋的测定。     

水热法合成多金属氧酸盐棒状超细晶体

以SrCl₂·6H₂O、(NH₄)₆P₂Mo₁₈O₆₂·nH₂O为原料，在PEG-600/H₂O微乳体系中于80～130 ℃温度下水热反应8～12 h，从而制得一种多金属氧酸盐棒状超细晶体，组成是Sr₃P₂Mo₁₈O₆₂·nH₂O。该超细晶体具有长棒状形貌、高结晶度且分散性能较好，长度范围在10.0～20.0 μm，径度在1.0～2.0 μm。对反应体系中的PEG-600/H₂O体积比(V_PEC-600∶V_H2O)、水热温度以及(NH₄)₆P₂Mo₁₈O₆₂·nH₂O/SrCl₂·6H₂O质量比(W_POMs∶W_SrCl2·6H2O)3个影响因素进行了探讨，结果表明：V_PEC-600∶V_H2O主要对棒状超细晶体的形貌、长径比以及晶体结晶度有着重要影响，体积比在范围V_PEC-600∶V_H2O=(1.50～2.00)∶1.00有利于大长径比的棒状超细晶体的形成；水热温度则优选80～130 ℃范围，过低则不发生反应，过高则发生了多金属氧酸盐与PEG-600的氧化-还原反应；W_POMs∶W_SrCl2·6H2O基本上不影响超细晶体的形成。还初步探讨了该棒状超细晶体的形成机理。