Two Uranyl Complexes with Pyromellitic Acid. A Heterometallic Complex with U=O–CuII Interaction

Two uranyl complexes based on pyromellitic acid were hydrothermally synthesized, and their X‐ray single‐crystal diffraction structures were determined. Complex [UO₂(Hbtec)]^–(Himd)⁺ · H₂O ( 1 ) (H₄btec = pyromellitic acid, imd = imidazole), is an ionic complex, which shows a typical (4, 4) topological structure in the space. A heterometallic complex, UO₂Cu(btec)(phen) ( 2 ) (phen = 1,10‐phenanthroline) results from the reaction of uranyl nitrate and copper(II) bromide with pyromellitic acid. The structure of complex 2 revealed that the chains of UO₇ and CuO₃N₂ units were connected to each other through the carboxyl groups and U=O–Cu interactions to create a two‐dimensional framework.     

石榴状凝胶微球固定化漆酶的制备、 表征及降解双酚A

采用铜/锌复合金属磷酸盐晶体和海藻酸钙凝胶双重包覆技术对漆酶进行固定化, 制得石榴状Alg@Cu₃/Zn₃(PO₄)₂@Lac的凝胶微球. SEM, EDX和FTIR表征结果表明, 在凝胶微球内部, 漆酶被成功固定于由海藻酸钙凝胶包覆的铜/锌复合金属磷酸盐晶体内, 铜/锌复合金属磷酸盐晶体镶嵌于海藻酸钙凝胶网格的孔隙中而呈石榴状. 以2,2′-联氮双(3-乙基苯并噻唑啉-6-磺酸)(ABTS)为底物, 经酶学性质研究表明, 在无机盐晶体和海藻酸钙凝胶的双重保护下, Alg@Cu₃/Zn₃(PO₄)₂@Lac的耐热性、 耐酸性以及储存稳定性比游离漆酶均有不同程度增强. 将Alg@Cu₃/Zn₃(PO₄)₂@Lac应用于双酚A(BPA)的降解, 采用孔径约1 mm滤网实现快速回收, 经6次循环利用, 对BPA的降解率下降约14%, 显示出比较稳定的重复利用性和便捷的可操作性, 这主要得益于海藻酸钙和铜/锌无机盐晶体对漆酶蛋白分子的双重保护.     

Highly efficient elimination of thorium(IV) from aqueous solution using poly(cyclotriphosphazene-co-melamine) microspheres

Highly crosslinked organic–inorganic hybrid polymer poly(cyclotriphosphazene-co-melamine) microspheres (PZM) were synthesized by a simple method. The microspheres was characterized by FTIR, SEM and EDX. It was applied to eliminate thorium(IV) from aqueous solution under various conditions, i.e., pH, initial concentration, dosage and contact time. The experimental data were well-imitated via the pseudo-second-order kinetic model and its adsorption processes comply with the Langmuir isotherm model. Adsorption thermodynamic studies demonstrated that the adsorption process, in essence, was spontaneous and endothermic. Furthermore, the maximum experimental adsorption capacity was 98.6 mg g^?1 for initial thorium(IV) concentration 50 mg L^?1. When pH?=?0.0, the thorium(IV) removal efficiency reached at 76.9%, which indicates that the adsorbent can also was used in a peracid environment. Adsorption behavior of thorium(IV) onto the microspheres were weakly affected via temperature, implying that adsorption would be done at room temperature.

     

Fabrication of oriented zeolite L monolayers employing luminescent perylenediimide-bridged silsesquioxane precursor as the covalent linker

Oriented zeolite L (LTL, (M)(9)[Al(9)Si(27)O(72)].nH(2)O (M = K(+) and Na(+))) monolayers with dense packing and high coverage degree has been obtained by using a luminescent perylenediimide-bridged silsesquioxane precursor as the novel molecular binder.     

Preparation and Properties of Transparent Ultrathin Lanthanide‐Complex Films

Highly transparent ultrathin films (UTFs) based on alternative layer‐by‐layer assembly of Eu‐ and Tb‐based lanthanide complexes (LCs) and Mg–Al‐layered double hydroxide (LDH) nanosheets are reported herein. UV–visible absorption and fluorescence spectroscopy showed an orderly growth of the two types of ultrathin films upon increasing the number of deposition cycles. AFM and SEM measurements indicate that the films feature periodic layered structures as well as uniform surface morphology. Luminescent investigations reveal that (LCs/LDH)_n UTFs can detect Fe³⁺ with relative selectivity and high sensitivity (Stern–Volmer constant K_SV=8.43×10³ L mol^?1); this suggests that (LCs/LDH)_n UTFs could be a promising luminescent probe for selectively sensing Fe³⁺ ion.     

The existence of solutions for boundary value problem of fractional hybrid differential equations

In this paper, we study the existence of solutions for the boundary value problem of fractional hybrid differential equations$D_{0^{+}}^{\alpha }\left[\frac{x(t)}{f(t\text{,}x(t))}\right]+g(t\text{,}x(t))=0\text{,}0<t<1\text{,}$$x(0)=x(1)=0\text{,}$where $1<\alpha ?2$ is a real number, $D_{0^{+}}^{\alpha }$ is the Riemann–Liouville fractional derivative. By a fixed point theorem in Banach algebra due to Dhage, an existence theorem for fractional hybrid differential equations is proved under mixed Lipschitz and Carathéodory conditions. As an application, examples are presented to illustrate the main results.     

Solvability for nonlinear singular fractional differential systems with multi-orders

In this paper, we consider the existence of positive solutions for a class of nonlinear singular fractional differential systems with multi-orders. Our analysis relies on fixed point theorems on cones. Some sufficient conditions for the existence of at least one or two positive solutions for boundary value problem of nonlinear singular fractional differential systems with multi-orders are established. As an application, an example is presented to illustrate the main results.     

Synthesis and luminescence properties of spherical bridged polysilsequioxanes activated by lanthanide ions

Luminescent microspherical bridged polysilsequioxane were prepared by heating the mixture of lanthanide ions (EuCl₃ or TbCl₃) and bis-silylated bipyridine having dual roles, i.e. the bipyridine moieties can sensitize the luminescence of Eu³⁺ (or Tb³⁺) ions and the alkoxysilane substituent can be hydrolyzed and condensed via sol–gel process to create inorganic silica framework. The obtained microspheres were systematically investigated by IR spectroscopy, scanning electron microscopy, absorption spectroscopy, PL excitation and emission spectroscopy. IR spectra indicate that the silylated bipyridine has been hydrolyzed under the reaction conditions. SEM images show the microspherical morphology of the luminescent materials. It has been confirmed that the strong luminescence of the spherical bridged polysilsequioxanes is due to the effective energy transfer from the silylated bipyridine to the chelated lanthanide ions.