基于5-甲氧基间苯二甲酸构筑的两个金属配位聚合物:晶体结构、荧光和催化性质

以5-甲氧基间苯二甲酸(CH_3O-H_2ip),2,2′-二甲基-4,4′-联吡啶(dmbpy)和四水硝酸镉/六水硝酸钴为原料,在混合溶剂中合成2个一维金属有机配位聚合物,{[Cd_2(CH_3O-ip)_2(ethanol)_2(H_2O)_4]·3H_2O}_n(1)和{[Co_2(CH_3O-ip)_2(dmbpy)(H_2O)_4]·H_2O·C_2H_3N}_n(2)(C_2H_3N=乙腈)。通过元素分析、红外光谱、差热分析、X射线粉末衍射和X射线单晶衍射等手段对配合物进行了结构表征。结果显示,化合物1为一维浪形结构,通过O-H…O分子间氢键作用构筑成二维结构;而2为一维梯形结构,通过O-H…O,O-H…N和C-H…O分子间氢键作用构筑成三维结构。常温固态下,考察了配合物1的荧光性质,并考查了化合物1和2对甲基橙的催化降解活性。     

Eu3+掺杂B2O3-CaO发光材料的制备及其发光性能

采用溶胶凝胶法制得高纯的B_2O_3-CaO∶Eu~(3+)荧光粉。用XRD、IR对不同退火温度下所得样品的结构进行表征,结果发现随退火温度的变化,能形成不同结构的硼酸盐基质。通过对以不同结构硼酸盐为基质荧光粉的激发、发射谱图及荧光衰减曲线的分析,探讨了材料的发光性能和发光机理。结果表明,在不同结构硼酸盐基质中,Eu~(3+)都处于无反演对称中心格位,以(5D0→7F2)电偶极跃迁为主,所以材料主要发红光;且900℃退火所得高纯相的CaB2O4基质最有利于发光、对应的荧光衰减时间最长,这都因在此荧光粉中Eu~(3+)更易取代Ca~(2+),并形成相对较多的p-n结和陷阱所致。     

基于一个四羧酸配体的镧系金属-有机框架材料及其对有机小分子的检测

以四羧酸3,5-双间苯二甲酸-1,2,4-三氮唑(H4L)为配体,与镧系金属Ln髥盐反应,自组装合成了2个具有三维孔洞结构的镧系金属-有机框架材料(Ln-MOFs):{[Ho_3L_2(H_2O)_6]OH·2DMF}_n(1),{[Tb_3L_2(H_2O)_6]OH·2DMF}_n(2)。单晶X射线衍射分析表明,1与2属于异质同构晶体,为单斜晶系C2/m空间群。3个LnⅢ离子通过8个羧基桥联形成三核[Ln3(COO)8]次级结构单元,晶体由[Ln3(COO)8]次级结构单元相互连接形成一维无机链,链与链之间通过配体L4-相连形成具有一维孔道的三维网络结构。有机小分子溶剂交换荧光研究表明,2在硝基苯溶剂中表现出荧光猝灭现象,Tb-MOF材料对硝基苯等爆炸物具有良好的荧光探测功能。     

Reversible Phase Transition of Robust Luminescent Hybrid Hydrogels

We report herein on remote control over a reversible phase transition of robust luminescent hybrid hydrogels as enabled by the rational selection and incorporation of photoswitches. Azobenzene units functionalized with a guanidinium group were utilized as the photoswitches and incorporated through a host–guest inclusion method involving α‐cyclodextrins functionalized with 2,6‐pyridinedicarboxylic acid (PDA) groups. While the guanidinium functional groups bind to the negatively charged Laponite matrix surface to connect organic and inorganic components, the PDA groups enable simultaneous coordination with different lanthanide metal ions, thus rendering the hydrogel broadly luminescent. Owing to its conformation‐dependent binding behavior with α‐cyclodextrin, the isomerization of azobenzene induced association or dissociation of the inclusion complexes and thus lead to a reversible photocontrolled sol?gel phase transition of the luminescent hybrid hydrogels.     

Off-on-off Luminescent Switching of a Novel Ru(II) Complex

There has been explosive interest in the synthesis and applications of novel Ru(II) polypyridyl complexes with respect to molecular sensors1,2, switches3, and sensitizers of Gr鋞zel solar cells based on nanocrystalline TiO24. Here we report a novel Ru(II) complex, which can serve as pH-induced remarkable off-on-off luminescent switch. Scheme 1 The acid-base equilibria of the complex UV-vis absorption and emission spectroscopic pH titration experiments of the Ru complex wit…     

Ca_2YSbO_6:RE~(3+)磷光体温度猝灭的研究(RE=Sm,Eu,Dy,H0,Er)

木文研究了Ca_2YSbO_6:RE~(3+)(RE=Sm,Eu,Dy,Ho,Er)等磷光体的荧光强度随温度的变化规律。发现所研究的磷光体随温度的增加荧光强度趋于下降。定性地解释了热猝灭的原因及Dy~(3+)离子的黄兰发射强度之比R与温变的关系。     

Mn(HPO3): A new manganese (II) phosphite with a condensed structure

A new manganese (II) phosphite with the formula Mn(HPO₃) has been synthesised under mild hydrothermal conditions and autogenous pressure. Large pink coloured single crystals were obtained, allowing the resolution of the structure by x-ray diffraction. Mn(HPO₃) crystallises in the P2₁/c monoclinic space group with a=8.036(3) Å, b=8.240(3) Å, c=10.410(3) Å, β=124.73(3)° and Z=8. The structure consists of a three-dimensional, compact framework of edge sharing MnO₆ octahedra linked to phosphite groups via oxygens. The presence of the phosphite anion has been confirmed by IR spectroscopy. Mn(HPO₃) presents a high thermal stability limit of 580 °C, before rapid transformation to Mn₂P₂O₇ occurs. Photoluminescence and diffuse reflectance spectroscopy studies show the presence of high spin Mn(II) in significantly distorted octahedral coordination with Dq and Racah parameters of Dq=820, B=910 and C=3135 cm⁻¹. The ESR spectra, performed at different temperatures, are isotropic with a g-value of 2.00(1). Magnetic measurements indicate global antiferromagnetic interactions with a ferromagnetic transition at 15 K, attributed to a canting of the antiferromagneticaly aligned spins.     

Direct syntheses,characterization and optical analysis of PbX2 (X = I,Br and Cl) nanoparticles without any additives

Lead iodide, bromide and chloride nanoparticles (NP-PbX₂, X = I, Br and Cl) with various morphologies were successfully prepared through a simple hydrothermal method without any additives or stabilizers. By treating the PbX₂ in EtOH/CH₂Cl₂ solution at 170 °C for 12 h, the corresponding PbX₂ nanoparticles were synthesized. The average sizes of PbX₂ nanoparticles were between 30 and 80 nm. The structure, morphology, surface and size of PbX₂ nanoparticles were determined by X-ray diffraction powder, Scanning Electron Microscopy, solid state Photo Luminescent, BET surface area and solid state UV.