微孔镧系配位聚合物

微孔配位聚合物与通常的微孔无机材料相比, 具有非常明显的优势. 而镧系离子特殊的光学和磁学性质, 更使得微孔镧系配位聚合物的研究成为热点. 本文简要地报道了微孔镧系配位聚合物的研究现状, 对一些微孔镧系配位聚合物的结构特点进行了描述, 讨论了影响微孔配位聚合物形成的主要因素. 一般来说, 线型配体往往能很好地将金属离子连接起来, 得到理想的微孔镧系配位聚合物; 选择合适的第二配体, 有利于构筑结构新颖的微孔镧系配位聚合物; 镧系收缩对能否形成微孔配位聚合物的影响并不明显, 只是轻稀土离子往往倾向于多结合一些小分子配体来满足更高的配位数.     

Extraction of macro- and microamounts of lanthanides by D2EHPA

The effect of macroconcentration (Ma) lanthanide extraction on the microcomponent (Mi) extraction by D2EHPA was investigated. The investigation corroborated that the macrocomponent suppresses the microcomponent extraction. The extractability of Mi decreases with increasing Ma concentration and with increasing proton lanthanide number in macroconcentrations. Semi-empirical relations were derived describing lanthanide extraction in lanthanide macro- and microconcentrations as a function of the extraction of lanthanide macroconcentrations. Under the conditions discussed, these relations can be used to estimate for any lanthanide the distribution ratios for the lanthanide applied as a macrocomponent and for Eu applied as a microcomponent.     

A dipicolinic acid tag for rigid lanthanide tagging of proteins and paramagnetic NMR spectroscopy

A new lanthanide tag was designed for site-specific labeling of proteins with paramagnetic lanthanide ions. The tag, 4-mercaptomethyl-dipicolinic acid, binds lanthanide ions with nanomolar affinity, is readily attached to proteins via a disulfide bond, and avoids the problems of diastereomer formation associated with most of the conventional lanthanide tags. The high lanthanide affinity of the tag opens the possibility to measure residual dipolar couplings in a single sample containing a mixture of paramagnetic and diamagnetic lanthanides. Using the DNA-binding domain of the E. coli arginine repressor as an example, it is demonstrated that the tag allows immobilization of the lanthanide ion in close proximity of the protein by additional coordination of the lanthanide by a carboxyl group of the protein. The close proximity of the lanthanide ion promotes accurate determinations of magnetic susceptibility anisotropy tensors. In addition, the small size of the tag makes it highly suitable for studies of intermolecular interactions.     

Electrochemical reduction of the lanthanide ions: Part II. Second reduction step of europium(III), ytterbium(III) and samarium(III) in acidic tetramethylammonium perchlorate solution

The second reduction step of Eu(III), Yb(III) and Sm(III) in 0.04 M tetramethylammonium perchlorate in the pH range 1.8–7 was investigated by cyclic voltammetry and d.c. polarography. The proposed reaction scheme at large hydrogen ion/lanthanide ion concentration ratios involves the reduction of the lanthanide(II) ion to the metallic state accompanied by a surface catalytic reaction in which the reactant is regenerated and also hydroxyl ions are formed which induces the precipitation of lanthanide(II) hydrous oxide on the electrode surface. This lanthanide(II) hydroxide is reduced at more negative potentials than the hydrated lanthanide(II) species. At lower hydrogen ion/lanthanide ion concentration ratios a preceding chemical reaction, probably involving hydrolyzed lanthanide(II) species, becomes rate determining.     

Chiral tripode approach toward multiple anion sensing with lanthanide complexes

A chiral tripodal ligand was demonstrated to form a series of lanthanide complexes exhibiting multiple anion-sensing profiles, which incorporated a fluorescent quinoline and a stereo-controlled substituent in a tetradentate skeleton. This mainly gave 1:2 (lanthanide cation/ligand) complexes with lanthanide triflates but 1:1 complexes with lanthanide nitrates. Since addition of external guest anion dynamically changed the preferred stoichiometry, the chiral lanthanide complexes exhibited anion-responsive fluorescence, luminescence, and circular dichroism spectral characteristics as multiple anion-sensing probes.     

Preparation and luminescence properties of lanthanide (Eu3+, Sm3+) complexes and their hectorite-based composites

The complexes of europium and samarium with phthalates ligands were synthesized and characterized. The luminescence behaviors of the lanthanide complexes as well as their hectorite-based composites were investigated by fluorescence spectra. The results indicated that the lanthanide complexes showed slightly lower intensities in hectorite matrix than that of corresponding pure complexes. The lanthanide ion relative fluorescence intensity (LRFI) was enhanced when the lanthanide complexes were doped into hectorite.     

原位复合法制备含铽(Ⅲ)配合物光学树脂及其荧光性质的研究

稀土元素因其独特的电子结构而具有光、电、磁、激光等特性,被誉为新材料的宝库,尤其是稀土配合物具有的Antenna效应,使发光强度明显增强.含稀土的高分子材料既具有稀土离子的发光性能,又具有高分子材料质量轻、抗冲击力强和易加工成型等优点,从而引起广泛的关注.我们曾用直接掺杂法制备含稀土配合物的光学树脂,但因稀土配合物与树脂的亲和性较小,难以均匀地.     

Luminescent lanthanide complexes as analytical tools in anion sensing, pH indication and protein recognition

Although lanthanide complexes are recently used in luminescence labeling of bio-targets, this review focuses on sensing profiles of synthetic and biological lanthanide complexes. Rational design and combinatorial screening approaches toward synthetic lanthanide complexes applicable as luminescent sensing materials are described. Iron-carrying transferrin and ferritin proteins further form lanthanide complexes working as pH indicators and protein recognition reagents.     

Lanthanide reagents in solid phase synthesis

From solid-supported ytterbium(III) catalysts to linkers cleaved by electron transfer from samarium(II) species, lanthanide reagents are beginning to find widespread application in solid phase organic synthesis. This tutorial review introduces the use of lanthanide(III) Lewis acids and lanthanide(IV) oxidants in solid phase chemistry before concentrating on the growing use of lanthanide(II) reagents in the area.     

Thermolysis of lanthanide dithiocarbamate complexes

Polycrystalline lanthanide sulfide materials were formed at low temperatures using a single-source precursor based on the lanthanide dithiocarbamate complex. The synthesis temperatures are generally lower than standard solid state preparations, avoid toxic sulfurizing gases and provide a convenient route to prepare lanthanide chalcogenide nanoparticles. Depending on the reaction conditions and oxophilicity of the lanthanide, the sulfide material was formed with oxidized products including oxysulfides, oxysulfates and the oxide.     

过渡金属-稀土异核配合物发光研究进展

借助于d-f能量传递,利用在可见区有很强电荷跃迁吸收的过渡金属有机发色团(d-block chromophore)作为稀土离子光捕获剂是本世纪初发展起来的获得高效敏化稀土发光的一条有效途径。为此,本文简要介绍稀土离子的相关电子特征和有机配体与稀土离子之间的能量传递简易模式;系统介绍了目前获得敏化稀土离子(近红外)发光的研究方法;重点介绍了d-f能量传递方面的研究成果及其在相关领域的应用。本文最后系统地介绍了本研究组近年来利用某些功能化的炔基桥联配体设计合成系列d-f异金属化合物在稀土发光材料方面的研究进展,并对该领域的研究热点和发展趋势作了初步展望。     

近红外稀土荧光在功能材料领域的研究进展

稀土近红外荧光材料具有特征发射峰尖锐、光稳定性好和毒性低等特点。近年来,稀土近红外荧光材料在光纤通讯、激光系统、生物分析传感器及生物成像等方面的应用价值日渐突显,引起了研究者们的极大关注。特别是稀土近红外荧光材料已发展成一种新兴的荧光标记材料,并有希望替代有机染料和量子点应用于生物分析和医学成像。基于稀土近红外发光的荧光探针具有低自荧光背景、宽斯托克斯位移、强抑制光漂白、深层穿透组织和短暂分辨的优势,有潜力成为高灵敏度、高选择性的检测手段。利用稀土离子制备的各种荧光材料,如上转换纳米晶、介孔材料、脂基胶体、离子液体、离子胶体、金属有机框架等,由于荧光敏化机理不同,其近红外荧光性能也各有千秋。然而,稀土近红外荧光的真正挑战仍是提高近红外发光的量子效率。本文结合近红外荧光领域的最新进展,综述了不同的稀土近红外荧光设计思路,介绍了各种近红外稀土荧光功能材料,阐述了稀土离子在近红外荧光功能材料中的优势,并展望了稀土近红外荧光材料的发展前景。     

The Lanthanide Contraction beyond Coordination Chemistry

The lanthanide contraction is conceptualized traditionally through coordination chemistry. Here we break this mold in a structural study of lanthanide ions dissolved in an amphiphilic liquid. The lanthanide contraction perturbs the weak interactions between molecular aggregates that drive mesoscale assembly and emergent behavior. The weak interactions correlate with lanthanide ion transport properties, suggesting new strategies for rare‐earth separation that exploit forces outside of the coordination sphere.     

Luminescent lanthanide coordination polymers with transformative energy transfer processes for physical and chemical sensing applications

The photophysical process of lanthanide(III) ion is based on the 4f-4f transition, which is the Laporte forbidden with narrow emission band and long emission lifetime. The 4f-4f emission process is affected by introducing aromatic organic ligands. In this review, recent progress of one-, two-, and three-dimensional polymer-typed lanthanide complexes, luminescent lanthanide coordination polymers, are focused for physical and chemical sensing applications. Their changeable luminescence depended on the physical and chemical environments come from the energy transfer between lanthanide(III) ions and aromatic organic ligands. The characteristic physical (temperature, pressure, pH and mechanical force) and chemical (adsorption of metal ions and molecules) sensitive luminescence of lanthanide coordination polymers are useful for future sensing applications.     

Thermal decomposition of metal complexes V. Lanthanide(III) complexes of benzo-15-crown-5

Thermal dissociation reactions of lanthanide(III) nitrates and thiocyanates solid complexes of the cyclic polyether benzo-15-crown-5 were studied in dynamic atmosphere of dry nitrogen and under reduced pressure (5·10^?2 mm Hg). The complexes of lanthanide nitrates undergo dissociation with ligand decomposition while from those of lanthanide thiocyanates the ligand is released undecomposed. Values of enthalpy change and “activation energy” for the dissociation reactions of the complexes with lanthanide thiocyanate were obtained and briefly discussed.     

镧系水合离子的密度泛函理论研究

用密度泛函理论(DFT)方法研究了镧系水合离子[Ln(H2O9)]^3+(Ln=Ce,Pr,Nd,Pm,Ho,Er,Tm,Yb)的几何构型、电荷分布和Ln^3+与水的结合能,计算结果与实验基本符合,表明DFT方法也适用于计算镧系离子与中性配体形成的化合物,对计算结果的分析表明,Ln^3+与H2O之间主要通过Ln5d轨道与氧孤对电子相互作用成键而结合,其余轨道起的作用比较小,用镧系化合物成键模型解释了镧系离子与水的结合能从La到Lu逐渐增加的事实。     

1-Azathioxanthone Appended Lanthanide(III) DO3A Complexes That Luminesce Following Excitation at 405 nm**

Since the pioneering report by Selvin, we have been fascinated by the potential of using lanthanide luminescence in bioimaging. The uniquely narrow emission lines and long luminescence lifetimes both provide the potential for background free images together with full certainty of probe localization. General use of lanthanide based bioimaging was first challenged by low brightness, and later by the need of UV (<405 nm) excitation sources not present in commercial microscopes. Here, we designed three lanthanide-based imaging probes based on a known motif to investigate the limitations of 405 nm excitation. These were synthesized, characterized, investigated on dedicated as well as commercial microscopes, and the photophysics was explored in detail. It was proven without doubt that the lanthanide complexes enter the cells and luminesce internally. Even so, no lanthanide luminescence were recovered on the commercial microscopes. Thus, we returned to the photophysical properties that afforded the conclusion that – despite the advances in light sources and photodetectors – we need new designs that can give us brighter lanthanide complexes before bioimaging with lanthanide luminescence becomes something that is readily done.     

Luminescence studies on europium-strontium phthalate system

New lanthanide luminescence materials were prepared. The main component lanthanide chelates generally need a relatively high content of rare earth. Inorganic luminescence materials only need low rare earth concentration using doped method. Similarly, lanthanide chelates can be added to complex matrix by doped method. In this way, low rare earth concentration emission was successful in the lanthanide chelates system as well. The influence of europium ion concentration on luminescence intensities was discussed. When the europium ion weight in the complex is only about 0.6%, the sample exhibits good luminescence properties. The fluorescence, Fourier transform infrared spectra, micro-Raman and electron spin resonance spectra of the samples were measured. And a possible luminescence mechanism was suggested by the inorganic doped mechanism and the luminescence of lanthanide complexes together.     

Chemiluminescence of systems containing lanthanide ions

A review of the chemiluminescent reactions in the systems containing lanthanide ions as emitters and different chemical compounds is presented. The systems in which lanthanide ions enhance the chemiluminescence intensity, thanks to the energy transfer processes, as well as the systems in which redox reactions involving lanthanide ions cause chemiluminescence and the systems showing electrogenerated luminescence and lyoluminescence are discussed.     

Self-assembly of luminescent ternary complexes between seven-coordinate lanthanide(III) complexes and chromophore bearing carboxylates and phosphonates

Luminescent lanthanide complexes have been prepared by exploiting the interaction between lanthanide DO3A complexes and chromophore bearing carboxylates or phosphonates. This interaction can be utilised to probe the choice of sensitising chromophore suited to a given lanthanide. Furthermore, ternary complexes obtained from chromophore appended carboxylates dissociate in the presence of phosphate, while those obtained from phosphonates do not.