基于环糊精构筑的镧系稀土发光超分子组装体

镧系元素由于其优异的发光特性,如长寿命的激发态、尖锐的线状发射带和较大的Stokes位移等,在发光材料中表现出极大的优势,被越来越多地应用于高级功能发光材料的设计中.而环糊精作为第二代超分子主体分子具有易于功能化修饰以及特异性结合发光客体等优势而被广泛地用于构筑发光材料、荧光传感等超分子体系.作者从基于环糊精的镧系稀土配位化合物超分子组装体的构筑出发,对不同镧系环糊精发光材料的最新研究进展进行综述,为开发构筑新型多功能化镧系发光材料提供参考.最后,提出了稀土发光材料目前所遇到的科学问题,并对基于环糊精稀土发光材料的发展方向进行了展望.     

近红外发光稀土配合物及杂化材料研究进展

稀土因其特殊的物理和化学性质,在信息技术、能源技术、生物技术等高科技领域及国防建设等方面都起着非常重要的作用,中国作为稀土大国,十分重视对稀土材料的研究和开发。稀土离子近红外发光(750～1700 nm)在激光和光纤通讯、医学诊断、免疫分析等热门领域的潜在应用,受到了科研人员的极大关注。稀土离子本身发光极弱,通过分子内传能有机配体可以敏化稀土离子发光,但稀土配合物常受外界干扰,其稳定性较差,若将其与凝胶、介孔材料、离子液体等无机基质复合,得到具有良好光、热稳定性和化学稳定性的有机/无机杂化材料。总结了近些年来近红外发光稀土配合物及近红外发光稀土杂化材料的研究进展,并对其发展前景进行了展望。     

配位聚合物[HgI_2(btx)]_n的制备、晶体结构及性能研究(btx=对二(1,2,4-三氮唑基甲基)苯)

选择具有较强配位能力的多齿有机化合物作为桥连配体,通过与过渡金属离子自组装制备具有新型骨架结构的一维、二维、三维配位聚合物,并进一步研究其电学、磁学、光学和催化等物理和化学性质[1～4],已成为当今化学学科和材料学科中最为活跃的领域之一.含有三氮唑、咪唑等基团的有机桥联配体由于其配位能力强、配位原子数目多、易与过渡金属离子形成具有特殊结构的配位聚合物等特点[5～7],引起了人们对于该类配体的极大兴趣,成为近年来配位化学的研究热点之一.例如,Richard Robson等人合成了一个含有咪唑基团的配体一对二(咪唑基甲基)苯,并使之与Ag(Ⅰ)及Zn(Ⅱ)自组装,制备出了两个具有二维多聚轮烷结构的配位聚合物[8,9].最近,我们课题组合成了一个含有三氮唑基团的有机配体对二(1,2,4-三氮唑基甲基)苯(btx),并通过分子的自组装作用,得到了一例新的一维锯齿状的配位聚合物[HgI2(btx)]n.本文报导了该配位聚合物的晶体结构和室温下固体化合物的荧光性质,并通过元素分析、红外光谱和热分析对其进行了表征.     

1D Lanthanide Coordination Polymers Based on 3-（Pyridin-4,yl）benzoic Acid： Syntheses, Structures and Luminescent Properties

Four novel 1D lanthanide coordination polymers with formula [Ln(3,4-pybz)3(H2O)2· H2O]n (Ln = 1 Sm; 2 Eu; 3 Tb; 4 Dy, 3,4-Hpybz = 3-(pyridin-4-yl)benzoic acid) have been synthesized by hydrothermal reactions of lanthanide oxide and 3-(pyridine-4-yl) benzoic acid. Single-crystal X-ray diffraction shows that the four compounds are isostructural. They all crystallize in a monoclinic system, space group P1. They have a doubly carboxylate-bridged infinite-chain structure with alternating Ln-(carboxylate)2-Ln linkages and one chelating carboxylate group on each metal center. The Ln ion also combines to two water molecules to form an eight-coordinate square antiprismatic geometry. The pyridine nitrogen atoms of the ligand do not coordinate to the metal centers but direct the formation of a 3D network through hydrogen bonding with coordinated water molecules. The photoluminescent properties of 2 and 3 have been also studied.     

配位聚合物[HgI2(btx)]n的制备、晶体结构及性能研究(btx=对二(1，2，4-三氮唑基甲基)苯)

A novel one-dimension coordination polymer [HgI₂(btx)]_n was synthesized through the reaction of alpha, alpha’-dichloro-p-xylene and HgI₂ in mixed MeOH-THF (1∶1) solution. The compound was characterized by X-ray crystallography and crystallizes in orthorhombic with space group Pnma. The cell parameters of the title compound are: a=0.936 3(2) nm, b=1.769 4(4) nm, c=1.032 2(2) nm, α=90°. Attractive I…I interactions link HgI₂(btx) chains directly resulting in the formation of three-dimensional network structure. In addition, the compound shows better luminescence spectroscopic property in the solid state, and is thermally stable below 126 ℃. CCDC: 233053.     

Lanthanide Complexes of Azidophenacyl‐DO3A as New Synthons for Click Chemistry and the Synthesis of Heterometallic Lanthanide Arrays

Lanthanide complexes of azidophenacyl DO3A are effective substrates for click reactions with ethyne derivatives, giving rise to aryl triazole appended lanthanide complexes, in which the aryl triazole acts as an effective sensitising chromophore for lanthanide luminescence. They also undergo click chemistry with propargylDO3A derivatives, giving rise to heterometallic complexes.     

Cationic Biphotonic Lanthanide Luminescent Bioprobes Based on Functionalized Cross-Bridged Cyclam Macrocycles

Cationic lanthanide complexes are generally able to spontaneously internalize into living cells. Following our previous works based on a diMe-cyclen framework, a second generation of cationic water-soluble lanthanide complexes based on a constrained cross-bridged cyclam macrocycle functionalized with donor-π-conjugated picolinate antennas was prepared with europium(III) and ytterbium(III). Their spectroscopic properties were thoroughly investigated in various solvents and rationalized with the help of DFT calculations. A significant improvement was observed in the case of the Eu³⁺ complex, while the Yb³⁺ analogue conserved photophysical properties in aqueous solvent. Two-photon (2P) microscopy imaging experiments on living T24 human cancer cells confirmed the spontaneous internalization of the probes and images with good signal-to-noise ratio were obtained in the classic NIR-to-visible configuration with the Eu³⁺ luminescent bioprobe and in the NIR-to-NIR with the Yb³⁺ one.     

Luminescent Europium(III) Coordination Zippers Linked with Thiophene‐Based Bridges

Novel Eu^III coordination polymers [Eu(hfa)₃(dpt)]_n (dpt: 2,5‐bis(diphenylphosphoryl)thiophene) and [Eu(hfa)₃(dpedot)]_n (dpedot: 2,5‐bis(diphenylphosphoryl)ethylenedioxythiophene) with hydrogen‐bonded zipper structures are reported. The coordination polymers are composed of Eu^III ions, hexafluoroacetylacetonato ligands, and thiophene‐based phosphine oxide bridges. The zig‐zag orientation of single polymer chains induced the formation of densely packed coordination structures with multiple intermolecular interactions, resulting in thermal stability above 300 °C. They exhibit a high intrinsic emission quantum yield (ca. 80 %) due to their asymmetrical and low‐vibrational coordination structures around Eu^III ions. Furthermore, the characteristic alternative orientation of substituents also contributes to the dramatically high ligand‐to‐metal energy transfer efficiencies of up to 80 % in the solid state.     

Investigations into cluster formation with alkyl-tethered bis-calix[4]arenes

Abstract

Calix[4]arenes are versatile ligands capable of forming a wide range of cluster motifs when reacted with 3d, 4f or 3d/4f metal ions. Synthetic modification at the calix[4]arene methylene bridge offers a unique opportunity to explore cluster formation with these alternative building blocks. Here, we present the synthesis of a range of bis-calix[4]arenes that are tethered by alkyl chains, as well as exploratory structural studies into cluster-forming reactions. Single crystals were formed in four cases, and from the X-ray structures elucidated it is possible to conclude that sufficiently long alkyl tethers allow for the formation of established cluster topologies without disruption to the core coordination chemistry.     

Synthesis of Lanthanide Coordination Polymers with Benzophenone-4,4-dicarboxylate: Effect of Lanthanide Contraction on Structures

Introduction Recently, the coordination polymers based on dicar-boxylic acid have been studied extensively for their importance as promising materials.1-7 So the rational design and synthesis of novel coordination polymers with useful functions attract considerable attention. As well known, the design of extended structure with po-tential applications can be realized by starting with connecting ligands capable of binding metal centers strongly and predictably to afford the structures with expe…     

Lanthanoid coordination with a tetrazole-substituted calix[4]diquinone and calix[4]dihydroquinone

The tetrazole-functionalised calixdiquinone 5,17-di-tert-butyl-26,28-bis-(1H-tetrazole-5-ylmethoxy)-calix[4]-25,27-diquinone Q was synthesised by chemical oxidation of the bis-tetrazole calix[4]arene precursor using PbO₂/HClO₄. The single crystal X-ray structure determination of Q confirmed the structure and showed binding of a water molecule in the solid state. Chemical reduction of Q to the dihydroquinone QR was achieved using N,N-diethylhydroxylamine. Comparison of the solution phase photophysical properties of Q or QR in the presence of terbium ions showed significant excitation only with QR, suggesting redox switching of the photophysical response may be possible with this or similar receptor.     

Highlighting Recent Crystalline Engineering Aspects of Luminescent Coordination Polymers Based on F-Elements and Ditopic Aliphatic Ligands

Three principal factors may influence the final structure of coordination polymers (CPs): (i) the nature of the ligand, (ii) the type and coordination number of the metal center, and (iii) the reaction conditions. Further, flexible carboxylate aliphatic ligands have been widely employed as building blocks for designing and synthesizing CPs, resulting in a diverse array of materials with exciting architectures, porosities, dimensionalities, and topologies as well as an increasing number of properties and applications. These ligands show different structural features, such as torsion angles, carbon backbone number, and coordination modes, which affect the desired products and so enable the generation of polymorphs or crystalline phases. Additionally, due to their large coordination numbers, using 4f and 5f metals as coordination centers combined with aliphatic ligands increases the possibility of obtaining different crystal phases. Additionally, by varying the synthetic conditions, we may control the production of a specific solid phase by understanding the thermodynamic and kinetic factors that influence the self-assembly process. This revision highlights the relationship between the structural variety of CPs based on flexible carboxylate aliphatic ligands and f-elements (lanthanide and actinides) and their outstanding luminescent properties such as solid-state emissions, sensing, and photocatalysis. In this sense, we present a structural analysis of the CPs reported with the oxalate ligand, as the one rigid ligand of the family, and other flexible dicarboxylate linkers with –CH₂– spacers. Additionally, the nature of the luminescence properties of the 4f or 5f-CPs is analyzed, and finally, we present a novel set of CPs using a glutarate-derived ligand and samarium, with the formula [2,2′-bipyH][Sm(HFG)₂ (2,2′-bipy) (H₂O)₂]•(2,2′-bipy) (α-Sm) and [2,2′-bipyH][Sm(HFG)₂ (2,2′-bipy) (H₂O)₂] (β-Sm).     

A Two-dimensional Lanthanide Coordination Framework with a New Amide-type Tripodal Ligand, 2,2'''',2"-Nitrilotris{[(2''''-benzylaminoformyl)phenoxy]ethyl}amine

Amide-type tripodal ligands have been used as ac-tive materials in ion-selective electrodes, ion recogni-tion and ion-transfer carrier, etc.,1-3 but their lanthanide complexes have not yet attracted much attention in spite of their high tendency to coordinate towards Ln(III) ions. The first three dimensional network of Eu(III) complex, which contains 1,1,1-tris{[(2-benzylaminoformyl)- phenoxy]methyl}propane (the hexadentate ligand) and Eu(NO3)3 as building block, assembled by coordination …     

Tunable Nonlinear Optical Property and Photocatalytic Activity on Luminescent Chiral Lanthanide Chains

Five chiral (P2₁) isostructural lanthanide coordination complexes Ln(pic)₃ [pic=picolinic acid, Ln=La ( 1 ), Gd ( 2 ), Nd ( 3 ), Sm ( 4 ) and Eu ( 5 )] have been hydrothermally generated, featuring one dimensional right‐handed 2₁ helical chains constructed from LnN₃O₆ of square antiprism geometry and N,O‐chelated pic^? groups, in which 3 , 4 and 5 have been reported, but we explore undiscovered properties of their own systematically. In special, 1 undergoes an abnormal transformation of symmetry as the temperature cooling to 100 K. TG‐DSC studies demonstrated that all isologues have good thermal stability with the decomposition temperature up to 400°C. Then, UV‐Vis‐NIR transmission spectroscopy measurements indicated that they possess a short‐wavelength absorption edge onset at 377 nm, corresponding to the optical band gap of 3.29 eV. Meanwhile, powder second harmonic generation (SHG) measurements revealed that the SHG intensity of 1 , 2 , 4 and 5 may be about 1.2, 2.0, 0.9 and 0.75 times that of KH₂PO₄, respectively. Interestingly, 1 and 3 exhibit efficient photocatalytic degradation for MB (Methylene Blue) upon UV‐light irradiation. Moreover, both 1 and 2 show strong blue luminescence.