发光金属-有机框架物作为传感材料的研究进展

金属-有机框架物(Metal-Orgamic Frameworks,MOFs)因其在吸附分离、储氢、磁性、催化以及荧光检测等多方面潜在的应用而成为当前的研究热点.简单介绍了发光MOFs的特点,着重评述了基于金属离子和基于有机配体发光的MOFs传感材料的研究.提出了发光MOFs作为传感材料存在的问题,预测了今后的发展趋势...     

基于MOFs材料的化学传感器的研究进展

近几年来,基于金属有机骨架材料(MOFs)材料的化学传感器的研究受到人们的广泛关注,MOFs材料可调的孔尺寸和巨大的比表面积提高了气体检测的选择性和灵敏度。MOFs作为传感材料最大的挑战就是信号的传导,本文详细总结了MOFs化学传感器的信号传导方式,如光学传感(如干涉法、局域表面等离子体共振、胶态晶体、溶剂着色、发光传感等)、导电传感和机电传感(如表面声波传感、石英晶体微天平和微悬臂梁等)等;并展望了MOFs化学传感器的应用前景,合成更多具有导电性质的MOFs材料或将MOFs传感材料与振动光谱及其他分析技术相结合是改善MOFs传感器检测灵敏性和选择性的非常有效的方法。     

基于金属有机框架材料的VOCs传感器应用进展

采用传感器对挥发性有机化合物(Volatile Organic Compounds,VOCs)进行实时监测对人体健康和环境保护具有重要意义。金属有机框架材料(MOFs)可调的孔径和开放的金属位点有利于气体的选择性吸附,被证明是提升气体传感性能的理想材料。本文综述了基于MOF材料的VOCs传感器的主要进展,分析了MOF材料在化学电阻和化学电容传感器中发挥的作用及作用机理,并对该领域面临的主要挑战和前景进行了展望。     

功能性金属有机框架在生物传感器中的应用

近年来,金属有机框架(MOFs)领域的飞速发展为新型功能MOFs在各种生物传感领域的应用提供了前所未有的发展机遇。MOFs与多种功能组分的结合,为基于MOFs的生物传感应用带来了新的结构和新的特点,如更高的稳定性、更高的灵敏度、更高的灵活性和更高的特异性。本文简述了近年来功能性MOFs在生物传感范畴的最新研讨进展,在这篇综述中,根据MOFs在生物传感器中的核心作用,简述了MOFs在生物传感器中的应用,包括敏感元件的载体、酶模拟元件、电化学信号和光信号等。最后,对功能性MOFs在生物传感范畴的应用现状和发展趋向进行了展望。     

金属有机框架复合材料在超级电容器中的合成及应用研究

电极材料是超级电容器（SCs）的关键部件，金属有机框架（MOFs）作为一种多孔材料，由于其具有比表面积大、结构可控、孔径可调等优点在SCs电极材料领域得到诸多关注，而MOFs的低导电性和稳定性仍然是实际应用中的主要挑战。MOF复合材料是一类由MOFs与一种或多种不同材料组成的复合材料，它可以有效地结合MOFs和其他功能材料的优势，例如优良的导电性和独特的电化学性质等。因此，MOF复合材料可以实现高可逆容量和优良的循环性能，克服MOFs材料的缺点，在超级电容器电极材料领域具有广阔的应用前景。根据与MOFs复合的材料维度分类，可分为0D、1D、2D和3D MOFs四类复合材料，重点综述了这四类复合材料的组成及合成方法，并系统介绍了MOF复合材料的SCs应用，对其发展前景进行展望。     

金属有机骨架材料在吸附分离CH_4/N_2中的研究进展

简单介绍了金属有机骨架材料的发展,主要从甲烷选择型MOF吸附剂、氮气选择型MOF吸附剂2个方面综述了金属有机骨架材料在CH4/N2分离中的研究进展,并对MOFs吸附剂与传统吸附剂的CH4/N2分离性能进行了比较,同时展望了MOFs吸附剂在低品质煤层气脱N2过程的应用前景。     

基于MOFs的混合基质膜在气体分离中的研究进展

简述了金属-有机骨架材料(MOFs)的合成方法及其分类,重点总结了近年来基于MOF材料混合基质膜的研究方向及进展,包括针对不同分离体系时MOF的选择、MOF和聚合物基质间的匹配及界面设计、MOF负载量和使用不止一种MOF填料的影响等,最后展望了MOF混合基质膜未来的研究方向。     

MOF复合材料在气体吸附分离中的研究进展

作为一种新型多孔材料,金属有机骨架（metal-organic framework, MOF）材料因其具有高孔隙率、大比表面积、孔尺寸高度可调、结构多样等优点,近年来在气体吸附与分离领域显示出广阔的应用前景。然而,在MOF材料的工业化进程中,仍存在稳定性差等问题需要解决。将MOF材料与其他功能材料进行复合,实现不同材料间的协同效应,在保证吸附分离性能的同时,显著提升MOF材料的结构稳定性。本综述概述了MOF基复合材料的构筑策略,与MOFs构筑复合材料的材料,包括碳基材料、离子液体、MOFs、分子筛等。分析了各种MOF复合材料在气体吸附与分离领域的应用进展,并对该研究方向进行了展望。     

CO2/CH4 and CH4/N2 separation on isomeric metal organic frameworks☆

Two isomeric metal-organic frameworks(MOFs) with 2-dimensional(2D) and 3-dimensional(3D) topologies both comprised of Cu(Ⅱ) and OTf(OTf = trifluoromethanesulfonate) ions were synthesized and characterized.The CO_2,CH_4 and N_2 adsorption properties of the two isomeric MOFs were investigated from 263 K to 298 K at0.1 MPa.The results showed that the 2D MOF exhibited a higher selectivity for CO_2 from CO_2/CH_4 and CH_4from CH_4/N_2 compared to the 3D MOF,even though it possessed a lower surface area and pore volume.The higher adsorption heats of gases on the 2D MOF inferred the strong adsorption potential energy in the layered MOFs.Dynamic separation experiments using CO_2/CH_4 and CH_4/N_2 mixtures on the two MOFs proved that the2 D MOF had a longer elution time than the 3D MOF as well as better separation abilities.     

金属有机骨架基复合相变储热材料研究进展

固-液相变材料的品种多且潜热大,是潜热储热技术的重要工作介质。因其存在的液相泄漏问题,现阶段常将此类相变材料与多孔载体复合以提升相变材料的应用性能及使用寿命。金属有机骨架（MOFs）是一种新型多孔材料,具有高比表面积、高孔隙率以及孔径和表面性质可调控等优势,将其用作相变材料的载体具有潜在的发展前景。本文对MOF基复合相变材料的研究进行了全面综述,详细介绍了以MOFs为载体、以MOFs衍生多孔碳为载体和以MOFs原位生长于高导热基体所得复合材料为载体而制得的多种复合相变材料。MOFs的微孔结构所产生的强毛细管力对固-液相变材料有很强的固定作用;制备较大孔径的MOFs或者对MOFs进行修饰以调节MOF与相变材料间的相互作用,都有利于提高相变材料的负载率,从而提升复合相变材料的潜热;对MOFs进行高温碳化处理得到MOFs衍生多孔碳能有效解决MOFs孔径过小的问题,并能通过对其进行氮掺杂或磷掺杂来增强载体与相变材料间的氢键作用,从而获得具有高负载率和相变潜热的复合相变材料;为了增强MOF基复合相变材料的导热性能,先将MOFs原位合成在高导热基体上以利用高导热基体提供连续的传热网络,可以有效提升复合相变材料的导热系数。将原位生长在高导热基体上的MOFs进行高温碳化处理可以得到MOFs衍生多孔碳与高导热基体的复合材料,将其作为载体可以进一步增强复合相变材料的导热性能。文中最后指出,今后对于MOF基复合相变储热材料所用MOFs和相变材料的种类、MOFs与相变材料间相互作用对储热性能的影响、MOFs与相变材料复合后的稳定性等方面还需进一步探索,将MOFs的催化、检测等功能与相变材料的储热控温功能相结合制备多功能材料也是未来的发展方向之一。     

Ultrafast microwave-enhanced ionothermal synthesis of luminescent crystalline polyimide nanosheets for highly selective sensing of chromium ions

Highly luminescent crystalline polyimide (PI) nanosheets in high yields (up to 95%) were facilely prepared through reaction between melamine and pyromellitic dianhydride via a microwave-enhanced high temperature ionothermal method within only a few minutes (~ 3 min). The as-synthesized luminescent crystalline PI nanosheets have been investigated as sensors for luminescence sensing investigations toward a series of metal ion solutions. Remarkably, such luminescent crystalline PI nanosheets exhibited highly sensitive and selective sensing of chromium ions in aqueous solution, without the interference of other metal ions, such as potassium, calcium, cadmium, plumbum, manganese, mercury, magnesium, cobalt, copper, and zinc.     

Optical temperature sensing and luminescent switching properties in Pr/Er-doped (K0.5Na0.5)NbO3 materials

For optical temperature sensing materials, the emission and excitation bands are extremely critical to measure the temperature by fluorescence intensity ratio (FIR) technique. Singly Ln-doped optical temperature sensing materials exhibit very few emission bands, which greatly constraints their practical applications of FIR technique. Here, the fabricated Pr/Er co-doped (K_0.5Na_0.5)NbO₃ materials exhibited multi-color (red-green) and dual-mode (downshifting/upconversion) luminescence properties. The temperature sensitivity can be effectively tuned by choosing different emission or excitation bands. The optimized optical temperature sensitivity reached up to 0.0094 K⁻¹, much higher than that of most temperature sensing materials. Besides, the samples also showed excellent luminescence modulation properties based on the photochromic reaction. Under sunlight irradiation, the luminescent switching contrast (ΔR_t) of the samples reached more than 60%. These results may provide a guiding role in designing and modulating optical temperature sensing properties for multifunctional materials.     

Y4.67Si3O13-based phosphors: Structure,morphology and upconversion luminescence for optical thermometry

How to improve the sensitivity of the temperature-sensing luminescent materials is one of the most important objects currently. In this work, to obtain high sensitivity and learn the corresponding mechanism, the rare earth (RE) ions doped Y_4.67Si₃O₁₃ (YS) phosphors were developed by solid-state reaction. The phase purity, structure, morphology and luminescence characteristics were evaluated by XRD, TEM, emission spectra, etc. The change of the optical bandgaps between the host and RE-doped phosphors was found, agreeing with the calculation results based on density-functional theory. The temperature-dependence of the upconversion (UC) luminescence revealed that a linear relationship exists between the fluorescence intensity ratio of Ho³⁺ and temperature. The theoretical resolution was evaluated. High absolute (0.083 K⁻¹) and relative (3.53% K⁻¹ at 293 K) sensitivities have been gained in the YS:1%Ho³⁺, 10%Yb³⁺. The effect of the Yb³⁺ doping concentration and pump power on the sensitivities was discussed. The pump-power–dependence of the UC luminescence indicated the main mechanism for high sensitivities in the YS:1%Ho³⁺, 10%Yb³⁺. Moreover, the decay-lifetime based temperature sensing was also evaluated. The above results imply that the present phosphors could be promising candidates for temperature sensors, and the proposed strategies are instructive in exploring other new temperature sensing luminescent materials.     

Fabrication of thermo-sensitive optical switches based on lanthanide-polyoxometalates and their “on-off” luminescence controlled by temperature

The temperature-responsive luminescent nanocomposites were prepared by the combination of poly (N-isopropylacrylamide) (PNIPAM) with lanthanide-polyoxometalates/SiO₂ spheres, exhibiting controlled reversible luminescent behavior with change in temperature. The structures and properties of nanocomposites were characterized by transmission electron microscopy, scanning electron microscope, FT-IR, UV-vis, dynamic light scattering and luminescence spectra. The research shows that the nanocomposites in aqueous solution display “on–off” luminescence by simple temperature stimuli. For example, the hybrid nanocomposites of PNIPAM/Eu-polyoxometalate/SiO₂ in aqueous solution show bright red luminescence under UV light, which could be observed by the naked eye when the temperature is below the lower critical solution temperature (LCST), showing the “on” state. However, the red luminescence of nanocomposites in aqueous solution is significantly decreased when temperature is above LCST, showing the “off” state.     

Preparation of stable luminescent poly(methyl methacrylate)–europium complex nanospheres and application in the detection of hydrogen peroxide with the biocatalytic growth of gold nanoparticles

A simple and effective solvent swelling method was developed for the preparation of poly(methyl methacrylate) (PMMA)/europium (Eu) complex hybrid nanospheres. Transmission electron microscopy and dynamic light scattering results indicate that the as‐prepared PMMA–Eu nanoparticles had a spherical morphology, with a narrow particle size distribution ranging from 100–200 nm. The PMMA–Eu nanospheres exhibited strong red emissions with a maximum peak at 612 nm under UV excitation, and the luminescence lifetime of the Eu complex was enhanced after it was swollen into PMMA nanospheres. Furthermore, the luminescence intensity of the PMMA–Eu nanospheres was very stable in various severe media, including aqueous solutions with various pHs, 1 mM Ca²⁺, 1 mM Fe²⁺, 1 mM Cu²⁺, 0.1M phosphate‐buffered saline solution, 1 mM citric acid solution, 1 mM lysine, and 1 mM glutamic acid. After the nanospheres were incubated at various temperatures for 1 h, the luminescence properties remained stable when the temperature was less than 40°C yet decreased slightly between 40 and 60°C and decreased rapidly at higher temperatures. These luminescent nanospheres were successfully applied in the luminescence‐sensing assay of hydrogen peroxide and exhibited a high sensitivity and broad linear concentration range. Because of their unique luminescence properties, the as‐synthesized PMMA–Eu nanospheres are expected to have great potential for use as luminescent labels or probes for long‐time imaging and analysis in which severe media situations are present. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Sol-gel synthesis and luminescent properties of YVO4 : Eu nanoparticles

Experimental results on the synthesis of luminescent YVO₄: Eu nanoparticles with the method of metalopolymer gel decomposition are presented. The sizes of the coherent scattering regions according to the X-ray diffraction data range from 25 to 40 nm and increase with the increase of the annealing temperature from 800 to 1000°C. It was shown that the obtained nanoparticles demonstrate good luminescent properties. The luminescence intensity and lifetime of the excited state increase with the increase of the annealing temperature. Nanoparticles are good candidates to use as luminescent labels.     

Up-conversion luminescence and temperature-sensing properties of Li+, K+ doped Na2Zn3Si2O8: Er3+ phosphors

In this work we detail the preparation of new luminescent Li⁺ and K⁺ doped Na₂Zn₃Si₂O₈: Er³⁺ up-conversion phosphors using the high-temperature solid-phase method. We investigate the phosphors phase structure, elemental distribution, up-conversion luminescence characteristics and temperature sensing properties. Our fabricated samples were found to be homogeneous and when excited using 980 nm light, they emitted wavelengths in the green and red visible wavelength bands, which correspond to two major emission bands of Er³⁺. Doping with Li⁺ and K⁺ increased the luminescence intensity of the Na₂Zn₃Si₂O₈: Er³⁺ phosphor at 661 nm by 36 and 21 times respectively. The highest relative temperature sensitivity (Sa) of the fabricated phosphor reached a value of 19.69% K^?1 and the highest absolute temperature sensitivity (Sr) reached 1.20% K^?1. These values are superior to other materials which utilize up-conversion by Er³⁺ ions as a tool for temperature sensing. We anticipate that these new phosphors will find significant application as components in optical temperature measurement systems.     

柔性金属有机骨架材料(MOFs)用于气体吸附分离

柔性金属有机骨架材料(MOFs)具有高度有序的网络结构与可变形的骨架,其骨架结构会对外界的温度、压力及客体分子的刺激产生独特的结构响应。近几年来,柔性MOFs在气体吸附、气体分离、传感等领域显示出巨大的应用潜力。截至目前,研究者们对柔性MOFs的研究仅局限于对其结构形变的机理解释,而缺乏对柔性MOFs应用于相关化工过程的性能研究。本文着重对近年来柔性MOFs在气体吸附分离领域的研究进展进行了综述,并详细地分析了柔性MOFs结构与其气体吸附分离性能之间的构效关系。通过分子模拟结合实验,讨论了柔性MOFs结构对气体分子的平衡吸附与动力学扩散的影响。分析表明,设计合成具有良好吸附选择性与扩散性能的柔性MOFs是其应用于绿色、高效气体分离过程的重要发展方向。     

浅析环境友好型稀土长余辉发光涂料

稀土发光材料具有余辉时间长、发光强度高、化学稳定性好等优点,可配制环境友好型长余辉发光涂料。介绍了该发光材料的制备方法及其发光涂料的发光机理。讨论了影响发光涂料性能的因素及其发展趋势。