两个金属有机框架化合物对硝基芳香化合物在气/液相的荧光传感

制备了2个金属有机框架化合物[Cd_2(DDCPB)(DMF)_2(H_2O)]_n(CHD-1)和{[Zn_2(DDCPB)(DMA)_2]·DMA}_n(CHD-2)(H_4DDCPB=1,1′∶3′,1″-三联苯-3,3″,5,5″-四羧酸)。荧光测试表明:2个化合物均能在气/液两相中高效地选择性识别系列硝基芳香化合物(NACs)。溶液中NACs对2个化合物的荧光有较高的淬灭率,其淬灭常数可通过定量实验计算。CHD-1和CHD-2对溶液中的NACs显示出高选择性、优异的灵敏度和低检测限。基于2个化合物的薄膜检测对硝基苯(NB)和2-硝基甲苯(o-MNT)蒸气时也具有高灵敏度。此外,详细讨论了化合物的荧光传感机理。     

ZIF-8/碳纳米管复合材料的制备及其用于4-氯苯酚电化学传感

以聚乙烯吡咯烷酮K30为分散剂,碳纳米管(CNTs)为导电增强材料,二水合乙酸锌和2-甲基咪唑(MeIM)为前驱体,合成出一种Zn-MeIM金属有机框架材料(ZIF-8)与CNTs的复合材料(ZIF-8@CNTs).研究表明,与ZIF-8及CNTs相比,所制备的ZIF-8@CNTs对4-氯苯酚(4-CP)的电化学氧化表...     

芳香硝基化合物原位液相加氢一锅法合成喹啉类化合物

以芳香硝基化合物为起始原料,以2%Pt-Sn/γ-Al2O3为催化剂,采用原位液相加氢法可以一锅法合成喹啉类化合物,考察了Pt/Sn摩尔比、反应温度、原料浓度和水含量等对反应性能的影响.结果表明,在Pt/Sn摩尔比0.5,220oC,5.0MPa,原料浓度6%,水含量30%及反应物停留时间为72s的条件下,生成产物6-甲氧基-2-甲基喹啉的收率可达72%.     

离子型手性金属有机框架材料的构筑及其对Fe3+和硝基化合物的荧光识别

合成了一例具有两重互穿qtz(quartz,石英)拓扑结构的离子型手性金属有机框架材料[CdL_2·2(Me_2NH_2)~+·6H_2O]_n(1),其中L为去质子化的H_2L配体(2-羟基对苯二甲酸)。荧光识别实验表明,配合物1可选择性的检测Fe~(3+)和硝基化合物(其中2,4,6–三硝基苯酚的猝灭常数为1.86×10~4/M,4-硝基甲苯的猝灭常数为8.61×10~3/M,Fe~(3+)的猝灭常数为2.52×10~4/M)。此外,使用密度泛函理论、紫外可见吸收光谱等手段讨论了硝基化合物的传感机制。     

Ag/AgCl/ZIF-8复合材料的制备及其对NO光催化氧化性能的研究

采用室温沉淀法合成菱形十二面体晶体结构ZIF-8(一种Zn金属有机框架材料), 然后通过光还原沉积法将Ag/AgCl纳米颗粒沉积于ZIF-8表面, 得到Ag/AgCl/ZIF-8复合光催化剂, 通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、比表面积测试法(BET)、紫外-可见漫反射吸收光谱(UV-Vis DRS)等一系列表征手段对其晶体结构、形貌、比表面积及吸光性能等进行了表征. 以低浓度NO作为目标去除污染物, 系统研究了Ag/AgCl/ZIF-8复合材料对NO的可见光催化氧化性能, 并对其反应机理进行了深入分析. 结果表明: (1) Ag/AgCl/ZIF-8复合材料中Ag⁰表面等离子体共振(SPR)效应增强了可见光的吸收; (2) ZIF-8具有大的比表面积, 使其能富集更多的氧分子和NO分子, 促进生成超氧自由基和NO光催化氧化; (3) 复合材料中光生空穴能够转移到AgCl的表面氧化Cl^-为Cl⁰, Cl⁰具有强氧化性, 一方面促进了NO光催化氧化, 另一方面有效抑制了光生电子-空穴的复合, 提高了催化剂的稳定性.     

Pd/C催化下汉斯酯1,4-二氢吡啶还原芳香叠氮化合物、芳香硝基 化合物以及碳碳双键的反应研究

汉斯酯1,4-二氢吡啶(HEH)在Pd/C催化下可以将取代的芳香叠氮化合物还原为相应的取代苯胺, 反应具有很好的选择性. 该方法也可以用于芳香硝基化合物的还原. 对于Pd/C催化下汉斯酯1,4-二氢吡啶还原碳碳双键的可行性, 论文中也进行了初步的探讨.     

一例对二硫化碳具有荧光传感性能的Mg-金属有机框架化合物

通过溶剂热合成了一例Mg-MOF化合物[Mg₄(1,4-NDC)₄(DMA)₂(CH₃OH)₂(H₂O)₂]·DMA·CH₃OH(1,1,4-H₂NDC=1,4-萘二酸,DMA=N,N'-二甲基乙酰胺),并对其结构表征及荧光性能进行了研究。 单晶X射线研究结果表明,化合物结晶于P2₁/c空间群,其晶体学数据为a=2.06090(12) nm, b=2.21014(13) nm, c=1.50385(10) nm, β=111.399(3)°, V=6.3776(7) nm³, Z=4, D_c=1.403 g/cm³, F(000)=2824, R=0.0596, wR=0.1225(I>2σ(I))。 化合物1中,二核的镁作为次级构筑单元通过桥连配体1,4-NDC连接形成沿c轴方向拓展的一维链。 一维链间进一步通过配体连接形成3D框架的化合物。 荧光性能研究表明,化合物1对CS₂具有灵敏的荧光传感性能,在0.4%的体积分数条件下可引起CS₂荧光的完全淬灭。 此外,化合物1的热稳定性也通过热重分析进行了研究,发现其可稳定到140 ℃左右。     

组合型Pt3Sn/Al2O3催化剂用于芳香硝基化合物一锅法合成N-烷基芳胺

采用吸附法制备了组合型Pt₃Sn/Al₂O₃双金属催化剂, 将该催化剂用于芳香硝基化合物原位液相加氢一锅法合成N-烷基芳胺. 研究表明, 在503 K, 空速为7.5 h^-1, 水体积分数为5%时, 1%(质量分数)Pt₃Sn/Al₂O₃催化剂具有较高的催化性能, 硝基苯的转化率为100%, N-乙基苯胺和N,N-二乙基苯胺的总选择性为98.2%. 同时,该催化剂对原位液相加氢烷基化反应具有一定普适性, 本文研究的14 种芳香硝基化合物与低级脂肪醇反应,均具有较高的N-烷基化产率.     

硝基基团修饰的金属有机框架化合物的合成及晶体结构表征

分别以2种硝基羧酸配体EBNB(1,2-二(3-硝基苯甲酸)-乙烯)和NPA(3-硝基邻苯二甲酸)与BPY(4,4′-联吡啶)及金属锌反应,配位溶剂热法合成了2种具有硝基基团修饰的二核金属簇为基本构筑单元的金属有机框架化合物[Zn2(EBNB)2(BPY)2·2H2O]n(1)和[Zn2(NPA)2(BPY)2·H2O]n(2)。通过X-射线单晶衍射法测定了2种配合物的结构,其中配合物1属于三斜晶系,P1空间群,a=0.818 62(9)nm,b=1.142 20(14)nm,c=1.428 63(17)nm,α=96.803 0(10)°,β=93.045 0(10)°,γ=102.472(2)°,V=1.290 8(3)nm3,Z=2,Mr=595.81,Dc=1.533 g·cm-3,μ=1.01 mm-1,F(000)=608,T=293(2)K;配合物2属于三斜晶系,P1空间群,a=1.154 06(14)nm,b=1.190 86(16)nm,c=1.459 52(19)nm,α=98.029(1)°,β=98.749(1)°,γ=113.579(2)°,V=1.771 9(4)nm3,Z=2,Mr=879.35,Dc=1.648 g·cm-3,μ=1.43 mm-1,F(000)=892,T=293(2)K。同时也对2种配合物的发光性能进行了测试,测试结果表明2种配合物具有较好的荧光性能。     

硝基基团修饰的金属有机框架化合物的合成及晶体结构表征

分别以2种硝基羧酸配体EBNB（1,2-二（3-硝基苯甲酸）-乙烯）和NPA（3-硝基邻苯二甲酸）与BPY（4,4’-联吡啶）及金属锌反应,配位溶剂热法合成了2种具有硝基基团修饰的二核金属簇为基本构筑单元的金属有机框架化合物[Zn₂（EBNB）₂（BPY）₂·2H₂O]_n（1）和[Zn₂（NPA）₂（BPY）₂·H₂O]_n（2）。通过X-射线单晶衍射法测定了2种配合物的结构,其中配合物1属于三斜晶系,P1空间群,a=0.81862（9）nm,b=1.14220（14）nm,c=1.42863（17）nm,α=96.8030（10）°,β=93.0450（10）°,γ=102.472（2）°,V=1.2908（3）nm³,Z=2,M_r=595.81,D_c=1.533g·cm^-3,μ=1.01mm^-1,F（000）=608,T=293（2）K;配合物2属于三斜晶系,P1空间群,a=1.15406（14）nm,b=1.19086（16）nm,c=1.45952（19）nm,α=98.029（1）°,β=98.749（1）°,γ=113.579（2）°,V=1.7719（4）nm³,Z=2,M_r=879.35,D_c=1.648g·cm^-3,μ=1.43mm^-1,F（000）=892,T=293（2）K。同时也对2种配合物的发光性能进行了测试,测试结果表明2种配合物具有较好的荧光性能。     

不同方法合成的沸石咪唑酯骨架结构材料(ZIF-8)的表征和催化性能

以二甲基咪唑为有机连接体和以Zn(OH)₂或Zn(NO₃)₂·6H₂O为Zn源,在甲醇与氨水的混合溶液、甲醇和DMF₃种不同的合成体系中合成了沸石咪唑酯骨架结构材料ZIF-8(分别记为ZIF-8(NH₄OH)、ZIF-8(MeOH)和ZIF-8(DMF),并采用XRD、FTIR、N₂吸附、SEM、TPD及Knoevenagel缩合反应等手段对所合成材料进行了表征。结果表明,采用这3种不同的合成方法均可成功制备出ZIF-8,所合成的ZIF-8的形貌基本一致,但其晶粒大小和酸碱性能有较大区别,同ZIF-8(NH₄OH)和ZIF-8(DMF)相比,ZIF-8(MeOH)晶粒分布集中、平均粒径较小且具有较大的外比表面积和较多的酸碱位。不同方法合成的ZIF-8在苯甲醛和丙二腈的Knoevenagel缩合反应中的催化性能有很大差异,ZIF-8(MeOH)催化活性明显高于ZIF-8(DMF)和ZIF-8(NH₄OH),其较高的催化活性,同其较大的外比表面积和酸碱性能密切相关。     

不同方法合成的沸石咪唑酯骨架结构材料(ZIF-8)的表征和催化性能

以二甲基咪唑为有机连接体和以Zn(OH)2或Zn(NO3)2·6H2O为Zn源,在甲醇与氨水的混合溶液、甲醇和DMF 3种不同的合成体系中合成了沸石咪唑酯骨架结构材料ZIF-8(分别记为ZIF-8(NH4OH)、ZIF-8(MeOH)和ZIF-8(DMF),并采用XRD、FTIR、N2吸附、SEM、TPD及Knoevenagel缩合反应等手段对所合成材料进行了表征。结果表明,采用这3种不同的合成方法均可成功制备出ZIF-8,所合成的ZIF-8的形貌基本一致,但其晶粒大小和酸碱性能有较大区别,同ZIF-8(NH4OH)和ZIF-8(DMF)相比,ZIF-8(MeOH)晶粒分布集中、平均粒径较小且具有较大的外比表面积和较多的酸碱位。不同方法合成的ZIF-8在苯甲醛和丙二腈的Knoevenagel缩合反应中的催化性能有很大差异,ZIF-8(MeOH)催化活性明显高于ZIF-8(DMF)和ZIF-8(NH4OH),其较高的催化活性,同其较大的外比表面积和酸碱性能密切相关。     

Laccase Encapsulation in ZIF-8 Metal-Organic Framework Shows Stability Enhancement and Substrate Selectivity

CgL1 laccase from Corynebacterium glutamicum was encapsulated into the metal-organic framework (MOF) ZIF-8 which was synthesized in a rapid enzyme friendly aqueous synthesis, the fastest in situ encapsulation of laccases reported to date. The obtained enzyme/MOF, i. e. laccase@ZIF-8 composite showed enhanced thermal (up to 70 °C) and chemical (N,N-dimethylformamide) stability, resulting in a stable heterogenous catalyst, suitable for high temperature reactions in organic solvents. Furthermore, the defined structure of ZIF-8 produced a size selective substrate specificity, so that substrates larger than the pore size were not accepted. Thereby, 2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) was used to verify that the enzyme is immobilized inside the MOF versus the outside surface. The enzyme@MOF composite was analyzed by atomic absorption spectroscopy (ASS) to precisely determine the enzyme loading to 2.1 wt%.     

Ni掺杂ZIF-65复合材料的制备及其电催化析氧性能

以ZIF-65作为前驱体,通过简单的化学沉淀法对其进行了镍的掺杂。X射线衍射仪和扫描电子显微镜表征结果显示成功合成了形貌均匀的Ni掺杂ZIF-65。我们检验了ZIF-65以及Ni掺杂ZIF-65在三电极体系中的电催化氧析出反应的活性。结果表明Ni的掺杂提高了ZIF-65的电催化活性,并优于传统贵金属催化剂二氧化钌的电催化性能。     

Polyhydroxy Fullerene-loaded ZIF-8 Nanocomposites for Better Photodynamic Therapy

Photodynamic therapy (PDT) has been received broad attentions as a cancer treatment, and fullerenes are potential photosensitizer owing to their unique electronic structures. However, fullerenes show insolubility in water for the special structure, which will induce aggregation to hinder the production of reactive oxygen species (ROS). Furthermore, the size of fullerenes is not conducive to reach the tumors through the enhanced permeability and retention (EPR) effect. Herein, a polyhydroxy fullerene-loaded metal-organic framework is designed and prepared to address the mentioned problems encountering with fullerenes as photosensitizers. The nanocomposite PHF@ZIF-8, which is synthesized by a simple one-pot method, displays great biocompatibility and outstanding photodynamic performance under the 448 nm laser irradiation. This work provides strong evidence for PHF@ZIF-8 as a promising photosensitizer candidate.     

Water stability of cobalt doped ZIF-8: a quantitative study using optical analyses

Zeolitic imidazolate frameworks (ZIFs), in particular ZIF-8 (made of Zn²⁺ and 2-methyilimidazolate) and cobalt-doped-ZIF-8, are found important for many energy and environmental applications. It was reported that ZIFs show excellent structural stability in water and thus ideal for aqueous applications. However, recent studies also found some evidence that ZIF-8 undergoes hydrolysis in water. Despite the importance of ZIF's stability in many aqueous applications, the extent of ZIFs' degradation in water is still not yet fully understood. In this study, we report a quantitative study of the water stability of 0–100 at% cobalt-doped ZIF-8, using a new combination of analytical tools. The study demonstrated the importance of analyzing both filtered powders and the filtrate liquid systematically, in particular by using UV–Vis spectroscopy and thermogravimetric analysis. The combination of analytical tools allowed the study on the effects of ZIF concentrations in water, cobalt doping levels, and amounts of ligands in water on the water stability of ZIF samples. The effect of cobalt-doping was investigated by using ZIF particles with identical sizes (200–400 nm), in order to eliminate the effects of particle size on hydrolysis. Unlike other synthesis methods, a mechanochemical ball milling method allowed the production of nano-scale ZIF-8 particles with similar sizes, independent of cobalt-doping levels. The proposed combination of analytical tools including UV–Vis spectroscopy can be applied to the study of the water stability of other MOF materials.     

A High Efficient Electrocatalytic Activity of Metal-organic Frameworks ZnO/Ag/ZIF-8 Nanocomposite for Electrochemical Detection of Toxic Heavy Metal Ions

A novel electrochemical sensor on ZIF-8 nanocomposites (Ag/ZnO/ZIF-8) was developed to analyze the mercury ions (Hg²⁺). The ZIF-8 materials are one of the 3-dimensional porous metal-organic frameworks with highly accessible pores and great surface area. The ZIF-8 nanocomposites were prepared through simple sol-gel methods and their physio-chemical properties were characterized via different analytical analyses. As a result of cyclic voltammetry, Ag/ZnO/ZIF-8 exhibited a better electrocatalytic behavior towards the detection of mercury ions (Hg²⁺). Furthermore, the composite modified electrode was then inspected as a sensor for DPV detection of mercury ions. The nanocomposite sensor performed a wide linear range from 0.5 μM to 140 μM with a low detection limit of 40 nM, and high sensitivity of 56.06 μA μM⁻¹ cm⁻². Moreover, the ZIF-8 composite sensor showed a higher selectivity toward the detection of mercury ions (Hg²⁺). The real-time applications of the ZIF-8 composites sensor were inspected in various samples with good sensitivity.     

Stability of ZIF-8 Nanoparticles in Most Common Cell Culture Media

Zeolite imidazolate framework-8 (ZIF-8) is a promising platform for drug delivery, and information regarding the stability of ZIF-8 nanoparticles in cell culture media is essential for proper interpretation of in vitro experimental results. In this work, we report a quantitative investigation of the ZIF-8 nanoparticle’s stability in most common cell culture media. To this purpose, ZIF-8 nanoparticles containing sterically shielded nitroxide probes with high resistance to reduction were synthesized and studied using electron paramagnetic resonance (EPR). The degradation of ZIF-8 in cell media was monitored by tracking the cargo leakage. It was shown that nanoparticles degrade at least partially in all studied media, although the degree of cargo leakage varies widely. We found a strong correlation between the amount of escaped cargo and total concentration of amino acids in the environment. We also established the role of individual amino acids in ZIF-8 degradation. Finally, 2-methylimidazole preliminary dissolved in cell culture media partially inhibits the degradation of ZIF-8 nanoparticles. The guidelines for choosing the proper cell culture medium for the in vitro study of ZIF-8 nanoparticles have been formulated.     

Tuning the Adsorption Selectivity of ZIF-8 by Amorphization

Amorphous metal–organic frameworks (a_mMOFs) with a partially collapsed structure are a new category of porous hybrid materials. Here, solid-state amorphization of ZIF-8 was achieved by mechanical compression at 0.75 GPa. The compression-induced amorphous ZIF-8 (a_mZIF-8) had a collapsed structure, but retained partial porosity. Benefiting from the deformed channel, the resultant a_mZIF-8 exhibited preferable adsorption of C₃H₆, resulting in higher thermodynamic adsorption selectivity of C₃H₆/C₃H₈ (6.72) than the crystalline counterparts (1.06). Further, a_mZIF-8 achieved complete separation of an equimolar C₃H₆/C₃H₈ mixture with the first breakthrough of C₃H₈. a_mZIF-8 also displayed an enhancement in CO₂/N₂ and CO₂/CH₄ adsorption selectivities. More importantly, a self-standing a_mZIF-8 membrane with boundary-free microstructure was constructed for the first time, and exhibited separation potential for H₂/CH₄, CO₂/N₂, CO₂/CH₄, and C₃H₆/C₃H₈ with ideal selectivities of 14.79, 12.83, 16.23, and 2.67, respectively.     

Post-Synthetic Modification of ZIF-8 Crystals and Films through UV Light Photoirradiation: Impact on the Physicochemical Behavior of the MOF

The physicochemical modification of Metal-Organic Frameworks (MOFs) is a current challenge in the search to improve their performance in different technological applications. In this work we analyze the post-synthetic modification of ZIF-8 crystals and films through a simple and clean treatment that involves the exposure to a UV lamp under environmental conditions. It is demonstrated that a short treatment alters the MOF structure and chemistry, providing a modified ZIF-8 due to partial disconnections of its structure which increase the amount of terminal surface species such as Zn−OH and −C=N-H, but without compromising the overall MOF structure, specific surface area or thermal stability. Additionally, it leads to changes in several properties of the ZIF-8, such as its capacity to accumulate charge through pseudocapacitive processes, its interaction with nitric oxide and its light absorption behavior. This strategy of modifying ZIF-8 without the use of chemicals through a gentle disconnection of its own structure could open new perspectives of post-functionalization of crystals and films of ZIF-8 to be used in a wide range of applications.