金属有机骨架及其复合材料在分离领域中的应用进展

金属有机骨架（MOFs）是一类由无机金属离子与有机配体自组装形成的新型有机-无机杂化多孔材料,因具有比表面积超高、结构多样、热稳定性良好、孔道尺寸和性质可调等优势,在分离领域表现出重要的应用价值。然而,采用传统方法制备的MOFs多为粒径在微米或亚微米尺度的晶体,且颗粒形貌不规则,因此限制了MOFs在样品前处理和色谱固定相等领域的应用和发展。构建基于MOFs的复合材料是弥补MOFs应用缺陷的一项有效措施,有望在保留MOFs优越的分离特性的同时,引入基体材料的特定性能。该文简要综述了近年来MOFs及其复合材料在吸附、样品前处理和色谱固定相等分离领域中的应用进展,并对MOFs在分离科学中的应用前景做出展望。     

Capillary column coated with graphene oxide as stationary phase for gas chromatography

The graphene oxide (GO) is carbon based material that has high surface area, high adsorption ability, and is stable at high temperature. In this work, the GO phase was prepared and used for gas chromatographic separation. GO nanosheets were covalently bonded onto the inner surface of fused silica capillary column using 3-aminopropyldiethoxymethyl silane as cross-linking agent. The prepared GO nanosheets were characterized with TEM and the GO coating was characterized with SEM. As a high performance stationary phase, GO provides not only a high surface area to increase the phase ratio but also rich functional groups for the formation of hydrophobicity, hydrogen bonding, and π–π electrostatic stacking interactions with volatile aromatic or unsaturated organic compounds. Thus, mixtures of a wide range of organic compounds including alcohols and aromatic compounds were well separated and an efficiency of 1990 theoretical plates per meter for anisole was obtained on GO coated 1.0 m × 200 μm i.d. fused silica capillary column. The experimental results demonstrate that GO coated capillary columns are promising for gas chromatographic separation.     

Improvement of the chromatographic separation performance of an imidazolium ionic liquid functionalized silica column by in situ anion‐exchange with dodecyl sulfonate and dodecylbenzene sulfonate anions

The anionic part of ionic liquids can provide additional interactions during chromatographic separations. In this work, the chromatographic separation performance of a silica column functionalized with 1‐propyl‐3‐methylimidazolium chloride ionic liquid was improved by in situ anion‐exchange from chloride anions to dodecyl sulfonate anions and dodecylbenzene sulfonate anions. The separation performances of these ionic liquid functionalized phases were investigated and compared with each other using polycyclic aromatic hydrocarbons, phthalates, parabens, and phenols as model compounds. Results indicated that the new columns presented a better chromatographic separation than the original one. This was ascribed retention mechanism from organic anions. The introduction of dodecyl sulfonate anions increased the hydrophobicity of stationary phase. Furthermore, the phenyl groups of dodecylbenzene sulfonate anions could provide an enhanced selectivity to aromatic compounds such as polycyclic aromatic hydrocarbons by π–π interactions. Analysis repeatability of the new columns was satisfactory (RSD of retention time, 0.10–0.40%; RSD of peak area, 0.66–0.84%).     

酯型十八烷基键合硅胶整体柱的制备、表征及性能评价

将硅烷偶联剂γ-(2,3-环氧丙氧)丙基三甲氧基硅烷与十八酸反应,再键合到硅胶整体柱上,得到了酯型十八烷基键合固定相,并用红外光谱、元素分析对其进行了表征。在以甲醇-水为流动相的反相色谱条件下分离了苯、联苯和蒽的混合样品,评价了该整体柱的色谱性能,考察了该整体柱适用的pH范围,以及柱压降、柱效与流速的关系。结果表明,该硅胶整体柱键合效果良好,具有较好的反相色谱性能,且在pH=2～8时稳定性好,柱压降、柱效受流速影响较小,可有效地用于化合物的快速分离分析。     

Ionic liquids-assisted fabrication of silica-based monolithic columns

The mesopores of a monolithic silica column are very important and useful for chromatographic separation since they can offer sufficiently large surface area. In this paper, a novel method with the assistance of an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate ([bmin]BF₄)) was developed for the preparation of a C18-modified monolithic silica column for the first time, in which, the through pores and mesopores were formed simultaneously during the sol-gel reaction. The method is effective to simplify the preparation process of the silica-based monolithic columns. The factors influencing the sol-gel process, including the content of methanol and pH, were studied. The chromatographic performance of the prepared monolithic column was evaluated by the separation of alkylbenzenes.     

Protein separation using a novel silica-based RPLC/IEC stationary phase modified with N-methylimidazolium ionic liquid

Ionic liquids (ILs) immobilized on silica as novel high performance liquid chromatography (HPLC) stationary phases have attracted considerable attention. However, it has not been applied to protein separation. In this paper, N-methylimidazolium IL-modified silica-based stationary phase (SilprMim) was prepared and investigated as a novel multi-interaction stationary phase charged positively for protein separation. The results indicate that all of the basic proteins tested cannot be absorbed on this novel stationary phase, whereas all of the acidic proteins tested can be retained, and the baseline separation of eight kinds of acidic protein standards can be achieved when performed in reversed phase/ ion-exchange chromatography (RPLC/IEC) mode. Compared with commonly used commercial octadecylated silica (ODS) column, the novel stationary phase can show selectivity and good resolution to acidic proteins, which has a promising application in the separation and analyses of acidic proteins from the complex samples in proteomics. In addition, the chromatographic behavior of proteins, the effect of the ligand structure and the retention mechanism on this stationary phase were also investigated.     

双阳离子型离子液体和十八烷基修饰的混合模式硅胶固定相的制备及色谱性能

通过分步键合反应制备了一种咪唑基双阳离子型离子液体和十八烷基共同修饰的混合模式硅胶色谱固定相(Sil-C18-IL-C4); 采用元素分析和红外光谱对其进行了表征. 分别评价了该固定相在反相色谱模式(RPLC)、 亲水色谱模式(HILIC)和RPLC/HILIC混合色谱模式下的色谱分离性能, 并在HILIC模式下对6种碱基核苷类化合物进行分离, 考察了流动相中有机相体积分数和水相中甲酸铵浓度对分离效果的影响. 此外, 还考察了该固定相的分离重复性. 制备的Sil-C18-IL-C4固定相的元素分析结果表明, 氮元素含量为1.65%, 碳元素含量为11.16%, 氢元素含量为2.44%. 该固定相的红外光谱中, 2928和2856 cm^?1处出现了—CH的不对称和对称伸缩振动峰, 1440 和660 cm^?1处出现了咪唑环上C=C的伸缩振动峰和C=N的弯曲振动峰, 说明十八烷基和1,5-双(咪唑-1-基)戊烷均已接枝到硅胶表面. 色谱性能评价结果表明, Sil-C18-IL-C4固定相可表现出反相色谱模式和亲水色谱模式分离性能, 对6种碱基核苷类物质能够实现完全分离, 而且在一定的色谱条件下可以在单根色谱柱单次运行中实现RPLC/HILIC混合模式色谱分离, 对于处理复杂样品中的碱基核苷类化合物等亲水物质具有良好的应用潜能.     

离子液体作高效液相色谱流动相添加剂分离测定芳香胺

建立了以离子液体作反相高效液相色谱流动相添加剂分离测定邻苯二胺、苯胺和对甲苯胺3种芳香胺的方法。实验以C18反相色谱柱为分离柱,采用紫外检测方法,考察了检测波长、甲醇含量、咪唑离子液体烷基链长度、离子液体溶液浓度等条件对分离和测定的影响,并与其它分离测定芳香胺的方法进行了比较。优化的色谱条件为:以甲醇/1-丁基-3-甲基咪唑四氟硼酸盐水溶液(3.0mmol/L,乙酸调节pH 3.5)=30/70(V/V)为流动相;检测波长254 nm;流速1.0mL/min;柱温30℃。在此条件下,3种芳香胺达到基线分离,在6.5 min之内分离完全;在1～40 mg/L范围内,线性回归方程的相关系数达到0.99以上;检出限为0.07～0.41 mg/L。将本方法应用于废水的测定,加标回收率在92.3%～96.7%之间,相对标准偏差小于3.5%。     

Porous Ionic Liquids or Liquid Metal–Organic Frameworks?

Porous liquids can be prepared from the dispersion metal–organic frameworks (MOFs) in ionic liquids (ILs). Porous liquids prepared from 5 % of ZIF‐8 in a phosphonium‐based ionic liquid are capable of absorbing reversibly up to 150 % more nitrogen and 100 % more methane than the pure ionic liquid.     

反相离子对色谱-直接电导检测法分析六氟磷酸根离子液体阴离子

建立了反相离子对色谱-直接电导检测六氟磷酸根(PF6-)离子液体阴离子的分析方法。用DiamonsilC18反相色谱柱为分离柱,以离子对试剂-柠檬酸-乙腈混合水溶液为流动相,考察了离子对试剂、乙腈含量、pH值及色谱柱温度对六氟磷酸根保留的影响,并讨论了相关保留机理。在优化的色谱条件下,即流动相为0.05 mmol/L氢氧化四丁铵-0.038 mmol/L柠檬酸-35%乙腈(pH 5.5),流速1.0 mL/min,色谱柱温度40℃时,PF6-与其它常见阴离子(F-、Cl-、Br-、NO3-、SO24-、BF4-)达到基线分离且保留时间在15 min内。方法检出限(S/N=3)为0.25 mg/L,标准曲线的线性范围为0.5～100.0 mg/L,峰面积和保留时间的相对标准偏差(n=5)分别为0.17%和0.15%。该法用于1-丁基-3-甲基咪唑六氟磷酸盐和1-丙基-2,3-二甲基咪唑六氟磷酸盐两种离子液体中PF6-的测定,加标回收率分别为99%和104%。该方法简单、准确、可靠,实用性好。     

Silica monolithic membrane as separation medium. Summable property of different membranes for high-performance liquid chromatographic separation

We studied an applicability of a silica monolithic membrane as separation medium for high-performance liquid chromatography (HPLC). We prepared porous monolithic silica membranes having a three-dimensional network structure to cut and shape into a membrane separation medium. We evaluated chromatographic properties of a variety of solutes using a column containing the membranes with HPLC to elucidate summable property of the membrane separation media. In addition, we made brief study on separation of HbA1c in whole blood with the stacked" membranes having different surface characteristics in one column, which is a membrane column. We confirmed that the membrane column was able to separate HbA1c from other matrix in whole blood to some extent, and it also had an excellent ability for hydrophobic and ion exchange adsorption.     

配位色谱法从葛根素浸膏中分离纯化葛根素

建立了采用配位色谱柱从葛根素浸膏中分离纯化葛根素的方法。以铜离子为中心离子,制备了中心离子含量为7%的配位色谱柱。样品上样于配位色谱柱后,以氯仿-甲醇（体积比为10∶1）混合溶剂洗脱,得到了较纯的葛根素,较之用传统的硅胶色谱柱纯化,纯度提高了11%,回收率提高了12%,且柱容量提高了两倍。配位色谱改变了葛根素在传统硅胶柱上的洗脱顺序,对目标物质的分辨率比传统硅胶色谱柱高。     

Chemically modified chiral monolithic silica column prepared by a sol-gel process for enantiomeric separation by micro high-performance liquid chromatography

In this work a new type of chiral monolith silica column was developed for the chiral separation by micro high-performance liquid chromatography (micro-HPLC). The chiral monolith column with a continuous skeleton and a large through-pore structure was prepared inside a capillary of 100 microm I.D. by a sol-gel process, and chemically modified with chiral selectors, such as L-phenylalaninamide, L-alaninamide and L-prolinamide, on the surface of the monolithic silica column. Based on the principle of ligand exchange, these chiral monolithic columns were successfully used for the separation of dansyl amino acid enantiomers, as well as hydroxy acid enantiomers by micro-HPLC. The chromatographic conditions, the enantioselectivity and the performance of columns are discussed.     

漆酚酯键合硅胶液相色谱固定相的制备与应用

以甲基丙烯酸漆酚酯为色谱配体,制备了一种新型色谱固定相。首先以漆酚和甲基丙烯酰氯为原料制备得到甲基丙烯酸漆酚酯,并通过物理吸附涂覆到由3-（甲基丙烯酰氧）丙基三甲氧基硅烷化学修饰的硅胶上,再通过自由基引发与硅烷化硅胶的双键聚合制得漆酚酯键合硅胶固定相（USP）。对固定相进行傅里叶红外光谱（FT-IR）、热重分析（TGA）、扫描电子显微镜（SEM）和元素分析（EA）表征,结果表明通过共聚反应成功地将漆酚酯固定在硅烷化硅胶上,且制备出的固定相具有良好的单分散性。采用匀浆法装柱,以乙腈-0.05%磷酸溶液（3：97,v/v）为流动相,流速为0.4 mL/min,检测波长为220 nm,考察固定相对天麻浸膏的分离性能。以乙腈-水（50：50,v/v）为流动相,流速为0.5 mL/min,检测波长为290 nm,考察固定相对吴茱萸浸膏的分离性能。结果表明该固定相对天麻浸膏和吴茱萸浸膏均具有良好的分离性能,从天麻浸膏中分离出5个色谱峰,从吴茱萸浸膏中分离出2个色谱峰。与商品化C₁₈ 柱相比,USP柱可以从天麻浸膏中分离出更多的有效组分并实现基线分离,分离吴茱萸浸膏的色谱条件更为环保和安全。采用低流速对天麻浸膏和吴茱萸浸膏进行分离,减少了流动相的使用量,分离结果令人满意。以天然产物漆酚制备色谱固定相,既为分离纯化天麻素和吴茱萸碱提供了一种新的方法,又为液相色谱固定相制备提供了新的思路,还拓展了生漆在色谱分离材料方面的应用。     

离子液体功能化金属/共价-有机框架材料在催化反应中应用

离子液体（ILs）功能化的金属有机框架（MOFs）和共价有机框架（COFs）材料兼具离子液体和MOFs/COFs的优点，是一种极具潜力的复合催化材料。MOFs和COFs材料固定的孔结构及较大的比表面积为负载高分散催化中心提供了天然的物理空间；多孔结构促使催化剂与反应物充分接触；丰富的孔道有利于运输催化反应底物和产物，进而实现催化反应的高效进行。特别是离子液体片段的引入，可以作为催化活性中心的配体（稳定剂）或分散剂，同时能够有效改善MOFs和COFs材料孔道和活性中心周围的微环境。此外，还可以充分利用离子液体片段在适当的反应条件下转化为氮杂环卡宾配体的特点，在MOFs和COFs材料中引入氮杂环卡宾有机金属配合物。因此，我们对近几年来离子液体功能化的MOFs或COFs催化体系在CO2环加成、CO2还原、C-C偶联、羰基化以及其它有机转化反应中的研究应用进行简要综述。并对复合材料在催化领域的发展进行总结和展望。     

Characterzation and separation of Al13 species using gel-filtration chromatography

A polyaluminum chloride (PAC) sample was prepared using a slow alkaline titration method. The Bio-Gel P-100 gel column chromatographic technique was used to separate and characterize the various forms of aluminum present in the prepared PAC solution. The effluents from a gel column were monitored using online chemical method: Al-Ferron timed complexation spectrophotometry and by 27Al nuclear magnetic resonance (NMR) spectroscopy. Effects of different experimental conditions such as eluent flow rate, ionic strength and pH on separation of Al13 were investigated. Experimental results indicated that molecule size exclusion was not the only parameter affecting the column chromatographic separation efficiency of Al13 but molecule charge as well. Reducing the eluent flow rate, increasing the ionic strength and suitable pH resulted in increase in the separation efficiency. Experimental results clearly indicated that by varying the experimental conditions, it is possible to produce pure Al13 species using a gel column chromatographic technique.     

Characterization and separation of Al13 species using gel-filtration chromatography

A polyaluminum chloride (PAC) sample was prepared using a slow alkaline titration method. The Bio-Gel P-100 gel column chromatographic technique was used to separate and characterize the various forms of aluminum present in the prepared PAC solution. The effluents from a gel column were monitored using online chemical method: Al-Ferron timed complexation spectrophotometry and by ²⁷Al nuclear magnetic resonance (NMR) spectroscopy. Effects of different experimental conditions such as eluent flow rate, ionic strength and pH on separation of Al₁₃ were investigated. Experimental results indicated that molecule size exclusion was not the only parameter affecting the column chromatographic separation efficiency of Al₁₃ but molecule charge as well. Reducing the eluent flow rate, increasing the ionic strength and suitable pH resulted in increase in the separation efficiency. Experimental results clearly indicated that by varying the experimental conditions, it is possible to produce pure Al₁₃ species using a gel column chromatographic technique.     

Characterization and separation of Al13 species using gel-filtration chromatography

A polyaluminum chloride (PAC) sample was prepared using a slow alkaline titration method. The Bio-Gel P-100 gel column chromatographic technique was used to separate and characterize the various forms of aluminum present in the prepared PAC solution. The effluents from a gel column were monitored using online chemical method: Al-Ferron timed complexation spectrophotometry and by ²⁷Al nuclear magnetic resonance (NMR) spectroscopy. Effects of different experimental conditions such as eluent flow rate, ionic strength and pH on separation of Al₁₃ were investigated. Experimental results indicated that molecule size exclusion was not the only parameter affecting the column chromatographic separation efficiency of Al₁₃ but molecule charge as well. Reducing the eluent flow rate, increasing the ionic strength and suitable pH resulted in increase in the separation efficiency. Experimental results clearly indicated that by varying the experimental conditions, it is possible to produce pure Al₁₃ species using a gel column chromatographic technique.     

以离子液体为流动相添加剂高效液相色谱法分离钩藤药材中的钩藤碱和异钩藤碱

以常用流动相添加剂三乙胺作为对照,建立了以离子液体为流动相添加剂,分离钩藤药材中钩藤碱和异钩藤碱的高效液相色谱方法。以分离度及相关色谱参数为指标,选择了离子液体中咪唑阳离子烷基链长度及阴离子的种类。并分别考察了咪唑阳离子烷基链长度、离子液体浓度、流动相pH值和流动相比例对钩藤碱和异钩藤碱分离的影响,初步探讨了离子液体的分离机理。结果显示,咪唑阳离子的烷基链越长,阴离子的离子液体序列越高,分离效果越好,即[HMIM][BF_4]为最优的流动相添加剂。当[HMIM][BF_4]浓度为16 mmol/L,流动相pH值为3.0,甲醇比例为37%时,钩藤碱和异钩藤碱能够实现基线分离,满足样品分离测定的需求。     

Controllable Synthesis of Porphyrin‐Based 2D Lanthanide Metal–Organic Frameworks with Thickness‐ and Metal‐Node‐Dependent Photocatalytic Performance

Synthesizing 2D metal–organic frameworks (2D MOFs) in high yields and rational tailoring of the properties in a predictable manner for specific applications is extremely challenging. Now, a series of porphyrin‐based 2D lanthanide MOFs (Ln‐TCPP, Ln=Ce, Sm, Eu, Tb, Yb, TCPP=tetrakis(4‐carboxyphenyl) porphyrin) with different thickness were successfully prepared in a household microwave oven. The as‐prepared 2D Ln‐TCPP nanosheets showed thickness‐dependent photocatalytic performances towards photooxidation of 1,5‐dihydroxynaphthalene (1,5‐DHN) to synthesize juglone. Particularly, the Yb‐TCPP displayed outstanding photodynamic activity to generate O₂^? and ¹O₂. This work not only provides fundamental insights into structure designing and property tailoring of 2D MOFs nanosheets, but also pave a new way to improve the photocatalytic performance.