决定离子液体/ MOF复合材料热稳定性极限的结构因素：咪唑鎓离子液体与CuBTC和ZIF-8的组合,Industrial & Engineering Chemistry Research

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决定离子液体/ MOF复合材料热稳定性极限的结构因素：咪唑鎓离子液体与CuBTC和ZIF-8的组合
Industrial & Engineering Chemistry Research ( IF 3.8 ) Pub Date : 2019-07-18 , DOI: 10.1021/acs.iecr.9b02415
Muhammad Zeeshan _{1,

2} , Vahid Nozari _{1,

2} , Seda Keskin _{1,

2} , Alper Uzun _{1,

2,

3}

Affiliation

将29种不同的咪唑鎓离子液体（IL）与两种不同的金属-有机骨架（MOF）ZIF-8和CuBTC混合，并通过结合X射线衍射（XRD）详细描述了所得的IL / MOF复合材料，扫描电子显微镜（SEM），布鲁瑙尔-埃米特-泰勒（BET）和傅立叶变换红外（FTIR）光谱。表征数据表明，MOF与IL结合后在结构上保持完整。对IL / MOF复合材料进行的热重分析表明，与整体IL和原始MOF相比，大多数复合材料的热稳定性较低，而在阴离子中具有官能团的IL的复合材料的热稳定性极限要高于整体IL。基于MOF和ILs的结构差异（例如烷基链长的变化，C2位上的甲基化以及阳离子的官能化和尺寸/电子），分析了代表复合材料最大耐受温度的导数开始温度。改变阴离子。数据表明，IL / MOF复合材料的最高容许温度随IL咪唑环上烷基链长度的增加而降低。IL的咪唑鎓环中的烷基被官能团取代也导致复合材料的最高容许温度降低。而阴离子的氟化导致相应的IL / MOF复合材料的热稳定性极限提高。此外，具有双氰胺，乙酸盐，与CuBTC组合使用时，磷酸根阴离子和磷酸根阴离子的最高耐受温度也比其体积较大的对应物有所提高。此外，通过密度泛函理论（DFT）计算定义了每种阳离子和阴离子的简单结构描述符，并将其用于定量结构-性质关系（QSPR）分析，以将IL / MOF复合材料的最高容许温度与IL的相关性联系起来。阳离子和阴离子结构。这项研究提出的结果将为根据IL / MOF复合材料在各个领域的应用温度选择合适的IL-MOF对提供指导。通过密度泛函理论（DFT）计算定义了每个阳离子和阴离子的简单结构描述符，并将其用于定量结构-性质关系（QSPR）分析，以将IL / MOF复合材料的最高容许温度与IL阳离子和阴离子结构。这项研究提出的结果将为根据IL / MOF复合材料在各个领域的应用温度选择合适的IL-MOF对提供指导。通过密度泛函理论（DFT）计算定义了每个阳离子和阴离子的简单结构描述符，并将其用于定量结构-性质关系（QSPR）分析，以将IL / MOF复合材料的最高容许温度与IL阳离子和阴离子结构。这项研究提出的结果将为根据IL / MOF复合材料在各个领域的应用温度选择合适的IL-MOF对提供指导。

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Structural Factors Determining Thermal Stability Limits of Ionic Liquid/MOF Composites: Imidazolium Ionic Liquids Combined with CuBTC and ZIF-8

Twenty-nine different imidazolium ionic liquids (ILs) were combined with two different metal–organic frameworks (MOFs), ZIF-8 and CuBTC, and the resulting IL/MOF composites were characterized in detail by combining X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), and Fourier transform infrared (FTIR) spectroscopy. Characterization data illustrated that MOFs remained structurally intact upon combining them with ILs. Thermogravimetric analysis performed on IL/MOF composites showed that most of the composites have lower thermal stabilities compared to the bulk ILs and pristine MOFs, whereas composites with ILs having a functional group in their anions showed thermal stability limits higher than those of bulk ILs. The derivative onset temperatures representing the maximum tolerable temperatures of the composites were analyzed based on the structural differences in MOFs and ILs, such as the changes in the alkyl chain length, methylation on the C2 site, and functionalization of the cation and the size/electronic changes on the anion. Data illustrated that the maximum tolerable temperatures of IL/MOF composites decrease with an increase in the alkyl chain length on the IL’s imidazolium ring. Substitution of the alkyl group with functionalized groups in the IL’s imidazolium ring also led to a decrease in the maximum tolerable temperatures of the composites. Whereas, fluorination of the anion resulted in an increase in the thermal stability limits of the corresponding IL/MOF composites. Furthermore, ILs having a dicyanamide, acetate, and phosphate anion also showed an increase in their maximum tolerable temperatures when combined with CuBTC compared to their bulk counterparts. Moreover, simple structural descriptors for each cation and anion were defined by means of the density functional theory (DFT) calculations and used in the quantitative structure–property relationship (QSPR) analysis to correlate the maximum tolerable temperatures of IL/MOF composites to the IL’s cation and anion structure. Results presented in this study will provide a guideline for the selection of proper IL–MOF pairs according to the application temperature of IL/MOF composites in various fields.

更新日期：2019-07-18

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