Shi Zhi-Qiang, Ji Ning-Ning, Wang Ming-Hao, Li Gang
College of Chemistry and Chemical Engineering, Taishan University, Tai'an 271021, P. R. China.
College of Chemistry and Green Catalysis Center, Zhengzhou University, Zhengzhou 450001, Henan, P. R. China.
Inorg Chem. 2020 Apr 6;59(7):4781-4789. doi: 10.1021/acs.inorgchem.0c00053. Epub 2020 Mar 9.
Until now, comparative studies on proton conductivity between organic ligands and related metal-organic frameworks (MOFs) have been very limited. Herein, a stable 2D Zn(II) MOF, [Zn(L)Cl] (), has been successfully synthesized by using a zwitterionic-type organic ligand, 2-(1-(carboxymethyl)-1-benzo[d]imidazol-3-ium-3-yl)acetate (HL). It is found that there are a large amount of free carboxyl groups and hydrogen bonds in the solid-state structure of HL, and a large number of chlorine ions are aligned in the channels of , which is favorable to the efficient proton transfer. Correspondingly, the proton conductivity values of and HL are almost of the same order of magnitude under the same conditions. Moreover, the optimal σ value of (4.72 × 10 S/cm at 100 °C and 98% relative humidity) is almost four times higher than that (1.36 × 10 S/cm) of the HL ligand. On the basis of the crystal data, SEM images, and calculated values, we discuss the differences on proton conductivities and conduction mechanisms of and HL. This report provides an inspiration for the preparation of highly conductive materials with free carboxyl groups and chloride ions.
到目前为止，关于有机配体与相关金属有机框架（MOF）之间质子传导率的比较研究非常有限。在此，通过使用两性离子型有机配体2-(1-(羧甲基)-1-苯并[d]咪唑-3-鎓-3-基)乙酸（HL）成功合成了一种稳定的二维Zn(II) MOF，即[Zn(L)Cl]（ ）。研究发现，HL的固态结构中存在大量游离羧基和氢键，并且大量氯离子在 的通道中排列，这有利于高效的质子转移。相应地，在相同条件下， 和HL的质子传导率值几乎处于同一数量级。此外， 的最佳σ值（在100 °C和98%相对湿度下为4.72 × 10 S/cm）几乎是HL配体的σ值（1.36 × 10 S/cm）的四倍。基于晶体数据、扫描电子显微镜图像和计算得到的 值，我们讨论了 和HL在质子传导率和传导机制上的差异。本报告为制备具有游离羧基和氯离子的高导电材料提供了启示。
