Liu Ya-Ru, Chen Yi-Yang, Jiang Yuan-Fan, Xie Li-Xia, Li Gang
School of Science, North University of China, Taiyuan 030051, Shanxi, P. R. China.
College of Chemistry and Green Catalysis Center, Zhengzhou University, Zhengzhou 450001, Henan, P. R. China.
Inorg Chem. 2022 Dec 5;61(48):19502-19511. doi: 10.1021/acs.inorgchem.2c03445. Epub 2022 Nov 22.
Finding more metal complexes with outstanding water stability and high proton conductivity still has important research significance for the energy field. Herein, two highly proton-conductive complexes, one hydrogen-bonded supramolecular framework (HSF) [Cd(CBIA)(HO)]·2HO () and one coordination polymer (CP), {[Cd(CBIA)(4,4'-bipy)(HO)]·(CBIA)·(OH)·2HO} () (4,4'-bipy = 4,4'-bipyridine), were triumphantly assembled using a zwitterionic organic compound, 2-(1-(carboxymethyl)-1-benzo[]imidazol-3-ium-3-yl)acetate (HCBIA). In the structure of HSF , there are several coordination and lattice HO units except for the two monodentate CBIA anions. CP with a one-dimensional (1D) cylindrical structure has free CBIA units and free HO units located in the cavity. Thanks to the ability of the uncoordinated carboxyl groups and coordination/lattice water molecules to construct the rich H-bonding networks, both complexes exhibit super-high proton conductivities, reaching 5.09 × 10 and 3.41 × 10 S cm under 100 °C/98% relative humidity (RH), respectively. Based on the exploration of crystal structure data, combined with the calculated activation energy, and adsorption/desorption plots of nitrogen and water vapor, the causes and differences in proton conductivity of the two complexes, especially the proton-conductive mechanism, are compared and analyzed. This study again confirms that the zwitterionic ligands can exert important effects on forming organo-inorganic hybrid materials with high proton conductivity.
寻找更多具有出色水稳定性和高质子传导率的金属配合物对于能源领域仍具有重要的研究意义。在此，使用两性离子有机化合物2-(1-(羧甲基)-1-苯并咪唑-3-鎓-3-基)乙酸盐（HCBIA）成功组装了两种高质子传导配合物，一种氢键超分子框架（HSF）[Cd(CBIA)(H₂O)]·2H₂O（）和一种配位聚合物（CP），{[Cd(CBIA)(4,4'-联吡啶)(H₂O)]·(CBIA)·(OH)·2H₂O}（）（4,4'-联吡啶 = 4,4'-联吡啶）。在HSF的结构中，除了两个单齿CBIA阴离子外，还有几个配位和晶格H₂O单元。具有一维（1D）圆柱结构的CP在其腔内有游离的CBIA单元和游离的H₂O单元。由于未配位的羧基以及配位/晶格水分子构建丰富氢键网络的能力，两种配合物均表现出超高的质子传导率，在100°C/98%相对湿度（RH）下分别达到5.09×10⁻³和3.41×10⁻³ S cm⁻¹。基于晶体结构数据的探索，结合计算得到的活化能以及氮气和水蒸气的吸附/解吸曲线，对两种配合物质子传导率的成因和差异，特别是质子传导机制进行了比较和分析。这项研究再次证实两性离子配体在形成具有高质子传导率的有机-无机杂化材料方面可发挥重要作用。
