The acidic amphiphilic compound H[Co(H₂L1)(HL1)(phen)]·3H₂O (H₄(Co-L1), H₃L1 = 5-(3′, 5′-dicarboxylphenyl)-pyridine-2-carboxylic, phen = phenanthroline) and the hydrophilic compound [Ni(HL2)(H₂O)₅]·H₂O (H(Ni-L2), H₃L2 = 5-(3′,5′-dicarboxylphenyl)-pyridine-3-carboxylic) were synthesized via hydrothermal reactions at acidic conditions. The acidity of H₄(Co-L1) is stronger than of H(Ni-L2); while the hydrogen bond continuity in H₄(Co-L1) extended monodirectionally, which is smaller compared to the three-directional extension observed in H(Ni-L2). The proton conduction behaviors of these two compounds as fillers of Nafion composite membranes have been investigated. The results indicate that the optimal doping amounts of H₄(Co-L1) and H(Ni-L2) are 2 and 1%, respectively; the proton conductivities of H₄(Co-L1)/Nafion-2 and H(Ni-L2)/Nafion-1 composite membranes are 0.243 and 0.212 S·cm^–1, respectively, which are approximately 50.2 and 30.6% higher than that of pure Nafion membrane, respectively. A higher doping amount of H₄(Co-L1) can be attributed to its hydrophobic phen ligand, which promotes compatibility with Nafion membrane and reduces aggregation. Hydrogen bond continuity has a more significant effect on proton conductivity than acidity at relatively low doping amounts; conversely, this relationship reverses at relatively high doping amounts.

中文翻译：

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两种酸性两亲亲水配位化合物在Nafion复合膜中质子传导行为的比较研究


酸性两亲化合物H[Co(H ₂ L1)(HL1)(phen)]·3H ₂ O(H ₄ (Co-L1)， H ₃ L1 = 5-(3′, 5′-二羧基苯基)-吡啶-2-羧基，phen = 菲咯啉) 和亲水性化合物 [Ni(HL2)(H ₂ O) ₅ ]·H ₂ O (H(Ni-L2), H ₃ L2 = 5-(3′,5′-二羧基苯基)-吡啶-3-羧基）通过酸性条件下的水热反应合成。 H ₄ (Co-L1)的酸性比H(Ni-L2)的酸性强；而H ₄ (Co-L1) 中的氢键连续性是单向延伸的，与H(Ni-L2) 中观察到的三向延伸相比要小。研究了这两种化合物作为 Nafion 复合膜填料的质子传导行为。结果表明，H ₄ (Co-L1)和H(Ni-L2)的最佳掺杂量分别为2%和1%； H ₄ (Co-L1)/Nafion-2 和 H(Ni-L2)/Nafion-1 复合膜的质子电导率分别为 0.243 和 0.212 S·cm ^–1 ，分别比纯 Nafion 膜高约 50.2% 和 30.6%。 H ₄ (Co-L1) 的较高掺杂量可归因于其疏水性 phen 配体，可促进与 Nafion 膜的相容性并减少聚集。在相对较低的掺杂量下，氢键连续性对质子电导率的影响比酸度更显着；相反，这种关系在掺杂量相对较高时发生逆转。