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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) 2 (H 2 O) 4 ]•2H 2 O (1) and one coordination polymer (CP), {[Cd 2 (CBIA) 2 (4,4′-bipy) 2 (H 2 O) 2 ]• (CBIA)•(OH)•2H 2 O} n (2) (4,4′-bipy = 4,4′-bipyridine), were triumphantly assembled using a zwitterionic organic compound, 2-(1-(carboxymethyl)-1H-benzo[d]imidazol-3-ium-3-yl)acetate (HCBIA).In the structure of HSF 1, there are several coordination and lattice H 2 O units except for the two monodentate CBIA − anions. CP 2 with a one-dimensional (1D) cylindrical structure has free CBIA − units and free H 2 O 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 −3 and 3.41 × 10 −3 S cm −1 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.

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