Synthesis, crystal structure and proton conductive properties of one stable cobalt(II) coordination polymer from thiourea carboxylate

Abstract

To search for more high-performance crystalline proton conducting materials and to accelerate the related research progress, in this paper, a one-dimensional coordination polymer (CP), [Co(BBOT)2(H2O)3·2H2O]n (1) (H2BBOT = N-benzoyl-N′-(4-benzoxy)thiourea) was firstly prepared by solvent volatilization approach. Subsequently, the thermal, H2O and chemical stabilities of the CP were tested and its high structural stability was confirmed. Furthermore, in 1, a stable solid three-dimensional framework can be constructed by intermolecular H-bonds and stacking interactions between phenyl units. Then, utilizing the AC impedance determination, the dependence of the proton conductivity of this CP on temperature and humidity in the water vapor environment was explored and the positive correlation was verified. Excitingly, the optimized proton conductivity of this compound under specific test conditions (100 °C/98 % relative humidity) can be as high as 10−4 S/cm, being in the forefront of similar crystalline solid materials. Finally, according to the value of activation energy and the characteristics of crystal structure, we speculate on the proton conduction mechanism.