Manipulation of Chemical and Crystal Structures of Multilayered Copper-Hexaaminobenzene Coordination Nanosheets to Modulate Conductivity with Precise Control of Liquid–Liquid Interfacial Synthesis

Multilayered coordination nanosheets made of copper ions and hexaaminobenzene (CuHAB) were synthesized in a liquid–liquid interfacial reaction in the presence of a base and an oxidizing agent. X-ray diffraction studies revealed the suitability of an oxidizing agent with a low oxidation potential for the synthesis of highly crystalline CuHAB. The base concentration affects the chemical and crystal structures of CuHAB. The nanosheets synthesized at low base concentrations exhibit humidity-responsive conductivity due to the ligating amino group. Meanwhile, the nanosheets prepared at high base concentrations have different stacking structures from the CuHABs formed at low base concentrations and show greater conductivity. These results indicate that the liquid–liquid interfacial synthesis with an appropriate oxidizing agent and quantitative addition of base can modulate chemical and stacking structures of coordination nanosheets composed of hexaaminobenzene ligand and their functionalities.