Morphologically Controlled Electrochemical Assembly of Pillar[6]quinone Crystals through the Interaction with Electrolytes

Abstract

AbstractThe morphology engineering of porous materials is advantageous for improving their properties and designing the structure of their nanopores. Among the synthetic methods available, electrochemical deposition is one of the most advantageous for shape engineering, because the reaction conditions can be easily controlled and the deposition only occurs at the electrode surface. Herein, we report the manipulation in size and shape of pillar[6]quinone (P[Q]6) crystal structure by varying the electrolytic conditions during the electrochemical synthesis. Significant morphological change was observed with the use of supporting electrolytes having different alkylammonium cations, presumably due to the host‐guest interaction between the cation and the 1,4‐dihydroxypillar[6]arene (P[HQ]6) precursor. However, when alkali metal cations were used, the morphology slightly changed, depending on the size of the alkali metal cation. Powder X‐ray diffraction analysis revealed that the electrochemical assembly of P[Q]6 gives the same crystal structure, while DFT calculations suggested that the change in the crystal morphology was caused by the incorporation of the cation species, which inhibited the crystal growth of P[Q]6. In addition, it was found that the manipulation in size and shape of the morphologies could also be achieved by changing the composition of the solvent.