Liquid-crystalline 1,4-benzoquinone derivative: Self-assembling behavior and redox properties

Abstract

1,4-Benzoquinone has an important structural motif and target to develop compounds for pharmacology, organic electronic, and natural products. Herein, we synthesized and characterized a series of benzoquinone derivatives BQ, BQ2, and BQ4. Cyclic voltammetry showed that BQ2 and BQ4 have both electron-accepting and electron-donating properties. X-ray diffraction, polarized optical microscopic observations, and DSC measurement indicated that BQ4 self-assembled into the hexagonal columnar liquid-crystalline (LC) phase in the wide temperature range including room temperature, whereas BQ2 was crystal. We carried out the single crystal X-ray analysis of BQ to investigate the molecular arrangement of benzoquinone cores in the column LC phase of BQ4, in which each benzoquinone core was isolated by surrounding of four phenyl moieties not to interact with each other. Also, BQ was nonpolar evaluated by density functional theory (DFT) calculations. As a result, propeller-like BQ4 molecules stack into the column structures dependent on molecular shape.