Origin of Self-Assembled Helical Supramolecular Structures in Achiral C6 Biphenyl Carboxylic Acid Compounds

Abstract

To understand the formation mechanism of helical supramolecular structures in the smectic C (SmC) liquid crystalline (LC) phase of BPCA-Cn-PmOH (n is the number of methylene units, n = 6−10) (see: Jeong, K.-U.; Jin, S.; Ge, J. J.; Knapp, B. S.; Graham, M. J.; Ruan, J.; Guo, M.; Xiong, H.; Harris, F. W.; Cheng, S. Z. D. Chem. Mater. 2005, 17, 2852), a series of newly designed achiral C6 4-biphenyl carboxylic acid compounds was synthesized, of which all of them have six methylene units (n = 6). To recognize the importance of hydrogen (H)-bonding between hydroxyl groups and the small kink at the end of the phenyl groups, the hydroxyl group at the meta-position of phenyl groups in BPCA-C6-PmOH was first moved to the para-position to become BPCA-C6-PpOH, and then changed to a methoxy group to become BPCA-C6-PmOH3. BPCA-C6-P, having no functional groups on the phenyl groups, was also synthesized. Finally, one more compound was synthesized to disrupt the formation of the H-bonded head-to-head dimers by replacin...