Columnar structures from asymmetrically tapered biphenylamide

Soo Jin Park, Seok Ho Hwang, Namil Kim, Shiao Wei Kuo, Hak Yong Kim, Seul Ki Park, Young Jin Kim, Changwoon Nah, Joong Hee Lee, Kwang Un Jeong

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

An asymmetrically tapered N,N'-tris[[(2-dodecylaminocarbonyl)ethyl]methyl]- 4-biphenylamide (asym-C12PhA, where n is the number of carbon atoms in the alkyl chains, n = 12) was newly designed and synthesized. In this asymmetrically tapered asym-C12PhA biphenylamide, H-bondable hydrophilic amide moieties are located at between a rigid hydrophobic biphenyl rod and three flexible hydrophobic alkyl chains. Computer energy minimization indicated that three-dimensional (3D) geometry of asym-C12PhA biphenylamide looks like a cone with dimensions of 3.01 nm in height and 1.44 nm in bottom radius. Phase transitions and supra- molecular structures were identified utilizing the combined techniques of differential scanning calorimetry, 1D wide-angle X-ray diffraction (1D WAXD), Fourier-transform infrared spectroscopy, and solid-state 13C nuclear magnetic resonance analyses. The asym-C12PhA self-assembled into a highly ordered columnar mesophase just below the isotropization temperature and then transformed to 3D columnar crystalline phase (øCr) on further cooling. Selected area electron diffractions in transmission electron microscopy (TEM) along with 1D WAXD and cross-polarized optical microscopy suggested that discotic building blocks were constructed by rotating 120° of three asym-C12PhA with respect to neighboring ones and the tmb (top-middle-bottom) stacked discotic building blocks further self-organized into columns. These columns are laterally intercalated to form the øCr phase. On the basis of the TEM image and polyethylene surface decoration technology, it was identified that the self-assembled asym-C12PhA fibers with ̃1 μm in diameter and several millimeters in length were braids of tiny single crystals.

Original languageEnglish
Pages (from-to)13499-13508
Number of pages10
JournalJournal of Physical Chemistry B
Volume113
Issue number41
DOIs
StatePublished - 15 Oct 2009
Externally publishedYes

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