Columnar phase

<h2 id="classes">Classes</h2>
<p>Columnar liquid crystals are grouped by their structural order and the ways of packing of the columns. <a href="/facts/Nematic/ehCCST89">Nematic</a> columnar liquid crystals have no long-range order and are less organized than other columnar liquid crystals. Other columnar phases with long-range order are classified by their two-dimensional lattices: hexagonal, tetragonal, rectangular, and oblique phases.
</p><p>The discotic nematic phase includes nematic liquid crystals composed of flat-shaped discotic molecules without long-range order. In this phase, molecules do not form specific columnar assemblies but only float with their short axes in parallel to the director (a unit vector which defines the liquid-crystalline alignment and order).
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<h2 id="current-topics-of-interest">Current topics of interest</h2>
<p>The first discotic liquid crystal was found in 1977 by the Indian researcher <a href="/facts/Sivaramakrishna_Chandrasekhar/xTRbnhPb">Sivaramakrishna Chandrasekhar</a>. This molecule has one central <a href="/facts/Benzene/Fguue7nr">benzene</a> ring surrounded by six <a href="/facts/Alkane/Qam7Hvmf">alkyl</a> chains. Since then, a large number of discoid <a href="/facts/Mesogen/U41VF0lf">mesogenic</a> compounds have been discovered in which <a href="/facts/Triphenylene/nXUhGdpp">triphenylene</a>, <a href="/facts/Porphyrin/lKNtdXp1">porphyrin</a>, <a href="/facts/Phthalocyanine/uqwbu5n0">phthalocyanine</a>, <a href="/facts/Coronene/3anj5fod">coronene</a>, and other <a href="/facts/Aromatic/wK0DzRY6">aromatic</a> molecules are involved. The typical columnar liquid-crystalline molecules have a pi-electron-rich aromatic core attached by flexible alkyl chains. This structure is attracting particular attention for potential molecular electronics in which aromatic parts transport electrons or holes and alkyl chains act as insulating parts. The advantages of liquid-crystalline conductors are their anisotropy, processibility, and self-healing characteristics for structural defects.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a>
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<ul><li>David Dunmur & Tim Sluckin (2011) <i>Soap, Science, and Flat-screen TVs: a history of liquid crystals</i>, pp 258–62, <a href="/facts/Oxford_University_Press/CYyTzzWG">Oxford University Press</a> <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 978-0-19-954940-5 .</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Lin, Lei (Lam, Lui) (1987). "Bowlic liquid crytals". Mol. Cryst. Liq. Cryst 146: 41-54. <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Kohei Sato, Yoshimitsu Itoh, and Takuzo Aida  http://pubs.acs.org/doi/abs/10.1021/ja203894r <a href="http://pubs.acs.org/doi/abs/10.1021/ja203894r" target="_blank">http://pubs.acs.org/doi/abs/10.1021/ja203894r</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>S. Chandrasekhar, B. K. Sadashiva and K. A. Suresh,"Liquid crystals of disc-like molecules", Pramana, 1977, 9 471. <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
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Columnar phase open-in-new

Columnar phase