Crystal chromonics

Chromoionophores, 20 517-518 Chromonema fibers, 17 612 Chromonic liquid crystals, 15 101 Chromophore interaction, in dye molecules, 20 511-512... 

Morita H, Kondo S, Abe T, Noguchi H, Sugio S, Abe I, Kohno T (2006) Crystallization and preliminary crystallographic analysis of a novel plant type III polyketide synthase that produces pentaketide chromone. Acta Crystallograph Sect F Struct Biol Cryst Commun 62 899-901... 

FIGURE 3. (A) Crystal structure of pentaketide chromone synthase with a bound CoA in the active site (2D3M, Plate II). (B) The active site showing part of the bound CoA and the three catalytically significant side chains. The Cys side chain is oxidized to —S02 in the crystal structure (Plate III). The reduced —SH group of Cysl77 is needed for catalysis... 

Li, Y., Yang, Z-Y., Wu, J-C. (2010). Synthesis, crystal structures, biological activities and fluorescence studies oftransition metal complexes with 3-carbaldehyde chromone thiosemicarbazone. Europ.. Med. Chem., 45, pp. 5692-5701, ISSN 0223-5234... 

Matsunaga D, Tamaki T, Ichimura K. 2003. Azo pendant polyamides which have the potential to photoalign chromonic lyotropic liquid crystals. J Mater Chem 13 1558 1564. 

Chromonic liquid crystals are a special class of lyotropic liquid crystals. Flat aromatic systems with polar substituents form columnar aggregates by n-n interactions in solution. The mesophases of concentrated DNA solutions or of copper-tetracarboxyphthalocyanine are examples for this. Special types of chiral mesophases have been observed [29]. 

Sordidone, a chromone occurring in the lichen Lecanora rupicola (5,99), has been synthesized by Huneck and Santesson (185) by the chlorination of eugenitol. More recently a total synthesis of sordidone has been reported 4), which incorporates the above-mentioned chlorination (Scheme 13). Thus treatment of methylphloroacetophenone with acetic anhydride-sodium acetate yielded a 1 1 mixture of the isomeric chromones (117) and (118). Alkaline hydrolysis and separation of the isomers by fractional crystalization yielded eugenitol (119), and this compound was subsequently chlorinated to give sordidone (120). 

Up until the last twenty years, the family of chromonic mesophases lay hidden like an uncharted continent. Occasionally explorers returned to give some partial account, but their reports usually fell on deaf ears, and they were largely unaware of each other s discoveries. A coherent overall picture was remarkably late coming. It is signiflcant that in the 500 pages of the two-volume earlier attempt at a comprehensive survey of liquid crystals by Gray and Winsor, published in 1974, there is no mention whatsoever of the systems we now call chromonic [9]. 

The misleading picture given by the crystal structure [52]. In the crystalline solid the molecules are not flat. They are butterfly-shaped with an angle of 52° between the two chromone rings. It was uncertain whether the molecules had the same conformation in the mesophases or... 

What is the discotics for the thermotropic liquid crystals that is the lyotropic chromonic liquid crystals (LCLCs) for the lyotropic materials. LCLC molecules are plank-like rather than rod-like, rigid rather than flexible, aromatic rather than aliphatic. Typical LCLC molecules and their aggregation in... 

Since very little is known about LCLC structures and properties, the recognition of these materials is not widespread. However, as one of the pioneers in the field, J. Lydon, writes "A single commercial application, however, could change this picture overnight. The liquid crystal literature will be as full of chromonic studies as it now is with ferroelectric chevron structures. Watch this space."... 

J. Lydon, Chromonic liquid crystal phases, Curr. Opin. Colloid Interface Sci., 3(5),... 

C.J. Woolverton, G.D. Niehaus, K.J. Doane, O. Lavrentovich, S.R Schmidt, S.A. Signs, Detection of ligands with signal amplification, U.S. Patent 6,171,802 (February 2001) O.D. Lavrentovich and T. Ishikawa, Bulk alignment of lyotropic chromonic liquid crystals, U.S. Patent 6,411,354 (June 25, 2002). 

Lavretovich, O. D. Schneider, T. Golovin, A. B. Lee, J. C. A design and fabrication of an aligned lyotropic chromonic liquid crystal films with improved optical properties and aUgmnent uniformity. U.S. Pat. Appl. Publ. US 2006040069, 2006 Chem. Abstr. 2006,144, 243534. 

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