2000 Fiscal Year Final Research Report Summary
PERSUIT OF CHEMISTRY TO VISUALIZE VAN DER WAALS FORCE
| Project/Area Number |
09640660
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Inorganic chemistry
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| Research Institution | Shinshu University |
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Principal Investigator |
OHTA Kazuchika Faculty of Textile Science and Technology, Shinshu University Associate Professor, 繊維学部, 助教授 (70160497)
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| Project Period (FY) |
1997 – 2000
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| Keywords | Liquid Crystal / Metal Complex / Metallomesogen / van der Waals force / Thermotropic liquid crystal / Termochromism / サーモクロミズム |
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| Research Abstract |
Columnar liquid crystalline bis[1,2-big(3,4-di-n-alkoxyphenyl)ethanedione dioximato]d^8 metal(II)complexes were successfully synthesized. Thermochromism of these liquid crystals is caused by fastening of the central metals by the surrounding long chains. We found that van der Waals force of the long chains can be visualized. "Apparent pressure" of the long chains for these(C_nO)_<8->M complexes could be estimated by using shift coefficients of the d-p band for the non-substituted core complex. Nevertheless, it was still ambiguous whether the metal-metal distance is elongated or the one-dimensionally stacked metals become to slip with heating, to cause the mesomorphic thermocromism. Hence, XANES spectra of the nickel complex were recorded and analyzed by using DV-Xα method. It was established for the first time that the one-dimensionally stacked metals slip with heating.
Then, the critical molecular structure change from columnar to lamellar mesophases in this system was investigated. When the number of the long chains surrounding the core complex part was reduced from eight to four, the mesophase changes its structure from columnar Col_<hd> to novel discotic lamellar D_<L.rec>(P2_12_1).
Interestingly, these present metal complexes form gels in an over-concentrated nhexane solution. In order to determine the structure of the gel by X-ray diffraction technique, a specific cell was developed. The gel has a two-dimensional hexagonal structure which is similar to the inverted hexagonal phase of lyotropic liquid crystals.
Polymerization of these present disk-like big(glyoximato)d^8 metal(II)complexes enables us to develop a novel functional material changing the color with pressure and/or temperature. Hence, the various synthetic routes were investigated and then a nickel complex having polymerizable groups has been successfully synthesized. We plan to synthesize a large amount of the complex in the next stage.
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