| Co-Investigator(Kenkyū-buntansha) |
YAMADA Jun-ichi University of Hyogo, Graduate School of Material Science, Associate Professor, 物質理学研究科, 助教授 (90191311)
NISHIKAWA Hiroyuki University of Tsukuba, Graduate School of Pure and Applied Sciences, Associate Professor, 数理物質科学研究科, 助教授 (40264585)
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| Research Abstract |
Aiming to investigate the chiral effect in molecular superconductors, we synthesized some molecular conductors based on three chiral donors, (R,R)-DMDO-MMT, (R,R)-DMDO-MET and (S,S)-DMDH-TTP. These donors are derivatives of BDH-TTP, which produces many molecular metals, and are expected to make molecular superconductors. We also synthesized their meso isomers.
All salts based on (R,R)-DMDO-MMT and (R,R)-DMDO-MET showed a semiconductiing behavior even at room temperature as well as the salts based on meso-DMDO-MMT and meso-DMDO-MET. Although these chiarl or meso donors have failed to achieve metallic conductivity, a subtle variation in the stereochemistry of two methyl groups added to the dioxolane ring of DO-MET or DO-MMT has been found to alter the transport properties of derived CT salts.
The mixture trans and cis isomers of DMDH-TTP have produced the crystals of (meso-DMDH-TTP)_2 X(X = AsF_6, PF_6, BF_4) and the I_3, AuI_2 and GaCl_4 salts. AsF_6, PF_6, BF_4 and I_3 salts have exhibited a metallic behavior form the room temperature down to the low temperature. AuI_2 and GaCl_4 salts are metallic below 9 and 12K, respectively. The salts of (meso-DMDH-TTP)_2X (X = AsF_6, PF_6) consist of alternate layers of the donor molecules arranged in the β or β" packing modes and layers of anions. In contrast, the packing pattern of donor molecules is λ form in (meso-DMDH-TTP)_2 BF_4, which has an one-dimensional open and a closed two-dimensional Fermi surfaces.
(R,R)DMDO-MMT was succeeded to be prepared from (R,R)-2,3-butandiol and have produced the AsF_6, BF_4 and AuI_2 salts, which showed a metallic behavior down to 96, 4.2, 110K, respectively.
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