Shirahata Takashi, Kibune Megumi, Yoshino Hiroko, Imakubo Tatsuro
Imakubo Initiative Research Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Chemistry. 2007;13(27):7619-30. doi: 10.1002/chem.200700314.
The unsymmetrical pi donor dimethyl(ethylenedioxy)tetraselenafulvalene (DMEDO-TSeF) has provided six new organic superconductors with a monovalent square-planar Au(CN)(4) ion and cyclic ethers as solvent of crystallization. The six new organic superconductors kappa-(DMEDO-TSeF)(2)Au(CN)(4) [solv.=1,3-dioxolane (DOL), 2,5-dihydrofuran (DHF), tetrahydropyran (THP), 1,3-dioxane (1,3-DOX), 3,4-dihydro-2H-pyran (DHP), or 1,4-dioxane (1,4-DOX)] are classified into two subphases kappa(L) and kappa' according to the differences in their space group symmetry. kappa(L)-(DMEDO-TSeF)(2)Au(CN)(4) (solv.=DOL, DHF, THP, 1,3-DOX or DHP) crystallizes in the orthorhombic space group Pnma, and T(c) of the kappa(L) phase varies by 1.7-5.3 K according to the size and shape of the solvent of crystallization. On the other hand, kappa'-(DMEDO-TSeF)(2)Au(CN)(4) (solv.=DOL or 1,4-DOX) crystallizes in the noncentrosymmetric monoclinic space group Cc. The kappa'-phase containing 1,4-DOX shows superconductivity at 4.2 K, but the kappa'-phase containing DOL does not show superconductivity down to 1.4 K. Systematic investigation of the six new organic superconductors, together with the two previously reported superconductors kappa(H)- and kappa(L)-(DMEDO-TSeF)(2)Au(CN)(4), revealed that the T(c) of the present system is finely tunable by utilizing the effect of the solvent of crystallization.
不对称π供体二甲基（乙二氧基）四硒富瓦烯（DMEDO-TSeF）与一价平面正方形[Au(CN)(4)]-离子及环状醚作为结晶溶剂，已得到了六种新型有机超导体。这六种新型有机超导体κ-(DMEDO-TSeF)(2)Au(CN)(4) [solv.=1,3-二氧戊环（DOL）、2,5-二氢呋喃（DHF）、四氢吡喃（THP）、1,3-二氧六环（1,3-DOX）、3,4-二氢-2H-吡喃（DHP）或1,4-二氧六环（1,4-DOX）]根据其空间群对称性的差异被分为两个亚相κ(L)和κ'。κ(L)-(DMEDO-TSeF)(2)Au(CN)(4)（solv.=DOL、DHF、THP、1,3-DOX或DHP）结晶于正交空间群Pnma，κ(L)相的T(c)根据结晶溶剂的大小和形状在1.7至5.3 K范围内变化。另一方面，κ'-(DMEDO-TSeF)(2)Au(CN)(4)（solv.=DOL或1,4-DOX）结晶于非中心对称单斜空间群Cc。含1,4-DOX的κ'相在4.2 K时呈现超导性，但含DOL的κ'相在低至1.4 K时未显示超导性。对这六种新型有机超导体以及之前报道的两种超导体κ(H)-和κ(L)-(DMEDO-TSeF)(2)Au(CN)(4)的系统研究表明，利用结晶溶剂的效应可精细调节本体系的T(c)。
