Design and development of photo-induced organic molecular metals

(1)设计了TTF与1，3-二硫醇-2-亚甲基(DT-TTF)和C60(1)的杂化体系，并研究了其电子结构。未取代-1的分子轨道计算表明，DT TTF和C&lt；60&GT；单元分别对HOMO和LUMO有主要贡献。DT TTf和C&lt；60&gt；基团分别为正和负，表明分子内电荷转移。另一方面，1的HOMO-LUMO能隙分别比DT TTF和C&lt；60&gt；小3.02 eV和1.07 eV。(2)合成了几种1的衍生物。1的循环伏安图由两个对应于TTF的可逆氧化波和四个由C_(60)部分引起的还原波组成。由于C&lt；60&gt；的吸电子作用，其氧化电位高于相应的DT-TTf衍生物。同样，由于给电子部分的给电子效应，还原电位比C&lt；60&gt；更负。在压片上的电导率为σ_&lt；RT&gt；=10^&lt；-8&gt；S cm&lt；-1&gt；(3)合成了几种含噻吩环的低聚熔体衍生物。三熔体衍生物的循环伏安图由两对双电子转移波和两对单电子转移波组成，而双熔体类似物表现出四对单电子转移波。上述结果表明，正电荷在整个分子上离域。在这些低熔体扩展TTF的UV-Vis光谱中，最大吸收峰出现在485 nm附近，并且没有观察到随着扩展TTF单元的增加而向更长波长区域的明显移动。

(1) Hybrid system composed of TTF fused with 1,3-dithiol-2-ylidene (DT TTF) and C60 (1) has been designed, and its electronic structure has been investigated. The molecular orbital calculation of the unsubstituted-1 suggests that the DT TTF and C_<60> units mainly contribute to the HOMO and LUMO, respectively. The DT TTF and C_<60> moieties have positive and negative, respectively, indicating intramolecular charge-transfer. On the other hand, HOMO-LUMO gap of 1 is significantly smaller by 3.02 and 1.07 eV compared with those of DT TTF and C_<60>, respectively.(2) Several derivatives of 1 have been synthesized. Cyclic voltammogram of 1 consists of two reversible oxidation waves corresponding to the TTF and four reduction ones due to C_<60> moiety. The oxidation potentials are higher than those of the corresponding DT TTF derivative due to electron-withdrawing effect of C_<60>. In a similar manner, the reduction potentials are more negative than those of C_<60> because of electron-donating effect of the donor moiety. They showed electrical conductivity of σ_<rt> = 10^<-8>S cm^<-1> on compressed pellets.(3) Several derivatives of oligo-fused extended-TTF, in which thiophene is inserted, have been synthesized. Cyclic voltammogram of the tris-fused derivative consists of two pairs of two-electron transfer waves and two pairs of one-electron ones, while the bis-fused analog exhibits four pairs of one-electron transfer waves. The above results indicate that the positive charges delocalize on the whole molecule. In the UV vis spectra of these oligo-fused extended-TTFs, the absorption maxima appeared around 485 nm, and no significant shift to the longer wavelength region was observed derived from increase of extended-TTF units.