EXPLOITATION OF CORE MOLECULES FOR SPIN-DEPENDENT SINGLE MOLECULAR DEVICES

为了研究取代官能团对有机IV化合物的IV-CT态的影响，我们合成了一种氮氧基团取代的间三联苯-4，4”-二胺1。经证实，未取代的间三联苯-4，4”-二胺2的自由基阳离子可被视为II-IV类化合物。的.作为自旋承载单元的氮氧自由基基团在间三联苯骨架的中心苯环的5 ′-位被取代，以保持两个氧化还原位点的对称排列。此外，两个三芳基胺氧化还原位点和氮氧自由基基团通过间位键彼此连接。预计这种取代不会像在2^+中观察到的那样，对对称排列的两个氧化还原活性位点之间的IV-CT产生实质性影响。然而，在1^+中，我们无法观察到在2^+中观察到的在1500 nm附近的特征IVCT吸收带。虽然原因目前尚不清楚，但存在两种可能的解释：（i）电子转移路径从两个三芳基胺位点之间的IV-CT变为氮氧自由基基团与两个三芳基胺位点之一之间的IVCT，以及（ii）产生的电荷（或自旋）完全局限于一个三苯胺位点。然而，从理论上考虑，强烈建议1^+中的电荷转移路径从两个三芳基胺位点之间的路径变为三芳基胺位点和氮氧自由基位点之间的路径。在任何情况下，1的双自由基阳离子给出了一个有趣的例子，用于通过官能团取代到双（三芳基胺）IV-CT系统中来调整ICT过程。

In order to investigate the influence of the substituted functional group on the IV-CT states of the organic IV compounds, we have carried out the synthesis of a nitroxide-group-substituted meta-terpheny1-4,4"-diamine 1. It is confirmed that the radical cation of an unsubstituted meta-terphenyl-4,4"-diamine 2 can be regarded as Class II IV compound. The. nitroxide radical group as a spin-bearing unit is substituted at the 5'-position of the central phenyl ring of meta-terphenyl backbone in order to retain the symmetrical arrangement of the two redox sites. Moreover, two triarylamine redox sites and the nitroxide radical group are connected to each other via meta-linkage. It was expected that such a substitution do not-essentially affect the IV-CT between symmetrically arranged two redox-active sites as is observed in 2^+. However, in 1^+, we could not observe the characteristic IVCT absorption band at around 1500 nm observed in 2^+. Although the reason is unclear at the present stage, there exist two possible explanations : (i) the change of the electron transfer path from the IV-CT between the two triarylamine sites into the IVCT between the nitroxide radical group and one of the two triarylamine sites, and (ii) the generated charge (or spin) is completely localized on one triphenylamine site. From the theoretical consideration, however, it was strongly suggested that the charge transfer path in 1^+ is changed from one between the two triarylamine sites to one between the triarylamine site and the nitroxide radical site. In any case, the diradical cation of 1 gives an intriguing example for tuning the ICT process by functional group substitution into the bis(triarylamine) IV-CT system.