Spin Alignment of π-Conjugated Spin Systems Using the Dynamics

在本项目中，我们获得了以下两个具有代表性的结果：(1)首次获得了通过离子对态(电荷分离态)产生唯一动态电子极化(DEP)的光激发四重态的证据。离子对的形成是由于分子内光致电子转移，使其从菲部分转移到BODIPY官能团。这种独特的DEP模式仅被报道用于光系统I、II和模型化合物的三重态。这是首次在四重态高自旋态中探测到独特的DEP图样。(2)我们还成功地探测到了由四个未配对电子产生的一个新颖的最低光激发态三重态(S=1)。低位五重态(S=2)位于光激发三重态之上。通过激发的三重态自旋耦合器，自由基自旋之间的反铁磁自旋排列降低了唯一的三重态的D值。给出了自由基-三重态-自由基体系的自旋排列和精细结构分裂减少的一般理论预测。此外，我们还研究了几种电荷转移络合物，其中的电子给体部分是具有光激四重态的π-自由基。我们还以光激发的高自旋有机分子为配体，阐明了一些金属络合物的磁性。此外，我们利用脉冲电子自旋共振技术和脉冲激光激发相结合的方法研究了π-自由基光激发高自旋态的自旋动力学。

In this project, we have obtained the following two representative results.(1)We have obtained the first evidence of the photo-excited quartet state with a unique dynamic electron polarization (DEP) generated through the ion-pair state (charge separated state). The ion-pair state is generated by the intramolecular photo-induced electron transfer from the anthracene moiety to the bodipy functional component. Such a unique DEP pattern has been reported only for the triplet states of the photosystems I, II and the model compounds. This is the first detection of the unique DEP pattern detected in the quartet high-spin state.(2)We have also succeeded to detect a novel lowest photo-excited triplet (S=1) state arising from four unpaired electrons. The low-lying quintet (S=2) photo-excited state was located above the photo-excited triplet state. The unique triplet state has D value reduced by the antiferromagnetic spin alignment between two radical spins through the excited triplet spin coupler. The general theoretical predictions of the spin alignment and the reduction of the fine-structure splitting of the radical-triplet-radical system are presented.In addition to the above results, we investigated several charge-transfer complexes, in which the electron donor parts are the π-radicals with the photo-excited quartet high-spin states. We also clarified the magnetic properties of the some metal complexes using the photo-excited high-spin organic molecules as ligands. Furthermore, we studied the spin dynamics of the photo-excited high-spin states of the π-radicals using a pulsed ESR technique combined with a pulsed LASER excitation.