Development of novel chromophores whose magnetic properties are controlled by photoexcitation

为了实现由光激发控制其磁性的新型发色团，合成了几种与氮氧自由基相连的发色团，并研究了其光激发后的磁性。以下是澄清的内容。通过合成与氮氧自由基配位的卟啉或酞菁配合物，系统地改变了激发态三重态发色团与双基态氮氧自由基之间的相互作用。阐明了键数、距离、电子交换相互作用、寿命和电子自旋极化之间的关系。研究了与两个氮氧自由基共价连接的酞菁硅烷。在几微秒内，基态的磁性受光激发的控制，如(热平衡)→(单重态)→(三重态)→(热平衡)。通过对瞬时吸收和时间分辨EPR结果的分析，合理地解释了这些自旋动力学。研究了光照对一氮氧自由基酞菁晶体磁性的影响。在Pc生色团的光激发下，氮氧自由基的β自旋有效地转变为α自旋。也就是说，我们已经成功地通过光激发控制了顺磁晶体的磁性。

In order to realize novel chromophores whose magnetic properties are controlled by photoexcitation, several chromophores linked to nitroxide radicals have been synthesized, and the magnetic properties after photoexcitation have been investigated. Followings are clarified.1. The interactions between the chromophores in the excited triplet state and nitroxide radical in the doublet ground state are systematically changed by synthesizing porphyrin or phthalocyanine complexes coordinated to nitroxide radical. The relationship between the bond number, distance, electron exchange interaction, lifetime, and electron spin polarization are clarified.2. Phthalocyaninatosilicons covalently linked to two nitroxide radicals have been investigated. In several microseconds, the magnetic properties in the ground state are controlled by photoexcitation, such as (thermal equillibrium)→(singlet)→(triplet)→(thermal equillibrium). These spin dynamics is reasonably interpreted by analyzing transient absorption and time-resolved EPR results.3. Light illumination effects on the magnetic properties of the crystal of phthalocyanine linked to one nitroxide radical have been studied. By the photoexcitation of Pc chromophore, the β spin of the nitroxide radical is efficiently changed to the α spin. That is, we have succeeded in controlling the magnetic properties of the paramagnetic crystal by photoexcitation.