Exploration of Neutral Radical Systems Based on Oxophenalenoxyl as New Spin Source

点击翻译按钮获取中文摘要

Syntheses of novel stable organic neutral radicals and understanding inherent in π-electronic systems with highly delocalized unpaired electrons play a crucial role in the molecular designs for novel intriguing organic molecule-based magnetic materials. 6-Oxophenalenoxyl derivatives were originally designed on the basis of the phenalenyl system, and showed high persistency enough to handle in air. Interestingly, this neutral π-radical system found to be unique in exhibiting both an "extremely spin-delocalized and highly spin-polarized nature" similar to that of the parent phenalenyl system, while the topology of the spin density distribution sharply contrasted with that of the phenalenyl system. These salient features in the electronic spin structures of 6-oxophenalenoxyl derivative enable us to discuss topological-symmetry control in spin density distribution in π-conjugated monoradical systems originating from the connectivities of the two oxygen atoms on the phenalenyl skeleton. This new concept was elucidated and exemplified experimentally on the basis of the preparation of topological isomers of 6-oxophenalenoxyl system, 3-and 4-oxophenalenoxyls. Furthermore, we have succeeded in the determinations of X-ray crystal structures of these oxophenalenoxyl derivatives, and demonstrated feasible crystal engineering for large intermolecular magnetic exchange interactions of phenalenyl-based neutral π-radicals.