Abstract
Diradical polycyclic hydrocarbons(PHs)have unique open-shell structures and interesting physical prop-erties.However,owing to high reactivity of unpaired electrons,such open-shell organic diradicaloids are usually less stable than closed-shell systems,limiting their practical applications.In this study,we report P=O-attaching of diradical PHs as a new strategy to enhance their stability while maintaining diradi-cal properties.Three P=O-attached PHs containing the indeno[1,2-b]fluorene,fluoreno[3,2-b]fluorene and indeno[2,1-b]fluorene π-skeletons,respectively,were designed and synthesized.As theoretically and ex-perimentally proved,two of them have the relatively large diradical characters and open-shell singlet diradical nature.In comparison to their all-carbon analogues,the attached electron-withdrawing P=O groups endow them with much lower LUMO/HOMO energy levels but preserved magnetic activities and physical properties,such as thermally accessible triplet species and multi-redox ability.Moreover,the P=O groups effectively decrease their oxidation activities and thereby lead to their remarkably excellent ambient stabilities.Thus,this P=O-attaching strategy will be applicable to other diradical PH systems and may promote the generation of stable organic diradicaloids for radical chemistry and materials.
维普
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