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 les...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]fluoreneπ-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.展开更多
Doping heteroatoms into polycyclic aromatic hydrocarbons(PAHs)is an efficient strategy to achieve fascinating electronic structures and materials.However,nanoscale B-doped PAHs remain very challenging because of the i...Doping heteroatoms into polycyclic aromatic hydrocarbons(PAHs)is an efficient strategy to achieve fascinating electronic structures and materials.However,nanoscale B-doped PAHs remain very challenging because of the intrinsic instability of the boron atom and the lack of suitable precursors.In this study,we report a C_(54)B_(2) polycyclicπ-system with one embedded 1,4-diboron-substituted benzene subunit,which was successfully synthesized from doubly B-doped heptazethrene.Thismolecule represents not only the largest B-doped PAH by far but also an unprecedented B-doped nanographene.The fully zigzag-armchair-edged structure creates a planar conformation,thus leading to its unique bilayer assembly behavior.More importantly,it possesses intriguing electronic structure and optoelectronic properties,such as very broad light absorption that covers 350–750 nm,sharp near-infrared fluorescence with a band width of only 26 nm,and reversible five-step redox capability,all of which are rarely observed for other B-doped PAHs.In addition,this molecule displays distinctive local aromaticity that cannot be reproduced via the reductive manipulation of an allcarbon congener.展开更多
基金supported by Jilin Scientific and Technological Development Program(Nos.20220101054JC,20220201085GX)National Natural Science Foundation of China(Nos.22175074,52373182).
文摘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]fluoreneπ-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.
基金supported by National Natural Science Foundation of China(grant nos.22175074 and 21822507).
文摘Doping heteroatoms into polycyclic aromatic hydrocarbons(PAHs)is an efficient strategy to achieve fascinating electronic structures and materials.However,nanoscale B-doped PAHs remain very challenging because of the intrinsic instability of the boron atom and the lack of suitable precursors.In this study,we report a C_(54)B_(2) polycyclicπ-system with one embedded 1,4-diboron-substituted benzene subunit,which was successfully synthesized from doubly B-doped heptazethrene.Thismolecule represents not only the largest B-doped PAH by far but also an unprecedented B-doped nanographene.The fully zigzag-armchair-edged structure creates a planar conformation,thus leading to its unique bilayer assembly behavior.More importantly,it possesses intriguing electronic structure and optoelectronic properties,such as very broad light absorption that covers 350–750 nm,sharp near-infrared fluorescence with a band width of only 26 nm,and reversible five-step redox capability,all of which are rarely observed for other B-doped PAHs.In addition,this molecule displays distinctive local aromaticity that cannot be reproduced via the reductive manipulation of an allcarbon congener.
