Language：English   Publishing type：Research paper (scientific journal)  

A kinetically-stabilized nitrogen-doped triangulene cation derivative has been synthesized and isolated as the stable diradical with a triplet ground state that exhibits near-infrared emission. As was the case for a triangulene derivative we previously synthesized, the triplet ground state with a large singlet-triplet energy gap was experimentally confirmed by magnetic measurements. In contrast to the triangulene derivative, the nitrogen-doped triangulene cation derivative is highly stable even in solution under air and exhibits near-infrared absorption and emission because the alternancy symmetry of triangulene is broken by the nitrogen cation. Breaking the alternancy symmetry of triplet alternant hydrocarbon diradicals by a nitrogen cation would therefore be an effective strategy to create stable diradicals possessing magnetic properties similar to the parent hydrocarbons but with different electrochemical and photophysical properties.

DOI： 10.1002/anie.202302714

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Publishing type：Research paper (scientific journal)   Publisher：Walter de Gruyter GmbH  

<jats:title>Abstract</jats:title>
<jats:p>Hydrocarbons with open-shell singlet and triplet ground states have long been studied. In contrast to studies of Kekulé hydrocarbons with an open-shell singlet ground state, studies of non-Kekulé and Kekulé hydrocarbons with a triplet ground state are quite limited, and no hydrocarbon with a triplet ground state has been isolated as single crystals. In this review, our work on the synthesis, isolation, and properties of <jats:italic>m</jats:italic>-quinodimethane-based non-Kekulé polycyclic hydrocarbon, a kinetically stabilized triangulene derivative, and Kekulé polycyclic hydrocarbon, a kinetically stabilized bisdibenzo[3,4:5,6]cyclohepta[1,2-<jats:italic>a</jats:italic>:2,1-<jats:italic>d</jats:italic>]benzene derivative, are described. Triplet ground states of these hydrocarbons were experimentally confirmed by ESR and magnetic measurements, and these are the first example of polycyclic hydrocarbons with a triplet ground state whose structures were characterized by X-ray crystal structural analysis. These studies will enable the development of various polycyclic hydrocarbon multi-radicals with high spin multiplicity.</jats:p>

DOI： 10.1515/pac-2023-0208

CiNii Research

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Other Link： https://www.degruyter.com/document/doi/10.1515/pac-2023-0208/pdf

Language：English   Publishing type：Research paper (scientific journal)  

The synthesis and isolation of hydrocarbons with a triplet ground state in crystalline forms have been sought in materials science. Triangulene is one of the most famous triplet-ground-state benzenoid hydrocarbons. Its unique electronic structure and highly symmetric structure have prompted many scientists to synthesize and isolate triangulene and its derivatives, but all attempts so far to isolate them as crystals have been unsuccessful. Herein we report the synthesis and isolation of a kinetically stabilized crystalline triangulene for the first time. The key to success is the introduction of bulky substituents onto the reactive zigzag edges. Its highly symmetric structure was confirmed by X-ray crystallography, and its fundamental properties, including the triplet ground state, were revealed. The achievement here will open the door for the synthesis and isolation of other hydrocarbons with higher spin multiplicity.

DOI： 10.1021/jacs.1c10151

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Language：English   Publishing type：Research paper (scientific journal)  

A polycyclic zwitterion, azoniadibenzo[a,j]phenalenide, having a singlet biradical character, was synthesized and isolated for the first time. The negative charge was found to be delocalized over the periphery of the main core of the zwitterion and the positive charge was localized near the nitrogen atom. Its singlet biradical character was confirmed by a small HOMO-LUMO energy gap with their spatial overlap, and observation of thermally excited triplet species together with DFT calculations.

DOI： 10.1002/anie.201902006

PubMed

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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Author：Myself 

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Author：Other 

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