Open-shell　graphene　fragments　(OGFs)　with　non-benzenoid　topologies　are　attracting　increasing　attention　due　to　their　potential　applications　in　organic　light-emitting　diodes　(OLEDs)　and　organic　radical　conductors.　Herein,　we　report　the　synthesis　of　an　air-stable　fluorenyl　radical　derivative　(AR1)　containing　a　seven-membered　ring,　achieving　thermodynamic　stabilization　through　the　fusion　of　a　naphthalene　ring　around　its　periphery　and　anthracene　substituent.　The　half-life　times　(τ1/2)　of　AR1　in　air-saturated　solution　is　71.9　h.　The　high　stability　was　ascribed　to　kinetic　blocking　of　reactive　sites　with　high　spin　densities.　The　geometric　and　electronic　structures　of　AR1　were　systematically　studied　by　combining　various　experimental　methods　and　density　functional　theory　(DFT)　calculations,　which　include　X-ray　crystallographic　analysis,　electron　spin　resonance　(ESR),　cyclic　voltammetry,　and　UV−vis−NIR　measurements.　©　2024　SIOC,　CAS,　Shanghai,　&　WILEY-VCH　GmbH.