Cycloparaphenylene–Phenalenyl Radical and Its Dimeric Double Nanohoop**

The first example of a neutral spin-delocalized carbon-nanoring radical was achieved by integration the open-shell phenalenyl unit into cycloparaphenylene (CPP). Spin distribution in this hydrocarbon is localized primarily on segment and partially CPP as consequence steric electronic effects. resulting geometry reminiscent diamond ring, with pseudo-perpendicular arrangement radial planar π-surface. phenylene rings attached directly to give rise effect that governs highly selective dimerization pathway, yielding giant double nanohoop. Its π-framework made 158 sp2-carbon atoms elucidated single-crystal X-ray diffraction, which revealed three-segment CPP-peropyrene-CPP structure. This nanocarbon shows fluorescence profile characteristic peropyrene, regardless gets excited. These results conjunction DFT suggest adjusting size segments nanohoop could deliver donor–acceptor systems.