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Updated: Feb 9, 2026

Synthesis and Catalytic Performance of Gold Intercalated in the Walls of Mesoporous Silica
Published on: July 9, 2015
Synthesis of open-shell ladder π-systems by catalytic C-H annulation of diarylacetylenes
Takehisa Maekawa1, Hiroshi Ueno1,2, Yasutomo Segawa1,2
1Graduate School of Science , Nagoya University , Chikusa , Nagoya 464-8602 , Japan . Email: ysegawa@nagoya-u.jp ;
Abstract:
A new open-shell ladder-shaped π-system has been synthesized. Pentaleno[1,2-b:4,5-b']difluorene derivatives, 8 fused ring systems bearing 5- and 6-membered rings, were constructed from alkynylfluorenone through a reaction sequence including Pd-catalyzed C-H/C-H annulation. X-ray crystallography and ESR spectroscopy revealed the open-shell character of these ladder-shaped molecules, which derives from their extended π-electron conjugation. Absorption peaks in the near IR region as well as narrow redox potentials observed by cyclic voltammetry indicated small optical and fundamental energy gaps of these fused ring systems.
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