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Updated: Jul 20, 2026

Real-time Monitoring of Ligand-receptor Interactions with Fluorescence Resonance Energy Transfer
Published on: August 20, 2012
Visible light sensitive cyclomer and its tautomeric dispiro compound formed from bispyridinyl diradical
Takashi Muramatsu1, Azumao Toyota, Miho Suzuki
1Environmental Education Center, Miyagi University of Education, Sendai 980-0845, Japan. t-mura@miyakyo-u.ac.jp
Abstract:
Two-electron reduction of 4,4'-(1,5-pentanediyl)bis(N-methylpyridinium) (52+) with sodium amalgam in degassed acetonitrile leads quantitatively to the formation of a cyclomer of 3,15-dimethyl-3,15-diazatricyclo[10.3.1.12,6]heptadeca-4,6(16),12(17),13-tetraene (6) by intramolecular cyclization. In degassed acetonitrile, 6 is stable for a long time at room temperature and, hence, a highly stable species. In contrast, 6 undergoes a photochemical reaction to give its valence tautomer having a dispiro structure, 3,10-dimethyl-3,10-diazadispiro[5.0.5.5]heptadeca-1,4,8,11-tetraene (7), when irradiated with visible light shorter than 450 nm. Noteworthy is the experimental fact that 7 is unstable to heat and, hence, reverts back to 6 by application of heat.
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