title: Multistate pi switches: synthesis and photochemistry of a molecule containing three switchable annelated dihydropyrene units.
abstract: [structure: see text] The synthesis of the multistate photochromic switch 3 is described. This switch contains three dihydropyrene (DHP) units in the most conjugated fully closed form 3-c,c,c. The thermally stable form has the central DHP unit open and is 3-c,o,c. NMR and laser flash photolysis experiments were used to characterize the multiple states in the photoswitching of 3 by visible and UV light. Three of the possible five isomeric states of 3-c,o,c were observed. Irradiation of 3-c,o,c by visible light led to the formation of 3-o,o,o via the isomer 3-c,o,o as an intermediate, which were observed by NMR. Irradiation by UV light led to the formation of 3-c,c,c, which decays with a lifetime of 7.5 ms.
authors.affiliation: Department of Chemistry, University of Victoria, PO Box 3065, Victoria, BC, Canada, V8W 3V6. regmitch@uvic.ca
authors.forename: Reginald H
authors.initials: RH
authors.lastname: Mitchell
authors.forename: Cornelia
authors.initials: C
authors.lastname: Bohne
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Wang
authors.forename: Subhajit
authors.initials: S
authors.lastname: Bandyopadhyay
authors.forename: Chelsea B
authors.initials: CB
authors.lastname: Wozniak