Vinylheptafulvene Research Articles

Signaling and Expression of Electronic Effects by Dihydroazulene-Vinylheptafulvene Photochromism

Dihydroazulene(DHA)/vinylheptafulvene(VHF) equilibration is based on photochemical ring opening and thermal cyclization. Optical and non-linear optical properties of DHA/VHF are reported. Multimode switching, comprising both photo-redox and off/on-fluorescence switching, are investigated. DHA covalently attached to cellulose shows multifold switching. A concept for cyclic multistate switching is proposed based on biphotochromic compounds.

Functional dyes for molecular switching. Dihydroazulene/vinylheptafulvene photochromism: Effect of π‐arylenes on the switching behavior

AbstractThe reversible interconversion of dihydroazulene (DHA) and vinylheptafulvene (VHF) can be utilized to switch a number of physical properties. This communication reports on a fluorescent switch. By a multistep sequence involving an [8 + 2] cycloaddition route 9‐anthracenyl‐1,4‐phenylene was covalently attached to C‐2 of the DHA chromophore affording DHA‐1 which undergoes complete and clean photochemical ring opening to vinylheptafulvene VHF‐1. The latter is thermally reverted to DHA‐1. The kinetics and the energetics of the thermal back reaction are discussed. On/off switching of luminescence was investigated: DHA‐1 displays fluorescence whereas VHF‐1 is nonfluorescent at ambient temperature.

Novel Multichromophoric Dyes for Chemical, and Physical Switching

Abstract Functionalized photochromic compounds and their applications in chemical and physical switching processes are under investigation. In this report exclusive consideration is given to the dihydroazulene @HA)/vinylheptafulvene (VHF) system ½. A short description of the photochromism of ½. is presented. Three topics of potential switching behaviour released by the photochromism of ½. are pointed out: (i) change of the pka and of proton transfer properties in anilinium derivatives, (ii) change of the redox potential in compounds with electron transfer active subunits, (iii) increase of second‐order nonlinear optical properties by irradiation of 1.

Molecular materials for chemical and physical switching IV: Photomodulation of electric current by light‐sensitive electron‐transfer compounds—aryl/dihydroazulene‐conjugates

Bichromophoric compounds containing the dihydroazulene ⇄ vinyl heptafulvene couple (see figure) with arenoid “R” groups which act as electron‐transfer groups can be triggered by visible light to produce an electric current. They are therefore of use as molecular switches. A number of different arenoid substituent have been employed and the compounds examined.magnified image