Dihydroazulene/vinylheptafulvene

Optoelectronic Molecular Switches Based on Dihydroazulene-Vinylheptafulvene (DHA-VHF)... [Pg.64]

Molecular switches based on the dihydroazulene-vinylheptafulvene system are discussed in Chapter 3. Chiroptical switching was achieved with a carbohydrate-modified chiral polyazuleneJ721... [Pg.153]

The dihydroazulene vinylheptafulvene couple (9) [85, 98], dihydroindolizine (10) [95], and fulgides are further examples of photochromic open-closed ring systems... [Pg.3232]

The dihydroazulene/vinylheptafulvene (DHA/VHF) system, first reported by Daub in 1984, represents such a photochromic system. DHAs such as 448, a ring-closed system, are prepared by [8+2] cycloaddition of 8-methoxyheptafulvene 449 and dicyanoethylenes 450. The double bond between C-2 and C-3 is introduced by elimination of methanol with phosphorus pentoxide (Scheme 6.117a). The yellow solutions of 448 turn dark red to 451 (VHP) on exposure to daylight. The thermolabile 451 rearranges quantitatively within 70 h at 25 °C into 448 in the dark (Scheme 6.117b) [272]. [Pg.226]

In a study of multimode switching based on dihydroazulene/vinylheptafulvene photochromism, Spreitzer and Daub [72] reported a [8+2]cycloaddition reaction of 8-methoxyheptafulvene 284 and dicyanovinylene compound 285 in chloroform to give the tetrahydroazulene 286 (Scheme 7.62). [Pg.283]

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