Beilstein J. Org. Chem.2024,20, 552–560, doi:10.3762/bjoc.20.47
inversephotochromism), such as merocyanine forms of spiropyrans and spirooxazines, azomethine imines, thioindigoid dyes and N→O acylotropic systems [12][13][14][15]. Recently, they have been actively used to create next-generation molecular switches, materials with new properties (in particular, color
PDF
Graphical Abstract
Scheme 1:
Synthesis of compound 1 and N-acylated compounds 2a–c.
Beilstein J. Org. Chem.2009,5, No. 20, doi:10.3762/bjoc.5.20
recovered by irradiation at 306 nm or by heating. This ‘inverse’ photochromic system has a potential for optical information storage, compound 4 being stable in visible light, at ambient temperature.
Keywords: anthracenes; cyclophanes; inversephotochromism; photocycloaddition; Introduction
Photochromism
established systems show a ‘positive’ photochromism in which the electronic absorption spectrum of the product P is red-shifted [1]. When the electronic absorption spectrum of P is blue-shifted, the photochromism is said to be ‘negative’ or ‘inverse’ [1].
Inversephotochromism is encountered in photoaddition
of conjugated systems [10][11][12][13][14][15][16][17] and may be interesting for information storage materials because the photoproducts can be operated in visible light. Inversephotochromism was recently observed for some vinylogs of cinnamophanes [18][19], such as compound 1 (Figure 2). Several
PDF
Graphical Abstract
Figure 1:
Schematic representation of a photochromic system. The reverse reaction can be a photochemical or t...