Multifunctional Molecular-level Systems - Photochromic Flavylium Compounds

Multistate/Multifunctional Molecular-level Systems-Photochromic Flavylium Compounds 

Mauro Maesri, Fernando Pina, and Vincenzo Balzani 

Typical bistable species are the so-called photochromic compounds molecules that can be reversibly interconverted, with at least one of the reactions being induced by light excitation, between two forms displaying different absorption spectra.17 8  

Photochromism was first described in the scientific literature in 1876. 7 In his famous paper entitled The Photochemistry of the Future (1912), G. Ciamician19 discussed the importance of photochromic substances and mentioned the possibility of using such compounds for fashion purposes. Photochromism is also a natural phenomenon most biologic photoreceptors exhibit photochromic behavior. 101 Until the middle of this century research on photochromic compounds was mainly carried out in academic centers, but around 1960 it was recognized that this subject is also of considerable commercial interest and since then most of the research has been done in industrial laboratories. The applications of photochromic materials can been classified as follows 7  

Apart from future applications for information processing at the molecular level,1141 the study of compounds capable of existing in different forms that can be interconverted by means of external stimuli is a topic of great fundamental interest.11-61 Recently it has been shown that suitably designed photochromic compounds may 

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I 70 Multistate/Multifunctional Molecular-level Systems - Photochromic Flavylium Compounds... 

Photochrome flavylium compounds as multistate/multifunction molecular-level systems 99CC107. 

NMR spectroscopy of flavan-3-ols and proantocyanidines 97KPS545. Photochrome flavylium compounds as multistate/multifunction molecular-level systems 99CC107. 

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