8  Photochromism

Photochromic researches on spiropyrans, spirooxazines, naphthopyrans, chalcones, diarylethenes, and fulgides published in 2002 have been reviewed. Photochromic compounds are classified into two categories, thermally reversible compounds such as spiropyrans, spirooxazine, naphthopyrans, and chalcones, and thermally irreversible compounds, such as diarylethenes and fulgides. This review describes new derivatives of both types of compounds, their photochromic performance and possible applications. Azobenzene derivatives are not included.