Applications fulgides

For practical applications, fulgides must retain their excellent photochromic properties in solvent and in a polymer matrix, because the ultimate photomemoiy media will certainly be provided as a plastic layer containing photochromic... 

The three main classes that have been much studied for ophthalmic applications are spiroindolinonaphthoxazines (see section 1.2.3), diarylnaphthopyrans (see section 1.2.4) and fulgides (see section 1.2.5). How these different photochromic classes match up to the desired criteria for use in lenses is shown in Table 1.9. From this it can be seen that fulgides exhibit only a fair fatigue resistance and spiroindolinonaphthoxazines suffer from a high temperature dependency. Consequently, for this photochromic outlet, naphthopyrans have become the molecules of choice. Typical... 

The use of photochromies in novelty printing is a signiheant commercial outlet. Because of their ability to show resistance to thermal fade rates fulgides have been the class most commonly used for this application. Typical uses are on children s toys and for logos on T-shirts. 

Fulgides. Several patents describe the use of fulgides in photographic applications. 

The great merit of thermal irreversibility is the permanent nature of the states. Therefore, fulgides have long been viewed as potential candidates for photon-mode optical recording materials. In addition, fulgides have been used as prototypes to demonstrate their potential applicability as photoswitchable functional materials. Those switch models that had appeared up until the end of 1999 are described in this chapter. 

Chapter 4 (Fulgides). The fiilgides are a class of photochromic compounds for which the thermal reversal or decoloration of the colored species is disallowed. Therefore, the reversion is largely driven photochemically as is illustrated with compound 4 (Scheme 4). Because of the stability of the colored species toward thermal reversion, the fulgides have potential application in the field of optical storage and security printing. Another use, in actinometry, is well known. 

Fulgide Family Compounds Synthesis, Photochromism, and Applications... 

Based on the five classes of fulgide family compounds, many realistic and potential applications have been developed and suggested for example, actinometry, optical storage, optical data processing, and nonlinear optical materials, optical waveguides, optical switches, security and printing applications, eyewear and leisure products. Applications of the fulgide family of compounds are discussed at the end of this chapter. 

Recently Fan et al.,78,79,81 84,86,87 Zhao et al.,so and Fan et al.85 have made an effort to study the molecular design, synthesis, photochromism, and application of pyrryl-substituted fulgides. A series of such fulgides (62) has been prepared by Fan s group, and the photochromic reactions investigated. The molecular structures and photochromic reactions are shown in Scheme 20. 

The applications of fulgides and their derivatives are discussed separately for advanced materials, photochromic inks, and fabrics. 

---