Fatigue resistivity, fulgides

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... 

Photochromic Reaction, Substituent Effects, and Fatigue Resistance of Phenyl Fulgides... 

R. Matsushima, A. Kaneko, A. Tomoda, M. Ishizuka, and H. Suzuki, Photochemical fatigue resistances and thermal stabilities of heterocyclic fulgides in PMMA film, Bull. Chem. Soc. Jpn., 61(10), 3569-3573 (1988). 

The fatigue resistance was improved when the furyl group was replaced with indole or oxazole [29, 30]. The coloration/decoloration cycles of oxazolyl fulgide 26 could be repeated more than 500 times in toluene, even in the presence of oxygen. The fatigue resistance strongly depends on the aryl groups. 

Figure 7. Fatigue resistance of fulgide derivatives a) in toluene and b) in PMMA film. Aq and A were the absorbances of the first cycle and after n coloration/decoloration cycles, respectively.

Fulgides and Fulgimides - A theoretical study of the photochromic compound 2,3-bis(2,4,5-trimethyl-3-thienyl)maleic anhydride has been reported. The photochromic properties of the indyl fulgide ( )-l-benzyl-2-methyl-3-indylethylindene(isopropylidene) succinic anhydride have been studied.The photochromism of (232) and (233) has been investigated. The cyclizations are reversible and the materials show reasonable fatigue resistance. 

Yu et al. [36] have reported applications of pyrryl fulgides with respect to optical data storage. More than 500 UV-irradiation and photobleaching (He-Ne laser, 632.8 nm) cycles of an optical disk coated with PMMA thin film doped with pyrryl fulgide without fatigue resistance of formation photodecomposed species were demonstrated. 

Mahmut Kose 86.6 Fulgides for Optical Devices Nondestructive Readout of Memories Fatigue Resistivity. 86-8... 

Resistance to fatigue toward the iterative photoirradiation is one of the most important features for a photochromic compound that might be used for optical memory media or switching devices. Dia-rylethenes are known to be more resistant to fatigue than fulgides. Efforts to improve the durabihty of fulgides have continued and some important results have recently been obtained. 

---