Applications spirooxazines

Indolinospirooxazines are inherently more fatigue resistant than the spiropyr-ans. As measured by the quantum yield for photodegradation, the spironaphthox-azines are two or three orders of magnitude more photostable than the spirobenzopyrans. 37 From the point of view of industrial applications, spirooxazines are reported to be stabilized even further by various protective methods. 

Spirooxazine compounds are useful in the field of plastic lenses, such as sunglasses and ski goggles. The plastic photochromic sunglasses have been in the marketplace since the early 1980s, and their market share is presently ca. 70%. The excellent lightfastness of the spironaphthooxazine series makes such applications possible, compared to other photochromic compounds. 

Other applications of spirooxazine compounds include toys, cosmetics, printing inks, and clothes. 

The medicinal use of the photochromic oxazine 379 was discussed in the previous section. The principle of photochromism was shown in Scheme 3, Section 8.06.5.1. Photochromic spirooxazines 101, 116, and 297 that have appeared in this chapter and their various substituted derivatives have been patented as photochromic materials <2003WO42195> and used as photochromic dyes in a microsphere-based sensor <2005USP19954>. The compound 299 is also used as photochromic material <2005S1876>. More detailed information about the applications of spirooxazines can be found in a review <2002RCR893>. The phenoxazine 380 has also been patented for use in optics <2005SUA2246491>. 

C. Moustrou, M. Campredon, A. Samat, F. Gamier, J. Robillard, and R. Guglielmetti, New spiropyran and spirooxazine compounds with one or two thiophene nuclei. Applications to anticopying protection materials, Mol Cryst. Liq. Cryst., 246, 29-32 (1994). 

There was essentially no activity in this area between the disclosure of Ono and Osada1 or Arnold and Vollmer2 and the U.S. patent issued to Hovey et al.3 During the 1980s there was a rapid acceleration of research and publications on spirooxazines. The vast majority of the publications available at this time are patents and patent applications. 

Spirooxazines have excellent resistance to light-induced degradation. This property, also called fatigue resistance, is considered to be due to photochemical stability of the oxazine molecule framework in the ring-closed form as well as in the open-ring form. The fatigue resistance of the spirooxazines has led to then-successful use in various applications, for example, eyewear. 

Spirooxazines (NISO) have UV activation properties and thermal bleaching properties that are convenient for eyewear applications. A plastic photochromic lens must have several features, such as (1) ultraviolet energy protection, (2) comfortably lightweight, and (3) tint from a fashionably light tint to a functionally darker tinted sun lens. 45... 

It is relevant to cite here two more examples of the application of molecular calculations to spiropyran derivatives. First, in a study of the relationship between photochromism and second-order nonlinear optical (NLO) properties in spiropyran- and spirooxazine-doped polymer films, dipole moments, polarizabilities, and hyperpolarizabilities were estimated by the MNDO method.46 Second, the relative stabilities of the radical anions as well as their spin density distributions for a spiroindolinic series were calculated by an ab initio method in a combined electron paramagnetic resonance (EPR)/electrochemistry study.47... 

Photochromism has many potential and existing applications that take advantage of a change in colour or other physicochemical properties during the process, for example variable-transmission optical materials such as photochromic eyeglass or ophthalmic lenses that darken in sunlight (using spiropyran and spirooxazine systems in addition to... 

The photochromism of spirooxazines has been investigated by Chu, Schneider, and many other researchers. Their application potential seems to be very powerful. Ring opening of the Sp form of SO occurs via the Sj state and takes place in the psec domain. " The quantum yield is rather large in solvents of either low or large polarity. A biexponential thermal decoloration was observed, which is consistent with fully established equilibria between the Sp form and two photoisomers. Therefore, two separate steps leading to the ring-closure were considered for SO. In addition, a more twisted isomer was spectroscopically and kinetically observed upon irradiation of the most stable... 

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