Spiroindolinonaphthoxazines

The commercially available spirooxazines are based on the spiroindolinonaphthoxazines (1.11) ring structure. The synthetic route to this ring system involves the reaction of a l-hydroxy-2-nitoso bearing aromatic ring with a 2-aUcylidene heterocycle, such as Fischer s base (1.6 R = H). The naphthoxazines are the derivatives of choice... 

The spiroindolinonaphthoxazine derivatives became commercially important compounds once detailed research work led to products which overcame many of their initial weaknesses, such as relatively poor fatigue resistance and a poor colour range (550-620 nm). The important positions for substitution in the ring of (1.11) are the 5-position which has a large effect on the colour, the 6 -position, which has a major effect on both the colour and properties such as optical density (OD) and molar absorption coefficient and the alkyl group on position 1, which has a kinetic effect on the rate of loss of colour back to the colourless state. ... 

The spectrum of the ring-opened form of the parent spiroindolinonaphthoxazine (1.11) has at 590 mn. Spiroindolinonaphthoxazines also show a negative solva-tochromic shift, the absorption moving hypsochromically (20-60 nm) in less polar solvents (e.g. toluene versus ethanol), the converse of what happens with spiroin-dolinobenzopyrans (see section 1.2.2.2). 

Introduction of dialkylamino substituents in the 6 -position of the spiroindolinonaphthoxazine (1.11) causes a hypsochromic shift in the absorption maximum of the coloured state and also an increase in its intensity. This hypsochromic shift can also be increased by introducing electron-withdrawing groups into the 5-position of (1.11), whilst electron-donating groups move the absorption maximum in the opposite direction. The data for these effects are given in Table 1.3. 

Table 1.3 Substituent effects on the absorption maximum of the coloured state of spiroindolinonaphthoxazines (1.11)...

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 first photochromic spirooxazine compounds synthesized (1970) belonged to the spiroindolinonaphthoxazine ring system. Generally, they were colorless in dilute organic solvents and polymer matrices and became blue upon exposure to UV light. 

This paper will deal briefly with the properties and synthesis of spiroindolinonaphthoxazines (SINOs) and ehromenes, and review some of the optieal and performance properties. 

Fig. 12 for thermal decoloration of spiroindolinonaphthoxazine in PMMA, cyclized isoprene rubber (CIR), and poly(2,6-dimefhyliAenyIene oxide) (PPO). It takes values close to unity above the of the matrix polymers. Around T, a rapidly... 

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