- Photochromic compounds
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A spiro (indolino) oxazine compound of general formula (I) STR1 wherein R1 represents a group of the formula --NR2 R3 wherein each of R2 and R3, which may be the same or different, independently represents an alkyl group, or a carbocyclic group, preferably aryl, or a heterocyclic group, or R2 and R3 taken together with the nitrogen atom to which they are attached represent a heterocyclic ring having one or more heteroatoms and which may optionally carry at least one substituent selected from alkyl, aryl or heteroaryl groups; --X-- is selected from --O--, --S--, --Se--, --NH-- or --NR-- wherein R represents an alkyl group, and ring A is a carbocyclic or heterocyclic ring which can be optionally substituted with a group of formula R8 as defined above, or may optionally have a carbocyclic or heterocyclic ring fused thereto; and wherein R4 -R8 are as defined in the specification. The spiro (indolino) oxazine compounds of the invention are useful as photochromic materials.
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- Red colouring photochromic 6′-substituted spiroindolinonaphth[2,1-b][1,4]oxazines
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Electron donating/withdrawing substituents and electronegative centres have been successfully employed in substantially widening the range of photo-generated colours available in the spiroindolinonaphthoxazine class of photochromic materials.
- Rickwood,Marsden,Ormsby,Staunton,Wood,Hepworth,Gabbutt
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