Pilkington Plc

Martin Rickwood

Sean D Marsden

John D Hepworth

Christopher D Gabbutt

Katharine E Smith

Victoria E Askew

A spiro (indolino) oxazine compound of general formula (I) ##STR1## wherein R.sub.1 represents a group of the formula --NR.sub.2 R.sub.3 wherein each of R.sub.2 and R.sub.3, which may be the same or different, independently represents an alkyl group, or a carbocyclic group, preferably aryl, or a heterocyclic group, or R.sub.2 and R.sub.3 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;

Photochromic compounds

Photochromic naphthopyran compounds

A naphthopyran compound of general formula (I) ##STR1## wherein R.sub.1 represents an alkyl group or an aryl group; each of R.sub.4 and R.sub.5, which may be the same or different, independently represents an alkyl, alkenyl, carbocyclic or heterocyclic group, or R.sub.4 and R.sub.5 taken together with the carbon atom to which they are attached form a carbocyclic ring or a heterocyclic ring; and

Photochromic compounds having the following structure II ##STR1## in which R.sup.1 is a group selected from hydrogen, alkyl, alkoxy, amino, aryl or heteroaryl;

Bridged spiroxazine photochromic compounds

A photo reactive material, such as a photochromic material, which has the following structure: ##STR1## where the variables, A, R, R', R', R*, R.sup.+, m, and n are defined in claim 1.

Photo reactive spiro-benzoxazine compounds

Photochromic materials which have a structure which includes a spiro-pyrrolidinebenzoxazine structure comprising a pyrrolidine part and a benzoxazine part and the benzoxazine part includes at least one mesomeric electron donating group chosen from amino and alkoxy moieties, the one or more mesomeric electron donating groups being linked to the 6' position via attachment to a conjugated system in which the unsaturated bonds forming the linkage are chosen from --C.dbd.C--, --C.tbd.C--, --C.dbd.N-- and --N.dbd.N--.

Photochromic spiroxazine compounds

A plastic organic photochromic article, typically a lens such as an ophthalmic lens or a window such as a vehicle roof light, comprisig a plastics host material having a photochromic compound incorporated therein or applied thereto, the article exhibiting the following properties, measured at Air Mass 2 at 25.degree. C.:

Photochromic articles

An azaindoline spiro-oxazine of the general formula (I): ##STR1## wherein R.sub.1 represents an aliphatic or aromatic group; each of R.sub.2 and R.sub.3 independently represents a hydrogen atom, an aliphatic or aromatic group or an alkoxy group, or R.sub.2 and R.sub.3 together with the carbon atom to which they are attached represent an alicyclic group;

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Southport, United Kingdom

Martin Rickwood