The Plessey Company Plc

British Telecommunications Public Limited Company

Stephen N Oliver

Harry G Heller

Clive Trundle

Martin W Baskerville

John Whittall

Jack Brettle

William Ramsey Maltman

James D Rush

Callum A Hill

Allan E Underhill

Christoper S Winter

Paul J Darcy

William Johncock

John Whittal

Harold H Heller

Stuart A Harris

##STR1## The specification identifies dithiolenes which give good performance as the critical region of an optical switch. The dithiolenes have the formula shown in FIG. 1 wherein: (A) the R groups, any two of which may be the same or different, are selected so as to tune the absorption bands of the molecule for use at the operational wavelength and/or to act as bridges to join molecules together: (B) the X groups, any two of which may be the same or different, are selected from S and Se: (C) M is selected from Ni, Pt, Pd and Cu: (D) C=-1 or 0: and (E) (i) when C=-1, Y is a cation to render the molecule electrically neutral: preferably Y is selected from ammonium, substituted ammonium, Na.sup.+, Li.sup.+ and K.sup.+, (ii) when C=0, Y is absent (since the molecule is neutral there is no change to balance). The dithiolene may be diluted with an organic polymer selected from polyacrylates, polymethacrylates, such as polymethymethacrylate, polycarbonates, polyisobutylene, polyethylene terephthalate, polystyrene and polysiloxane.

Optical switches

A series of novel photochromic spiropyrans are disclosed in which a spiro-adamantane group is introduced into the 2-position of the benzopyran or naphthopyran ring. The spiropyran compounds of the invention exhibit heliochromic properties, i.e. they color in sunlight and fade rapidly at ambient temperatures in the absence of U.V. light, making them good candidates for use in the manufacture of sunglasses. The invention includes lenses which darken in sunlight and incorporate the novel spiropyrans and a process for the preparation of the spiropyran compounds.

Photochromic spiropyran compounds

Photoreactive plastics lenses are disclosed which are coated or impregnated with an adamantane 2-spiro-benzo or naphthopyran and with a blue coloring photochromic benzo- or naphthopyran having a nitrogen containing substituent in the 2-position in the pyran ring. The lenses darken in sunlight and fade rapidly at ambient temperatures in the dark or in white light which does not contain a U.V. component. The combination of the yellow/orange coloring adamantane 2-spiro pyran compound with the purple/blue coloring pyran gives a desired brown/grey coloration in the sunlight-darkened lens. The invention includes novel blue-coloring pyran compounds in which the nitrogen-containing substituent in the 2-position is a phenyl group having an amino or substituted amino or nitrogen-containing heterocyclic substituent in the ortho- or para-position of the phenyl group. The basic chromene structure and the suffix N will be used to distinguish the blue-coloring pyran compounds having a nitrogen-containing substituent, namely: ##STR1##

Photoreactive lenses with adamantane spiro compounds

A series of novel 3-pyrryl fulgides and fulgimides are disclosed which are photochromic. The photochromic compounds are coloured by subjecting them to irradiation in the near ultraviolet and will revert to the colourless form on exposure to visible light, especially light having a wavelength in 600 to 650 nm band.

Photochromic 3-pyrryl fulgides and fulgimides

A series of photochromic compounds are disclosed which have the property of undergoing a reversible color change when exposed to unfiltered sunlight and reverting to their original color in the absence of U.V. light at room temperature. These compounds have the general formula: ##STR1## represents an adamantylidene or a substituted adamantylidene group;

Polychromic tetracyclo-spiro-adamatylidene derivatives, and polychromic

A method is disclosed for manufacturing transparent plastic articles, primarily plano or opthalmic photoreactive lenses, which comprises incorporating fulgides or fulgimides containing an adamantylidene group in plastics casting or moulding compositions or preformed plastics articles and converting the fulgide or fulgimide in situ into a form in which it confers on the article the property of darkening in the presence of sunlight and fading in its absence.

Photochromic compounds and their use in photoreactive lenses

Growing community of inventors

Felixstowe, United Kingdom

Stephen N Oliver