Polydialkylalloxane-bridged bi-photochromic molecules
The present invention relates to photochromic molecules, in particular
bi-photochromic molecules comprising a polydiakylalloxane oligomer linker, and to
products comprising them.
Photochromism is a well known physical phenomenon, which is defined as "a
reversible transformation of a single chemical species being induced in one or both
directions by electromagnetic radiation between two states having different
distinguishable absorption spectra". A detailed discussion of this phenomenon can
be found in "Photochromism : Molecules and Systems", revised edition, edited by H.
Durr and H. Bouas-Laurent, Elsevier, 2003. A review of the major classes of organic
photochromlc molecules can be found In "Organic Photochromlc and
Thermochromic Compounds, Volume 1, Main Photochromlc Families", edited by J.
Crano and R, Gugllelmetti, Plenum Press, 1909. A detailed review of photochromic
naphthopyrans can be found in "Functional Dyes", edited by Sung-Hoon Kim, pages
85-137, Elsevier, Amsterdam, 2008.
Currently the major business area for photochromlc molecules is the ophthalmic
market, where T-type (thermally reversible) photochromics are used. The most
important classes of organic photochromic molecules for the ophthalmic market are
the naphthopyrans (both the 1,2-b and 2,1-b ring systems), and the spiro-
naphthoxazlnes (both the 1,2-b and 2,1-b ring systems). This has been an area of
considerable patent activity, for example US 5,650,098 (1,2-b naphthopyrans,
Transitions), US 5,623,005 (2,1-b naphthopyrans, PIIkington), US 5,446,151 (2,1-b
naphthoxazines, Pilkington), and US 6,303,673 (1,2-b naphthoxazines, James
Robinson).
Work has been carried out to alter the photochromic properties and the physical
properties of the photochromic molecules, in an attempt to "tune" the properties of
the molecule to those required by particular applications. One approach has been to
attach various long chain substtiuents. Enichem (EP 0524692) claim oxazines with
long chain alkoxy substituents and long chain ester substituents.
A patent from Polymers Australia (WO 04/41961), reveals the effects of
polydlmothylslloxane chains, perfluoroalkyl chains, polyethylene glycol chains, and
alkyl chains on the fade speeds of single photochromic molecules in rigid polymeric
matrices of high glass transition temperature (To). This patent reveals that the
greatest increase in photochromic fade speeds of single photochromic molecules
was caused by polydimethylelloxane chains. Subsequent patents from Polymers
Australa reveal the effects of porymethyl (methacrylate) and polybutacrylate chains
generated by "living polymerisation" (WO 05/105876, WO 06/24098), and polyether
chains (WO 05/106874). A literature article from the authors of the Polymers
Australia patents (R. Evans et al, Nature 2005, Vol 4, p249) Indicates that use of
polydimethylsiioxane chains gave the greatest improvements in increasing the rate
of fade of single photochromic compounds In an ophthalmic tena matrix.
Commercially an increased rate of fade, whilst still achieving an acceptable intensity
of colour, is a desirable property for ophthalmic lenses.
Slloxanes have previously been attached to P-type photochromic molecules (JP 10-
101802, Dow Coming Toray Silicone), although these dithlenylethenes do not exhibit
thermal fade: These are polymeric materials with variable photochromic content
Yeda Research and Development have revealed photochromic spiro-oxazine
monomers and polyslloxanes (US 5322945) and photochromic spiro-oxazine
polymers containing both photochromic spino-oxazines and light-stabilizing groups
(US 6905148).
Polymerisable groups have been attached to oxazines (US 5821287, National
Science Cound Taiwan). Polymerisable polyalkoxylated pyrans have been claimed
by PPG (WO 00/16629) and Transitions (WO 03/56390).
Work has also been carried out to link two photochromic units by means of a bridge.
Gugllelmetti et al have linked oxazines and pyrans by means of ethane, ethylenic,
acetylenic, ester, mono-, bi- and ter-thlophene bridges (see F. Ortica et al, J.
Photochem. Photobiol A, (2001),139, 2-3; M. Frigoll et at, Helv. Chim. Acta. Vol 83.
(2000). P3043-3052; A. Yasser et al, Applied Physics Letters, (2002), Vol 80. 23.
P4297-4299). Rodonstock (EP 0686685) have linked pyrans by means of a
-CH2CH2- bridge which, It is taught, does not affect the photochromic properties of
the photochrome moieties: it is therefore dear that this bridge does not give any
advantages in terms of improved properties such as fade rate or colour intensity.
Zhao and Carreira (JACS 2002,124, 8, p1582) have prepared bis-naphthopyrarts
linked by a bis-thlophene, by phenyl groups (Organic Letters, 2006, Vol 8 No. 1, p99)
and by oligothiophenes (Chem. Eur. J. 2007, 13, 2671-2685). Coelho et al
(Tetrahedron, 2005, 61, p11730) have linked pyrans by means of phenyl, pnenyl-O-
pherryl, and phenyl-CH2CH2-phenyl bridges. Great Lakes (WO 00/38245)" claim a
trimeric species where three oxazlnes are attached to a central triazine. Great
Lakes (WO 00/05325 and WO 00/21968) also claim compounds where two, three or
four oxazlnes are linked to a central tetramethylcyclotetrasiloxane ring.
Photochromlc acrylate, styrene and slloxane polymers which are based on the P-
type photochromic phenoxynaphthacenequlnone have been described by Buchholtz,
Zelichenok and Krongauz (Macromolecules, 1993, Vol 26. No. 26, P906-910).
However, many of these known molecules suffer from disadvantages including slow
fade rates, poor colour strength, and poor heat stability. As a result marry of these
molecules are not well-suited for certain uses such as, for example, Incorporation
into ophthalmic lenses. There exists, therefore, a need for photochromic molecules
exhibiting Improved properties.
According to the present invention in its broadest aspect mere is provided a bi-
photochromic molecule comprising two photochromic moieties linked via a
polydialkylalloxane oligomer.
In a further aspect, there is provided a bi-photochromic molecule having the
structure set out In claim 4.
There is also provided an ophthalmic lens comprising a bi-photochromic molecule
according to the invention.
In a further aspect, the Invention provides a polymeric host material comprising a bi-
photochromic molecule according to the Invention.
It has been found that the molecules exhibit a considerable Improvement in the rate
of fade in polymer matrices compared to the parent photochromic molecules. The
compounds of the invention often exhibit increased strength of photochromic colour . .
compared to the parent photochromic molecule, allowing for molecular weight and
the number of photochromic units present The compounds of the invention are
particularly useful for use in photochromic ophthalmic lenses.
It has also unexpectedly been found that these molecules have improved heat
stablity when incorporated into polymers, compared to the individual photochromic
molecules which are not linked by the bridging group. This alows the molecules, of
the invention to be incorporated into polymers which require higher processing
temperatures than are compatible with the unlinked photochromic molecules.
The molecules of this invention also have the beneficial property of a lower
yellowness index compared to the individual photochromic molecules which are not
linked via a porydlalkylslloxane oligomer when processed at the same temperature in
the same polymer.
Similarly, we believe that the compounds of the Invention have advantages of
improved fade rate, improved photochromic colour strength, increased heat stability
and reduced yellowness index when compared to the known bi-photochromic
compounds comprising bridging groups.
In a preferred embodiment of the present invention, two photochromic molecules are
linked by means of a bridge which comprises a linking group at each end of a central
polydialkylslloxane (PDAS) chain to provide novel polydialkylslloxane bridged bi-
photochromic molecules. Preferably, the bridge consists of a linking group at each
end of a central PDAS chain.
The photochromic units may be the same or different, allowing for the possbility of
different chromophores with different fade rates to be present In the same molecule.
The molecules of the invention comprise two photochromic moieties or molecules
linked via a polydialkylslloxane chain. K is highly preferred that the
polydialkylsiloxane bridge, or linker, comprises a linking group at each end.
Preferably, the bridge, or linker, consists of a linking group at each end of a central . .
polydialkylslloxane chain. Any suitable polydialkylslloxane chain and linking groups
may be employed.
Preferably, the compounds are of the general formula:

wherein PC and PC represent a photochromic moiety; PDAS represents a
polydialkylsiloxane chain; and L and L' represent linking groups.
PC and PC may be the same or different it is particularly preferred that PC and
PC independently represent photochromic moieties of general structure I to IV:
wherein R1 and R2 independently represent hydrogen, linear or branched C1-10 alkyl,
linear or branched C1-10 alkoxy, C1-10 hydroxyalkoxy, C1-10 alkoxy(C1-10)alkoxy, phenyl,
C1-10 alkoxyphenyl, halogen, C1-5 haloalkyl, C1-5 alkylamino, C1-5dialkylamino,
arylamino, diarylamino, aryl C1-5 alkylamino, or a cyclic amino group;
R3 represents hydrogen, linear or branched C1-10 alkyl, C3-C20 cycloalkyl, C6-C20
bicycloalkyi, linear or branched C2-10 alkenyl, linear or branched C1-10 alkoxy, C1-10
hydroxyalkyl, C1-10 aminoalkyl, linear or branched C1-20 alkoxycarbonyl, carboxyl,
halogen, aryloxycarbonyl, formyl, acetyl or aroyl;
R4 represents phenyl, C1-10 alkoxyphenyl, C1-10 dialkoxyphenyl, C1-10 alkylphenyl, C1-10
dialkylphenyl, In addition to those groups specified for R3;
or R3 and R4 together form a cyclic structure of the type
R6. R6, R7, R8, R9, R10, R14, R15, R10 are as defined above for R1 and R2;
Rt 1 represents Inear or branched C1-20 alkyl C3-C20 cydoalkyl, C6-C20, bicycloalkyl,
(C1-5 alkyl)aryl, (C1-5 alkyl)cycloalkyl, (C1-5 alkyl)bicycloalkyl, C1-5 haloalkyl, C1-5
dihaloalkyl or C1-5 trihaloalkyl;
R12 and R13 represent C1-10 alkyl, C1-5 alkyl alkoxycarbonyl, or together form a C5-7 .
ring; and
R17 and R18 represent linear or branched C1-10 alkyl, C1-10 hydroxyalkyl, or together
form a C5-7 ring.
L and L", which may be the same or different, represent a finking group. Any suitable
linking group may be used. It is preferred that L and L' represent a linking group of the
form
wherein Y is independently oxygen or sulphur, R19 is hydrogen or C1-10 linear or
branched alkyl, R20 Is C1.10 linear or branched alkyl, p is an integer from 1 to 15, and r
is an integer from 0 to 10, and wherein Q is linear or branched C1-10 alkyl, C1-10 alkenyl
or 1,2-, 1,3, or 1,4-substituted aryl, or substituted heteroaryl.
Preferably Y is oxygen.
PDAS represents a polydialkylslloxane chain. Preferably, PDAS represents an oligomer,
of the form

wherein R19 is C1-10 alkyl, and n Is an integer of from 4 to 75.
Polydialkylslloxane oligomers are commercially available, for example from Gelest Inc,
Shin-Etsu Chemical Co. Ltd; Chisso Corp; Toshiba Silicone Co. Ltd; and Toray-Dow
Corning Co. Ltd.
Suitable polydialkylsiloxane oligomers include, but are not limited to,
polydimethylsiloxane oligomers, such that R19 is preferably methyl.
it is preferred that n is between 6 and 30 Inclusively. Particularly preferably, R19 is
methyl and n is an Integer of from 8 to 30.
Preferred polydimethylsiloxane oligomers include the oligomers DMS-B12 (a w-bis
carboxy-terminated polydimethylsiloxane). DMS-C15, DMS-C16 or- DMS-C21 (a w-bis
hydroxyl-terminated polydimethylsiloxanes) DMS-A11, DMS-A12, DMS-A15, DMS-
A21, DMS-A211 and DMS-A214 (a . w-bis amino-terminated polydimethylsiloxanes)
available from Gelest Inc; KF-6001, KF-6002, KF-6003, KF-8010, X-22-160AS, X-22-
162A, X-22-161A, X-22-161B and X-22-162C from Shin-Etsu; and Silaplane FM-44
from Chisso. Particularly preferred are the oligomers DMS-B12, DMS-C15, DMS-C16,
DMS-C21, DMS-A11, DMS-A12, DMS-A15, DMS-A21, DMS-A211 and DMS-A214
from Gelest These are quoted as having the following structures and approximate
molecular weight or molecular weight ranges. For convenience, the Gelest
nomenclature is used to name the following polydimethylsiloxane oligomers, rather
than the cumbersome (and not strictly accurate, as the oligomers are mixtures)
systematic names.
As the skilled person is aware, commercially available polydimethylsiloxane oligomers
are generally supplied either with an average molecular weight or a molecular weight
range, and any number quoted as the number of repeat units of the dimethylsiloxane is
to be interpreted as an average value.
The parent photochromic compounds may be prepared as described in US 5,650,098
(1,2-b naphthopyrans), US 5,623,005 (2,1-b naphthopyrans), US 5,446,151 (2,1-b
naphthoxazines), and US 6,303,673 (1,2-b naphthoxazines).
Typically a linking group is attached to the commercially available oligomer, if required,
and this reagent is then reacted with the parent photochromic compound to give the
polydialkylsiloxane-bridged bi-photochromic molecule. The linking group may also be
attached to the parent photochromic compound, which is then reacted with the
commercially available oligomer to give the polydialkylsiloxane-bridged bi-photochromic
molecule. Suitable reaction conditions will be apparent to the skilled person.
The following examples serve to illustrate the invention, and do not limit its scope.
Examples
Commercially available polydimethylsiloxane oligomers are supplied either with an
average molecular weight or a molecular weight range, and any number quoted as
the number of repeat units of the dimethylsiloxane is to be interpreted as an average
value. Accordingly, an yields quoted in the following
Examples are inevitably
approximate. The oligomers DMS-B12, DM8-C15, DM8-C16 and DMS-A214 are
available from Gelest inc. and are quoted as having the following structures and
approximate molecular weight or molecular weight ranges. The Gelest
nomenclature will be used to name the polydimethylsiloxane oligomer section of the
polydialkylsiloxane-bridged bi-photochromic molecules, rather than the cumbersome
(and not strictly accurate, as the oligomers are mixtures) systematic names. For
yield calculations with DMS-C16 end DMS-A214, the midpoint of the molecular
weight range has been used.
Example 1: Bis-succinyl-DMS-C15

The bis-hydroxy-terminated alloxans DMS-C15 (9.1 g, molecular weight - 1000) was
mixed with succinic anhydride (2.8 g) and toluene (120 ml) for 2 minutes. Triethyiamine
(5:0 ml- 3.5 g) was added and the mixture was heated to 70-75°C for 1.5 hours. The
solution was cooled to 25°C, then PEG rnonomethylether (2.6 g) was added and the
mixture stirred for 20 minutes.
The solution was washed twice with a mixture of HCI (5 ml) and water (100 ml), then
was washed with saturated brine (3 x 100 ml). The organic layer was dried over sodium
sulphate, and filtered to give 110.2 g. Theoretical yield 10.9 g, giving a maximum
strength of 9.9%.
Example 2:Bia-phthaloyl DMS-C15

The reagent bis-phthaloyl-DMS-C15 was prepared in analogous fashion to bis-succinyl-
DMS-C15 in Example 1, using an equivalent quantity of phthalic anhydride in place of
succinic anhydride.
Example 3: Bis-succinyl-DMS-C16

The reagent bis-succinyl-DMS-C16 was prepared in analogous fashion to bis-succinyl-
DMS-C15 (Example 1), using the bis-hydroxy-terminated polydimethylsiloxane DMS-
C16 (molecular weight range - 600-850).
Example 4: Bis-succinamido-DMS-A214

The reagent bis-succinamido-DMS-A214 was prepared in analogous fashion to bis-
succinyl-DMS-C15, using the bis-secondary amino terminated polydimethylslloxane
DMS-A214 (molecular weight range - 2500-3000).

1,3-Dihydro-3,3-dimethyl-1-neopentyl-6'-(4"-N-ethyl, N-hydroxyethylamino)spiro[2H-
lndole-2,3'-3H-naphtho[1,2-b][1,4]oxazine] (1.00 g) was mixed with a toluene solution of
bis-succinyl-DMS-C15 (prepared according to Example 1, 18.5 g at 6.4% in toluene -
1.18 g at 100%), dimethylaminopyridine (0.05 g) and toluene (20 ml). The mixture was
stirred at room temperature for 10 minutes, before addition of dicyclohexyl carbodiimide
(0.75 g). This was then stirred at room temperature for 45 minutes.
More bls-succinyl-DMS-C15 (6.0 g at 8.4% in toluene = 0.38 g) was added and the
mixture stirred for a further 40 minutes. TLC showed only a faint trace for unreacted
starting material.
The mixture was cooled in an ice bath for 15 minutes, then was filtered, and the solids
washed with toluene (5 ml). The solution was used for flash chromatography. The best
fractions were combined and evaporated down. The resulting green gum was
dissolved in acetone (15 ml), filtered, and then evaporated down to give 1.6 g of a
green oil which converted on standing to a pale green opaque soft solid. Approximate
yield = 77%

3-(4'-Methoxyphenyl),3-(4''-hydroxyethoxyphenyl)-6-morpholino-3H-naptho[2,1-
b]pyran (1.50 g) was mixed with a toluene solution of bis-succinyl-DMS-C16
(prepared according to Example 3, 14.7 g of 11.6% solution = 1.71 g at 100%),
toluene (20 ml) and dimethylaminopyridine (0.07 g). This was stirred for 2 minutes,
then dicyctohexyl carbodllmide (0.67 g) was added and the mixture stirred at room
temperature. The mixture became opaque after 1-2 minutes stirring.
After 45 minutes, thin layer chromatography (TLC) (3:1 petrol:acetone) indicated that
some unreacted starting material remained. More of the toluene solution of bis-
succinyl-DMS-C16 (6.1 g of 11.6% solution = 0.71 g at 100%) was added, and the
mixture stirred for 1 hour. At this point TLC Indicated virtually no starting material
remained.
The mixture was cooled to 4°C for 45 minutes, then was filtered and the solids
washed with toluene (5 ml). The solution was used for flash chromatography, eluting
with a mixture of petroleum ether and ethyl acetate. This gave 2.7 g of an orange oil
which hardened to an opaque orange solid. Yield = approximately 96%.

1,3-Dihydro-3,3-dimethyl-1-isobutyl-9'hydroxy-spiro[2H-indole-2,3'-3H-naphtho[2,1-
b][1,4]oxazine] (1.50 g) was mixed with a toluene solution of bis-succinyl-DMS-C16
(prepared according to Example 3, 29.8g of 9.7% toluene solution = 2.90 g at 100%),
toluene (20 ml) and dimethylamino pyridine (0.07 g). This was stirred for 2 minutes
until alt of the solid had dissolved. Dicyclohexyl carbodilmide (0.90 g) was added and
the mixture stirred at room temperature for 46 minutes. After about 10 minutes, the
solution became cloudy with the white precipitate of dicyciohexyl urea.
After 46 minutes, TLC (3:1 petrol:acetone) indicated that effectively all of the starting
material had been converted to a less polar photochromic product The mixture was
cooled to 4°C for 45 minutes, then was filtered and the solids washed with toluene (5
ml). The solution was used for flash chromatography, editing with a mixture of
petroleum ether and ethyl acetate. The best fractions were combined and
evaporated down. The resulting blue oil was redissolved in acetone (30 ml), filtered
and evaporated down again. This gave a pale blue-green oil: 2.3 g. Approximate
yield = 68%.
Example 8: (2-(4'-Pyrrolidinophenyl)-2-phenyl-5-phthaloylmethyl-6-anisyl-9-
methoxy-2H-naphtho[1,2]pyran)2-DMS-C15

2-(4'-Pyrrolldinophenyl)-2-phenyl-5-hydroxymethyl-6-anisyl-9-methoxy-2H-
naphtho[1,2-b]pyran (1.50 g) was mixed with a toluene solution of bis-phthaloyl-
DMS-C15 (prepared according to Example 2, 22.8 g at 92% = 2.10 g at 100%),
toluene (20 ml), and dimethylaminopyridine (0.06 g). This was stirred for 2 minutes,
then DCCI (0.60 g = 1.10 mol/mol) was added. This was stirred for 45 minutes, at
which point TLC showed that some unreacted staring material remained. More of
the toluene solution of bis-phthaloyl-DMS-C15 (1.0 g of solution = 0.17g at 100%)
was added and the mixture stirred for a further 40 minutes. TLC indicated that
virtually no starting material remained, and so the mixture was cooled to 4°C for 45
minutes. This was filtered and the solids washed with toluene (5 ml).
The solution was used for flash chromatography, eluting with a mixture of ethyl
acetate and toluene. The best fractions were combined and evaporated down. The
blue tar was dissolved in acetone (20 ml), filtered and evaporated down again to give
2.2 g of a dark blue tar. Approximate yield = 69%.

2,2-Bis(4'-methoxyphenyl)-5-hydroxymethyl-6-methyl-2H-naptho[1,2-b]pyran (1.50
g) was mixed with the bis-carboxy-terminated siloxane DMS-B12 (2.10 g),
dimethylaminopyridine (0.07 g) and toluene (35 ml) at room temperature. This was
stirred for 2 minutes, then dicyclohexyl carbodiimide (0.80 g) was added and the
mixture stirred for 45 minutes. TLC indicated that all of the starting material had
been consumed. The mixture was cooled to 4°C for 45 minutes. This was filtered
and the solids washed with toluene (5 ml).
The solution was used for chromatography eluting with a mixture of petroleum ether
and ethyl acetate. The best fractions were combined and evaporated down to give
an orange-red oil: 1.3 g Approximate yield = 41 %.
Example 10: (2-(4'-pyrrolidinophenyl)-2-phenyl-5-succinylmethyl-6-anisyl-9-methoxy-
2H-naphtho[1,2-b]pyran)-DMS-C15-(3-phenyl-3-(4'-(succinylethoxy)phenyl)-6-
morpholino-3H-naphtho[2,1-b]pyran)

2-(4'-Pyrrolidlnophenyl)-2-phenyl-5-hydroxymethyl-6-anisyl-9-methoxy-2H-
naphtho[1,2-b]pyran (0.57 g = 0.001 mol, blue-colouring pyran) was mixed with 3-
phenyl-3-4'-hydroxyethoxyphenyl)-6-morpholino-3H-naptho[2,1-b]pyran (0.48 g =
0.001 mol, yellow-colouring pyran), a toluene solution of bis-succinyl-DMS-C15
(prepared according to Example 1, 30.0 g at 6.8% = 1.92 g at 100%) and
dlmethyiaminopyridine (0.05 g) and stirred for 10 minutes at room temperature until
all of the solid dissolved. Dicyclohexyl carbodiimide (0.90 g) was added, and the
mixture stirred for 2 hours at room temperature. TLC (5:1 toluene:EtOAc) Indicated
that the two starting material photochromics had been consumed. The mixture was
filtered to remove dicyclohexyl urea, which was washed with toluene (5 ml).
The solution was used for chromatography, editing with a mixture of toluene and
ethyl acetate. The first chromatography column removed most of the product with
the blue-colouring pyran at each end of the chain, and most of the product with the
yellow-colouring pyran at each end of the chain, with the remaining fractions
containing mostly the required "mixed" product. These fractions were combined,
evaporated down and chromatographed again. The best fractions were combined,
evaporated down, dissolved In acetone (20 ml), filtered, and evaporated down again
to give a viscous yellow-brown oil: 1.15 g. Approximate yield - 52%.
Example 11: (1,3-Dihydro-3,3-dimethyl-1-neopentyl-9'-succinyl-spiro[2H-indole
3H-naphtho[2,1-b][1,4]oxazine])2-DMS-A214

1,3-Dihydro-3,3-dimethyl-1 -neopentyl-9'-hydroxy-spiro[2H-indole-2,3'-3H-
naphtho[2,1-b][1,4]oxazine](0.47 g) was mixed with bis-Succinamido-DMS-A214
(12.5 g of 17.1% toluene solution - 2.14 g at 100%). Dimethylaminopyridine (0.03 g)
was added and the mixture stirred for 1 minute before addition of dicyclohexyl
carbodilmlde (0.29 g). The mixture was stirred for 45 minutes and TLC indicated a
non-polar product smear, and no spot for unreacted starting material.
The mixture was cooled in an ice bath for 45 minutes, then was filtered to remove
dicydohexyl urea. The solution was used for chromatography, eluting with ethyl
acetate and petroleum ether. The best fractions were combined and evaporated
down. The resulting green-brown oil was dissolved in acetone (30 ml), filtered and
then evaporated down again to give 1.8 g = 82%.
Example 12: (2,2-Bis(4'-methoxyphenyl)-5-succinylmethyl-6-methyl-2H-
naphtho[1,2-b]pyran)2-DMS-C15

2,2-Bis(4'-methoxyphenyl)-5-hydroxymethyl-6-methyl-2H-naphtho[1 ,2-b]pyran
was mixed with bis-succinyl-DMS-C15 (2.0 g), toluene (20 ml) and
dirnethylaminopyridine (0.05 g). This was stined for 2 minutes, then dicyclohexyl
carbodimide (0.51 g) was added. The mixture was stirred for 45 minutes and TLC (3:1
tolune:EtOAc) Indicated a main spot for polydialkylalloxane-bridged bi-photochrormic
product, with effectively no starting material remaining. The mixture was cooled in an
ice bath for 1 hour, then was filtered and the dicyclohexyl urea washed with toluene (5
ml).
The solution was used for chromatography, eluting with ethyl acetate and petroleum
ether. The best fractions were combined and evaporated down to give a dark orange
oil. This was dissolved in acetone (approx 40 ml) and filtered. The solution was
evaporated down to give: 2.1 g. Approximate yield 90%.
Testing for fade speed and intensity in acrylate-based lenses
Samples of the Examples 5 to 11 and the comparative compounds C1 to C6 were
dissolved in ethoxylated(4)bisphenol A dimethacrylate monomer at 250 ppm by weight,
and then cured at 200°C in lens moulds. The resulting lenses were allowed to cool and
stand for at least 24 hours before testing. The lenses were activated for 10 minutes in a
constant temperature water bath at 23°C, with a 50 Klux light source filtered to Air Mass
2 standard. The resulting induced absorption (Delta Abs) was measured at lambda max
of the compound. The light source was turned off and the resulting fade was monitored,
giving the time to fade to half the initial absorption (T1/2) and to one quarter of the initial
absorption (T3/4).
The parameter "Adjusted Delta Abs" allows for the molecular weight of the
polydialkylsiloxane-bridged bi-photochromic compound, the molecular weight of the
unbridged comparative compound and the number of photochromic units present This
is calculated as follows:
Adjusted Delta Abs = (Delta Abs Example compound x (Mol Wt example
compound)/(Mol Wt comparative compound))/Number of photochromic units
present in Example compound
For Example 10, which has a different photochromic unit at each end of the chain, the
absorptions from each photochromic unit are treated separately.
As can be seen from (he above table, the T1/2 values for the talled dimers are between
29.4% and 65.4% of the T1/2 values of the corresponding comparative compounds. The
T3/4 values of the tailed dimers show even greater improvements, being between 13.9%
and 40.0% of the T3/4 values of the corresponding comparative compounds.
The values for Adjusted Delta Abs indicate that the colour strengths of the
polydialkytslloxane-bridged bi-photochromic compound range from slightly weaker than
the comparative compounds (Example 11) to considerably stronger (Examples 6, 8, 9
and 10).
Heat stability testing
Samples of compounds of Example 7 and Example 12 and the corresponding
comparative compounds C4 and C2 were Incorporated at 250 ppm into polycarbonate,
and polystyrene at different processing temperatures using a Boy 35M injection
moulding machine, giving rectangular chips. The chips were measured for absorption
using the same equipment as was used for measuring lenses. The chips were
measured for yellowness index (as ASTM D1925) using a Datacolor Spectraflash
SF450 colour spectrometer.
(0 Example 12 and C2 incorporated at 250 ppm in polycarbonate, processed at 315°C
and 330°C.
WE CLAIM
1. A bi-photochromic molecule comprising two photochromic moleties linked via a
polydialkylslloxane (PDAS) oligomer, and having the general formula

wherein PC and PC', which may be the same or different, represent photochromic
moieties of general structure I to IV,

wherein R1 and R2 independently represent hydrogen, linear or branched C1-10 alkyl,
linear or branched C1-10 alkoxy, C1-10 hydroxyalkoxy, C1-10 alkoxy(C1-10)alkoxy, phenyl,
c1-10 alkoxyphenyl, halogen, C1-5 haloalkyl, C1-5 alkylamino, C1-5 dialkylamino,
arylamino, diarylamlno, aryl C1-5 alkylamino, or a cyclic amino group;
R3 represents hydrogen, linear or branched C1-10 alkyl, up to C20 cycloalkyl, up to C20
bicycloalkyl, linear or branched C2-10 alkenyl, linear or branched C1-10 alkoxy, C1-10
hydroxyalkyl, C1-10 alkoxy(C1-10)alkyl, C1-10 aminoalkyl, linear or branched C1-20
alkoxycarbonyl, carboxyl, halogen, aryloxycarbony), formyl, aoetyt or aroyl;
R4 represents, phenyl, C1-10 alkoxyphenyl, C1-10 dialkoxyphenyl, C1-10 alkylphenyl, C1-10
dialkylphenyl or one of the groups specified for R3;
or R3 and R4 together form a cyclic structure of the type

R5, R6, R7, R8, R9, R10, R14, R15, R16 are as defined for R1 and R2;
R11 represents linear or branched C1-20 alkyl, C3-20 cycloalkyl, C5-20 bicycloalkyl, (C1-5
alkyl)aryl, (C1-5 alkyl)cycloalkyl, (C1-5 alkyl) bicycloalkyl, C1-5 haloalkyl, C1-5 dihaloalkyl,
or C1-5 trihaloalkyl;
R12 and R13 represent C1-10 alkyl, C1-5 alkyl alkoxycarbonyl, or together form a C5-7
ring;
R17 and R18 represent linear or branched C1-10 alkyl, C1-10 hydroxyalkyl, or together
form a C5-7 ring;
L and L' which may be the same or different, represent a inking group.
2. A bi-photochromic molecule according to claim 1 wherein the polydialkylslloxane
(PDAS) oligomer Is of the formula:
wherein R19 is C1-10 alkyl, and n is an integer of from 4 to 75 inclusively.
3. A bi-photochromic molecule according to claim 1 or 2 wherein the-
polydialkylsiloxane oligomer is a polydimethylsiloxane oligomer.
4. A bi-photochromic molecule according to any preceding claim, wherein L and L'
represent a linking group of the form;

wherein Y is Independently oxygen or sulphur, R19 is hydrogen or C1-10 linear or
branched alkyl, R20 is C1-10 linear or branched alkyl, p is an integer from 1 to 15, and r
Is an integer from 0 to 10, and wherein Q is linear or branched C1-10 alkyl, C1-10 alkenyl
or 1,2-, 1,3, or 1,4-substituted aryl, or substituted heteroaryl.
5. A bi-photochromic molecule according to claim .3 or 4 wherein the
polydlaJkylslloxane oligomer is selected from DMS-B12, DMS-C15, DMS-C16, DMS-
C21, DMS-A11, DMS-A12, DMS-A15, DMs-A21, DMS-A211, DMS-A214, KF-6001,
KF-6002, KF-6003, KF-8010, X-22-160AS, X-22-162A, X-22-161A, X-22-161B, X-22-
162C, and Silaplane FM-44, the structures of which are shown below:
6. A bi-photochromic molecule according to claim 4 or 5 wherein each of PC and
PC' is either a naphtho [1, 2 - b] pyran of general structure 1 or a naphtho p, 1 - b]
pyran of general structure 2.
7. A bi-photochromic molecule according to claim 6 wherein both PC and PC' are a
naphtho [1,2-b] pyran of general structure 1.
8. A bi-photochromic molecule according to claim 6 wherein both PCand PC are a
naphtho [2,1 - b] pyran of general structure 2.
9. A bi-photochromic molecule according to claim 6 wherein one of PC and PC' is a
naphtho [1,2 - b] pyran of general structure 1, and the other is a naphtho [2,1 -b]
pyran of general structure 2.
10. A bi-photochromic molecule according to any one of claims 4 to 9 wherein Y
represents oxygen, Q represents -(CH2CH2)-, and R19 Is methyl.
11. A bi-photochromic molecule according to any one of claims 4 to 9 wherein Y
12. A bi-photochromic molecule according to claim 4 which is (1,3-dihydro-3,3-
dimethyl-1-neopentyl-6'-(4'-N-ethyl, N-(succinylethyl)anllino)spiro[2H-indole-2,3-3H-
naphtho[1,2-b][1,4]oxazine)2-DMS-C15, where DMS-C15 is as defined in claim 5.
13. A bi-photochromic molecule according to claim 4 which is (3-(4'-
methoxyphenyl),3-(4n-(succinylethoxy)phenyl)-6- 1 -b]pyran)2-
DMS-C16, where DMS-C16 is as defined in claim 5.
14 A bi-photochromic molecule according to claim 4 which is (3-(4'-
methoxyphenyl),3-(4"-(succinylethoxy)phenyl)-6-morpholino-3H-naphtho[2,1-b]pyran)2-
DMS-C15 where DMS-C15 is as defined in claim 5.
15. A bi-photochromic molecule according to claim 4 which is (1,3-dihydro-3,3-
dimethyl-1-isobutyl-9'-succidinyl-spiro[2H-indole-2,3'-3H-naphtho[2,1-b][1,4]oxazine)2-
DMS-C16 where DMS-C16 is as defined in claim 5.
16. A bi-photochromic molecule according to claim 4 which is (2-(4'-
pyrrolidinophenyl)-2-phenyl-5-phthaloylmethyl-6-anisyl-9-methoxy-2H-naptho[1,2
b]pyran)2-DMS-C15, where DMS-C15 is as defined in claim 5.
17. A bi-photochromic molecule according to claim 4 which is (2,2-bis(4,-
methoxyphenyyl)-5-hydroxymethyl-6-methyl-2H-naphtho[1,2-b]pyran)2-DMS-B12, where
DMS-B12 is as defined in claim 5.
18. A bi-photochromic molecule according to claim 4 which is (2-(4'-
pyrrolidinophenyl)-2-phenyl-5-suucinylmethyl-
b]pyran)-DMS-C15-(3-phenyl-3-(4'-(succinylethoxy)phenyl)-6-morpholino-3H-
naphtho[2,1-b]pyran), where DMS-C15 is as defined In claim 6.
19. A bi-photochromic molecule according to claim 4 which is (1,3-dihydro-3,3-
dimethyl-1 -neopentyl-9'-succinyl-spiro[2H-indole-2,3'-3H-naphtho[2,1-b][1,4]oxazine])2
DMS-A214, where DMS-A214 is as defined in claim 5.
20. A bi-photochromic molecule according to claim 4 which is (2,2-Bis(4'-
methoxyphenyl)-6-succinylmethyl-6-methyl-2H-naphtho[1,2-b]pyran)2-DMS-C15, where
DMS-C15 is as defined in claim 5.
21. An ophthalmic lane comprising a bi-photochromic molecule according to any
preceding claim.
22. A polymeric host material comprising a bl-photochromic molecule according to
any preceding claim.
23. A method of manufacturing a bi-photochromic molecule as defined in any one of
claims 1 to 20, comprising reacting a polydialkylsiloxane oligomer, linking group, and
one or more photochromic compounds to form the bi-photochromic molecule.
24. A method according to claim 23 wherein the linking group is attached to the
polydialkyisiloxane oligomer prior to reaction with the one or more photochromic
compounds.
25. A method according to claim 23 wherein the linking group is attached to the one
or more photochromic compounds prior to reaction with the polydialkylsiloxane
oligomer.

A bi-photochromic molecule comprises two photochromic moieties linked via
a polydialkylsiloxane oligomer. An ophthalmic lens comprises the bi-photochromic
molecule. A polymeric host material comprises the bi-photochromic
molecule.