Photostable mimics of macular pigment
Described are visible light absorbing compounds. The compounds have a visible light absorption maximum between 430 and 480 nm and a full width half maximum (FWHM) at the visible light absorption maximum of at least 35 nm and up to 100 nanometers, wherein the compounds are photostable. The compounds substantially mimic the visible light absorbance properties of macular pigment while remaining photostable. The compounds may be used in a variety of articles, including ophthalmic devices.
1. A compound comprising a chromophore, the chromophore having a substructure of formula I:
wherein EWG at each occurrence is independently an electron withdrawing group, the compound having a visible light absorption maximum between 430 and 480 nm and a full width half maximum (FWHM) at the visible light absorption maximum of at least 35 nm and up to 100 nanometers, wherein the compound is photostable.
2. The compound of claim 1 wherein EWG at each occurrence is independently cyano, amide, ester, keto, or aldehyde.
3. The compound of claim 1 wherein EWG at each occurrence is cyano.
4. The compound of claim 1 that is of formula II:
wherein EWG at each occurrence is independently an electron withdrawing group; n is 1, 2, or 3; and R 1 is at each occurrence is independently H, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, C 1 -C 6 thioalkyl, C 3 -C 7 cycloalkyl, aryl, halo, hydroxy, amino, NR 3 R 4 , benzyl, SO 3 H, or SO 3 M (M is a monovalent cation, such as sodium or potassium), or —Y—P g , wherein R 3 and R 4 are independently H or C 1 -C 6 alkyl, Y is a linking group; and P g is a polymerizable group.
5. A compound according to claim 1 that is:
2-((9-(dicyanomethylene)-9H-thioxanthen-2-yl)oxy)ethyl methacrylate.
6. The compound of claim 1 wherein the visible light absorbance maximum is between 440 nm and 470 nm.
7. The compound of claim 1 wherein the FWHM at the visible light absorption maximum is at least 40 nm and up to 95 nm.
8. The compound of claim 1 wherein photostability comprises a loss of absorbance at the visible light absorption maximum of no more than 20 percent.
9. The compound of claim 1 , wherein the compound is more photostable than macular pigment.
10. An ophthalmic device comprising a compound according to claim 1 .
11. A contact lens or intraocular lens that is a polymerization reaction product of a reactive mixture comprising: a monomer suitable for making the ophthalmic device; and (b) a compound according to claim 1 .
12. A spectacle or sunglass lens comprising (a) a mineral material or an organic material or combination thereof, and (b) a compound according to claim 1 .
13. An optical device comprising a compound according to claim 4 that is: 2-(9H-thioxanthen-9-ylidene)malononitrile; or
2-((9-(dicyanomethylene)-9H-thioxanthen-2-yl)oxy)ethyl methacrylate.