Method of quenching electronic excitation of chromophore-containing organic molecules in photoactive compositions
View Patent ↗The photostabilizing electronic excited state energy—particularly singlet state energy from a UV-absorbing molecule has been found to be readily transferred to (accepted by) α-cyanodiphenylacrylate compounds of formulas (I) and (V) having an alkoxy radical preferably in the four (para) position (hereinafter methoxycrylenes) on one or both of the phenyl rings: wherein at least one of R 1 and R 2 is a straight or branched chain C 1 -C 12 alkoxy radical, preferably C 1 -C 8 , more preferably C 1 -C 4 , and most preferably methoxy, and any non-alkoxy radical R 1 or R 2 is hydrogen; and R 3 is a straight or branched chain C 1 -C 24 alkyl radical, preferably C 12 -C 24 , more preferably C 20 ; wherein A and B are the same or different and are selected from the group consisting of oxygen, amino and sulfur; R 1 and R 3 are the same or different and are selected from the group consisting of C 1 -C 30 alkyl, C 2 -C 30 alkylene, C 2 -C 30 alkyne, C 3 -C 8 cycloalkyl, C 1 -C 30 substituted alkylene, C 2 -C 30 substituted alkyne, aryl, substituted aryl, heteroaryl, heterocycloalkyl, substituted heteroaryl and substituted heterocycloalkyl; R 2 is selected from the group consisting of C 1 -C 30 alkyl, C 2 -C 30 alkylene, C 2 C 30 alkyne, C 3 -C 8 cycloalkyl, C 1 -C 30 substituted alkyl, C 3 -C 8 substituted cycloalkyl, C 1 -C 30 substituted alkylene, C 2 -C 30 substituted alkyne; R 4 , R 5 , R 6 and R 7 are the same or different and are selected from the group consisting of C 1 -C 30 alkoxy straight chain or branched and a, b, c and d are each either 0 or 1, and a, b, c and d add up to 1, 2, 3, or 4.
1. A method of increasing the UV absorbing life of a sunscreen composition containing (a) a dibenzoylmethane derivative that reaches a singlet excited state or fluoresces when exposed to UV radiation and (b) a cinnamate ester comprising adding a compound of formula (I) in an amount effective to quench the singlet excited state energy from the dibenzoylmethane derivative and transfer the singlet excited state energy from the dibenzoylmethane derivative to the compound of formula (I) thereby returning the dibenzoylmethane derivative to its ground state so that the dibenzoylmethane derivative can absorb more photons from ultraviolet light before it undergoes a photochemical reaction destructive to its UV-absorbing capability thereby photostabilizing (a) and (b)
wherein one of R 1 and R 2 is a straight or branched chain C 1 -C 30 alkoxy radical, and the non-alkoxy R 1 or R 2 is hydrogen; and R 3 is a straight or branched chain C 1 -C 30 alkyl radical.
2. The method of claim 1 , wherein the cinnamate ester is an ester of an alkoxycinnamate.
3. The method of claim 2 , wherein the alkoxycinnamate ester is a methoxycinnamate ester.
4. The method of claim 3 , wherein the cinnamate ester is selected from the group consisting of 2-ethyihexyl p-methoxycinnamate, isoamyl p-methoxycinnamate, and a combination thereof.
5. The method of claim 4 , wherein the cinnamate ester is 2-ethylhexyl p-methoxycinnamate.
6. The method of claim 5 , wherein the dibenzoylmethane derivative comprises butylmethoxy dibenzoylmethane.
7. The method of claim 1 , wherein R 1 or R 2 of formula (I) is a methoxy radical.
8. The method of claim 7 , wherein the compound of formula (I) is added in an amount sufficient to absorb the singlet excited state energy of both the dibenzoylmethane derivative and the cinnamate ester when both are subjected to UV radiation.
9. The method of claim 1 , wherein the compound of formula (I) is present in an amount in the weight range of 0.1% to 20%, based on the total weight of the composition.
10. The method of claim 9 , wherein the compound of formula (I) is present in an amount in the weight range of 0.1% to 10%, based on the total weight of the composition.
11. The method of claim 10 , wherein the compound of formula (I) is present in an amount in the weight range of 3% to 8%, based on the total weight of the composition.
12. The method of claim 10 , wherein the compound of formula (I) is present in an amount in the weight range of 0.1% to 5%, based on the total weight of the composition.