Zinc oxide complexes
Disclosed are compounds and methods of making said compounds comprising a zinc oxide molecule chemically bound to one or more molecules having an acidic hydrogen, such as an organic acid. The invention also provides compositions comprising such compounds and methods of preparing such compounds. The compounds of the invention may be provided in, for example, topical skin formulations, pharmaceutical compositions, or delivery systems for active ingredients.
1. A method for covalently binding a zinc molecule to a carboxylic acid molecule, the method comprising mixing the zinc molecule and the carboxylic acid molecule in a liquid comprising at least about 80% by weight of alcohol, wherein the zinc molecule covalently binds to the carboxylic acid molecule to form a zinc molecule-carboxylic acid molecule complex.
2. The method of claim 1 , wherein the zinc molecule is zinc oxide.
3. The method of claim 1 , wherein the liquid comprises at least about 90% by weight of alcohol.
4. The method of claim 3 , wherein the liquid is anhydrous.
5. The method of claim 1 , wherein the alcohol includes ethanol, methanol, or isopropanol.
6. The method of claim 5 , wherein the alcohol includes ethanol.
7. The method of claim 1 , wherein the zinc molecule and the carboxylic acid molecule are mixed in about a 1:2 to about a 2:1 molar ratio of zinc molecules to carboxylic acid molecules.
8. The method of claim 1 , wherein the molecules are mixed for about 5 to about 60 days.
9. The method of claim 1 , wherein the mixing occurs in a sealed container.
10. The method of claim 1 , further comprising purifying the zinc molecule-carboxylic acid molecule complex by filtering, evaporation, rotary evaporation, drying, spray drying, centrifugation, or precipitation.
11. The method of claim 1 , wherein the zinc molecule-carboxylic acid molecule complex is in particulate or crystalline form.
12. The method of claim 1 , wherein zinc molecule-carboxylic acid molecule complex dissociates into the zinc molecule and the carboxylic acid molecule when placed in an aqueous composition.
13. The method of claim 1 , wherein the zinc molecule is zinc oxide and the carboxylic acid molecule is lactic acid, and wherein the zinc molecule-carboxylic acid molecule complex has the following structure:
wherein R 1 is hydrogen or zinc oxide, R 2 is hydrogen or zinc oxide, and at least one of R 1 and R 2 is zinc oxide.
14. The method of claim 1 , wherein the zinc molecule is zinc oxide and the carboxylic acid molecule is lactic acid, and wherein the zinc molecule-carboxylic acid molecule complex has the following structure:
15. The method of claim 1 , wherein the zinc molecule is zinc oxide and the carboxylic acid molecule is salicylic acid, and wherein the zinc molecule-carboxylic acid molecule complex has the following structure:
wherein R 1 is hydrogen or zinc oxide, R 2 is hydrogen or zinc oxide, and at least one of R 1 and R 2 is zinc oxide.
16. The method of claim 1 , wherein the zinc molecule is zinc oxide and the carboxylic acid molecule is glycolic acid.
17. The method of claim 1 , wherein the zinc molecule is zinc oxide and the carboxylic acid molecule is hydroxyproline.
18. The method of claim 1 , wherein the zinc molecule is zinc oxide and the carboxylic acid molecule is azelaic acid.
19. The method of claim 1 , wherein the zinc molecule is zinc oxide and the carboxylic acid molecule is oleic acid.
20. The method of claim 1 , wherein the zinc molecule is zinc oxide and the carboxylic acid molecule is citric acid.
21. The method of claim 1 , wherein the zinc molecule is zinc oxide and the carboxylic acid molecule is malic acid.