Structural Studies of Curcuminoids. I. The Crystal Structure of Curcumin.

Abstract

The crystal and molecular structure of the food additive 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-hepatadien-3,5-dione(curcumin) was determined at 121.degree. K by X-ray crystallographic methods using 3368 reflections observed by counter methods. The crystals are monoclinic space group P2/n with unit cell dimensions (a = 20.028(3) .ANG., b = 7.073(1) .ANG., c = 12.609(2) .ANG., .beta. = 94.94(1).degree.. The structure was refined to a conventional R-factor of 0.055. Estimated SD are 3 .times. 10-3 .ANG. 0.2.degree. in interatomic distances and angles, respectively, when H atoms are not involved.