Abstract: A single crystal of curcumin was obtained from the turmeric of Shuangliu County of Sichuan Province, China by usingseparation and purification technique of solvent extraction, column chromatography and recrystallization etc. The molecular andcrystal structure of curcumin were identified by IR, UV, MS, 1HNMR, 13CNMR and X-ray single crystal diffraction. Curcumincrystal belongs to monoclinic with P2/n space group. The unit cell data are: a = 1.2695(3)nm, b = 0.72075(16) nm, c=1.9960(4) nm,α=90°β=95.098°γ=90°. The molecule of curcumin damonstrates a nonlinear keto-enol tautomerism structure andthere are four curcumin molecules in each cell.

Key words: curcumin, turmeric, separation and purification, characterization, molecular structure