The photo- and electrophysical properties of curcumin in aqueous solution

An investigation of the photo- and electrophysical properties of curcumin (1,7-bis[4-hydroxy-3-methoxyphenyl]-1,6-heptadiene-3,5-dione) revealed well-defined color changes upon the addition of Hg2+ or OH−. Curcumin exhibited high selectivity for Hg2+ ions, as compared with Cu2+, Fe2+, Fe3+, Zn2+, Na+ and Ni2+ ions in DMSO/H2O (5:1, v/v) which was attributed to the formation of a 4:1 Hg2+–curcumin coordination complex. Spectral responses at λmax = 434 nm revealed that curcumin can function as a NOR logic gate with OH− and Hg2+ as input variables. The electrochromic properties of curcumin were studied using an ITO/curcumin-Bu4NClO4/ITO cell. The electrochromic cell colored red at 3 V, but changed to yellow in open-circuit condition.