Mercury ion induced activation of the C–O bond in a photo-responsive spiropyran

The conversion of 7-hydroxy-BIPS in solution from colourless form to colored form can be induced using both light and the addition of Hg2+ ion. No significant color change is observed when other ions (Ca2+, Mg2+, Zn2+, Cd2+, Co2+, Cu2+, Mn2+, Fe2+, Ni2+, Pb2+, K+, Na+, Li+, and Ag+) were used.