Selective electrochemical molecular recognition of benzenediol isomers using molecularly imprinted TiO2 film electrodes

In this paper, selective recognition of benzenediol isomers was studied using molecularly imprinted TiO2 film formed on a graphitic electrode. The imprinting process was investigated in detail using IR. The electrode process for p-hydroquinone follows a ErCr mechanism. The cavities formed by p-phthalic acid have good selectivity toward p-hydroquinone among the isomers. The complex ratio between p-hydroquinone and binding sites was estimated to be 1:2 with an apparent equilibrium constant of 2.98×10^6 l2 mol^-2. For o-hydroquinone and m-benzenediol, the ratio decreased to 1:1 with an apparent equilibrium constant of 1.20×10^3 and 1.35×10^3 l mol^-1. The apparent complexing ratio and equilibrium constants could shed some insight on the nature of isomeric selectivity of the recognition sites with respect to different isomers of benzenediol. The cavities designed by o-phthalic acid present good selectivity toward o-hydroquinone.