Ferrous Hemin Oxidation by Organic Halides at Nanocrystalline TiO2 Interfaces

The photoreduction of organic halides CCl 4, CBr 4, and CHCl 3 and chloroacetanilides alachlor (2-chloro-2‘,6‘-diethyl- N -(methoxymethyl)acetanilide) and propachlor (2-chloro- N -isopropylacetanilide) by iron(III) protoporphyrin IX chloride (hemin) in fluid solution and anchored to a mesoporous nanocrystalline (anatase) TiO 2 thin film immersed in solution is reported. Band gap illumination resulted in the reduction of Fe(III) to Fe(II) when the films were immersed in acidic water (pH 4) and in dimethyl sulfoxide with photochemical quantum yields of (2.0 ± 0.3) × 10 -3 and (1.6 ± 0.3) × 10 -2, respectively. The ferrous hemes were reacted with organic halides in the dark. Second-order kinetic rate constants were quantified and were found to be larger than the corresponding rate constants for ferrous hemin in fluid solution.