UV-visible spectral analysis for the characterization of the titanium(iv)-4-(2-pyridylazo)resorcinol complex as a reagent for determining hydrogen peroxide

Titanium(iv)-4-(2-pyridylazo)resorcinol (Ti-PAR) has been effectively used for the determination of hydrogen peroxide. In 1985, Takamura et al. proposed its molecular structure showing the absorption peak at 508 nm. However the results obtained from computational calculations showed the absorption peak at 472 nm. Based on the UV-visible spectral simulations and crystal structures of metal-PAR registered in the Cambridge Structural Database (CSD), the structure of Ti-PAR-H₂O₂ showing the absorption peak at 508 nm was determined. Then the reaction profiles and the reaction mechanism were clarified.