Investigation of tautomeric structures of thionin by satellite holes: matrix dependence

We have applied the satellite hole spectroscopy to study the tautomeric structures of thionin dye in glycerol:water glass. Slightly different frequencies (∼15 cm−1) are observed for several satellite holes of thionin upon tuning the burning wavelength, implying that two conformational structures exist. However, only one set of satellite holes occurring in the spectrum of thionin doped in polyvinyl butyral film allows us to investigate the tautomeric structures of thionin in different matrices. Our results suggest that the appearance of two tautomeric structures of thionin in glycerol:water glass is due to the proton exchange between different sites of thionin and the matrix through intermolecular hydrogen bond.