Degradation of eosin Y complexes during natural ageing: Spectroscopic markers and parameters that affect their stability

Eosin Y complexes find applications in several fields, including dye sensitized solar cells, medical therapies or artistic pigments. However, their lack of stability, leading to fading upon light exposure, hinders optimal performance. This study focuses on the natural ageing of aluminum (Eo-Al) and lead (Eo-Pb) eosin Y complexes. The monitoring by Fourier transform infrared (FTIR) and Raman spectroscopy revealed the spectral markers and molecular changes during these processes. These findings have the potential to broaden the applicability of eosin Y complexes, whether used as pigments in an artistic context or in any other field where mid- to long-term stability is crucial.