Estimation of Singlet Oxygen Quantum Yield Using Novel Green‐Absorbing Baird‐type Aromatic Photosensitizers<sup>†</sup>
Jayla Morgan, Young Ju Yun, Anoklase J.‐L. Ayitou
Abstract
Abstract We report two new organic green‐absorbing singlet oxygen ( 1 O 2 ) photosensitizers: Quinoidal naphthyl thioamide ( QDM ) and bis ‐iodol‐dipyrrolonaphthyridine‐dione ( I 2 – DPND ), with triplet energies of 40.8 and 47.5 kcal mol −1 (at 77 K in a glassy matrix) , respectively. The UV–vis absorption and emission characteristics of QDM and I 2 – DPND are similar to other commercially available organic 1 O 2 photosensitizers such as Rose Bengal, which was used as standard/reference to estimate the 1 O 2 quantum yield (Φ ∆ ) of the chromophores under study. Using 9,10‐diphenylanthracene ( DPA ) as an 1 O 2 quencher, we estimated the Φ ∆ ≈ 67–85% for QDM and Φ ∆ ≈ 25–32% for I 2 – DPND . The discrepancy in the Φ ∆ values could be explained by the apparent photo‐decomposition of the later dye. Nevertheless, the high Φ ∆ value for QDM is unprecedented, as this chromophore exhibits relatively low structural complexity and could further be derivatized to create novel photodynamic agents.