ABSTRACT The luminescence properties of N 2 ,3‐etheno‐2‐aminopurine (N 2 ,3‐ε2APu) have been studied using steady‐state and time‐resolved spectroscopy. N 2 ,3‐ε2APu was embedded in poly(vinyl alcohol) (PVA) polymer, which is known for effective immobilization of dissolved fluorophore molecules. Upon UV excitation, N 2 ,3‐ε2APu shows a bright dark‐blue fluorescence with high fluorescence anisotropy, indicating efficient immobilization. Time‐resolved fluorescence measurements show a somewhat heterogeneous lifetime, requiring a lifetime distribution model to fit the data. The fit reveals a central lifetime of about 5 ns and a half‐width of the Lorentzian distribution of about 2 ns. We attribute this lifetime spread to the varying surroundings of fluorophore molecules in the polymer matrix. The N 2 ,3‐ε2APu‐doped PVA films exhibit strong room‐temperature phosphorescence (RTP) centered at 500 nm, with a lifetime of approximately 0.15 s. The excitation at 330 nm results in negative phosphorescence anisotropy. Interestingly, N 2 ,3‐ε2APu–doped PVA films can be directly excited to a triplet state at longer wavelengths (above 400 nm). This excitation results in a high positive phosphorescence anisotropy, reaching a value of 0.3 at about 450 nm. The ability to excite a molecule at longer wavelengths may find applications in the biomedical sciences, particularly in the study of photo‐chemically labile proteins and their complexes with emitting ligands.
Wielgus‐Kutrowska et al. (2026) studied this question.