Steady state and time-resolved spectroscopic studies of 7-hydroxyquinoline in various polymeric matrices

The photophysical behavior of 7-hydroxyquinoline (7HQ) is studied in four polymer matrices, viz. polymethyl methacrylate (PMMA), cellulose acetate (CA), polyvinyl alcohol (PVA) and Nafion-117, at ambient temperature using both steady state and time-domain measurements. The study reveals both ground as well as excited state tautomerization in the case of PVA. In PMMA and CA, the intermolecular hydrogen bond to the host polymer results in proton transfer. Edge excitation red shift (EERS) and excitation and emission wavelength dependent decays are observed for normal emission in PMMA and CA matrices. These results are attributed to the trapping of a normal molecule in different geometries. In Nafion, the results show the presence of 7HQ cationic species trapped in the polymer.