Phasing chromism in poly-N-isopropylacrylamide gel analyzed using Förster energy transfer phenomena

Förster energy transfer phenomena were observed in the system of anthracene (AN) - tetracene (TE) and anthracene (AN) - perylene (PE) doped in poly- N -isopropylacrylamide (PNIPA) gel, which exhibits volume-phase transfer phenomena. In the shrunken state, the energy transfer occurred slightly. By contrast, in the swollen state, we observed that energy transfer occurred efficiently from AN to TE or PE. In general, the energy transfer process depends on the concentration and distance between the energy donor and acceptor. The actual concentration and distances between probe molecules were estimated using equations for the Förster energy transfer. The average distance changes were ca. 1 nm during swollen–shrunken processes. We were able to use Förster energy transfer phenomena for quantitative elucidation at the molecular level.