The PL behavior of DMAC-py-TRZ was also characterized in polyTHF, a viscous solvent where conformational relaxation is hindered. Interestingly, two emission bands are observed in this viscous medium (Figure ). The first emission band at 410 nm is similar to the one observed in the glassy matrix at 77 K while the second emission at 600 nm is similar to the emission observed in DMSO at room temperature. Apparently, at ambient temperature, the excited state relaxation, fully hindered in glassy matrices at low temperature, is only partially hindered in the viscous polyTHF. Accordingly, the presence of the two emission bands is evidence of the simultaneous presence of the unrelaxed (bent) emissive species (as in the glassy matrix) as well as of relaxed (orthogonal) species (as in the liquid solvent).