The quenching rate constants for NHPI and DIPEA are reported in Table . The efficiency of quenching of the HE fluorescence was calculated as 35% for NHPI and 0.40% for DIPEA, indicating that NHPI is the predominant quencher of the emission of HE. To further probe the possible mechanistic pathways of the reaction, the UV-Vis absorption spectrum and 1 H NMR spectrum of pDTCz-DPmS were each monitored upon addition of increasing equivalents of HE (Figure and S10, respectively). In the former, the absorption spectrum of HE was simply superimposed onto that of pDTCz-DPmS while in the 1 H NMR spectrum, no discernible changes could be determined. These experiments imply that in the ground state, no species is formed between pDTCz-DPmS and HE, ruling out the possibility of an EDA complex. We also evaluated whether an EDA complex forms between NHPI and HE. After mixing the two compounds no significant changes are observed in the UV-Vis absorption spectra (Figure ) and no new bands related to the EDA complex were observed.