To verify the prediction results, NDI-polyVPy was first synthesized by ATRP. Due to the strong π-π stacking of the pyrene groups, the obtained polymer showed a low molecular weight (MW) and a broad distribution (Table and Figure ). Limited control of the polymerization was also observed for additional monomers (e.g., VBp, FluoMA, 1VNaph, and AntMAc). Despite that, the fluorescence of these polymers exhibited significant redshifted peaks (Figure ) reaching λem = 645 nm for NDI-polyVPy (Figure ), which is in reasonable agreement with the MLREM predicted results (670 nm, Table ). However, the strong π-π stacking of the pyrene groups resulted in a bimodal spectrum with strong emission from pyrene dimers , which made the fluorescence color unpredictable and the subsequent emission tuning challenging.