Terminal modulation of asymmetrical D−A−D−π furan-containing diketopyrrolopyrrole chromophores for intramolecular charge transfer properties.

Three furan-based diketopyrrolopyrrole (DPP) chromophores have the same D−A−D structure and various tetraphenylethylene, pyrene and dibenzothiophene tails with intramolecular donor-acceptor spacers. Different π -extended chromophores show different intramolecular charge transfer properties. Furthermore, according to UV–Vis and emission spectral studies, dyes F1 – F3 exhibit aggregation-caused quenching (ACQ) in tetrahydrofuran aqueous solutions. Interestingly, dyes F1 and F3 show aggregation-induced emission (AIE) behaviors in DMSO/toluene mixtures, while pyrene-functionalized DPP dye F2 still has ACQ character. It is noted that a contour plot is firstly carried out to be better understood the AIE and ACQ phenomena. Moreover, the energy gaps for the methyl counterpart of dyes F1 – F3 are 2.30, 2.29 and 2.35 eV, respectively, which indicate that introducing asymmetrical D−A−D− π furan-containing DPP structures can reduce the HOMO–LUMO gaps easily and rapidly. In addition, a computational and experimental investigation has been provided, including theoretical and optical energy gaps for full comparison. Image 1 • A contour plot is firstly demonstrated to be understood AIE and ACQ phenomena. • Three asymmetrical D−A−D− π furan-based DPPs have been constructed. • The fluorescence quantum yield of dye F1 is 49%, showing the strong peaks. • A computational and experimental investigation has been provided. [ABSTRACT FROM AUTHOR]