Swallow tail bay-substituted novel perylene bisimides: Synthesis, characterization, photophysical and electrochemical properties and DFT studies

[Display omitted] •Swallow tail bay-substituted novel perylene bisimides have been synthesized.•Such a long and swallow type substituent at the bay position is first time reported.•Novel perylene bisimides have reduced HOMO–LUMO energy gaps.•The products can be exploited as an off-on fluorescence probes.•Novel products are potential candidates for electron transport materials. Novel, one bay-substituted perylene bisanhydride (6) and two bay-substituted perylene bisimides (7, 10) have been successfully synthesized with a large and swallow tail type, 2-decyl-1-tetradecanoyl substituents at the bay area (1 and 7 positions). The non-bay-substituted perylene bisimides with the same N-substituents were prepared as model compounds (3, 9) for comparison. Absorption and fluorescence, electrochemical, spectroelectrochemical, morphological properties of the compounds were investigated, and then, density functional theory (DFT) simulations were conducted. The compounds 6, 7 and 10 have shown J-aggregated featureless, very broad absorbance through the UV–vis-NIR region with a strong fluorescence quenching attributed to efficient intramolecular electron transfer from electron donor 2-decyl-1-tetradecanoyl substituent to PDI acceptor and scaffolds allow π–π intermolecular interactions, induced molecular aggregation. The absolute positions of LUMO and HOMO values for 3, 9, 6, 7 and 10 in solutions were −3.91/−6.09 eV, −3.93/−6.08 eV, −4.02/−5.90 eV, −4.02/−5.91 eV and −4.02/−5.97 eV, respectively. The onset reduction potential of compounds 6, 7 and 10 are lower than those of compounds 3 and 9. Similarly, the onset oxidation potential values of the compounds 6, 7 and 10 are smaller than those of the non-bay-substituted perylene dyes 3 and 9. The synthesized compounds (3 with 7; 9 with 10) can be exploited as an off-on fluorescence probes for photonic applications.