Synthesis, crystal structure, spectroscopic and theoretical studies of a new fluorescent heterocyclic compound containing diketopyrrolopyrrole (DPP) moiety

Abstract

A new diketopyrrolopyrrole (DPP) derived fluorescent heterocyclic compound, DPP-BA, has been synthesized and characterized by SXRD, FL spectroscopy and computational methods. SXRD studies indicate that hydrogen bonding and π-π stacking interactions are crucial for the assembly of its 3D supramolecular structure. The weak interactions within the compound were studied using IRI and NCI methods, while the planarity of DPP-BA in the DPP-BA-DMSO was quantified using MPP and SDP descriptors. The MEP map highlighted the nucleophilic and electrostatic regions in DPP-BA. In addition, Hirshfeld surface analysis and RESP atomic charges were used to visualize the interactions and to delineate the charge distribution within DPP-BA. The interaction energy and 3D energy frameworks facilitated an intuitive examination and understanding of the molecular arrangement and stability within the crystal. A comparison between the experimental and computational FL spectra was made using a range of DFT functionals, with the PBE0 functional providing the most accurate results. Analyses of the HOMO-LUMO and hole-electron distributions have shed light on the molecular electronic structure, thereby deepening our understanding of the electronic excitation processes within the molecule.