The enthralling effect of packing on the light emission of pyridazinone based luminophore: Crystallographic, electronic absorption and computational studies.

The present study unfolds the synthesis and characterization of a new butylidine linked hetero dimer of pyridazinone (PNP). The crystal structure analysis of PNP reveals that it exhibited infinite 1D linear chains connected through C-H∙∙∙O interaction and interlayer connectivity was supported by the unconventional orthogonal dipolar interaction via nitro-aromatic (ONO2···π(C)Ar). These interactions are also described using DFT calculations and are potentially studied. Here we discuss the influence of crystal structure on the photophysical properties of a new solid state emitter containing brick layer packing. Furthermore, we conducted detailed exploration of the intermolecular interactions that maintain the crystal packing of the structure by employing the Hirshfeld surface analysis and its corresponding two-dimensional fingerprint plots revealing that the C-H∙∙∙O interaction mainly stabilized the crystal structure. Time-dependent density functional theory (TDDFT) studies and observed nitro aromatic interactions (ONO2∙∙∙(C)Ar) in the crystal helped to explain the electronic behaviour of PNP. The validity of the computations is supported by a good agreement between the estimated and experimental values of the excitation energy transfer. Furthermore, we conducted detailed research on the Hirshfeld surface analysis and the intermolecular interactions that stabilize the crystal packing using their corresponding two-dimensional fingerprint plot. Some standard thermodynamical parameters such as specific heat, entropy and free energy have also been computed. In addition to this, the variation of specific heat with temperature has been explored.