Analysis of Solid-State Emission of the <i>p</i>-Bis(2,2-dicyanovinyl)benzene Analogue through Combined X-ray, Synchrotron, and Microcrystal Electron Diffraction

Organic solid-state emissive materials have recently gained significant attention for their optoelectronic properties, leading to the design of various optical devices and sensors. Achieving highly efficient solid-state fluorescence is challenging. Moreover, understanding a structure–property relationship is crucial for designing and improvising solid-state emitters. Herein, we have synthesized different compounds having p-bis(2,2-dicyanovinyl)benzene as a core structure and varied the substitution position and linker length. However, after several batches of failed crystallization for a few analogues, microcrystal electron diffraction (MicroED) and synchrotron were used for structure elucidation that helps in better understanding the solid-state emission behavior of the synthesized organic fluorophores. During the analysis, MicroED helps us to characterize a novel polymorph of 4,4′-biphenyldicarboxaldehyde (starting material for BP-1 and BP-2) and an intermediate product of BP-2, i.e., monoaldehyde derivative, from a powdered mixture. Based on the structural analysis, it was observed that π–π interactions and C–H···O/N interactions play a dominant role in tuning the photophysical properties of these organic fluorophores.