Subtle Molecular Engineering around Flavin core for Stimuli‐Responsive Solid‐State Luminophore

The present manuscript discusses the design, synthesis, and stimuli-responsive solid-state properties of two novel flavin analogues, Phenyl Flavin (PhFl) and Pyridinyl Flavin (PyFl), featuring covalently linked phenyl and pyridinyl rings to isoalloxazine. Stimuli-responsive properties of PhFl and PyFl were examined, where PyFl displayed more pronounced and reversible emissive behavior in the solid state in response to external stimuli. To elucidate the mechanism underlying the mode for switching behavior, single crystal- and powder-X-ray diffraction, as well as differential scanning calorimetry studies, were performed. Furthermore, a simple dip-in method was used to demonstrate its usage as ink free rewritable material.