In this study, we conducted a comprehensive study on metastable DAAN radicals with various substituents, that are generated by polymeric mechanochemical reactions. We discovered a significant change in fluorescence wavelength depending on the nature and location of these substituents, which is a phenomenon that has not previously been observed for the extensively studied fluorescent triaryl methyl radicals. The amount of generated DAAN radicals evaluated by EPR is greater for smaller BDE values and higher sC-H energy levels when the substituent are located exclusively at the para-position. When a substituent is introduced at the ortho-position, the thermodynamic stability of the radical is reduced, albeit that the kinetic effect of the steric bulk of the radical center is outweighed, and the amount of DAAN radicals increases. We thus expect that the present study will inspire the development of unexplored fluorescent radicals and their applications in advanced chemosensors, bioimaging, and organic light-emitting diodes.