Exploring the Unusual Optical Rotation and Photophysical Properties of a Meisenheimer Complex

Here we report the occurrence of an unusual optical activity from the solution of a Meisenheimer complex 1 derived from picric acid and N,N-dicyclohexylcarbodiimide. 1 shows dynamic optical rotation which always changes with time and never settles down to zero permanently. However, the crystal structure analysis of compound 1, possessing two trisubstituted chiral nitrogens, confirmed the presence of two enantiomers as a racemic mixture. Despite being a racemic mixture in the solid phase, the dichloromethane solution of 1 showed detectable optical activity after some time interval. The reason behind this observation must be the varying percentage of both enantiomers via absorption of thermal energy mediated interconversion of enantiomers. Apart from the optical activity, 1 shows bright luminescence in the solid state. We have demonstrated the utility of 1 as a dye for creating luminescent fabric, luminescent rubber sheet, and road sign drawing which might be useful for mining, excavation, and military applications.