Mechanochromic studies of new cyanopyridone based fluorescent conjugated molecules

In the recent time, mechanochromic investigations of new organic luminescent compounds have attracted the attention of research community due their academic importance and commercial applications. However, among the reported mechanochromic organic compounds in the literature, the pyridine based derivatives possessing emission properties are quite rarely recognized. The present work deals with the mechanochromic luminescent (MCL) investigations of four conjugated cyanopyridones (M1-4) in their solid state. From the fluorescence emission spectra, it was observed that compounds (M1-4) exhibited the different emission wavelengths. Further, their powder X-ray diffraction (XRD) spectra showed the distinctly different diffraction patterns for both as-prepared and ground samples, in particularly, M1 and M3 samples exhibited a crystalline to partial amorphous phase transition, while M2 showed a crystalline to amorphous phase transition and M4 exhibited a crystalline to crystalline phase transition. All these results further supports that the dissimilar arrangement of molecular packing is the main cause for the perceived solid state emission phenomenon.