Alkyl length dependent reversible mechanofluorochromism of phenothiazine derivatives functionalized with formyl group

In this study, a series of D-A typed phenothiazine derivatives functionalized by formyl group (PCAn, n = 1, 2, 4 and 6) with different lengths of N-alkyl chains have been designed and synthesized to systematically investigate the effect of chain length on their solid-state fluorescence properties. PCAn solids exhibit not only naked-eye visible and reversible mechanochromic behavior, but chain length-dependent emission properties. PCA1, PCA2 and PCA4 exhibited mechanochromic behaviors, XRD and DSC revealed that the transformation between crystalline and amorphous states upon various external stimuli is responsible for the MFC behavior.243