The effective transfer of electrons has been demonstrated as a viable method for the construction of multistimuli-responsive materials. Herein, two new pyridinium ion-based complexes have been successfully designed and synthesized by using the 5-(1-(3-carboxybenzyl)pyridin-4-yl)isophthalic acid (H3cbby) ligand and transition metals Cd(II)/Mn(II). Two complexes exhibit reversible color changes under light (365 nm) and electrical stimulation, which are attributed to electron transfer. In particular, complex 1 is distinguished by its eutectic structure, a property that sets it apart from other photochromic complexes. These two components can be utilized as electron-rich groups to transfer electrons or as electron-deficient groups to accept electrons. Furthermore, 1 can also selectively detect Cr2O72− and significantly improve the degradation of tetracycline (TC). More significantly, a visual photochromic film based on 1 and 2 was designed to detect UV light by color change. They also are widely used in inkless printing, information transmission and two-dimensional code anti-counterfeiting.
