A Novel Viologen-Based Coordination Polymer with Multi -Stimulate Chromic Properties: Photochromism, Thermochromism, Chemochromism and Electrochromism
The increasing interests in chromic materials are due to the growing demand. However, most chromic materials exhibit color only in one stimulus, but there are multiple stimuli in nature. Therefore, the construction of multistimuli responsive chromic materials still faces great challenges. Herein, a new multi-responsive coordination polymer [Zn2(2,3-PDC)2CV•(H2O)2]•H2O (1) (2,3-PDC=2,3-pyridine dicarboxylic, CV = N,N′-4,4′-Bipyridiniodipropionate) has been successfully synthesized，which exhibits photochromism under a 300W Xenon lamp irradiation accompanied by an obvious color change from colorless to light blue. Meanwhile, compound 1 displays excellent thermochromic property with color change from colorless to light yellow when heated at 106 °C. The product of thermochromism named 1T, and loss of free water has improved photoresponsive property of 1T. Moreover, the compound can differentiable detects amines because of the electron-deficient nature of viologen. Finally, 1 has excellent electrochromic property and turns colorless to purple in the state of E=-3 V. In conclusion, compound 1 exhibits multi-chromic behaviors in response to the light, heat, amines and electricity, which is prominent in viologen-based coordination polymers.