Responsive chromogenic materials have attracted increasing interest among researchers; however, up until now, few materials have exhibited multifunctional chromogenic properties. The coordination polymers (CPs) provide intriguing platforms to design and construct multifunctional materials. Here, a multifunctional photo/electricity responsive CP named Zn-Oxv, which is based on the "extended viologen" (ExV) ligand, was synthesized. The Zn-Oxv exhibited reversible photochromism, photomodulated fluorescence, electrochromism and electrofluorochromism. Furthermore, we prepared Zn-Oxv thin films and investigated electrochromic (EC) properties of viologen-based CPs for the first time. Zn-Oxv thin films showed excellent EC performance with a rapid switching speed (both coloring and bleaching time within 1 s), high coloration efficiency (102.9 cm2/C) and transmittance change (exceeding 40%). Notably, the Zn-Oxv is by far the fastest CP EC material based on redox-active ligands ever reported, indicating that the viologen-based CPs could open up a new field of materials for EC applications. Therefore, viologen-based CPs are attractive candidates for the design of novel multi-responsive chromogenic materials and EC materials that could promise creative applications in intelligent technology, dynamic displays and smart sensors.
Keywords: coordination polymer; electrochromism; electrofluorochromism; multi−responsive; photochromism; photomodulated fluorescence.