bias. This phenomenon of bias induced color change, called electrochromism, was first observed in the nineteenth century\[1\]. Electrochromism has been studied in recent times because of many applications in science and technology.\[2–-5\] Detailed reviews are available in the literature about electrochromic effects from different chemicals and materials.\[2,6\] Electrochromic effects are observed as a result of redox processes either in a solid-state device or in an electrochemical cell. Origin of this property lies in the fact that many materials show multiple redox states with different optical properties (e.g. absorption spectra). Different electrochromic materials are used as the active material, which could be in the form of metal oxide like tungsten oxide\[7\] or a cationic molecule.\[8–-10\]

One particularly intriguing class of materials in this context is bipyridinium species, which are formed upon N,N-diquaternization of 4,4’- bipyridine, also known as viologens. An example of such a violgen molecule is shown in scheme-1. Viologen is an organic compound for potential use in flexible electrochromic devices due to its activity in reversible redox reaction and excelent electron accepting nature. In other words, Viologens\[9\],\[11–-14\] are reducible materials used in solid-state electrochromic devices, which may undergo one- or two-electron reductions.\[9\],\[11–-14\] Ease of processing and use have stimulated 