Viologen-based compounds
Viologens are organic molecules composed of conjugated bi- or multi-pyridyl groups (‒C5H4N, derived from pyridine). They constitute an important class of redox chromophores involved in electrocromic materials [1], often in solution. Viologens present three redox states between which reversible transitions can be operated. Depending on the exact composition and structure, the dication (molecule bearing a +2 charge) is pale yellow to colorless, the radical cation (+1 charge) is violet to green and the neutral specie is colorless.
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Ball-and-stick model of the paraquat, the trade name of a methyl viologen in its V2+ dication form, with formula C12H14N2. This organic molecule consists of 4,4'-bipyridine bearing two N-methyl substituents loctated at the 1- and 1'-positions. |
- "Viologen-based electrochromic materials and devices" K. Madasamy, D. Velayutham, V. Suryanarayanan, M. Kathiresan, and K.-C. Ho J. Mater. Chem C 7 (2019) 4622-4637 [DOI: 10.1039/C9TC00416E].