Unveiling a new fully-organic and redox-active methyl viologen salt: Sustainable synthetic strategy, multifaceted spectroscopic characterization, and pesticide properties

Methyl viologen (MV) is a highly versatile redox-active species, renowned for its stable redox reaction between MV²⁺ and MV• + . Its structure and properties are significantly influenced by the choice of counter-anion. Herein, we introduce a tosylate ion as an organic counter-anion to methyl viologen dication to obtain a new, fully organic methyl viologen derivative (MVT). The effects of tosylate as a counter-anion on the structure, physicochemical, and electrochemical anti-pesticidal properties of MV have also been elucidated. MVT has been synthesized by a straightforward, single-step process for the first time. The integration of tosylate ion with MV cation results in enhanced thermal stability and redox activity of MVT as compared to the well-known viologen derivative methyl viologen chloride (MVC). These improvements are attributed to the unique structural characteristics of MVT, as revealed through its vibrational spectroscopic studies. The vibrational profile of MVT reveals disruption in the symmetry of the bipyridyl moiety, leading to a distinct molecular arrangement compared to MVC. Additionally, MVT displayed comparable antimicrobial activity to the MVC, reinforcing its potential for pest control applications. Overall, the outcomes of this study inherently suggest that tosylate anion can be a promising counter-anion for methyl viologen, enhancing its suitability as an aqueous-organic redox-active molecule for diverse applications. • MVT is synthesised for the first time using a straightforward, single-step process. • Tosylate incorporation enhances the thermal stability and redox activity of MVT over methyl viologen chloride. • Vibrational spectroscopy reveals altered structural symmetry in the bipyridyl unit of MVT. • MVT shows antimicrobial activity comparable to MVC, indicating potential for pest control applications.