High Sensitivity Viologen for a Facile and Versatile Sensor of Base and Solvent Polarity in Solution and Solid State in Air Atmosphere

• DOI: 10.1021/acsami.5b03932
• Publication Date: 2015-06-11T12:43:27Z
• Authors: Wei Shi; Feifei Xing; Yue-Ling Bai; Meiling Hu; Yongmei Zhao; Ming-Xing Li; Shourong Zhu
• Keywords: Viologen; Naked eye; Polarity (international relations); Base (topology)

Viologen cations are excellent electro- and photochromic materials. They generally have no response or very low sensitivity to bases. In this paper, three compounds, 1,1′-bis(2-oxo-2-phenylethyl)-4,4′-bipyridinium (viologen) with different substituents, including H (1), Cl (2), OH (3), were synthesized. All three, especially 1 2, high base in both solution solid state air atmosphere. These viologens responsive not only bases but also solvent polarity. NMR shows became enolic then a radical, whereas 3 is colored the radical form. results agreement EPR spectra. Crystal structures show that C–C links two pyridinium N–C distances coplanar (radical) form clearly longer than of pale-yellow form, indicating color due viologen radical. Viologens containing an electron-withdrawing phenacetyl group most sensitive compounds for fast, naked eye detection