Effects of Different Counter Anions on Solid-State Electron Transfer in Viologen Compounds: Modulation of Color and Piezo- and Photochromic Properties

• DOI: 10.1021/acs.jpclett.0c02690
• Publication Date: 2020-10-21T19:16:09Z
• Authors: Qi Sui; Peng Li; Rong Sun; Yu-Hui Fang; Lin Wang; Bing-Wu Wang; En-Qing Gao; Song Gao
• Keywords: Viologen; Modulation (music)

Charge transfer (CT) and electron (ET) underlie the various applications of viologen compounds. However, CT ET in solids are still insufficiently understood difficult to control, which is challenging but fundamental design multifunctional materials. Our strategy attempt a delicate control by subjecting model compounds pressure. In this work, series viologens same cation with different anions show anion-dependent color piezo-/photochromism due ground-state stimuli-induced ET; ease solid-state can be tuned order Cl– > Br– I–/BF4–/PF6–/ClO4–. With situ high pressure UV–vis experiments, we also observed unexpectedly pressure-induced [H2bcpV]·I2 besides modulation absorption. It proves more powerful stimulus than light tuning ET.