Impact of Lattice Water on Solid-State Electron Transfer in Viologen Pseudopolymorphs: Modulation of Photo- and Piezochromism

Abstract

Stimuli-induced solid-state electron transfer (ET) underlies the use of viologen compounds as responsive materials, but unequivocal structure-property correlations for solid-state ET are still lacking. With different pseudopolymorphic solids derived from N,N'-bis(4-carboxylphenyl)viologen ([HbcpV]), here we report a systematic study on photo- and piezochromic properties associated with ET. We show that the higher the water content in the lattice, the less sensitively the compounds respond to light and pressure. It is proposed that the lattice water does not act as an electron donor but serves to change the ET energetics through its unique polarity and hydrogen bonding capability. The impedimental impact of water on solid-state ET of viologen compounds has not yet been recognized and elucidated prior to this work. The study also suggests that pressure is more powerful than light in inducing ET.

A photochromic zinc-based coordination polymer for a Li-ion battery anode with high capacity and stable cycling stability

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Metal–organic framework bearing new viologen ligand for ammonia and Cr2O72− sensing

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Strategic modification of ligands for remarkable piezochromic luminescence (PCL) based on a neutral Ir(iii) phosphor

“…[1][2][3][4] They have been extensively studied over the past decade as a class of 'smart' functional materials due to their promising potential as pressure sensors, optical devices and memory chips. [5][6][7][8][9][10][11] Various small organic molecules, 12,13 polymers, 14,15 metal complexes, 16,17 co-crystals 18 , metal-organic frameworks 19 and perovskites 20 with interesting PCL properties have been investigated. Especially, phosphorescent Ir(III) complexes have attracted extensive attention owing to their favourable photophysical properties, controllable excited-state characteristics and tunable emission colours.…”