Polycyano–polycadmate host clathrates including a methylviologen dication. Syntheses, crystal structures and photo-induced reduction of methylviologen dication

Photochromism of a Methyl Viologen Bismuth(III) Chloride: Structural Variation Before and After UV Irradiation

“…EPR studies show that 1) before UV irradiation, no EPR signal is detected; 2) after UV irradiation, a symmetric EPR signal with a g value of 20 000 is observed; and 3) after color conversion by heating, this EPR signal has disappeared again (see the http://www.wiley-vch.de/contents/jc_2002/2007/z700122_s.pdf), which indicates that the formation of monocation radical MV .+ is induced by UV irradiation and that MV .+ can be oxidized to MV 2+ by O 2 at elevated temperatures 1. 4b The photochromism of the title complex arises from reversible interconversion between monocation radical MV .+ and dication MV 2+ , which is similar to the cases found in some viologen compounds 1. 4b…”

“…The production of MV .+ can be confirmed by UV/Vis spectroscopy and electron paramagnetic resonance (EPR) measurements. Two absorption bands appear at approximately 484 and 640 nm for 2 , which can be ascribed to the charge‐transfer absorptions of monocation radical MV .+ 4a,b. EPR studies show that 1) before UV irradiation, no EPR signal is detected; 2) after UV irradiation, a symmetric EPR signal with a g value of 20 000 is observed; and 3) after color conversion by heating, this EPR signal has disappeared again (see the http://www.wiley-vch.de/contents/jc_2002/2007/z700122_s.pdf), which indicates that the formation of monocation radical MV .+ is induced by UV irradiation and that MV .+ can be oxidized to MV 2+ by O 2 at elevated temperatures 1.…”

Photochromism of a Methyl Viologen Bismuth(III) Chloride: Structural Variation Before and After UV Irradiation

“…The production of MV .+ can be confirmed by UV/Vis spectroscopy and electron paramagnetic resonance (EPR) measurements. Two absorption bands appear at approximately 484 and 640 nm for 2 , which can be ascribed to the charge‐transfer absorptions of monocation radical MV .+ 4a,b. EPR studies show that 1) before UV irradiation, no EPR signal is detected; 2) after UV irradiation, a symmetric EPR signal with a g value of 20 000 is observed; and 3) after color conversion by heating, this EPR signal has disappeared again (see the http://www.wiley-vch.de/contents/jc_2001/2007/z700122_s.pdf), which indicates that the formation of monocation radical MV .+ is induced by UV irradiation and that MV .+ can be oxidized to MV 2+ by O 2 at elevated temperatures 1.…”

Two viologen-based crystalline photoactive complexes constructed by zinc chloride and N-(3-cyanophenyl)-4,4′-bipyridinium units: Structural arrangement of donor–acceptor units and photoresponsive characteristics

“…And the g (g = 2.0022 for 1 and g = 2.0025 for 2) values indicate that they are viologen radicals (Fig. S4, see SI) [17]. In the two complexes, the CNPBPY cation, which exhibits a good electronaccepting ability, is able to accept one electron from the chloride anion, creating stable charge separation systems with photochromic characteristics [18].…”