Photochromic Reaction of a Novel Room Temperature Ionic Liquid: 2-Phenylazo-1-hexyl-3-methylimidazolium Bis(pentafluoroethylsulfonyl)amide

Kawai, Akio; Kawamori, Daiki; Monji, Tomoo; Asaka, Tooru; Akai, Nobuyuki; Shibuya, Kazuhiko

doi:10.1246/cl.2010.230

Cited by 23 publications

(21 citation statements)

References 13 publications

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“…2 These characteristic features appeal to many researchers, interested in making new solvents with unique properties. [3][4][5][6][7][8][9][10][11][12][13] Various novel ILs that have paramagnetic and/or photochromic properties have been synthesized. [5][6][7][8][9] Recently, a new type of ILs having photochromic activity has been developed.…”

Section: Introductionmentioning

confidence: 99%

Isomerization dynamics of the 2-phenylazo-1,3-dimethylimidazolium cation photoexcited to the S2 (π, π*) state as studied by transient absorption spectroscopy in the time domain of 10−13 to 103 seconds

Ida

Cohen

Asaka

et al. 2011

Phys. Chem. Chem. Phys.

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Photoinduced isomerization of a novel photochromic cation, [2PA-Mmim](+) (2-phenylazo-1,3-dimethylimidazolium cation), was studied by optical spectroscopic methods. The UV-Vis absorption spectra of the [2PA-Mmim](+) cation show two prominent bands starting around 410 and 520 nm, corresponding to the S(0)-S(2) (π, π*) and S(0)-S(1) (n, π*) transitions, respectively. The photoisomerization mechanism is studied by femtosecond time-resolved transient absorption experiments performed after S(0)-S(2) (π, π*) excitation in several solvents with different viscosity, including ionic liquids. The transient absorption signals at two representative wavelengths were fitted by bi-exponential functions, which yield four decay components. The photoisomerization mechanism is discussed in light of the relaxation schemes available for azobenzene. Only one of the components depends on the solvent viscosity and it changes from 1.2 ps (dichloromethane, 0.4 cP) to 5.6 ps ([Bmim][BF(4)], 93 cP). This component is assigned to a molecule at the S(1) state, which is responsible for the "rotational" isomerization. The weak dependence on the solvent viscosity of this component is explained in terms of local change in the viscosity as a result of local heating due to excess energy released at S(2)-S(1) internal conversion. The other three components of ∼0.4, 1.0 and 10 ps are attributed to relaxation processes of the molecule at S(2), S(1) and S(0) states, respectively. The quantum yields for the forward E-Z photoisomerization are ∼0.15 after S(2) excitation. The backward Z-E isomerization is slow with a lifetime of 1 hour and an activation energy of 91 kJ mol(-1) through an "inversion" mechanism.

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Section: Introductionmentioning

confidence: 99%

Isomerization dynamics of the 2-phenylazo-1,3-dimethylimidazolium cation photoexcited to the S2 (π, π*) state as studied by transient absorption spectroscopy in the time domain of 10−13 to 103 seconds

Ida

Cohen

Asaka

et al. 2011

Phys. Chem. Chem. Phys.

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“…[11] Furthermore, these compounds have been examined as photochromic ionic liquids. [12] Different methods for the synthesis of azoimidazolium dyes have been described in the literature. One route starts with an azo coupling of imidazole and diazonium salts, followed by N-alkylation (Scheme 1 A).…”

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confidence: 99%

Synthesis of Azoimidazolium Dyes with Nitrous Oxide

et al. 2014

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A new method for the synthesis of industrially important azoimidazolium dyes is presented. The procedure is based on a reagent which is rarely used in the context of synthetic organic chemistry: nitrous oxide ("laughing gas"). N2O is first coupled to N-heterocyclic carbenes. Subsequent reaction with aromatic compounds through an AlCl3-induced C-H activation process provides azoimidazolium dyes in good yields.

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“…Un-catalysed imine isomerisation is known to procced either by inversion or rotation and can be stimulated thermally or by light irradiation. [24][25][26][27][28] Thermali somerisation of hydrazine-based iminesi sg enerally associated with ah igh activation barrier, leading to coalescence temperatures above 200 8C. [29] Isomerisationb yl ight, for which interconversion occurs in the excited state, was also not observed.…”

Section: Synthesis and Characterisationmentioning

confidence: 99%

Tuneable Redox Chemistry and Electrochromism of Persistent Symmetric and Asymmetric Azine Radical Cations

Werr

Kaifer

Wadepohl

et al. 2019

Chemistry A European J

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Molecular organic radicals have been intensively studied in the last decades, due to their interesting optical, magnetic and redox properties. Here we report the synthesis and characterisation of persistent organic radicals from one‐electron oxidation of redox‐active azines (RAAs), composed of two guanidinyl or related groups. By connecting two different groups together, asymmetric compounds result. In this way a series of compounds with varying redox potential is obtained that could be oxidised reversibly to the mono‐ and the dicationic charge states. The accessible redox states were fully determined by chemical redox reactions. The standard Gibbs free energy change for disproportionation of the radical monocation into the dication and the neutral molecule in solution, estimated from cyclovoltammetric measurements, varies between 43 and 71 kJ mol−1. While the neutral RAAs absorb predominately UV light, the radical monocations display strong absorptions covering almost the entire visible region and extending for some compounds into the NIR region. A detailed analysis of this highly reversible electrochromism is presented, and the fast switching characteristics are demonstrated in an electrochromic test device.

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Photochromic Reaction of a Novel Room Temperature Ionic Liquid: 2-Phenylazo-1-hexyl-3-methylimidazolium Bis(pentafluoroethylsulfonyl)amide

Abstract: We synthesized a new room temperature ionic liquid, [2PA-Hmim][Pf2N], and characterized the photochromic behavior by absorption spectroscopy. [2PA-Hmim][Pf2N] was found to be a photochromic liquid where solvent itself undergoes photochromic reaction.

Cited by 23 publications

References 13 publications

Isomerization dynamics of the 2-phenylazo-1,3-dimethylimidazolium cation photoexcited to the S2 (π, π*) state as studied by transient absorption spectroscopy in the time domain of 10−13 to 103 seconds

Isomerization dynamics of the 2-phenylazo-1,3-dimethylimidazolium cation photoexcited to the S2 (π, π*) state as studied by transient absorption spectroscopy in the time domain of 10−13 to 103 seconds

Synthesis of Azoimidazolium Dyes with Nitrous Oxide

Tuneable Redox Chemistry and Electrochromism of Persistent Symmetric and Asymmetric Azine Radical Cations

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