Abstract:Photochemical properties of the ionic liquid (RTIL) 1-butyl-3-methylimidazolium hexafluorophosphate [bmim] [PF 6 ] and its binary mixed solutions with organic solvent (DMF and MeCN) were investigated by laser photolysis at an excitation wavelength of 355 nm, using anthraquinone (AQ) as a probe molecule. It was indicated that the triplet excited state of AQ ( 3 AQ*) can abstract hydrogen from [bmim] [PF 6 ]. Moreover, along with the change of the ratio of RTIL and organic solvent, the reaction rate constant c… Show more
“…Previously, we had measured the electrical conductivity of [bmim][PF 6 ]/MeCN binary mixtures and shown that the maximum conductivity of [bmim][PF 6 ]/MeCN is 37.9 mS cm -1 at V IL =0.32 . This value is consistent with the critical point (or turnover) for the k obs indicated in this work.…”
Section: Resultssupporting
confidence: 90%
“…Since the absorption decays monotonically by first-order kinetics, it is concluded that the 3 DQ* decays mainly via self-quenching under a N 2 atmosphere. This observation is different from that of anthraquinone or benzophenone, whose excited states decay mainly via hydrogen abstraction of alkyl groups on the cations of [bmim][PF 6 ] under similar conditions. , 1 (a) Transient absorption spectra of 3 DQ* recorded at 0.1 μs after 355 nm laser excitation in a IL/MeCN solution containing 1 × 10 -4 mol·dm -3 DQ under N 2 . V IL : (○) 0 and (▪) 0.8.…”
Section: Resultsmentioning
confidence: 97%
“…The properties of RTILs have recently been characterized using various experimental measures (NMR, IR, Raman, etc. ). − Pulse radiolysis, laser photolysis, and steady-state and time-resolved fluorescence have also been applied to study the reaction processes occurring in RTILs. − These studies mainly focused on solvent relaxation dynamics, − electron and energy transfer kinetics. − A few papers on photoinduced electron transfer by transient absorption spectroscopy in pure RTILs are noteworthy. − Effects of RTILs on transient absorption spectra and bimolecular reaction rate constants of solutes have been partly revealed. It is suggested that most of the imidazolium ionic liquids are more polar than acetonitrile but less polar than methanol .…”
Section: Introductionmentioning
confidence: 99%
“…Binary liquid solutions, such as IL/water and IL/organic, are frequently used in a variety of applications such as electrochemistry and organics synthesis. − Many studies on binary systems, including our previous work, have been carried out experimentally or theoretically. Although many RTILs can be dissolved in water or organic solvents, such IL/organic solutions may be not homogeneous.…”
The transient absorption spectra and photoinduced electron-transfer process of duroquinone (DQ) in mixed binary solutions of ionic liquid (IL) [bmim][PF6] and acetonitrile (MeCN) have been investigated by laser photolysis at an excitation wavelength of 355 nm. A spectral blue shift of 3DQ* was observed in the IL/MeCN mixtures compared to MeCN. At lower VIL(volume fraction of IL), the interaction between DQ and the solvent is dominant, and the decay rate constant (kobs) of 3DQ* increases steadily with the increasing of VIL; to the contrary, at higher VIL, the network structures due to the hydrogen bond and viscosity are dominant, and the decay rate constant decreases obviously with increasing VIL. A critical point (turnover) was observed at VIL = approximately 0.30. The dependence of the observed growth rate (kgr) of the photoinduced electron-transfer (PET) products on VIL is complex and shows a special change; kgr first decreases with increasing VIL, then increases, and finally decreases slowly with further increasing of VIL. It is speculated that the PET process in the mixture can be affected by factors including the local structure and the reorganization energy of the solvent and salt and cage effects. The change of local structure of [bmim][PF6]/MeCN is supported by following the steady-state fluorescence behavior of the mixture, in combination with the molecular dynamics simulation of the thermodynamic property. The results revealed that the degree of self-aggregation of monomeric cations (bmim+) to associated forms increases with increasing VIL. This is in good agreement with the laser photolysis results for the same solutions.
“…Previously, we had measured the electrical conductivity of [bmim][PF 6 ]/MeCN binary mixtures and shown that the maximum conductivity of [bmim][PF 6 ]/MeCN is 37.9 mS cm -1 at V IL =0.32 . This value is consistent with the critical point (or turnover) for the k obs indicated in this work.…”
Section: Resultssupporting
confidence: 90%
“…Since the absorption decays monotonically by first-order kinetics, it is concluded that the 3 DQ* decays mainly via self-quenching under a N 2 atmosphere. This observation is different from that of anthraquinone or benzophenone, whose excited states decay mainly via hydrogen abstraction of alkyl groups on the cations of [bmim][PF 6 ] under similar conditions. , 1 (a) Transient absorption spectra of 3 DQ* recorded at 0.1 μs after 355 nm laser excitation in a IL/MeCN solution containing 1 × 10 -4 mol·dm -3 DQ under N 2 . V IL : (○) 0 and (▪) 0.8.…”
Section: Resultsmentioning
confidence: 97%
“…The properties of RTILs have recently been characterized using various experimental measures (NMR, IR, Raman, etc. ). − Pulse radiolysis, laser photolysis, and steady-state and time-resolved fluorescence have also been applied to study the reaction processes occurring in RTILs. − These studies mainly focused on solvent relaxation dynamics, − electron and energy transfer kinetics. − A few papers on photoinduced electron transfer by transient absorption spectroscopy in pure RTILs are noteworthy. − Effects of RTILs on transient absorption spectra and bimolecular reaction rate constants of solutes have been partly revealed. It is suggested that most of the imidazolium ionic liquids are more polar than acetonitrile but less polar than methanol .…”
Section: Introductionmentioning
confidence: 99%
“…Binary liquid solutions, such as IL/water and IL/organic, are frequently used in a variety of applications such as electrochemistry and organics synthesis. − Many studies on binary systems, including our previous work, have been carried out experimentally or theoretically. Although many RTILs can be dissolved in water or organic solvents, such IL/organic solutions may be not homogeneous.…”
The transient absorption spectra and photoinduced electron-transfer process of duroquinone (DQ) in mixed binary solutions of ionic liquid (IL) [bmim][PF6] and acetonitrile (MeCN) have been investigated by laser photolysis at an excitation wavelength of 355 nm. A spectral blue shift of 3DQ* was observed in the IL/MeCN mixtures compared to MeCN. At lower VIL(volume fraction of IL), the interaction between DQ and the solvent is dominant, and the decay rate constant (kobs) of 3DQ* increases steadily with the increasing of VIL; to the contrary, at higher VIL, the network structures due to the hydrogen bond and viscosity are dominant, and the decay rate constant decreases obviously with increasing VIL. A critical point (turnover) was observed at VIL = approximately 0.30. The dependence of the observed growth rate (kgr) of the photoinduced electron-transfer (PET) products on VIL is complex and shows a special change; kgr first decreases with increasing VIL, then increases, and finally decreases slowly with further increasing of VIL. It is speculated that the PET process in the mixture can be affected by factors including the local structure and the reorganization energy of the solvent and salt and cage effects. The change of local structure of [bmim][PF6]/MeCN is supported by following the steady-state fluorescence behavior of the mixture, in combination with the molecular dynamics simulation of the thermodynamic property. The results revealed that the degree of self-aggregation of monomeric cations (bmim+) to associated forms increases with increasing VIL. This is in good agreement with the laser photolysis results for the same solutions.
“…By swelling study, in addition with several instrumental analysis, a very stable hydration structure of phenol was revealed by investigation on the ion-effect of P4VPh gel [12,14]. In these studies, p-hydrogen bond, cation-p interaction and hydrophobic interaction were found to play significant roles on phase transition of P4VPh gel in the presence of different ion species and concentrations [15][16][17][18]. However, the interactions involved with phenyl rings is still far from fully elucidated.…”
Ionic liquids (ILs) are low-melting organic salts often liquid at room temperature, whose unique properties are the reason of increasing interest for their applications as solvents, reaction media and functional additives. The exceptional properties of ILs have proved to be particularly useful in polymer science giving the potential to produce polymeric materials with improved properties or to immobilize ILs in polymer matrices while keeping their special characteristics. One of the possibilities is polymerization in ILs which can also affect positively polymerization reactions. An especially attractive technique is photopolymerization due to the ease of process control, short reaction time and ambient working temperature. This review gives a literature survey of developments in photopolymerization processes carried out in ILs as well as applications of these processes. It covers both the photopolymerization in ILs as well as photopolymerization of IL monomers. The first part presents a short overview of physicochemical and photochemical properties of ILs; it includes also photochemical reactions and photoinitiation of polymerization in ILs. The second part covers both the basic research (kinetics of photopolymerization including polymerization rate coefficients and polymerization of IL monomers) as well as applications of UV-induced polymerization in ILs.
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