We have investigated phase-transition behaviors of a typical room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim]PF6), using calorimetric and Raman spectroscopic techniques. Although there was some confusion on its phase in previous reports, our measurements with laboratory-made calorimeter at slow scanning rate (5 mK/s) definitely revealed that [C4mim]PF6 has three crystalline phases. From the study, conformations butyl group for these phases are assigned...

The proton at the 2 position of cation ring in imidazolium-based ionic liquids (ILs) strongly interacts with anions; therefore, methylation this (C(2) methylation) causes significant changes physicochemical properties these liquids. We investigated C(2) effects on phase behaviors and conformations ILs by calorimetric Raman spectroscopic measurements, focusing pairs 1-butyl-3-methylimidazolium salt ([C4mim]X) 1-butyl-2,3-dimethylimidazolium ([C4C1mim]X), where X− is Cl−, Br−, I−, BF4−, PF6−....

We have established a new cellulose modification protocol without any additional catalysts and corrosive chemicals.

Ionic liquids (ILs) are salts with an extremely low melting point. Substantial efforts have been made to address their point from the enthalpic standpoint (i.e. interionic interactions). However, this question is still open. In study, we report our findings that entropic (large fusion entropy), rather than enthalpic, contributions primarily responsible for lowering in many cases, based on a large thermodynamic dataset. We established computational protocol using molecular dynamics...

A fundamental mechanistic understanding of the pressure- and/or temperature-induced facile transformation coordination environment boron is important for changing physical properties glass. We have used in situ high-pressure (up to 2 gigapascals) boron-11 solid-state nuclear magnetic resonance spectroscopy combination with ab initio calculations investigate nature transition state pressure-induced BO3→ BO4 conversion a borosilicate glass at ambient temperature. The results indicate an...

Abstract X-ray scattering and 13C spin-lattice relaxation time (T1) measurements were performed for three ionic liquids (ILs): 1-methyl-3-octylimidazolium ethanesulfonate ([C8mim][C2SO3]), 1-methyl-3-pentylimidazolium pentanesulfonate ([C5mim][C5SO3]), 1-ethyl-3-methylimidazolium octanesulfonate ([C2mim][C8SO3]). Although these imidazolium sulfonates have the same total carbon number in alkyl chains, their nanoscale structure picosecond local dynamics differ significantly. The position of...

We investigated the rotational dynamics of two imidazolium-based ionic liquids, 1-butyl-3-methylimidazolium bromide ([C4mim]Br) and 1-butyl-2,3-dimethylimidazolium ([C4C1mim]Br), to reveal effects methylation at position 2 imidazolium ring (C(2) methylation). The correlation time (τlocal) for each carbon in cations is derived from spin−lattice relaxation 13C nuclear magnetic resonance. τlocal results obtained here provide three principle insights into liquids. First, all values [C4C1mim]Br...

We investigate the cation rotational dynamics of a room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim]PF(6)) in its three crystalline states by (1)H NMR spectroscopy. Spin-lattice and spin-spin relaxation time (T(1) T(2), respectively) measurements as function confirm presence polymorphic crystals [C(4)mim]PF(6): α, β, γ, which we previously discovered using Raman spectroscopy calorimetry. Second moment calculations spectra reveal that certain...

We performed structural investigations of cellulose mixed with 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) in the entire concentration range (0-100 mol %) by wide-angle X-ray scattering aid quantum chemical calculations and 13C solid-state NMR spectroscopy. particularly focused on a highly concentrated region (≥30 %), which has previously been overlooked. At concentrations 15-30 %, periodic peak corresponding to chain alignment emerged; this is associated lyotropic cholesteric...

Cellulose triacetate was synthesised by the transesterification reaction of mild acid-pretreated lignocellulosic biomass with a stable acetylating reagent (isopropenyl acetate, IPA) in an ionic liquid (1-ethyl-3-methylimidazolium EmimOAc) which enabled dissolution lignocellulose as well organocatalytic reaction. The homogeneous acetylation pretreated sugar-cane bagasse carried out under conditions (80 °C, 30 min), and subsequent reprecipitation processes led to enriched cellulose high degree...

The rotational dynamics of the hexafluorophosphate anion (PF(6)(-)) in crystalline and liquid states archetypal room temperature ionic (RTIL) 1-butyl-3-methylimidazolium ([C(4)mim]PF(6)) are investigated using (31)P NMR spectroscopy line shape analyses spin-lattice relaxation time measurements. PF(6)(-) performs isotropic rotation all three polymorphic crystals phases α, β, γ as well state with a characteristic scale that ranges from few ps to hundred over range 180-280 K. correlation τ(c)...

Ionic liquids with cationic organosilicon groups have been shown to a number of useful properties, including reduced viscosities relative the homologous cations hydrocarbon substituents on cations. We report structural and dynamical properties four ionic having trimethylsilylpropyl functional group, 1-methyl-3-trimethylsilylpropylimidazolium (Si-C3-mim+) cation paired three anions: bis(fluorosulfonyl)imide (FSI-), bis(trifluoromethanesulfonyl)imide (NTf2-),...

We studied the crystallization process of 1-butyl-3-methylimidazolium bromide ([C(4)mim]Br) using measurements supersensitive scanning calorimetry, free induction decay (FID) signals (1)H NMR, and direct observation. These three methods provided consistent, complementary results, which showed extremely slow dynamics at crystallization. This sample does not crystallize during cooling process, loses mobility, changes to a coagulated state, is thermodynamic glass state. The FID observation in...

The flexibility and conformational variety of the butyl group in cations ionic liquids (ILs) play an important role dictating macroscopic microscopic properties ILs. Here we calculate potential energy surfaces for dihedral angles four different types cyclic cations, imidazolium, pyridinium, pyrrolidinium, piperidinium, using density functional theory method. calculation results highlight these by comparison five-membered six-membered rings, aromatic alicyclic terms stable conformations...

The excited-state intramolecular proton transfer (ESIPT) reaction of 4′-N,N,-diethylamino-3-hydroxyflavone (C2HF) was studied using time-resolved fluorescence measurements in ionic liquids (ILs) various anions with a fixed cation (1-ethyl-3-methylimidazolium [C2mim]+). C2HF showed an ESIPT from the normal excited state (N*; keto form) to tautomer (T*; enol where both states are emissive. rate and yield were obtained by analyzing spectra measured optical Kerr gate method. Both decreased...

This paper describes micromachining of pure metal surfaces in air by a scanning probe microscope that has very sharp diamond tip mounted on the end cantilever beam. Samples metals, such as Ni, Cu, and Au, were prepared vapor deposition or mechanical polishing bulk metals. Sample scratched with x-y 3 μm x direction span, 30 nm y feed 0.98–19.6 μN loading force, topographies area observed. On scanning-scratched Cu ridge caused adhesion removed materials other hand, case flat square hollows...

We constructed an apparatus that enables us to simultaneously detect structural changes of molecules and the accompanying thermal phenomena by combining a commercially available Raman spectrometer hand-made calorimeter. The use thermoelectric modules as heat flux sensor pump in our calorimeter measure with high sensitivity stability at very slow heating cooling rates. Efficiency is important treat small amount sample also make experimental conditions nearly quasi-static balancing effect...

We have performed single crystal X-ray diffraction analyses of two 1-alkyl-3-methylimidazolium hexafluorophosphate ([Cnmim]PF6) salts, [C1mim]PF6, and [C3mim]PF6. The thermodynamically metastable crystalline phase (β phase) the former was obtained by crystallization from melt in a capillary for crystallographic analysis. Both cation anion β [C1mim]PF6 show higher point group symmetry than those stable α phase. This result is shown to be consistent with fact that melting polymorph (314 K)...

A highly efficient hydrolytic method using an acidic ionic liquid is proposed: pretreatment of biomass with H2SO4; simple in situ synthesis liquid, 1-(1-butylsulfonic)-3-methylimidazolium hydrosulfate ([(HSO3)4C4C1im]HSO4), through addition a zwitterion to the pretreated solution; and subsequent hydrolysis [(HSO3)4C4C1im]HSO4 solution at 100 °C under microwave heating. The high yields glucose xylose (around 80 100%, respectively) were attributed by H2SO4 catalytic activity...