Sputtering properties for polyimide by vacuum electrospray droplet impact (V‐EDI) using size‐selected cluster ions

Recently, the vacuum electrospray droplet impact (V‐EDI) was developed as a cluster ion beam source in our laboratory. To attain the ion beam stability and compact design of the ion source, a silica nano‐capillary with 15 µm i.d. was used as the emitter of the beam. It was found that stable electrospray was generated from the capillary tip without the use of laser heating when aqueous solution of 20% ethanol was used. The m/z distribution of electrospray droplets was measured by pulsing the primary beam. By assuming that the charged droplets contain 50% of the excess charges defined by the Rayleigh limit equation, the average mass, and charge of the droplets generated by the present V‐EDI are estimated as 2.5 × 10⁸ u and + 625 charges, respectively, i.e. [(H₂O)_14,000,000 + 625H]⁶²⁵⁺. By chopping the primary cluster beam, clusters composed of smaller m/z clusters (group 1: G1, [(H₂O)_46,000 + 36H]³⁶⁺) and those of larger m/z clusters (group 2: G2, [(H₂O)_560,000 + 125H]¹²⁵⁺) were generated. Surface analysis for polyimide (PI) film by X‐ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) was made using G1, G2, and non‐selected cluster beams. No selective etching was observed when G1, G2, and non‐selected beams were used. However, larger surface roughening was observed when smaller size cluster beams were used. This suggests that larger size clusters cure the surface damage caused by the smaller ones. Copyright © 2016 John Wiley & Sons, Ltd.     

Conformational changes of ubiquitin during electrospray ionization as determined by in‐ESI source H/D exchange combined with high‐resolution MS and ECD fragmentation

In the paper, we have demonstrated the possibility of performing hydrogen/deuterium (H/D) exchange of proteins in the region of gas‐phase ion formation in an electrospray ion source by saturating the electrospray ionization source with vapors of a deuterating agent (D₂O or MeOD). In this region, charged droplets are shrinking and the protein ions transfer into the gas phase. As a model protein, we have used ubiquitin whose ion mobility spectrometry and gas‐phase H/D exchange in the vacuum part of a mass spectrometer demonstrated the presence of gas‐phase conformers with different cross sections and H/D exchange rates. In our experiments, we observed monomodal deuterium distributions for all solvents, charge states, desolvating capillary temperature and types of deuterating agent. Also, we found that the number of H/D exchanges increases with an increasing desolvating capillary temperature and decreasing charge state. We observed that solution composition (49 : 50 : 1 H₂O : MeOH : formic acid or 99 : 1 H₂O : formic acid) influences the charge‐state distribution but did not change the degree of H/D exchange for the same charge state. Electron‐capture dissociation fragmentation shows that higher charge states contain a segment that is protected from access by the deuterating agent. Copyright © 2014 John Wiley & Sons, Ltd.     

Alcohol‐Vapor Inclusion in Single‐Crystal Adsorbents [MII2(bza)4(pyz)]n (M=Rh,Cu): Structural Study and Application to Separation Membranes

The vapor absorbency of the series of alcohols methanol, ethanol, 1‐propanol, 1‐butanol, and 1‐pentanol was characterized on the single‐crystal adsorbents [M^II₂(bza)₄(pyz)]_n (bza=benzoate, pyz=pyrazine, M=Rh ( 1 ), Cu ( 2 )). The crystal structures of all the alcohol inclusions were determined by single‐crystal X‐ray crystallography at 90 K. The crystal‐phase transition induced by guest adsorption occurred in the inclusion crystals except for 1‐propanol. A hydrogen‐bonded dimer of adsorbed alcohol was found in the methanol‐ and ethanol‐inclusion crystals, which is similar to a previous observation in 2 ?2EtOH (S. Takamizawa, T. Saito, T. Akatsuka, E. Nakata, Inorg. Chem. 2005 , 44, 1421–1424). In contrast, an isolated monomer was present in the channel for 1‐propanol, 1‐butanol, and 1‐pentanol inclusions. All adsorbed alcohols were stabilized by hydrophilic and/or hydrophobic interactions between host and guest. From the combined results of microscopic determination (crystal structure) and macroscopic observation (gas‐adsorption property), the observed transition induced by gas adsorption is explained by stepwise inclusion into the individual cavities, which is called the “step‐loading effect.” Alcohol/water separation was attempted by a pervaporation technique with microcrystals of 2 dispersed in a poly(dimethylsiloxane) membrane. In the alcohol/water separation, the membrane showed effective separation ability and gave separation factors (alcohol/water) of 5.6 and 4.7 for methanol and ethanol at room temperature, respectively.     

Highly Selective Water Adsorption in a Lanthanum Metal–Organic Framework

We present a new metal–organic framework (MOF) built from lanthanum and pyrazine‐2,5‐dicarboxylate (pyzdc) ions. This MOF, [La(pyzdc)_1.5(H₂O)₂] ? 2 H₂O, is microporous, with 1D channels that easily accommodate water molecules. Its framework is highly robust to dehydration/hydration cycles. Unusually for a MOF, it also features a high hydrothermal stability. This makes it an ideal candidate for air drying as well as for separating water/alcohol mixtures. The ability of the activated MOF to adsorb water selectively was evaluated by means of thermogravimetric analysis, powder and single‐crystal X‐ray diffraction and adsorption studies, indicating a maximum uptake of 1.2 mmol g^?1 MOF. These results are in agreement with the microporous structure, which permits only water molecules to enter the channels (alcohols, including methanol, are simply too large). Transient breakthrough simulations using water/methanol mixtures confirm that such mixtures can be separated cleanly using this new MOF.     

Pre‐Irradiation Grafting of Styrene/Divinylbenzene onto Poly(tetrafluoroethylene‐co‐hexafluoropropylene) from Non‐Solvents

Pre‐irradiation grafting of styrene/divinylbenzene (DVB) onto poly(tetrafluoroethylene‐co‐hexafluoropropylene) (FEP) films was studied with respect to the influence of solvent. Particularly favorable grafting conditions with long radical lifetimes and reasonably high polymerization rates were achieved with solvents that are precipitants for the newly formed polystyrene, e.g., low‐molecular‐mass alcohols like ⁱPrOH, AcOH, their mixtures with H₂O, and H₂O/surfactant systems. Using one of these solvents significantly extended the range of accessible graft levels, and a specific degree of grafting was obtained at a much lower monomer concentration and irradiation dose than with grafting in a good solvent such as toluene. As practical consequences, the monomer was used more efficiently, and the radiation damage of the perfluorinated base material was reduced with the result of improved mechanical properties of the grafted films.     

Ultrafast Intercalation Enabled by Strong Solvent–Host Interactions: Understanding Solvent Effect at the Atomic Level

Solvents play an essential role in many areas of chemistry and is the cornerstone of understanding reactivity in solution‐phase reactions. Solvent effects have been widely observed in intercalation reactions; however, understanding of the influence of solvents on the thermodynamics and kinetics remains largely elusive in intercalation chemistry. Now, the solvent‐dependent kinetics of ferrocene intercalation into a layered vanadyl phosphate (VOPO₄?2 H₂O) host is presented, with a special focus on primary alcohols. From methanol to 1‐hexnaol, the intercalation rate peaks in 1‐propanol (80 times faster than the slowest case in methanol). Similar kinetics of exfoliation are also found in these solvents without ferrocene. The correlation between intercalation and exfoliation is understood at atomic level by DFT calculations, which reveal the role of pre‐intercalated solvent molecules play in intralayer interactions, interlayer expansion, and layer sliding.     

Highly Efficient Hydrogenation of Methyl Propionate to Propanol over Hydrous Zirconia Supported Ruthenium

Hydrous zirconia supported ruthenium catalyst Ru/ZrO₂·xH₂O, prepared by co‐precipitating ruthenium trichloride and zirconium oxychloride with ammonia, was able to catalyze efficiently methyl propionate to propanol under the mild conditions. In aqueous system, the propanol yield of >99% was achieved under the conditions of reaction temperature of 150°C and hydrogen pressure of 5.0 MPa, while in non‐aqueous system the maximum propanol yield was only 47.0%. FTIR spectra and hydrogenation results indicated that the high catalytic performance of Ru/ZrO₂·xH₂O in aqueous phase results from the cooperation effect between water as a solvent and hydroxyl groups on the surface of carrier.     

Synthesis of 2‐Phenylquinoline and its Derivatives by Multicomponent Reaction of Aniline,Benzylamine, Alcohols,and CCl4 Catalyzed by FeCl3·6H2O

2‐Phenylquinolines, 2‐phenyl‐3‐methyl‐quinolines, and 2‐phenyl‐3‐ethylquinolines were synthesized in high yields (78–90%) by the reaction of aniline, benzylamine, aliphatic alcohols (ethanol, n‐propanol, n‐butanol), and CCl₄ catalyzed by FeCl₃·6H₂O in tetrachloromethane.     

4‐Pyridone–terephthalic acid–water (2/1/2) and bis(3‐hydroxypyridinium) terephthalate

4‐Hydroxypyridine and terephthalic acid cocrystallize as a hydrate, 4‐pyridone–terephthalic acid–water (2/1/2), 2C₅H₅NO·C₈H₆O₄·2H₂O, from a methanol–water solution. The molecules form a two‐dimensional hydrogen‐bonded network resulting in sheets of hydrogen‐bonded molecules that lie parallel to the (10) plane. In contrast, 3‐hydroxypyridine and terephthalic acid form the salt bis(3‐hydroxypyridinium) terephthalate, 2C₅H₆NO⁺·C₈H₄O₄²⁻, giving rise to two‐dimensional hydrogen‐bonded sheets extending through the lattice parallel to the (10) plane.     

The mechanism of photocatalytic reaction over Pt/TiO2: Production of H2 and aldehyde from gaseous alcohol and water

Two types of reaction mechanism were found to proceed in the photocatalytic reaction between various alcohols and water over Pt/TiO₂: the reaction of physisorbed alcohol with a hole and with the ?O11 produced by the hole from H₂O. The selectivity of these reactions depends strongly on the electron donor level of the absorbed alcohol species compared with that of H₂O.     

Photochemical and photocatalytic degradation of 1‐propanol using UV/H2O2: Identification of malonate as byproduct

1‐propanol is a primary alcohol extensively used in the pharmaceutical, chemical, and food industries. It has been also found as a contaminant in the atmosphere and is considered a model compound to mimic the behavior and fate of aliphatic alcohols exposed to environmental conditions. In order to understand that role of relevant variables, this paper presents results obtained with a simple experimental set‐up to investigate the reactivity of 1‐propanol under mild oxidizing conditions. Coupling this system with CE‐C⁴D allowed the quantification of the carboxylic acids formed. For the described experiments, aqueous solutions of 1‐propanol were placed inside a photoreactor and oxidized upon the addition of TiO₂ and/or H₂O₂. According to the described results, the addition of H₂O₂ (0.1% w/w) was the most significant variable, roughly tripled the amount of carboxylic acids generated and led to the conversion of up to 70% of the initially available 1‐propanol (1 mmol/L). More importantly, the reaction yielded the formation (within 10 min) of propionate (50 µmol/L), acetate (400 µmol/L), formate (50 µmol/L), and malonate (200 µmol/L). The latter is critically important because it represents the first example of the photochemical oxidation of both terminal carbons of the C₃‐chain of 1‐propanol under mild conditions, and opens new avenues for the production of this important chemical building block.     

Moxifloxacinium chloride–water–methanol (2/1/1), a novel anti­bacterial agent

Moxifloxacin, a novel fluoro­quinolone with a broad spectrum of anti­bacterial activity, is available as the solvated monohydro­chloride salt 7‐[(S,S)‐2‐aza‐8‐azoniabicyclo­[4.3.0]non‐8‐yl]‐1‐cyclo­propyl‐6‐fluoro‐8‐meth­oxy‐4‐oxo‐1,4‐dihydroquinoline‐3‐carboxylic acid chloride–water–methanol (2/1/1), C₂₁H₂₅FN₃O₄⁺·Cl⁻·0.5H₂O·0.5CH₃OH. The asymmetric unit contains two cations, two chloride ions, a mol­ecule of water and one methanol mol­ecule. The two cations adopt conformations that differ by an almost 180° rotation with respect to the piperidinopyrrolidine side chain. The cyclo­propyl ring and the meth­oxy group are not coplanar with the quinoline ring system. The carboxylic acid function, the protonated terminal piperidyl N atom, the water mol­ecule, the chloride ion and the methanol mol­ecule participate in O—H⋯O, O—H⋯Cl, N—H⋯O and N—H⋯Cl hydrogen bonding, linking the mol­ecules into extended two‐dimensional networks.     

Efficient and Ecofriendly Protocol for Tetrahydropyranylation/Depyranylation of Alcohols in the Presence of Tin(II) Chloride Dihydrate

A mild, efficient, and solvent‐free protocol for tetrahydropyranylation of alcohols in the presence of a catalytic amount of SnCl₂ · 2H₂O is reported. Simple filtration of the reaction mixture through a short silica‐gel pad gives the pure products in excellent yields. Depyranylation can also be achieved by adding methanol under similar reaction conditions.     

A bis(amine–carboxylate) copper(II) coordination compound forms a two‐dimensional metal–organic framework when crystallized from water and methanol

When {2,2′‐[(2‐methyl‐2‐nitropropane‐1,3‐diyl)diimino]diacetato}copper(II), [Cu(C₈H₁₃N₃O₆)], (I), was crystallized from a binary mixture of methanol and water, a monoclinic two‐dimensional water‐ and methanol‐solvated metal–organic framework (MOF) structure, distinctly different from the known orthorhombic one‐dimensional coordination polymer of (I), was isolated, namely catena‐poly[[copper(II)‐μ₃‐2,2′‐[(2‐methyl‐2‐nitropropane‐1,3‐diyl)diimino]diacetato] methanol 0.45‐solvate 0.55‐hydrate], {[Cu(C₈H₁₃N₃O₆)]·0.45CH₃OH·0.55H₂O}_n, (II). The monoclinic structure of (II) comprises centrosymmetric dimers stabilized by a dative covalent Cu₂O₂ core and intramolecular N—H...O hydrogen bonds. Each dimer is linked to four neighbouring dimers via symmetry‐related (opposing) pairs of bridging carboxylate O atoms to generate a `diamondoid' net or two‐dimensional coordination network. Tight voids of 166 ų are located between these two‐dimensional MOF sheets and contain a mixture of water and methanol with fractional occupancies of 0.55 and 0.45, respectively. The two‐dimensional MOF sheets have nanometre‐scale spacings (11.2 Å) in the crystal structure. Hydrogen‐bonding between the methanol/water hydroxy groups and a Cu‐bound bridging carboxylate O atom apparently negates thermal desolvation of the structure below 358 K in an uncrushed crystal of (II).     

Determination of steroids by liquid chromatography/mass spectrometry

On-line atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) liquid chromatography/mass spectrometry (LC/MS) were evaluated for the analysis of a variety of steroids. Steroids were classified into three major groups based on the spectra and the sensitivities observed: (I) those containing a 3-one, 4-ene functional group, (II) those containing at least one ketone group without conjugation, and (III) those containing hydroxy group(s) only. In the APCI mode, the best sensitivity and the lowest detection limit for all three groups were obtained by using a mobile phase consisting of methanol and 1%–2% acetic acid in water. The APCI spectra were characterized by MH⁺, MH⁺-H₂O, MH⁺-2H₂O, etc., with the degree of H₂O loss being compound dependent: group I steroids produced stable MH⁺ and group III steroids showed extensive water loss. In the electrospray mode the best sensitivity and the lowest detection limit for the first two groups were obtained when pure methanol and water were used as the mobile phase. This condition produced abundant stable MNa⁺ due to ubiquitous sodium. Detection limits in the 5–15 pg range can be easily achieved using ESI LC/MS. Addition of ammonium acetate or use of acetonitrile in the mobile phase, common in the LC/MS analysis of steroids, decreased the sensitivity for the group I and II steroids and thus should be avoided. For group III steroids, the detection limit can be improved by the addition of acetic acid to the mobile phase.     

Oxazoline chemistry part III. Synthesis and characterisation of [2‐(2′‐anilinyl)‐2‐oxazolines] and some related compounds

The syntheses and characterisation of a series of chiral and achiral 2‐(aminophenyl)‐2‐oxazolines and some related compounds is reported. All of the derivatives have been produced by a one‐step procedure involving the treatment of isatoic anhydride (i.e. [2H]‐3, 1‐benzoxazine‐[1H‐2,4‐dione: 1 ) or its 5‐chloro analogue with a slight excess of appropriate amino‐alcohols. In most cases, anhydrous ZnCl₂ is shown to be an effective Lewis acid catalyst for this reaction at reflux temperature in high boiling aromatic solvents (PhCl or PhMe). Oxazolines have been readily formed using rac‐2‐amino‐1‐butanol, (S)‐phenylglycinol, 2‐methyl‐2‐amino‐1‐propanol and (1S,2R) or (IR,2S)‐cis‐ 1 ‐amino‐2‐indanol; yields range from 85% to 22%. The use of aminoalcohols such as 2‐ethanolamine, (±)‐2‐amino‐1‐phenyl‐1‐propanol or 3‐amino‐1‐propanol (to give the corresponding 4,5‐dihydro‐1,3‐oxazine) results in poor yields. The use of other Lewis acid catalysts (silicic acid, Cd(acac)₂·2H₂O, CuCl₂·2H₂O, InCl₃) or higher temperatures did not improve the yields with these latter two substrates. Benzoxazoles and N‐substituted benzoxazoles can also be obtained in reasonable yields from 1 using 2‐aminophenol (36%) or 2‐amino‐3‐hydroxypyridine (45%).     

The static dielectric constant of solutions of water inn-alcohols at 15, 25, 35, and 45°C

Dielectric constants (measured at 1 MHz) are reported for solutions of water (concentration range 0 to 0.2 mole fraction) in 1-propanol at 25°C, and in 1-butanol, 1-pentanol, and 1-hexanol at 15, 25, 35, and 45°C. These results, together with literature values for solutions of water in methanol, ethanol, 1-heptanol, and 1-octanol, show that water interacts with alcohols in at least two ways: (1) it can participate in the formation of dynamic hydrogen-bonded chains, thereby raising the polarizability; (2) it can form relatively stable structures such as H₂O(ROH)₄ which have zero net dipole moment and consequently diminish volume polarizability. For C _n H _2n+1 OH alcohols,n≥4, most of the initially added water forms complexes: consequently, addition of water to these alcohols lowers the dielectric constant.     

High Performance Pd,PdNi, PdSn and PdSnNi Nanocatalysts Supported on Carbon Nanotubes for Electrooxidation of C2C4 Alcohols

Nanocatalysts Pd, Pd₈Ni₂, Pd₈Sn₂ and Pd₈Sn₁Ni₁ supported on multi‐walled carbon nanotubes (MWCNTs) were successively synthesized by the chemical reduction method in the glycol‐water mixture solvent. Transmission electron microscopy results show that the prepared Pd, Pd₈Ni₂, Pd₈Sn₂ and Pd₈Sn₁Ni₁ nanoparticles are uniformly dispersed on the surface of MWCNTs. The average particle sizes of the nanocatalysts are 3.5–3.8 nm. Electroactivity of the prepared catalysts towards oxidation of ethanol, 1‐propanol, 2‐propanol, n‐butanol, iso‐butanol and sec‐butanol (C2? C4 alcohols) in alkaline medium was studied by cyclic voltammetry and chronoamperometry. The current density obtained for the electrooxidation of C2? C4 alcohols depends on the catalysts and the various structures of the alcohols. Addition of Sn or/and Ni to Pd nanoparticles enhances the electroactivity of the Pd/MWCNT catalyst. Furthermore, the ternary Pd₈Sn₁Ni₁/MWCNT catalyst presents the highest electroactivity for the oxidation of C2? C4 alcohols among the prepared catalysts. Electrocatalytic activity order among propanol isomers and butanol isomers is as follows respectively: 1‐propanol > 2‐propanol, and n‐butanol > iso‐butanol > sec‐butanol > tert‐butanol. This is consistent with the Mulliken charge value of the carbon atom bonded with hydroxyl group in the corresponding alcohol molecule.     

γ Radiolysis of C60 fullerene in water and water/ammonia mixtures: relevance of fullerene fate in ices of interstellar medium

The γ radiolysis of fullerene C₆₀ dispersed in H₂O, H₂O/NH₃, H₂O/methanol and H₂O/NH₃/methanol was studied at 250 and 500 kGy. It was found that C₆₀ originally insoluble in the above mentioned hosting matrix became soluble as a consequence of multiple hydroxylation and oxidation reaction produced by the free radicals generated by the radiolysis of the hosting matrix. The changes undergone by C₆₀ were studied by infrared spectroscopy (FT-IR) and by electronic absorption spectroscopy. The astrochemical consequences of the present study are that C₆₀ ejected in the interstellar medium for instance from protoplanetary and planetary nebulae can condense together with water and other ices in dense molecular clouds. Under the action of high energy radiation C₆₀ reacts with the free radicals generated from the matrix where it is embedded it is solubilized and consequently its carbon content becomes available for further abiotic processes of synthesis of molecules of astrobiological interest. The behavior of C₆₀ appears comparable to that of common PAHs which are also hydroxylated and oxidized under similar conditions.     

The Inhibition of the Hydrolysis of Cephanone by CTAB/n‐C5H11OH/H2O Microemulsion

Abstract

The hydrolysis of cephanone in water, cetyl trimethyl ammonium bromide (CTAB) micelle, and CTAB/n‐C₅H₁₁OH/H₂O O/W microemulsion was studied through UV‐VIS absorption spectroscopy. The mechanism of the hydrolysis and the effects of both the acidity of the media and the composition of O/W microemulsion on the hydrolysis were studied. The results show that the hydrolysis rate of cephanone increases with the acidity. Compared with water, CTAB micelle and CTAB/n‐C₅H₁₁OH/H₂O O/W microemulsion suppress this hydrolysis. The inhibition of the hydrolysis of cephanone by CTAB micelle and CTAB/n‐C₅H₁₁OH/H₂O O/W microemulsion is related to the location of cephanone in the interphases of CTAB micelles and CTAB/n‐C₅H₁₁OH/H₂O O/W microemulsion droplets.