CH3OH Solution Research Articles

Synthesis, structural characterization and theoretical approach of 3-(2,6-dichlorobenzyl)-5-methyl-N-nitro-1,3,5-oxadiazinan-4-imine

3-(2,6-Dichlorobenzyl)-5-methyl-N-nitro-1,3,5-oxadiazinan-4-imine (DNOI) was synthesized and characterized by X-ray diffraction, FT-IR, FT-Raman and UV–Vis spectra. The X-ray diffraction study showed that DNOI has a one dimensional configuration, due to the intermolecular C9H⋯O1 and N4H⋯O2 hydrogen bonds. The benzene ring and the oxadiazine rings are tilted with respect to each other by 63.07° (C3N1C5C6). Vibrational spectra and electronic spectra measurements were made for the compound. Optimized geometrical structure and harmonic vibrational frequencies were computed with DFT (B3LYP, B3P86, and M062X) methods using 6-311++G(d,p) basis set. Assignments of the observed spectra were proposed. The equilibrium geometries computed by all of the methods were compared with X-ray diffraction results. The absorption spectra of the title compound were computed both in gas phase and in CH3OH solution using TD-B3LYP/6-311++G(d,p) and PCM-B3LYP/6-311++G(d,p) approaches, respectively. The calculated results provide a good description of positions of the bands maxima in the observed electronic spectrum. Temperature dependence of thermodynamic parameters in the range of 100–1000K were determined, entropy, heat capacity and enthalpy changes were increasing with temperature increasing, while for Gibbs free energy is decreasing with temperature increasing. The bond orbital occupancies, contribution from parent natural bond orbital (NBO), the natural atomic hybrids was calculated and discussed.

Self-assembly of 2-aldehyde-8-hydroxyquinolinate-based lanthanide complexes and NIR luminescence

Self-assembly reaction of 2-aldehyde-8-hydroxyquinoline, tris(hydroxymethyl)aminomethane and LnCl3⋅6H2O affords a series of mononuclear lanthanide complexes Ce(baho)2·Et2O (1) (H2baho=2,8-bis(2-(8-hydroxylquinolinyl))-1-aza-5-hydroxymethyl-3,7-dioxabicyclo[3.3.0]octane), Dy(nhm)2Cl·0.5H2O (2) and Ln(nhm)2Cl·0.5C6H14 (Ln=Ho (3), Er (4), Yb (5) and Hnhm=N-(2-(8-hydroxylquinolinyl)methylene)(trishydroxymethyl)methylamine. The crystal structures have been determined by X-ray crystallographic analysis, and the tetravalence of Ce in 1 has been proven by XPS. Interestingly, the positive charge of Ce4+ ion in 1 is neutralized by two deprotonated baho2− ligands, while two deprotonated nhm− ligands and one Cl− compensate the positive charge of Ln3+ ions in 2–5. Complex 5 exhibit essential NIR luminescence of Yb3+ ion with lifetime of 17.64μs in solid and 9.96μs in CH3OH solution.

Electrodeposition fabrication of pore-arrayed hydrogen tungsten bronze as support of platinum nanoparticles for electrocatalytic oxidation of methanol oxidation

Pore-arrayed hydrogen tungsten bronze (p-HxWO3) is fabricated with polystyrene as template by electrodeposition and used as the support of platinum nanoparticles as electrocatalyst (Pt/p-HxWO3) for methanol oxidation. The surface morphology, structure, and compositions of p-HxWO3 and Pt/p-HxWO3 are characterized with scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The activity and stability of Pt/p-HxWO3 toward methanol oxidation are evaluated in 0.5M H2SO4+1.0M CH3OH solution by cyclic voltammetry (CV), chronoamperometry (CA), and chronopotentiometry (CP), and cell discharge test. The characterizations from SEM, XRD, TEM, and FTIR demonstrate that p-HxWO3 contains uniform pores of about 200nm and the platinum particles can be uniformly distributed with an average size of 3.01nm on it. The electrochemical evaluations indicate that Pt/p-HxWO3 exhibits better activity and stability toward methanol oxidation than the platinum supported by non-pore arrayed HxWO3.

Visible light driven (Fe, Cr)-codoped La2Ti2O7 photocatalyst for efficient photocatalytic hydrogen production

Highly visible-light response (Fe, Cr)-codoped La2Ti2O7 photocatalysts are synthesized by sol–gel process. The crystal phase, morphology and optical absorption activity of the samples are characterized by X-ray diffraction, scanning electron microscope, X-ray photoelectron spectroscopy, and UV–vis diffuse reflectance spectra. The results reveal that the calcination temperature and dopant concentration have strong influence on the phase structures, crystallinity and morphology. The UV–vis diffuse reflectance spectra indicate that Fe and Cr ions codoping can extend optical absorption to the visible-light region and narrow the band gap obviously. The photocatalytic hydrogen and oxygen production activities are evaluated in CH3OH and AgNO3 aqueous solution under solar light irradiation. NiOx (0.5 wt%) loaded (Fe, Cr)-0.005-LTO-1150 shows the best photocatalytic H2 production activity with the productivity of 360.203 μmol g−1 h−1 and the apparent quantum efficiency of 2.44%, which suggests that the synergistic effect of Fe and Cr codoping is favorable to enhance the photocatalytic efficiency. The photocurrent of (Fe, Cr)-codoped La2Ti2O7 is more than two times of that for Fe-doped La2Ti2O7 photocatalyst. The efficient photocatalytic hydrogen production and the high photocurrent of (Fe, Cr)-0.005-LTO-1150 are originated from the optimized combination of the physical–chemical properties, the small band gap and the low recombination rate of photoelectron–holes.

A novel blue-emitting indium(III) complex: Synthesis, crystal structure, and effect of solvents and temperature on the luminescent properties

A novel indium complex {[InL(NO3)(OH)]·NO3·CH3OH}2 (1) is isolated from the refluxing reaction of a tetradentate Schiff base ligand, N,N′-bis(2-pyridinylmethylene)cyclohexane-1,2-diamine (L), and In(III) nitrate hydrate. The room temperature (298K) and cryogenic temperature (77K) emission spectra of 1 are recorded in solid state and different solvents (CH3OH, CHCl3, CH3CN and DMSO). Complex 1 exhibits a pronounced bathochromic shift in emission spectra as solvent polarity increases (polarity order: DMSO>CH3CN>CHCl3), indicating a change in dipole moment of 1 upon excitation. Further bathochromic shift exists in CH3OH (467nm) solution. An extended work is developed to discuss on maximum emission and lunminescent lifetime of 1 dispersed in the deuterated reagents (CD3OD, CDCl3, CD3CN and DMSO-d6). The results exhibit that the similar emission also exists in deuterated reagents and the longer lifetime is observed due to the scarcity of OH, NH, and CH oscillators. The quantum yield of 1 decreases with increasing polarity of solvent within the region of 7.8–15.4%. Commission Internationale de L'Eclairage (CIE) 1931 demonstrates that the color gamut of 1 is blue.

Synthesis and characterization of mesoporous composite silica monolith

Coumarin4 (Cou4) was loaded into mesoporous silicon SBA-15 monolith channels by a simple postgrafting method at room temperature. The obtained Cou4/SBA-15 composite monolith was compared with the blank SBA-15 monolith. The investigation of X-ray diffraction, transmission electron microscopy (TEM), UV–vis and photoluminescence (PL) reveals the existence of cou4 in the channels of SBA-15 monolith. In addition, a red-shift and strong fluorescence in PL spectrum was observed from the composite monolith compared with that of Cou4 in C2H5OH solution. This is good for the new application of optical materials.

Effect of the Amount of H2O on the Crystallization of TiO2 Films Prepared from Alkoxide Solutions Containing Acetylacetone

Sol–gel‐derived TiO2 films were prepared by dip‐coating from Ti(OC3H7i)4–CH3COCH2COCH3–HNO3–H2O–C2H5OH solutions, and the effect of the H2O content in solutions on the crystallization of TiO2 films during the heat treatment at 800°C was discussed. The crystalline phase, crystallite size, grain size, and refractive index of the TiO2 films depended on the H2O/Ti(OC3H7i)4 mole ratios (x) in the coating solutions. Highly dense and crystalline rutile films were obtained at x = 0.5–10, where the crystallites and grains became larger with increasing x. The further increase in x from 10 to 50 reduced the crystallite size and refractive index of the films, where anatase phase appeared at x = 30–50.

Conjugated polyelectrolytes with guanidinium side groups. Synthesis, photophysics and pyrophosphate sensing

Two cationic poly(phenylene ethynylene) conjugated polyelectrolytes (CPEs) featuring guanidinium side groups were the subject of investigation. Two polymers were examined, one is an alternating co-polymer (P1) in which the guanidinium groups are on every other repeat unit and the second is a homopolymer with the guanidinium groups on every repeat unit. The photophysical properties of the CPEs were investigated in CH3OH and H2O solution by absorption, steady-state fluorescence and fluorescence lifetime spectroscopy. The results indicate that P1 and P2 are molecularly dissolved in CH3OH solution; however, in water the polymers aggregate as evidenced by a substantial reduction in the fluorescence yield. Addition of the non-ionic surfactant (Triton X-100) into the weakly fluorescent aqueous solution of P1 increased the fluorescence by forming a polymer/surfactant complex. The fluorescence of the polymer/surfactant complex in aqueous solution was effectively quenched by the addition of pyrophosphate (PPi) with Stern-Volmer quenching constants (K(sv)) ∼ 1.7 × 10(5) M(-1); the quenching occurs because PPi binds to the guanidinium groups and induces the aggregation of the polymer/surfactant complex. In addition, by using fluorescence correlation spectroscopy it was found that the diffusion time of the aggregated complex is increased 9-fold in comparison with the free CPE/surfactant complex. A sensor is developed utilizing the significant changes in fluorescence induced by the addition of PPi.

Transition-metal ion modified monolacunary tungstates: Synthesis, structural characterization and property

Two organic–inorganic hybrids (H2bpp)4[PW11CuO39][PW12O40] (1) (bpp=1,3-di(4-pyridyl)propane), H5(bpe)3[SiW11CoO39]·2H2O (2) (bpe=1,2-di(4-pryridyl)ethylene) have been hydrothermally synthesized and characterized by IR, UV, powder and single crystal X-ray diffraction. The analysis results reveal that both of two compounds contain one-dimensional polyanionic chains of monosubstituted Keggin clusters through M–O–M (M=Cu/W/Co) linkages. In the crystal framework of 1 there are two types of nanosized polyanionic clusters of classic saturated Keggin-type [PW12O40]3− and Cu-doped [PW11CuO39]5− anions. The protonated discrete organic substrates either flexible bpp in 1 or rigid bpe in 2 are attached to the surrounding of polyanions via non-covalent interactions. The photoluminescence emissions of 1 and 2 in CH3OH solution at room temperature have been investigated. The photocatalytic activity of two complexes for methylene blue (MB) degradation under UV irradiation is explored.

Optical performance of mesostructured composite silica film loaded with organic dye

A mesoporous composite silica film loaded with organic dye has been successfully synthesized by a solgel reaction process and a simple postgrafting method at room temperature. The composite film was characterized by x-ray diffraction, transmission electron microscopy, UV-Vis, photoluminescence (PL) spectra, and laser performance, and the results confirmed the existence of dyes in the channels of the silica film. A blue-shift and fluorescence property in the PL spectrum was observed from the composite film compared with that of dye molecules in C₂H₅OH solution. The spectrum narrowing phenomena has been observed when the composite film is pumped at λp=355 nm by a Nd:YAG pulsed laser. A narrower, higher peak was observed in emission spectra from the mesostructured composite silica film compared with the PL spectrum of dye in C₂H₅OH solution. There is a substantial reduction in the full width at half-maximum of the emitting light, which results in peaks with linewidths of 26 nm or more. This collapse of the emission spectrum is one of the signatures of the presence of amplified spontaneous emission.

Synthesis of Pt nanoparticles on electrochemically reduced graphene oxide by potentiostatic and alternate current methods

Reduced graphene oxide (RGO) has been synthesized on Pt wires by means of a potentiodynamic method between +0.6V and −1.4V for 20 scans. Cyclic voltammetry characterization of the coatings showed the typical capacitative behavior of graphene. Pt nanoparticles were synthesized on Pt–RGO electrodes by means of potentiostatic methods and a comparison between different synthesis potentials (−0.16, 0, +0.2 and +0.4V) for the same synthesis charge (mC·cm−2) was established. The electrodes obtained were characterized in 0.5M H2SO4 solution to observe the characteristic oxidation and reduction processes of the Pt surface. A 0.5M H2SO4/0.5M CH3OH solution was used to measure the catalytic properties of the deposits against methanol oxidation. The most appropriate potential to perform the synthesis was 0V followed by −0.16V and +0.2V. The morphology of the coatings varied depending on the potential applied as observed by scanning electron microscopy. Alternate current methods were also used to synthesize Pt nanoparticles and compare the results with the traditional potentiostatic method. Different frequencies were used: 0.1, 1, 10, 100, 1000 and 10000Hz. Alternate current synthesis is more efficient than traditional potentiostatic methods, obtaining more electroactive coatings with less effective synthesis time.

Preparation of platinum nanoparticles on n-GaN(0001) substrate by means of electrodeposition

Nanoparticles of platinum (Pt) were directly prepared on n-GaN(0001) by a potentiostatic electrodeposition in 0.5M H2SO4+8mM H2PtCl6 solution and fully characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive X-ray analysis (EDAX). The as-deposited nanoparticles, whose morphology and size were dependent on the applied potential and time, were made of platinum. The real surface area and catalytic properties of Pt nanoparticles prepared at different potentials were estimated by cyclic voltammetry in 0.5M H2SO4 and by chronoamperometry in 0.5M H2SO4+0.2M CH3OH solutions, respectively. The maximum of real surface area and the best catalytic activity of Pt nanoparticles were obtained at the potential of −0.7V.

Investigation of the optical and electrical properties of p-type porous GaAs structure

Porous GaAs layers have been formed by electrochemical anodic etching of (100) heavily doped p-type GaAs substrate in a HF:C2H5OH solution. The surface morphology of porous GaAs has been studied using atomic force microscopy (AFM).Nano-structural nature of the porous layer has been demonstrated by X-ray diffraction analysis (XRD) and confirmed by AFM. An estimation of the main size of the GaAs crystallites obtained from effective mass theory and based on PL data was close to the lowest value obtained from the AFM results. The porous p-GaAs samples are characterised by spectroscopic ellipsometry and modulation spectroscopy techniques. The objective of this study is to determine the porosity, refractive index, and thickness. The porosity of GaAs determined by atomic force microscopy confirmed by the value obtained from the spectroscopic ellipsometry. In fact the current–voltage I(V) characteristics of metal–semiconductor Au/p-GaAs are investigated and compared with Au/p-porous GaAs structures. From the forward bias I(V) characteristics of these devices, the main electrical parameters such as ideality factor, barrier height, and series resistance have been determined.

Experimental and DFT studies on the vibrational and electronic spectra of 2-(1H-Imidazo [4,5-ƒ][1,10]phenanthrolin-2-yl)phenol

The compound 2-(1H-Imidazo [4,5-ƒ][1,10] phenanthrolin-2-yl) phenol (IPP) was synthesized, followed by structure determination by X-ray diffraction, the results of which agree well with the calculated optimized, lowest energy geometrical structure. Vibrational information was obtained by FT-IR and Raman spectroscopy which also agree well with calculations (of harmonic vibration frequencies). The calculations were carried out with density functional theory B3LYP methods using 6-311G** and LANL2DZ basis sets. Absorption UV–Vis experiments of IPP in CH3OH solution reveal three maximum peaks at 237.0, 274.0 and 335.0nm, which are in agreement with calculated electronic transitions using TD-B3LYP/6-311G** in CH3OH solution, and agree to a lesser extent with gas-phase calculations.

Investigation of aluminum complexes in alcoholic tetraoctylammonium (TOA) aluminate solutions using aluminum-27 NMR spectroscopy

27Al NMR spectroscopy is a powerful tool for investigation of the aluminate species existing in both aqueous and non-aqueous solutions. This method can also be used to determine thermodynamic properties of complexes in solution. In the present work, 27Al NMR spectroscopy was used to characterize species present in the alkaline aqueous and alcoholic aluminate solutions. Tetraoctylammonium hydroxide (TOAOH) was used as the base. In a solution of CH3OH and H2O at a mole ratio of 20:1, it was possible to detect five signals by 27Al NMR spectra, indicating formation of the [Al(OH)4−n(CH3OH)n](n−1)+ (n=0, 1, 2, 3, and 4) species. 27Al NMR spectroscopy was also used in order to investigate the species present in the ethanolic and propanolic TOA aluminate solutions. The equilibrium constants for the formation of alcoholic aluminate complexes were also determined. Finally, the 27Al NMR spectra of butanolic TOA aluminate solutions were studied.

Photo-induced isomerization of ethylene-bridged azobenzene explored by ab initio based non-adiabatic dynamics simulation: A comparative investigation of the isomerization in the gas and solution phases

Azobenzene is one of the most widely used photoactive units and recently an ethylene-bridged azobenzene (BAB) was reported to have greatly enhanced conversion efficiency, quantum yield, and other favorable properties. As the first step towards exploring its photo-switchable character in real systems, we report here a systematic study on the photoisomerization dynamics between trans (E) and cis (Z) isomers in the gas phase and the CH3OH solution, using ab initio based surface hopping and molecular dynamics, which is the first report of dynamics simulation to reveal the environmental effects on BAB photoreactions. Results show that while the relatively faster S1 relaxation of the photo-induced E → Z process is only mildly affected by the solvent effect, the relatively slower S1 relaxation of the reverse reaction becomes even slower in the solution compared to the gas phase. The subsequent S0 dynamics from the conical intersection between S1 and S0 (CI_E) to Z is accelerated in solution compared to the gas phase because of avoided re-crossing to the S1 state, while the S0 dynamics from the conical intersection between S1 and S0 (CI_Z) to E are basically the same in both phases. Overall, the solvent effect was found to enhance the back-and-forth photo-switch efficiency between the Z and E isomers compared to the gas phase, while the quantum yields are reduced. But the solution yields of both the forward and backward photoreactions are still around 0.4. Therefore, BAB may have good photo-responsive properties if used as a photoactive unit in real systems. These results will facilitate future experimental and theoretical studies in this area to help design new azobenzene derivatives as photoactive units in biological processes, nanoscale devices, and photo-responsive materials.

Synthesis, spectral characterization, and luminescence properties of a cup-like ligand and its magnesium(II) complex

A new tripodal ligand, N,N′,N″-tri(salicylaldehyde)triaminotriethylamine (1) has been synthesized and characterized by elemental analysis, IR and UV spectroscopy, MS, and X-ray crystallography. X-ray diffraction analysis reveals that the three chains of the ligand form a cup-like structure. The ligand’s magnesium(II) complex has been synthesized and characterized by elemental analysis, conductivity, and IR and UV spectroscopy. The luminescence properties of the ligand and its magnesium(II) complex were investigated in DMF, CH3OH, and CH3CH2OH solution and in the solid state at room temperature.

Calculation of the stability constants for the complex formation of dioxovanadium (V) with methyliminodiacetic acid in various H2O + CH3OH solutions using kamlet-abboud-taft equation

The stability constants for the complex formation of VO2+ cation with methyliminodiacetic acid (MIDA) have been determined in this research for various volume fractions of methanol (0-45% v/v) at T = 298 K, I = 0.1 mol dm-3 of sodium perchlorate. Potentiometric and UV spectrophotometric methods have been utilized for the collection of experimental data. Different species were investigated but the best model contains VO2HL and VO2L- for our data treatment. One, two and three parameters Kamlet-Abboud-Taft (KAT) equations have been applied for the determination and calculation of KAT model solvatochromic regression coefficients

BETS3[Cu2(C2O4)3](CH3OH)2: an organic–inorganic hybrid antiferromagnetic metal (BETS = bisethylene(tetraselenfulvalene))

The organic–inorganic hybrid charge-transfer salt of BETS and a two-dimensional oxalate–metalate: BETS3[Cu2(C2O4)3](CH3OH)2 (1) was obtained by the electrochemical oxidation of neutral BETS in the presence of [(C2H5)3NH]2Cu(C2O4)2 in a C6H5Cl–CH3OH solution. 1 crystallizes in a triclinic crystal system with cell parameters: a = 8.7716(3) A, b = 16.9903(6) A, c = 20.5716(7) A, α = 104.794(2)°, β = 102.209(2)°, γ = 92.243(2)°, V = 2883.1(2) A3 and P1 in 293 K. Donor layers and Jahn–Teller distorted honeycomb anions stack alternatively along the c axis in 1. The crystal structure of 1 is similar to the reported compound [BEDT–TTF]3[Cu2(C2O4)3](CH3OH)2 (BEDT–TTF = bis(ethylene-dithio)tetrathiafulvalene, ET). Compared with the BEDT–TTF salt, the c axis expands by 2.3% at room temperature, the shorter interaction between the donor molecules increases, the room temperature conductivity increases from 4 S cm−1 to 140 S cm−1 and the antiferromagnetic interaction between the metal atoms with Jahn–Teller distortion through the oxalato-bridge enhances.

Synthesis and Photocatalytic Properties of Single Crystalline (Ga1‐xZnx)(N1‐xOx) Nanotubes

AbstractRecently, (Ga1‐xZnx)(N1‐xOx) has gained widespread attention as a comparatively high efficiency photocatalyst for visible‐light‐driven overall water splitting. Despite significant gains in efficiency over the past several years, a majority of the photogenerated carriers recombine within bulk powders. To improve the photocatalytic activity, we used an epitaxial casting method to synthesize single‐crystalline, high surface area (Ga1‐xZnx)(N1‐xOx) nanotubes with ZnO compositions up to x=0.10. Individual nanotubes showed improved homogeneity over powder samples due to a well defined epitaxial interface for ZnO diffusion into GaN. Absorption measurements showed that the ZnO incorporation shifts the absorption into the visible region with a tail out to 500 nm. Gas chromatography (GC) was used to compare the solar water splitting activity of (Ga1‐xZnx)(N1‐xOx) nanotubes (x=0.05–0.10) with similar composition powders. Cocatalyst decorated samples were dispersed in aqueous solutions of CH3OH and AgO2CCH3 to monitor the H+ reduction and H2O oxidation half reactions, respectively. The nanotubes were found to have approximately 1.5–2 times higher photocatalytic activity than similar composition powders for the rate limiting H+ reduction half reaction. These results demonstrate that improvements in homogeneity and surface area using the nanotube geometry can enhance the photocatalytic activity of GaN:ZnO for solar water splitting.