Methanol Molecules Research Articles

3D TM-N-C Electrocatalysts with Dense Active Sites for the Membraneless Direct Methanol Fuel Cell and Zn-Air Batteries.

Electrocatalysts with high cost-effectiveness for the oxygen reduction reaction (ORR) are essential for fuel cells (FC) and Zn-Air batteries (ZAB), which need highly active sites and suitable carbon substrates to accelerate the charge transfer kinetics. Herein, a simple and extensible method using ball milling and space-confinement pyrolysis is reported to prepare a series of transition metals and N-C catalysts (M-NLPC), which possess three-dimensional porous carbon substrates and dense active sites for efficient ORR. M-NLPC catalysts (especially Fe-NLPC) exhibit outstanding ORR activity with a half-wave potential (E1/2, 0.88 V) in an alkaline medium, high stability, and strong methanol resistance. The M-N4 sites are proven to be the active centers in M-NLPC by theoretical calculation, and methanol molecules are more likely to desorb than react on the Fe-N4 sites, which is the origin of the inactivity for the methanol oxidation reaction (MOR). Furthermore, Fe-NLPC was applied to membraneless alkaline direct methanol FC (DMFC) in practice, exhibiting outstanding performance. Meanwhile, the Fe-NLPC-based ZAB also shows excellent electrochemical performance.

Mixed-Linker Strategy for the Construction of Metal-Organic Framework Combined with Dyes toward Alcohol Detection.

Herein, a N-rich metal-organic framework (MOF) with four kinds of cages, Zn4(ade)2(TCA)2(H2O) (NENU-1000, Hade = adenine, H3TCA = 4,4',4″-tricarboxytriphenylamine, NENU = Northeast Normal University), was prepared by the mixed-ligand strategy. Cationic dyes can be selectively absorbed by NENU-1000 at proper concentrations, but not neutral and anionic dyes, which perhaps can be assigned to the N-rich neutral framework of NENU-1000. When NENU-1000 was introduced to a relatively lower concentration of cationic dye solutions (e.g., rhodamine B or basic red 2), the colors of these systems faded quickly. Furthermore, the faded solutions can be used for the detection of methanol and other small alcohol molecules with either the naked eye or common UV-vis spectra. The effect of the length of carbon chain, the position of the -OH group, and the number of the hydroxyl group of the alcohols was explored for the color development rate. In addition, the performance of NENU-1000 in iodine sorption and release was also studied.

Crystal structure of cis-7,8-dihy-droxy-5,10,15,20-tetra-phenyl-chlorin and its zinc(II)-ethyl-enedi-amine complex.

The title chlorin, 2PhH2 , hydrogen-bonded to di-methyl-amino-pyridine (DMAP), C44H32N4O2·C7H10N2, and its corresponding zinc(II) complex, 2PhZn, axially coordinated to ethyl-enedi-amine (EDA), [Zn(C44H30N4O2)]·C2H8N2, were isolated and crystallized by adventitious reduction of the corresponding osmate esters by DMAP and EDA, respectively. Known since 1996 and, inter alia, used for the preparation of a wide range of (planar and non-planar) chlorin analogues (so-called pyrrole-modified porphyrins), their conformational analyses in the solid state are important benchmarks. Both macrocycles are only modestly distorted from planarity and both are slightly more non-planar than the corresponding dimeth-oxy-derivative, but less planar than a free-base meso-penta-fluoro-phenyl-based osmate ester. NSD analyses provide qu-anti-tative and qualitative analyses of the distortion modes. One origin of the non-planarity is presumably the avoidance of the eclipsed configuration of the two vic-cis diols on the pyrroline moiety; the resulting deformation of the pyrroline translates in some cases into the macrocycle. The structure of 2PhH2 features voids making up ca 26% of the unit-cell volume filled with highly disordered solvate mol-ecules (chloro-form and hexa-nes). 2PhZn crystallized with a 13.6 (4)% occupied solvate methanol mol-ecule.

The simulation of a green room-temperature ternary solution of water, methanol and 1-ethyl-3-methyl imidazolium chloride by all-atom Monte Carlo and DFT computational approaches

A highly dense ternary solution of water, methanol and 1-ethyl-3-methyl imidazolium chloride [emim][Cl] was investigated by a Monte Carlo (MC) program written in C language, Density Functional Theory (DFT) and Atoms-In-Molecules (AIM) theory. The all-atom approach in MC calculations of a ternary solution, the use of nonzero LJ parameters for all hydrogen atoms in simulation box and the creation of a new strategy for filling simulation box with many molecules were adopted in this research to yield a comprehensive, accurate and different work. The radial distribution function, the molar heat capacities in constant volume and pressure, the thermal expansivity, and the isothermal compressibility of the ternary system were calculated. The chemical potentials were calculated at different temperatures through Widom insertion method and the behaviors of both ideal and excess parts of chemical potentials were analyzed versus temperature. The value of electric permittivity of solution, the change of number of methanol and water molecules and the replacement of chloride anion with iodide in ionic liquid were also explored through separate simulations. The solvation structure and coordination number were investigated for various systems. The optimized sites for water and methanol around [emim]+ recognized by DFT and the HOMO and LUMO isosurfaces were discussed. Also, the hydrogen bonds between components of ternary solution were determined by AIM theory. It was shown that the results of quantum mechanics calculations confirm those of MC simulations.

Coordination-driven self-assemblies of two hetero‐trinuclear [Cu(II)2Ln(III)] (Ln = La and Ce) complexes with a flexible bis(salamo)‐type ligand

d-Block transition metal(II)-lanthanide(III) (3d-4f) hetero‐trinuclear [Cu(II)2Ln(III)] (Ln = La and Ce) complexes [Cu2La(L)(ƞ 2-NO3)3(CH3OH)2]·2CH3OH (1) and [Cu2Ce(L)(ƞ 2-NO3)3(CH3OH)2]·2CH3OH (2) are described, both of which are formed by a flexible symmetrical bis(salamo)-type ligand H4L. The two 3d-4f complexes have been synthesized and characterized by elemental analyses, IR spectra and UV–Vis spectroscopy. The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction analyses. In 1 and 2, each Cu(II) ion (Cu1 or Cu2) is located in the N2O2 cavity of an (L)4− unit, while the apex is occupied by one oxygen atom of the coordinated methanol molecule, forming a penta-coordinated square pyramidal geometry. The lanthanide(III) (La or Ce) ion is located in the O6-donor coordination sphere of the completely deprotonated (L)4− unit and coordinated with the other six oxygen atoms of the three nitrate ligands to form a twelve-coordinated icosahedron. At the same time, the supramolecular structures are formed by intermolecular hydrogen bonding interactions and quantitatively determined by Hirshfeld surfaces analyses. Fluorescence properties and DFT calculations of 1 and 2 were also studied.

Design of Dinuclear Lanthanide Complexes from N2O2 Donor Ligand for Single Molecule Magnets: Crystalline Architecture and Slow Magnetic Relaxation Studies

AbstractThree new dinuclear lanthanide complexes [Ln2L2(μ2‐benzoate)2(MeOH)2] ⋅ 4MeOH (H2L=2‐Bis(2‐hydroxybenzyl)aminomethyl]pyridine); Ln=Nd (1), Tb (2), Dy (3)) have been synthesized and structurally characterized by single‐crystal X‐ray diffraction analyses. Compounds 1, 2 and 3 are isomorphous and thus the framework connectivity features are the same for all the three compounds. In the dimeric form of the complexes, each metal centre is octacoordinated with square antiprism (D4d symmetry) geometry, which is completed by a coordinated methanol molecule. In addition, the methanol that present in the structural voids also acts as linkers of paddle‐wheel like complexes. Magnetic properties of the compounds have been investigated in detail using direct‐current and alternating‐current susceptibility measurements. From the analysis of all three complexes, the decrease of susceptibility value at low temperatures is due to the depopulation of Stark sublevels and the existence of intramolecular antiferromagnetic interactions. In addition, complex 3 shows slow relaxation of magnetization behavior, a characteristic feature of single molecule magnets (SMMs). An effective energy barrier value (Ueff) of 38.87 K and relaxation time (τ0) of 1.665×10−7 s for the magnetic relaxation process was obtained for 3. Solid state luminescence spectra for complex 2 show characteristic green emission peaks at 543 nm region having potential for applications in the solid state as light emitting diodes and photoluminescent materials.

Elucidating structure and dynamics of crystalline α-zirconium phosphates intercalated with water and methanol by multinuclear solid-state MAS NMR: A comprehensive NMR approach.

Solid-state NMR experiments on 2 H, 31 P, 13 C, and 1 H nuclei, including 31 P T1 , 1 H T1 , and 1 H T1ρ measurements, as well as on the kinetics of proton-phosphorus cross-polarization have been performed to characterize the crystalline and amorphous α-zirconium phosphates, which were intercalated with D2 O and/or CD3 OD. The 13 C{1 H} CP MAS NMR experiment performed for compound 1-CD3 OD (Zr (HPO4 )2. 0.2CD3 OD) with carbon cross-polarization via protons of phosphate groups has provided a prove that the methanol was intercalated into the interlayer spaces of this compound. The variable-temperature 2 H solid-echo MAS NMR spectra of intercalated compounds demonstrated that the methanol molecules, in contrast to the mobile water, were immobile, keeping, however, free CD3 rotations around the C3 -axis. It has been demonstrated that the intercalated species, D2 O and CD3 OD, do not affect the high-frequency motions of the phosphate groups. By utilizing local structural models that satisfy the constraints of the experimental data, it has been suggested that the immobile methanol molecules are located in the cavity between two neighboring layers of the zirconium phosphates. Thus, the present work illustrates the reliable criteria in a comprehensive NMR approach to structural and dynamic studies of such systems.

Hydrogen bonds between valsartan and solvents (water and methanol): Evidences for solvation dynamics using local energy decomposition and abinitio molecular dynamics analysis

The change in Gibbs energy when an ion or molecule moves from a vacuum to a solvent is known as solvation energy and solvation is the process of attracting and associating molecules of a solvent with molecules or ions of a solute. Valsartan belongs to the class of drugs known as angiotensin II inhibitors. It is primarily used to treat excessive blood pressure, congestive heart failure and improve the odds of living longer after a heart attack. The main aim of this paper is to study how solvent molecules like water and methanol interact with valsartan. The systems are optimized using the level DFT/B3LYP cc-pVDZ and this geometry was used for Natural bond orbital (NBO), bin-covalent interactions (NCI), and wavefunction assay. PBE0-D3/def2-TZVP is used to perform abinitio molecular dynamics (AIMD) simulations and DLPNO-CCSD(T) for Local Energy Decomposition (LED). Valsartan can produce five fragments: biphenylmethane-, butyl, isopropyl-, N-acyl-Nmethylglycine- and tetrazole, and bond energy (change in enthalpy) is 2451.11 kcal/mol. NBO shown orbital energies of valsartan in a vacuum and its complexes are in order of oxygen electron pairs is valsartan-water > valsartan-methanol > valsartan; similarly, nitrogen electron pairs valsartan-methanol > valsartan > valsartan-water and carbon electron pairs valsartan-water = valsartan-methanol > valsartan. NCI explains the noncovalent interactions of valsartan in vacuum and valsartan with water and methanol (complex) molecules; inter and intra interactions of them. Binding energies of interactions and total binding energies indicated that valsartan-water is of lower energy with more stability than valsartan-methanol is higher energy with less stable. AIMD of valsartan-water is greater simulations and valsartan-methanol is poor simulations between them.

Atomistic insights into the performance of thermodynamic inhibitors in the nucleation of methane hydrate

Figure TOC Comparison of methane hydrate nucleation process (a) without or (b) with EG molecules. Critical nucleus size increase under the influence of Thermodynamic hydrate inhibitors. • Hydrophobic groups from the alcohols could approach the initial hydrate cages and destroy initial clusters. • The –OH groups were observed to form hydrogen bonds with the cage clusters and even initiate a new hydrate cage. • Alcohols can increase the critical nucleus size of gas hydrate. Thermodynamic inhibitors are intensively used in oil and gas pipelines to modify the formation conditions of gas hydrate, preventing the blockage of pipelines. However, their kinetic performance in hydrate nucleation is largely unclear. Herein, the molecular interactions of the small molecules of ethylene glycol and methanol with hydrate clusters were investigated. It was found that the hydrophobic groups from the glycols could approach the initial hydrate cages, thereby constricting the regional distribution of adjacent water molecules; thus, they functioned in the same way as the guest molecules that transiently helped to stabilize the water framework. However, these glycols would eventually dissolve into the solution to stay at the water/nanobubble interface; this would consequently destroy the initial cages upon losing the constraint from the surrounding hydrophobic molecules. In addition, the –OH groups were observed to form hydrogen bonds with the cage clusters and even initiate a new hydrate cage; however, they cannot stably reside there due to different atom coordination. Notably, these glycols can increase the critical nucleus size, which is considered the intrinsic mechanism of thermodynamic inhibition. Our results provide atomistic insights into the performance of glycols in the kinetic nucleation of gas hydrates and can help understand the interactions between guest and host molecules in the presence of hydrophobic and hydrophilic functional groups.

Methanol Negative Ion Fragmentation Probed in Electron Transfer Experiments.

In this contribution, we report a novel comprehensive investigation on negative ion formation from electron transfer processes mediated by neutral potassium atom collisions with neutral methanol molecules employing experimental and theoretical methodologies. Methanol collision-induced fragmentation yielding anion formation has been obtained by time-of-flight mass spectrometry in the wide energy range of 19 to 275 eV in the lab frame. The negative ions formed in such a collision process have been assigned to CH3O-, OH-, and O-, with a strong energy dependence especially at lower collision energies. The most intense fragment anions in the whole energy range investigated have been assigned to OH- and CH3O-. Additionally, the potassium cation energy loss spectrum in the forward scattering direction at 205 eV impact energy has revealed several features, where the two main electronic states accessible during the collision events have vertical electron affinities of -8.26 ± 0.20 and -10.36 ± 0.2 eV. Quantum chemical calculations have been performed for the lowest-lying unoccupied molecular orbitals of methanol in the presence of a potassium atom, lending strong support to the experimental findings.

Novel zinc (II) and nickel (II) complexes of a quinazoline‐based ligand with an imidazole ring: Synthesis, spectroscopic property, antibacterial activities, time‐dependent density functional theory calculations and Hirshfeld surface analysis

AbstractTwo complexes [Zn(L)2(CH3OH)2](NO3)2 (1) and [Ni(L)3]·(NO3)2 (2) (L = 2‐[2‐imidazolyl]‐4‐methyl‐1,2‐dihydroquinazoline‐N3‐oxide) were obtained successfully by means of slow evaporation solution technique (SEST) and characterized using elemental analysis, FT‐IR, UV–vis, and fluorescence spectroscopic. X‐ray diffraction revealed that the metal in complex 1 is chelated by two L ligands and two lattice methanol molecules, whereas in 2 by three L ligands, counterbalanced by nitrate ions. The crystal structures of both showed infinite 1‐D, 2‐D, and 3‐D supramolecular architecture due to intermolecular interactions. Most strikingly, Zn (II) complex showed different fluorescence properties in diverse solvents. The antimicrobial activities of all compounds were compared and showed perceptible efficiency against Gram‐negative and Gram‐positive bacteria. Electrostatic potential (ESP) calculation was used to predict the nucleophilic and electrophilic attack sites. Density functional theory (DFT) calculation results showed good agreement with experimental data, as well as the frontier molecular orbital energy gaps were detected by time‐dependent (TD)‐DFT method with HOMO–LUMO calculations. Additionally, the non‐covalent interactions of both complexes were further quantified and explored with the help of Hirshfeld surface analysis.

Non-equilibrium molecular dynamics simulation to evaluate the effect of confinement on fluid flow in silica nanopores

The flow of fluids in nano-confinement has applications in separations, water purification, medical systems and in the recovery of fluids in petroleum systems. It is believed that fluids do not obey continuum laws when flowing in nanopores (or in confinement). This paper attempts to shed light on various nano confinement effects such as fluid-wall interactions, pore size and molecular geometry, using molecular dynamic simulation. Water, hexane, and methanol flow behaviors were simulated for pore diameters ranging from 1 to 8 nm. In addition to the density analysis of the confined fluids, the fluid flows in saturated nanopores were simulated by the sectional flow method. Water and methanol molecules were completely stabilized in the 1 nm pore. Hexane molecules could not enter the 1 nm pore, due to geometric considerations. For the 2 – 8 nm pores, all fluids showed reduced flow rate compared to the Hagen–Poiseuille flow, due to an interfacial molecular layer stabilized at the pore surface. Flow reduction observed in these studies is contrary to significant flow enhancements observed for fluid flow in carbon nanotubes of similar dimensions. Water flow showed almost constant stick length for all the pore sizes. Methanol flow had the largest stick length. Hexane flow was reduced because of overcrowding of molecules at the pore surface. The effect of confinement diminished with an increase in pore diameter.

Experimental and molecular perspective on VOCs adsorption and separation: Study of the surface heterogeneity and oxygen functionalizing

Heteroatoms doping brings a burgeoning class of adsorbents for the removal of volatile organic compounds (VOCs). It is of great importance to reveal the molecular interaction and adsorption mechanism on account of the nanoscale nature of adsorption. Herein, we combined adsorption experiments and theoretical calculations (using porous carbon as adsorbent and graphene as computational model) to reveal the influence of doping oxygen atoms on the surface heterogeneity and the VOCs adsorption performance, and to investigate the synergistic effect of oxygen-containing functional groups. The results show that oxygen doping can significantly change the charge distribution and improve the adsorption and separation of methanol and acetone (the selected representative of VOCs). Among various oxygen-containing functional groups, the carboxyl doped surface displays the largest theoretical adsorption capacity of methanol (36.74 mmol/g) and acetone (18.35 mmol/g) and the highest selectivity (16.11 at 0.1 kPa). Specifically, the doped oxygen containing groups significantly changed the charge distribution on the carbon surface (e.g., –0.50 to 0.43 e for carboxyl group), and enhanced the electrostatic interaction between the surface and VOCs molecules, thereby increasing the adsorption capacity. Moreover, the stronger binding energy between the oxygen-functionalized surface and methanol contributed to the preferential adsorption of methanol on the oxygen active sites, leading to the aggregation of methanol molecules, which is responsible for the high selectivity. Meanwhile, no obvious synergistic effect between oxygen functional groups was found. This study provides fundamental understanding of the role of oxygen-containing groups toward VOCs adsorption.

A insight into structural characterization, Hirshfeld surface analysis and DFT theoretical calculation of new hexanuclear Ni(II) complex containing two different coordination modes of N3 − anions

A centrosymmetric hexanuclear Ni(II) complex [Ni6(Py)6(µ 2 -η 2-N3)4(µ 3 -η 3-N3)2(µ 2 -OAc)4(µ 3 -CH3O)2(CH3OH)2] was synthesized via the reaction of the metal salts NaN3, Ni(CH3COO)2·4H2O and the salamo-based ligand 6,6′-di(tert-butyl)-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol (H2L) in methanol/acetone/pyridine mixed solvents, respectively, and characterized by IR, UV-Vis and X-ray crystallography. X-ray analysis showed that the ligand H2L is not involved in the Ni(II) complex, but by the coordination of N3 − and CH3COO− anions, deprotonized methanol, pyridine and methanol molecules with Ni(II) atoms. All Ni(II) atoms are six-coordinated distorted octahedral geometries. Interestingly, N3 − anions possess two different coordination modes (μ 3-η 3-N3 − and μ 2-η 2-N3 −), and one of them (μ 3-η 3-N3 −) has hardly appeared in previous reports. Hirshfeld surface analysis and DFT theoretical calculation were carried out to discuss the interaction and stability of the Ni(II) complex.

Heterogeneous Pair Approximation of Methanol Oxidation on TiO2 Reveals Two Reaction Pathways

We propose a novel method to simulate the chemical kinetics of methanol oxidation on the rutile TiO2(110) surface. Such a method must be able to capture the effects of static disorder (site-to-site variations in the rate constants), as well as dynamic correlation (interdependent probabilities of finding reactants next to each other). Combining the intuitions of the mean-field steady state (MFSS) method and the pair approximation (PA), we consider representative pairs of sites in a self-consistent bath of the average pairwise correlation. Preaveraging over the static disorder in one site of each pair makes this half heterogeneous pair approximation (HHPA) efficient enough to simulate systems of several species and calibrate rate constants. According to the simulated kinetics, a static disorder in the hole transfer steps suffices to reproduce the stretched exponentials in the observed kinetics. The dominant hole scavengers are found to be temperature-dependent: the methoxy anion at 80 K and the methanol molecule at 180 K. Moreover, two distinct subpopulations of 5-coordinate titanium (Ti5c) sites emerge, a high-activity group and a low-activity group, even though no such division exists in the rate constants. Since the division is quite insensitive to the details of static disorder, the emergence of the two groups might play a significant role in a variety of photocatalytic processes on TiO2.

Why Methanol Electro-oxidation on Platinum in Water Takes Place Only in the Presence of Adsorbed OH

Untangling the mechanism of the methanol electro-oxidation on platinum in water as a model reaction is essential to optimize fuel cells using alcohols as fuel. Recent experiments unexpectedly suggested that this electro-oxidation process would take place only in the presence of adsorbed OH. The here reported results, carefully obtained under low methanol concentrations on the three basal planes of platinum at different scan rates to discriminate between oxidation and adsorption processes, confirm such an unexpected preliminary observation. It is found that adsorbed CO from methanol is only formed when adsorbed OH is already present on the surface. This observation is a clear indication that adsorbed OH is involved in the mechanism beyond providing the oxygen group required to oxidize adsorbed CO, which has never been considered before. Supported by density functional theory calculations, the role played by adsorbed OH in the methanol electro-oxidation to CO on platinum in water and the reason why this reaction is not observed in the absence of adsorbed OH are also here both elucidated. A combination of kinetic and thermodynamic factors, such as the presence of multiple water molecules per methanol molecule, the high adsorbed OH mobility on the surface, the favorable coadsorption of methanol in the presence of adsorbed OH, and the favorable and virtually barrier-less hydrogen transference from the hydroxy group of methanol to adsorbed OH to yield water result in the immediate activation of methanol (as soon as the molecule approaches the surface) through the favorable substitution of adsorbed OH by adsorbed methoxy. This contribution represents a change of paradigm in the understanding of how alcohols are electro-oxidized in reference systems and have crucial implications in the search for better electrocatalysts.

Counteranion-solvent-dependent construction of two octahedral homopolynuclear Ni(II) complexes with a symmetrical multi-halogen-substituted bis(salamo)-based ligand

Two counteranion-solvent-dependent homopolynuclear Ni(II) complexes, [Ni2(L)(OAc)(MeOH)]·CH3CN·MeOH (1) and [Ni4(L)2(acac)2(EtOH)2]·2CH3CN (2) have been constructed by exploiting the flexibility of a symmetrical multi-halogen-substituted bis(salamo)-based ligand H3L. The structures of complexes 1 and 2 were confirmed by single crystal X-ray diffraction studies. Complex 1 is a di-nuclear Ni(II) complex, where two octahedral Ni(II) atoms are located in the N2O2 cavities of the salamo units, and bridged via a acetate ion. Complex 2 possesses a centrosymmetric tetra-nuclear structure with two di-nuclear [Ni2(L)(acac)(EtOH)] units. It is worth noting that one acetylacetonate anion is coordinated to Ni2 atom in bidentate fashion along with one methanol molecule that completes its hexa-coordinated geometry. It is possible that the existence of the acetylacetone anion makes the ligand (L)3- unit exhibit its flexibility, which promotes the formation of tetra-nuclear complex 2. The close surveillance of the crystal structure of complexes 1 and 2 discloses some notable non-covalent interactions like H-bonding, CH⋯π and π⋯π. Moreover, both complexes 1 and 2 form three-dimensional supramolecular structures with the help of intermolecular hydrogen bonds. It was found that the synthesis of complexes 1 and 2 weakened the fluorescence intensity of H3L until quenching. Hirshfeld surfaces analyses confirmed that hydrogen bond interactions play the most important role in the stability of crystal structures. The high kinetic stability and low chemical reactivity of complexes 1 and 2 were investigated based on the band gap energy.

Probing the electron-to-proton mass ratio gradient in the Milky Way with Class I methanol masers

ABSTRACT We estimate limits on non-universal coupling of hypothetical hidden fields to standard matter by evaluating the fractional changes in the electron-to-proton mass ratio, μ = me/mp, based on observations of Class I methanol masers distributed in the Milky Way disc over the range of the Galactocentric distances $4 \lesssim R \lesssim 12$ kpc. The velocity offsets ΔV = V44 − V95 measured between the 44- and 95-GHz methanol lines provide, so far, one of the most stringent constraints on the spatial gradient kμ ≡ d(Δμ/μ)/dR < 2 × 10−9 kpc−1 and the upper limit on Δμ/μ <2 × 10−8, where Δμ/μ = $(\mu _{\rm \scriptscriptstyle obs}-\mu _{\rm \scriptscriptstyle lab})/\mu _{\rm \scriptscriptstyle lab}$. We also find that the offsets ΔV are clustered into two groups which are separated by $\delta _{\scriptscriptstyle \Delta V} = 0.022 \pm 0.003$ km s−1 (1σ confidence level). The grouping is most probably due to the dominance of different hyperfine transitions in the 44- and 95-GHz methanol maser emission. Which transition becomes favoured is determined by an alignment (polarization) of the nuclear spins of the four hydrogen atoms in the methanol molecule. This result confirms that there are preferred hyperfine transitions involved in the methanol maser action.

Kinetic evidence for methanol trimer assisted proton transfer: Transient absorption study on excited triplet state of 4-hydroxy-4′-nitrobiphenyl

Hydroxyaromatic compounds have a wide range of applications in catalytic synthesis and biological processes due to their enhanced acidity upon photo-excitation. Most hydroxyaromatic compounds with a medium excited state acidity are unable to deprotonate in non-aqueous solvents such as alcohol due to their short-lived excited singlet states. The nitro group in 4-hydroxy-4′-nitrobiphenyl (NO2-Bp-OH) increases the spin-orbit coupling between excited singlet states and the triplet state, resulting in ultrafast intersystem crossing and the formation of the long-lived lowest excited triplet state (T1) with a high yield. Using transient absorption spectroscopy and kinetic analysis, we discover that, despite its moderate acidity, the T1 state of NO2-Bp-OH (3NO2-Bp-OH) is able to transfer proton to methanol. Following the formation of the hydrogen-boned complex between 3NO2-Bp-OH and three methanol molecules in a consecutive process, proton transfer occurs very fast. This finding suggests that the long lifetime of the photoacid excited state allows for the formation of alcohol oligomer with sufficient basicity to induce photoacid deprotonation.

Evaluation of antitumor potential of Cu(II) complex with hydrazone of 2-acetylthiazole and Girard’s t reagent

In this paper, the previously synthesized Cu(II) complex ([CuL1(N3) (CH3OH)]BF4) with N,N,N-trimethyl-2-oxo-2-(2-(1-(thiazol-2-yl)ethylidene)- hydrazinyl)ethan-1-aminium chloride, has been characterized and its biological activity has been studied in detail. The Cu(II) complex consists of ligand coordinated in a deprotonated, formally neutral zwitter-ionic form, via NNO atoms, one azido ligand and one methanol molecule. The Cu(II) complex was selected due to results of the cytotoxic activity, the brine shrimp test and DPPH radical scavenging activity, which were previously performed. The effects of Cu(II) complex on cell cycle phase distribution of cervical adenocarcinoma HeLa cells were investigated in order to examine the mechanisms of its anticancer activity. The measurement of intracellular ROS levels in HeLa and HaCaT cell lines were evaluated in order to explore their possible generation and the role in cytotoxic activity. The possible anti-invasive and anti-angiogenic properties of Cu(II) complex were evaluated. DNA binding experiments, including fluorescence displacement study and DNA cleavage experiments, were performed in order to obtain information on the type of DNA-metal complex interactions.