H2O In Methanol Research Articles

Thermally Stable Heteroleptic Trans‐Bis(Chelate) Ruthenium(II) Complex Bearing 2,2’‐Bipyridine and Acetylacetonato: Synthesis, Isomerization, and Crystal Structure

AbstractThermally stable trans‐bis(chelate)‐type Ru(II) complexes are challenging to prepare owing to steric hindrance between the two chelate ligands. Herein, we investigated the isomerization of a heteroleptic cis‐bis(chelate) complex to obtain its trans form. cis‐[Ru(acac)(bpy)(dmso‐S)2](OTf)⋅0.5H2O (1⋅(OTf)⋅0.5H2O; acac−=acetylacetonato; bpy=2,2’‐bipyridine; dmso=dimethyl sulfoxide; OTf−=CF3SO3−) was prepared by reacting trans(O,S)‐[Ru(bpy)(dmso‐S)2(dmso‐O)2](OTf)2 (P0) with Li(acac) in acetone at 298 K. In 1⋅(OTf)⋅0.5H2O, the two labile dmso‐O ligands of P0 were replaced by an acac− ligand. The dihedral angle between the chelate rings of bpy and acac− in 1+ was 76.7°, suggesting steric hindrance between ligands owing to the two bulky dmso‐S ligands at the cis position. 1⋅(OTf)⋅0.5H2O was thermally stable in DMSO and acetone; however, in methanol and water, a dmso‐S ligand was dissociated from 1+, and the complex isomerized to trans‐[Ru(acac)(bpy)(dmso‐S)(solvent)]+. Refluxing of 1⋅(OTf)⋅0.5H2O in methanol for 18 h, evaporation to dryness under vacuum, and treatment with water yielded trans‐[Ru(acac)(bpy)(dmso‐S)(OH2)](OTf) (2⋅(OTf)) with excellent purity. 2⋅(OTf) was characterized by X‐ray crystallography, elemental analysis, and 1H NMR spectroscopy. As expected, steric hindrance was not observed between the trans‐arranged bpy and acac−, and the two chelates laid flat on the equatorial plane in 2+.

Synthesis and Evaluation of Cytotoxicity and Molecular Docking of New Symmetrical Macroacyclic Schiff Base Ligands and Their Ni(II) and Zn(II) Complexes

To synthesize new symmetrical macroacyclic Schiff base ligands (L1 and L2), polyamine (A) was condensed with 2-formylpyridine and salicylaldehyde. Furthermore, Ni(ClO4)2.6H2O and Zn(ClO4)2.6H2O in methanol were reacted with the ligands to prepare corresponding metal complexes. The cytotoxicity of the synthesized complexes against MCF-7 and A549 adenocarcinoma cells was evaluated, where Zn-complexes displayed greater cytotoxic effects than Ni-complexes. Conductivity measurements, ESI-MS, UV-Vis, molar conductivity, IR, 1H, and 13C NMR spectra were used to characterize the products. Furthermore, molecular docking was performed to assess the biological activity of the complexes, and it was observed that Zn-complexes exhibited the highest inhibition effect against cytotoxic receptors.

Stimuli-responsive triplet-triplet annihilation upconversion with guanidyl functionalized annihilators for enhanced ratiometric sensing of trace water in MeOH

Adding stimuli-responsiveness to TTA-UC is appealing as it provides a unique platform for biosensing and chemosensing. Here, we synthesized three guanidyl functionalized annihilators A-1∼A-3 for stimuli-responsive TTA-UC. The annihilator A-1 self-assembled into microparticles in aprotic solvent like THF, CHCl3 and toluene with the DPA units arranged in an ordered manner via the strong hydrogen bonding interactions between the guanidyl groups, which guaranteed effective energy migration of triplet excitons, thus, efficient TTA-UC with ΦUC of 10.2% was observed in THF. While MeOH degraded the well-aligned aggregates, accompanied by the decrease of ΦUC to 2.9%. For A-2 and A-3, weak UC emissions in all the investigated solvents were observed due to π-π stacking of anthracene core. Interestingly, the destroyed hydrogen-bonding network of A-1 was successfully reconstructed by the addition of trace water with ΦUC recovered from 2.9% to 9.2% when 3% water was added. We also found that the well-aligned aggregates significantly accelerated the TTA process but have no impact on the TTET process, thus, enhanced ratiometric sensing of trace H2O in methanol was achieved with the unchanged phosphorescence as the internal standard and a detection limit as low as 0.084% (v/v) was achieved.

An Electrochemical Investigation of Methanol Oxidation on Thin Films of Nickel Oxide and Its Composites with Zirconium and Yttrium Oxides

The present work is focused on the fabrication of NiO-ZrO2/FTO and NiO-Y2O3/FTO thin films via a simple dip-coating method. The films are deposited from precursor solutions of Ni(CH3COO)2·2H2O, Zr(CH3COO)4, Y(CH3COO)3·H2O in methanol. The synthesized films, after proper characterization, are employed for electrochemical oxidation of methanol. The analytical techniques such as X-ray diffraction (XRD), Raman, and Infrared (IR) spectroscopy reveal the successful formation of crystalline thin films of mixed metal oxide without any additional impurities. Further, X-ray photoelectron spectroscopy (XPS) results, confirm the composition and oxidation state of all the elements present in thin films. The field emission scanning electron microscopy (FESEM) further aided to identify the uniformity and porous nature of composite thin films while the energy-dispersive X-ray spectroscopy (EDS) confirms the targeted elemental composition of the prepared thin films is in good agreement with precursors. The electrochemical oxidation of methanol results reveals that NiO-Y2O3/FTO and NiO-ZrO2/FTO thin films showed current densities of 6.2 mA/cm2 and 10 mA/cm2 at 0.65 V, respectively, against Ag/AgCl/3M KCl using 0.6 M methanol solution. Furthermore, Chronoamperometric (CA) results show good stability of NiO-ZrO2/FTO and NiO-Y2O3/FTO thin films with observed current decay of 10% and 6.8% of the initial current density, respectively. Moreover, the effect of scan rate and concentration of metals in a catalyst was also investigated. The Electrochemical impedance studies (EIS) further support electrochemical results, where the lower charge transfer resistance (Rct) values are recorded for composite thin films as compared to the pure metal oxide thin films (NiO/FTO, ZrO2/FTO, and Y2O3/FTO).

SINTESIS DAN TRANSISI ELEKTRONIK KOMPLEKS TEMBAGA (II)-KLOROFIL

The copper (II)-chlorophyll complex was prepared from the reaction between the chlorophyll isolated from cassava leaves and the metal ion precursor, CuSO4.5H2O in methanol under reflux for four hours. The FTIR spectra of the reaction product compared to the chlorophyll spectra show an indication of a complexation through metal coordination with the N atom from the phyrol ring replacing the magnesium (II) ion in chlorophyll.This assumption is drawn based on changes on FTIR spectra, i.e. vibration absorption originating from the CN and NH groups in the porphyrin ring and the appearance of the distinctive vibration band of nitrogen-metal bonds which is annotated as Cu-N groups at 599.88 cm-1. Another sign is the change in the OH and CO vibration bands which imply changes in aggregate properties that occur through inter-molecular interactions due to the introduction of copper (II) metal into the chlorophyll structure. The formation of copper (II)-chlorophyll compounds is also shown from the results of atomic absorption spectroscopy by recording copper metal in the product and reducing magnesium metal concentration. UV-vis spectra of chlorophyll in methanol show a characteristic band in the dark area (Soret band) at a maximum wavelength of 404 nm and the visible area (Q band) with the strongest intensity at 665 nm. These peaks appear to shift hypsochromically in the copper (II)-chlorophyll compound to 397 nm and 650 nm with higher absorptivity, indicating a change in the electronic transition of the chlorophyll after coordinating with the copper (II) ion. A new peak at 411 nm was also observed which is suggested to indicate that the copper (II) -chlorophyll complex is in an octahedral geometry in the aggregate coordinated via nitrogen atoms in the phyrol ring in place of the magnesium (II) ion.

Detecting Cu2+ and H2O in methanol based on aggregation-induced emission fluorescent enhancement

A tridentate Schiff base probe L (2-NC5H4)C(H)=N(C6H4OH-2) was synthesized via a facile reaction. Probe L showed weak fluorescence emission that originated from intermolecular proton transfer in solution. With addition of Cu2+, the emission of L was quenched by the paramagnetic nature of Cu2+. However, after the solution of L and Cu2+ was refluxed, the emission presented a completely opposite result changing from fluorescent quenching to fluorescent enhancement. The fluorescent enhancement was attributed to a planar cis-structure of Cu2+ complex. Hence, a strategy for change of emission behavior of fluorescent probe L to Cu2+ was developed; a “turn on” mode of detection Cu2+ was realized in methanol solution. A simple refluxing made probe L work as a light-up fluorescent sensor for Cu2+ in methanol solution and gave improvement of sensitivity and selectivity in detection of Cu2+. When H2O was added into the solution of the Cu2+ complex, fluorescent enhancement increased and it can be used to detect water content in methanol.

Organotin(IV) selenate derivatives – Crystal structure of [{(Ph3Sn)2SeO4} ⋅ CH3OH] n

Abstract Crystallization of [(Ph3Sn)2SeO4] ⋅ 1.5H2O in methanol leads to the formation of [{(Ph3Sn)2SeO4} ⋅ CH3OH] n (1) which constitutes a new specimen of organotin(IV) selenate derivatives. In the solid state, complex 1 is arranged in polymeric zig-zag chains, composed of alternating Ph3Sn and SeO4 groups. In addition, pendant Ph3Sn ⋅ CH3OH moieties are branched along chains according to a syndiotactic organization and via Sn-O-Se connections. From a supramolecular point of view, intermolecular hydrogen bonds established between the selenate groups (uncoordinated oxygen) and the hydroxyl functions (CH3OH) of the pendant groups link the chains together.

CHROMIUM (III) COMPLEX OF 2-AMINO-3-CARBOMETHOXY-4,5,6,7-TETRAHYDROBENZO[B] THIOPHENE: SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY

A new chromium (III) coordination compound of 2-amino-3-carbomethoxy-4,5,6,7-tetrahydrobenzo[b]thiophene (ACTT) (3) with Cr(NO3)3.9H2O in methanol at room temperature for 48 hours has been prepared. The composition of the new complex compound (4) has been confirmed by a number of instrumental methods including IR, NMR, MS and elemental analysis. It was found that the ACTT ligand behaves as bidentate chelating agent and coordinates to the central metal ion through the nitrogen atom of the amino-group and the oxygen atom of the carbonyl function of the ester group. The results showed that in the coordination sphere of the complex, the metal ion is coordinated by three chelating ACTT ligands. In the structure of the cation core [Cr(ACTT)3]3+, the three ACTT ligands are linked to the chromium ion through three Cr-N and three Cr-O bonds forming a square bipyramidal geometry. The metal complex and the ACTT ligand were screened for their antimicrobial activities against several strains of bacteria (Staphylococcus aureus ATCC25923, Escherichia coli S2 (1), Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa ATCC27853, Shigella flexneri SDINT) and fungi (Candida albicans ATCC10231, Candida tropicalis PK233, Cryptococcus neoformans H99). The chromium complex showed promising antimicrobial activity against the microorganisms with minimum inhibitory values between 4 and 16 μg/mL.

Supramolecular assembly of lanthanide-2,3,5,6-tetrafluoroterephthalic acid coordination polymers via fluorine⋯fluorine interactions: a platform for luminescent detection of Fe3+ and nitroaromatic compounds

F⋯F interactions stabilize {[Ln(TFTA)1.5(H2O)2]·H2O}n 2D coordination polymers which selectively detect Fe3+ and p-nitrophenols.

Tracking the Process of a Solvothermal Domino Reaction Leading to a Stable Triheteroarylmethyl Radical: A Combined Crystallographic and Mass‐Spectrometric Study

AbstractA new free carbon radical was obtained in a microwave‐assisted solvothermal reaction of the primary amine (1‐methyl‐1H‐benzo[d]imidazol‐2‐yl)methanamine with FeCl3⋅6 H2O in methanol at 140 °C. Through a combination of crystallography and electrospray ionization mass spectrometry, the reaction process was studied. The longest domino reaction includes 14 steps and forms up to 12 new covalent bonds (9 C−N and 3 C−C bonds) and 3 five‐membered heterocycles. For the first time, the homolytic cleavage of a C−O bond was used to synthesize a triarylmethyl radical.

Tracking the Process of a Solvothermal Domino Reaction Leading to a Stable Triheteroarylmethyl Radical: A Combined Crystallographic and Mass-Spectrometric Study.

A new free carbon radical was obtained in a microwave-assisted solvothermal reaction of the primary amine (1-methyl-1H-benzo[d]imidazol-2-yl)methanamine with FeCl3 ⋅6 H2 O in methanol at 140 °C. Through a combination of crystallography and electrospray ionization mass spectrometry, the reaction process was studied. The longest domino reaction includes 14 steps and forms up to 12 new covalent bonds (9 C-N and 3 C-C bonds) and 3 five-membered heterocycles. For the first time, the homolytic cleavage of a C-O bond was used to synthesize a triarylmethyl radical.

Impact of mechanochemical treatment of organophilic Indian bentonites: implications for their rheology

To study and determine the dependency of rheological properties and flow behaviour of organobentonites on mechanochemical modification viz. grinding and preparation temperature of organobentonite, stearyldimethylbenzylammonium-bentonites (SDMBA-bentonites) were prepared by interacting stearyldimethylbenzylammonium chloride with Indian bentonite at different reaction temperature of 40, 60, 80, 90 and 100 °C and the products were ground and passed through sieve (micronization) of 100 mesh BSS (< 150 µm) and also the product obtained at 40 °C was further processed for micronization using 150 (< 105 µm), 240 (< 63 µm) and 350 (< 45 µm) mesh BSS sieves. As there was increase in the micronization and the reaction temperature, the bulk density and particle size decreased with simultaneous increase in the surface area of SDMBA-bentonites. The enhancement of the viscosity, rheological parameters and gel index of the toluene dispersions of these SDMBA-bentonites was also observed. The decrease in particle size and bulk density with simultaneous increase in specific surface area and swelling in nitrobenzene SDMBA-bentonites leads to the formation of larger hydrogen bond network to generate improved rheological properties by increased magnitude of chemical interaction between SDMBA cations and toluene. The rheological behaviour study revealed that all the toluene–SDMBA-bentonite dispersions exhibit the shear-thinning flow behaviour and the micronization and reaction temperature influence the degree of shear-thinning, stability of the gel structures and yield stress of the dispersions. The incorporation of a mixture of 5 vol% of H2O in methanol as polar activator studied in the range of 33–100 wt% of SDMBA-bentonite reinforced the rheological properties, viscosity and gel volume, degree of shear-thinning, stability of the gel structures and yield stress of the toluene–SDMBA-bentonite dispersions. The SDMBA-bentonites with polar activator having concentration of 65 wt% exhibited the optimum rheological reinforcement. The rheological properties were found to be more enhanced by the ultrasonication relative to conventional stirring/shearing. Power law and Casson equations have been used to describe the rheological properties of the toluene–SDMBA-bentonite dispersions.

Nitrite-bonded nickel(II) complex of N-cyclohexyl-N-(2-pyridinylmethyl)amine; Synthesis, spectroscopic characterization, X-ray structure and DFT calculations

A combined experimental and computational investigation on a nickel(II) complex of N-cyclohexyl-N-(2-pyridinylmethyl)amine, L, was carried out. The compound [NiL2(ONO)]NO2·½CH3CN has been prepared by the addition of L to a suspension of K4[Ni(NO2)6]·H2O in methanol and structurally characterized by a combination of analytical, spectroscopic and crystallographic methods. The nickel(II) center in the complex is surrounded by two amine nitrogen and two oxygen atoms of the nitrite ion (η2-ONO) in the basal plane and two nitrogen atoms of pyridine moieties in apical positions, forming a distorted octahedral geometry. The relative stability of the geometrical isomers (cis and trans) and linkage isomers (η1-NO2, η2-ONO and η1-ONO) of the complex were investigated by density functional theory (DFT) calculations. In support of the X-ray structure, the calculated results verified that in all cases the cis-bidentate η2-ONO isomer is more stable than the other four-coordinated nitro isomers. A further theoretical analysis of the electronic structure of the complex has also been carried out to achieve deeper insight into the properties of the relevant molecular orbitals.

Tetra(μ3-hydroxo) bridged copper(II) tetranuclear cubane complexes: synthesis, crystal structure, and DNA binding studies

The tridentate Schiff base H2L was synthesized by the condensation of equimolar amount of 1-amino-2-propanol and salicylaldehyde. The reaction of H2L with an equimolar amount of Cu(CH3COO)2·H2O in methanol leads to the formation of the tetranuclear Cu4L4, 1. However, reaction of equimolar amount of H2L, copper(II) acetate, and 2,4,6-trimethylaniline in methanol forms a mixture of products which includes a discrete mononuclear complex Cu(L′)2, 2m (where HL′ is a bidentate ligand), in addition to the tetranuclear Cu4L4 species, 2c. In both tetranuclear cubane species, the tridentate H2L is both a chelating and a bridging ligand, after deprotonation of the enolic and the phenolic OH. The copper(II) centers are five-coordinate with a [N, O4] donor set from the ligands. The coordination geometry about each copper is distorted square pyramidal with one nitrogen and two oxygen from one ligand and two oxygen from adjacent ligands in the next unit of the cubane. In mononuclear 2m, the ligand is bidentate and the coordination geometry around copper(II) is square planar. The absorption spectra strongly suggest that tetranuclear 1 interacts with CT-DNA.

Synthesis and Characterization of a Cobalt(II) Complex with(E)-Ń-(2-Hydroxy-3-Methoxybenzylidene)Isonicotinohydrazide and (E)-Ń-(2-Hydroxy-3-Methoxybenzylidene)Isonicotinohydrazidanium Nitrate as a By-Product

A Schiff base ligand was synthesized from the reaction of isonicotinic acid hydrazide with 3-methoxysalicylaldehyde. The reaction of LH with Co(NO3)2 .6H2O in methanol gave dark red crystals of [Co(HL)2](NO3)2.3H2O and colorless crystals of the protonated ligand (HLH)+ with nitrate as the counter ion, (HLH)(NO3). In coordination to metal, Schiff base ligand was protonated via hetrocyclic nitrogen atom of the pyridine ring and deprotonated on the phenolic OH group, two ligands behave as neutral tridentate ligands. The extensive O–H···O and N–H···O hydrogen bonding interactions in the solid state contribute to the formation of an infinite one-dimensional chain in the complex.

ChemInform Abstract: Type 2 Ring‐Opening Reactions of Cyclopropanated 7‐Oxabenzonorbornadienes under Acid Catalysis.

A novel ring-opening mode of cyclopropanated 7-oxa­benzonorbornadiene under acid catalysis has been discovered, providing various 2-(alkoxymethyl)naphthalenes through the use of alcohol nucleophiles. The reaction was most effective with catalytic p-TsOH∙H2O in methanol, offering yields up to 91%. The compatibility of secondary and tertiary alcohols, as well as functionalized substrates was also demonstrated.

Preparation, structure, and thermochemical properties of a copper(II) Schiff-base complex

A copper(II) Schiff-base complex [CuL·2MeOH·H2O] was prepared by reaction of the ligand [H2L = N, N′-o-phenylene-bis(3-methoxysalicylideneimine)] and Cu(OAc)2·H2O in methanol at 328.15 K. X-ray diffraction analysis revealed that the title complex was crystallized in the triclinic crystal system with space group P–1, in which copper(II) ion was located in the N2O2 ligand binding sites. According to two designed thermochemical cycles, the dissolution enthalpies of relevant substances of two reactions in the calorimetric solvents were determined by a solution-reaction isoperibol calorimeter, respectively. Combined with some other auxiliary thermodynamic data, the standard molar enthalpies of formation of the ligand and the complex were calculated to be: $$ \Delta_{\text{f}} H_{\text{m}}^{\theta } $$ [H2L(s), 298.15 K] = −(384.2 ± 9.10) kJ mol−1 and $$ \Delta_{\text{f}} H_{\text{m}}^{\theta } $$ [CuL·2MeOH·H2O (s), 298.15 K] = −(1072.6 ± 9.2) kJ mol−1.

Type 2 Ring-Opening Reactions of Cyclopropanated 7-Oxabenzonorbornadienes under Acid Catalysis

A novel ring-opening mode of cyclopropanated 7-oxa­benzonorbornadiene under acid catalysis has been discovered, providing various 2-(alkoxymethyl)naphthalenes through the use of alcohol nucleophiles. The reaction was most effective with catalytic p-TsOH∙H2O in methanol, offering yields up to 91%. The compatibility of secondary and tertiary alcohols, as well as functionalized substrates was also demonstrated.

Ni(II) complexes of dithiophosphonic acids

The reaction of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson reagent) with isobutanol, cyclohexylamine and phenylethylamine produced (4-methoxy-phenyl)-phosphonodithioic acid o-isobutyl ester HS2P(p-C6H4OMe) (OCH2CH(CH3)2) (I), [S2P(C6H11NH)(p-C6H4OMe) H3N+C6H11] (II) and [S2P(phCH2CH2NH) (p-C6H4OMe)H3N+CH2CH2ph] (III), respectively. The reaction of alcohol with Lawesson reagent produced neutral product (I) while that with amines led to an ion pair (II, III). Furthermore, reaction of I, II and III with NiCl2.6H2O in methanol produced novel complexes: IV, V and VI. The compounds were characterized by 1H, 13C and 31P NMR, IR spectroscopy and elemental analysis. The single crystal X-ray structures of IV and V showed that the nickel complexes are square planar. Compound V formed a three-dimensional supramolecular structure via intermolecular P–O …H–N hydrogen bonds. The X-ray crystallography of V showed that those three hydrogens of + NH 3 cation produced three hydrogen bonds with different distances. The new compounds were additionally tested in view of their anti-bacterial properties. The ligands containing amine substituents exhibited more activity toward tested bacteria than their alcohol substituents, while the Ni(II) complexes including alcohol substituents exhibited high potential. The reaction of HS2P(p-C6H4OMe) (OCH2CH(CH3)2) (I), [S2P(C6H11NH)(p-C6H4OMe)H3N+C6H11] (II) and [S2P(phCH2CH2NH) (p-C6H4OMe)H3N+CH2CH2ph] (III) with NiCl2.6H2O in methanol led to novel complexes (IV, V and VI). Compound V formed a three-dimensional supramolecular structure via intermolecular P–O…H–N hydrogen bonds. The compounds were additionally tested for antibacterial properties.

1,2-Addition of Dihydrogen across Rhodium(III)–OMe Bonds

The Rh(III) complexes [((t)bpy)2Rh(OMe)(L)][X]n ((t)bpy = 4,4'-di-tert-butyl-2,2'-bipyridyl; L = MeOH, n = 2, X = OTf (OTf = trifluoromethanesulfonate), TFA (TFA = trifluoroacetate); L = TFA, n = 1, X = OTf) have been shown to activate dihydrogen via net 1,2-addition of the H-H bond across the Rh(III)-OMe bond. The bis(methoxide) complex [((t)bpy)2Rh(OMe)2][OTf] was synthesized by addition of CsOH·H2O in methanol to [((t)bpy)2Rh(OTf)2][OTf] in CH3CN. The addition of HTFA to [((t)bpy)2Rh(OMe)2][OTf] leads to the formation of [((t)bpy)2Rh(OMe)(MeOH)][OTf][TFA], which exists in equilibrium with [((t)bpy)2Rh(OMe)(TFA)][OTf]. The mixture of [((t)bpy)2Rh(OMe)(MeOH)][OTf][TFA] and [((t)bpy)2Rh(OMe)(TFA)][OTf] activates dihydrogen at 68 °C to give methanol and [((t)bpy)2Rh(H)(TFA)][OTf]. Studies indicate that the activation of dihydrogen has a first-order dependence on the Rh(III) methoxide complex and a dependence on hydrogen that is between zero and first order. Combined experimental and computational studies have led to a proposed mechanism for hydrogen activation by [((t)bpy)2Rh(OMe)(MeOH)][OTf][TFA] that involves dissociation of MeOH, coordination of hydrogen, and 1,2-addition of hydrogen across the Rh-OMe bond. DFT calculations indicate that there is a substantial energy penalty for MeOH dissociation and a relatively flat energy surface for subsequent hydrogen coordination and activation.