Electrolytes In DMF Research Articles

Synthesis, characterization, and antibacterial studies of some of first transition series metals and zinc complexes with mixed ligands of trimethoprim-isatin and nitrogen base

Complexes of mixed-ligand Schiff bases [trimetho-prim (TMP) with isatin] (L1) and nitrogen bases [2,2′-bipyridine (bipy)] (L2), [1,10-phenanthroline (phen) (L3)] with metal chlorides: M = Cr3+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+ were prepared and characterized by metal content determination (%), FT-IR, electronic, nuclear magnetic resonance, mass spectroscopy, magnetic susceptibility, conductance measurements and elemental analysis (CHN). The bacterial activity of the ligands and their metal compounds was evaluated via various microorganisms. Infrared spectra of Schiff base showed an azomethine peak shifted in complexes that coincide synthesis and coordination of Schiff base through the nitrogen atom of azomethine C=N) and the oxygen atom of the carbonyl group of L1 with metal ions. L2, L3 (bipy, phen) coordinated through the di imine nitrogen atoms. Conductance dimensions suggested the non-conductance nature of all the compounds except Cr(III) complexes, this outcome fits in with the molar conductance value estimated for 1:1 electrolyte in DMF. Magnetic susceptibility analysis and electronic spectra indicated an octahedral geometry for all complexes. Biological study for prepared compounds have been evaluated towards pathogenic microbes Staphylococcus aureus and Bacillus subtilis. Some compounds have stronger antibacterial action than Schiff base towards tested microbes. KEY WORDS: Antimicrobial, Heterocyclic compounds, Schiff base, Trimethoprim drug, 2,2-Bipyridyl, 1,10-Phenanthroline Bull. Chem. Soc. Ethiop. 2024, 38(4), 1013-1025. DOI: https://dx.doi.org/10.4314/bcse.v38i4.16

Solvation and Electrochemical Properties of Cobalt Tetrasulfophthalocyaninate in Water−N,N-Dimethylformamide Mixtures

The effect of the composition and properties of the mixed water–N,N-dimethylformamide solvent (χDMF = 0.0–1.0 mole fraction) on changes in the solvated state of cobalt 3(4),10(11),17(18),24(25)-tetrasulfophthalocyaninate (CoTSPc) was studied. The region of electrochemical stability of the CoTSPc–DMF electrolyte system at 25.0°C was determined. The study was performed by the interphase distribution method, electronic absorption spectroscopy, and cyclic voltammetry.

Zn anode sustaining high rate and high loading in organic electrolyte for rechargeable batteries

Rechargeable aqueous Zn battery, the promising candidate for future energy storage devices still suffers from multiple disadvantages of low reversibility, uncontrolled dendrite growth, and limited electrochemical potential window. Alternatively, organic electrolytes can theoretically resolve the thermodynamic instability of Zn anode, but at the expense of high-rate capability due to their inferior ionic conductivity. Here we report N, N-dimethyl formamide (DMF) based non-aqueous electrolyte containing Cu2+ ions as an additive (Cu2+-DMF). The combined effect of high thermodynamic stability of Zn anode in DMF electrolyte and in-vitro Cu-Zn alloy interphase can surpass both aqueous and non-aqueous electrolyte performance. High-rate capability, low overpotential of ∼50 mV at 20.0 mA cm−2/20.0 mAh cm−2, supreme stability over 1400 h at 5.0 mA cm−2/5.0 mAh cm−2, high Coulombic efficiency (CE, ∼99.60 %) and wide electrochemical stability window (∼2.45 V vs. Zn/Zn2+) is observed for Cu2+-DMF electrolyte. As a proof-of-concept, Zn||δ-MnO2 battery configuration in DMF electrolyte exhibits stable cycling, high-rate capability, and excellent reversibility. For deep understanding, the electrochemical kinetics and storage mechanism are also validated through multiple characterization techniques. This work is a substantial step towards the cost-effective construction of rechargeable non-aqueous Zn ion batteries.

Iron Sulphur Cluster [Fe4S4(SPh)4]2– Catalyzed Electrochemical Reduction of CO2 on Carbon Electrodes in [Bu4N][BF4]-DMF Mixture

Background:An efficient, selective and durable electrocatalytic carbon dioxide (CO2) reduction system is a prerequisite to tackle energy and pollution-related issues. In this context, both organic and inorganic materials have gained a significant interest worldwide.Objective:In the present work, the electrocatalytic reduction activity of an iron-sulphur (Fe-S) cluster, [Fe4S4(SPh)4]2– for CO2 → carbon monoxide (CO) conversion has been investigated. The effect of catalyst concentration on the yield of CO and H2 was determined. Besides, the influence of reaction conditions (presence or absence of a Brønsted acid, electrolysis time etc.) on faradaic yield and product selectivity was also investigated.Methods:Cyclic voltammetry (CV) was carried out on vitreous carbon electrode in 0.1 M [Bu4N] [BF4]-DMF electrolyte. At the end of electrolysis, products were collected by tight-gas syringe and analyzed by gas chromatography (GC) system coupled with a thermal conductivity detector.Results:The Fe-S cluster was found to efficiently catalyse the process on carbon electrode in 0.1 M [Bu4N][BF4]-DMF electrolyte. Moreover, the presence of cluster shifted the reduction potential by ~ 200 mV towards the positive. GC analysis confirmed the formation of CO with a current efficiency of ca. 70%. On the other hand, 12% H2 was observed at the end of electrocatalysis.Conclusion:In summary, Fe-S cluster was used for the electrocatalytic reduction of CO2 in 0.1 M [Bu4N][BF4]-DMF electrolyte. The use of cluster (catalyst) was found to be important for CO2 reduction as no CO was detected in the absence of the catalyst. This study highlights the potential application of Fe-S cluster for CO2 reduction.

Remarkable Selectivity and Photo‐Cytotoxicity of an Oxidovanadium(IV) Complex of Curcumin in Visible Light

AbstractOxidovanadium(IV) complexes of 2‐(2′‐pyridyl)‐1,10‐phenanthroline (pyphen), viz. [VO(pyphen)(acac)](ClO4) (1), [VO(pyphen)(anacac)](ClO4) (2) and [VO(pyphen)(cur)](ClO4) (3), where acac is acetylacetonate (in 1), anacac is anthracenylacetylacetonate (in 2) and cur is curcumin monoanion (in 3) were synthesized, characterized and their photo‐induced DNA cleavage activities and photo‐cytotoxicities studied. The complexes are 1:1 electrolytes in DMF. The one‐electron paramagnetic complexes show a d‐d band near 760 nm in DMF. Complexes 2 and 3 are blue and green emissive, respectively, in DMSO. The complexes exhibit irreversible VIV/VIII reductive responses near –1.1 V and VV/VIV oxidative responses near 0.85 V vs. SCE in DMF–0.1 M TBAP. Complexes 2 and 3 display significant and selective photo‐cytotoxicity upon irradiation with visible light giving an IC50 value of about 5 μM against HeLa and MCF‐7 cancer cells; they are significantly less‐toxic against normal 3T3 control cells and in the absence of light. Complex 1 was used as a control. Both cytosolic and nuclear localization of the complexes were observed on the basis of fluorescence imaging. The complexes, avid binders to calf thymus (ct) DNA, were found to photocleave supercoiled pUC19 DNA upon irradiation with near‐IR light (785 nm) by generating hydroxyl radical (·OH) as the reactive oxygen species (ROS). Cell death events noted with HeLa and MCF‐7 cell lines likely are attributable to apoptotic pathways involving light‐assisted generation of intracellular ROS.

Application of high-performance MnO2 nanocomposite electrodes in ionic liquid hybrid supercapacitors

This work reports the synthesis of novel nanocomposite electrodes based on MnO2 nanosheets, Pt, Au, or Pd nanoparticles (NPs), exfoliated carbon nanotubes (CNTs), and Ni foam (NF) substrates. The MnO2–Pd–CNT–NF electrode in 1-butyl-3-methyl-imidazolium hexafluorophosphate (BMIM-PF6)/N, N-dimethylformamide (DMF) electrolyte exhibits a high specific capacitance of 559.1F/g based on MnO2 with a wide potential window (2.1V). To the best of our knowledge, this is one of the highest capacitance for MnO2 in ionic liquid (IL) electrolytes ever reported. The IL hybrid supercapacitors are assembled using MnO2–Pd–CNTs–NF positive electrode, activated carbon (AC) negative electrode, and BMIM-PF6/DMF electrolyte displaying high operating voltage (3V), high energy density (78.4Wh/kg) and high power density (12.7kW/kg). The superior performances of the MnO2 IL hybrid supercapacitors suggest their potential application for the future generation of electrochemical power sources.

Copper-catalyzed electrochemical synthesis of alkylidene lactones from carbon dioxide and 1,4-diarylbuta-1,3-diynes

The novel synthesis of alkylidene lactones from carbon dioxide with 1,4-diarylbuta-1,3-diynes via copper-catalyzed electrochemical route is described. The procedure was smoothly performed in an undivided electrochemical cell fitted with Ni cathode and Al anode, containing n-Bu4NBr–DMF electrolyte with a constant current under 4 MPa pressure of CO2. The corresponding alkylidene lactones could be obtained in moderate to good yields in the presence of catalyst CuI, while the γ-keto carboxylic acids as main products were obtained without any catalysts. A reaction mechanism was also briefly discussed.

Photocytotoxic Oxidovanadium(IV) Complexes of Polypyridyl Ligands Showing DNA‐Cleavage Activity in Near‐IR Light

AbstractOxidovanadium(IV) complexes [VO(pyphen)(L)]Cl2 (1, 2) and [VO(pydppz)(L)]Cl2 (3, 4), where L is 1,10‐phenanthroline (phen in 1 and 3) and dipyrido[3,2‐a:2′,3′‐c]phenazine (dppz in 2 and 4) are prepared and characterized. The crystal structure of [VO(pyphen)(phen)](ClO4)2 (1a) shows a six‐coordinate VN5O geometry with a VO2+ moiety in which the polypyridyl ligand binds in a meridional fashion and the phen ligand displays a chelating binding mode with an N‐donor site trans to the oxidovanadyl group. The complexes show a d–d band within 720–750 nm in DMF. The one‐electron paramagnetic complexes are 1:2 electrolytes in DMF. The complexes exhibit an irreversible VIV/VIII redox response near –0.85 V vs. SCE in DMF/0.1 M TBAP. The complexes bind to calf thymus (ct) DNA giving Kb values within 7.5 × 104 to 1.1 × 106 M–1. The complexes show poor chemical nuclease activity in the dark and exhibit significant DNA‐photocleaving activity in near‐IR light of 705 and 785 nm forming ·OH radicals. Complexes 2–4 show remarkable photocytotoxicity in HeLa cancer cells. FACS analysis of the HeLa cells treated with complex 4 shows cell death as highlighted by the sub G1 peak. Propidium iodide staining data indicate apoptosis as the primary mode of cell death.

Synthesis and characterization of heterobimetallic complexes of the type [Cu(pn)2][MCl4] where M = Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II)

A series of new bimetallic transition metal complexes of the type [Cu(pn)2] [MCl4] have been synthesized (where M=Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II), pn=1,3-diaminopropane) and characterized by elemental analysis, molar conductance, TGA, IR and electronic spectra. All the compounds are 1:1 electrolyte in DMF. The Cu(II) ion is square-planar while metal ions in the anionic moiety acquire their usual tetrahedral arrangement. On the basis of these studies it is concluded that anionic moiety is electrically stabilized by its cationic counterpart.

ChemInform Abstract: Electrosynthesis of Substituted 1H‐Indoles from o‐Nitrostyrenes.

AbstractThe reaction proceeds electrochemically on the carbon cathode using Me4NBF4 as a supporting electrolyte in DMF in the presence of phenol as a proton source.

Electrochemical behavior of graphene nanosheets in alkylimidazolium tetrafluoroborate ionic liquid electrolytes: influences of organic solvents and the alkyl chains

In this study, the electrochemical properties of graphene nanosheets (GNSs) in alkylimidazolium tetrafluoroborate ionic liquids/organic solvent electrolytes are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS). The organic solvents with different functional groups exhibit a significant influence on the electrochemical properties of the GNSs. From series of organic solvents, in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4)/N,N-dimethylformamide (DMF, C3H7NO) electrolyte the GNS electrode shows the best electrochemical performance. Furthermore, the effect of the alkyl chains of ionic liquids on the electrochemical properties of GNSs was also evaluated through the electrochemical tests. The electrochemical properties of GNS electrode in 1-methyl-3-methylimidazolium tetrafluoroborate (MMIMBF4)/DMF electrolyte are better than those in EMIMBF4/DMF and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4)/DMF electrolytes. This may be attributed to the difference in the length of the alkyl chain on the imidazole ring, which results in the structural change of the electrode/ionic liquid interface and thus affects the electrochemical performance of the GNS electrode.

Synthesis and physico-chemical studies of metal(II) complexes with diacetyl benzaldehyde acyldihydrazones and their bio-activity

Complexes of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with diacetyl benzaldehyde oxalic acid dihydrazone (dbodh), CH3COC(CH3)=NNHCOCONHN=CHC6H5 and diacetyl benzaldehyde malonic acid dihydrazone (dbmdh), CH3COC(CH3)=NNHCOCH2CONHN=CHC6H5 of general composition [M(dbodh)Cl]Cl and [M(dbmdh)Cl]Cl were synthesized and characterized by microanalyses, molar conductance, magnetic susceptibility, UV–Vis, ESR and IR spectra and X-ray diffraction studies. The complexes are 1 : 1 electrolytes in DMF and are insoluble in water and common organic solvents. The dbodh and dbmdh are neutral tridentate ligands in most complexes and coordinate via one >C=O and two >C=N–groups. In Cu(II) complexes the ligands are pentadentate coordinating through three >C=O and two >C=N–groups. The magnetic moment values and UV–Vis spectra suggest square-planar geometry for Co(II) and Ni(II) complexes and distorted octahedron for both Cu(II) complexes. The ESR spectra of Cu(II) complexes show well-defined copper hyperfine lines in DMSO solution at 120 K and exhibit d x 2 −y 2 as the ground state. The X-ray diffraction parameters for [Ni(dbodh)Cl]Cl and [Co(dbmdh)Cl]Cl correspond to a tetragonal crystal lattice. The complexes show significant antifungal activity against Alternaria sp., Curvularia sp. and Colletotrichum sp. and fair antibacterial activity against Bacillus subtilis and Pseudomonas fluorescence.

Synthesis, electrolytic behaviour and antimicrobial activities of cadmium complexes of isomers of 3,10-C- meso -3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane

Reactions of two diastereoisomers of 3,10-C-meso-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecanes, Me8[14]ane (LA and LB) with Cd(NO3)2 in methanol produced trans-[CdL(NO3)2] (L = LA or LB). However, the third diastereoisomer, Me8[14]ane (LC) did not react with Cd(NO3)2. Trans-[CdLB(NO3)2] undergoes axial ligand substitution reactions with KSCN, KNO2, KCl, KBr and KI, in the ratio of 1 : 2 to yield white solid products corresponding to molecular formula [CdLBX2] where X = NCS−, , Cl−, Br− or I−. Characterization has been carried out on the basis of elemental analysis, IR, UV-visible and 1H-, 13C- and 113Cd-NMR spectroscopy, as well as by magnetic moment and conductivity measurement. These complexes show different electrolytic behaviours in different solvents. In chloroform, they are noneletrolytic indicating that both anions coordinate to cadmium(II) with retention of original molecular formula [CdLBX2]; their 1 : 2 electrolytic nature in water reveals the formation of diaquo complexes [CdLB(H2O)2]X2. On the other hand, conductance values corresponding to 1 : 2 electrolyte in DMF indicate the formation of square pyramidal complexes [CdLB(DMF)]X2. The antimicrobial activities of these ligands and their complexes have been tested against some selected fungi and bacteria.

Triferrocenes Built on a C3-Symmetric Ligand Platform: Entry to Redox-Active pseudo-Triphenylenes via Chelation-Driven Stereoselection of Triple Schiff Bases

An expedient tandem deprotonation-trapping protocol was employed to prepare a tris(difluoroboronyl) complex of a triferrocenyl ligand that is geometrically analogous to substituted triphenylenes. A triple Schiff base condensation reaction between 1,3,5-triformylphloroglucinol and aminoferrocene afforded the tris(N-salicylideneamine) adducts 5a + 5b in ca. 1:1 ratio. The keto-enamine tautomeric core of this isomeric mixture could be converted to a common enolate-imine intermediate. Subsequent trapping with BF3.Et2O cleanly afforded the tris(difluoroboronyl) adduct 6 in essentially quantitative yield. The electronic and structural properties of this new class of ferrocene compounds were investigated using various methods including UV-vis, cyclic voltammetry (CV), differential pulse voltammetry (DPV), and X-ray crystallography. In CH2Cl2-CH3CN, 6 displayed a reversible three-electron oxidation process at E1/2ox = +210 mV (vs Fc/Fc+). Despite the sharing of a common [pi,pi]/[n,pi]-conjugated core, no significant electronic communication was observed among the three ferrocenyl units in 6 under either CV or DPV conditions. On the other hand, the broad oxidation wave of 5a + 5b at E1/2ox = +60 mV in CH2Cl2-CH3CN was comprised of at least two major components at +20 and +90 mV, which collapsed to become a single peak in DMF electrolyte, despite that the ratios between the two isomers 5a,b remained essentially invariant to the change in solvent.

Synthesis, Characterization and Fluorescence of N,N′‐Bis(6‐methyl‐2‐pyridinecarboxylamide‐N‐oxide)‐1,2‐ethane and Corresponding Rare Earth(III) Complexes

A new ligand, N,N′‐bis(6‐methyl‐2‐pyridinecarboxylamide‐N‐oxide)‐1,2‐ethane (L), and its six lanthanide(III) complexes (RE=La, Sm, Eu, Tb, Gd, Yb) were synthesized and characterized in detail. The results indicate that the composition of the binary complexes was determined as [REL(H2O)2(NO3)2] NO3 · nH2O (n=0–2), that the six complexes are 1∶1 electrolytes in DMF, and that the Eu3+ complex has bright red fluorescence in a solid state. At the same time, we synthesized three complexes of Eu3+, Tb3+, and Gd3+ with 6‐methylpicolinic acid N‐oxide (L,). The intensity of sensitized luminescence for Eu3+ increases in the following order: L>L′. The energies of an excited triplet state for the ligands are 20704 cm−1 (L) and 20408 cm−1 (L′), respectively. The fact that the ligands strongly sensitized Eu3+ and the order of the emission intensity for the Eu3+ complexes were explained by the relative energy gap between the lowest triplet energy level of the ligands (T) and 5D of Eu3+ or Tb3+. This means that the triplet energy level of the ligand is the chief factor, which dominates RE3+ luminescence.

Homogeneous electro-mediated reduction of unsaturated compounds using Ni and Fe as mediators in DMF

The homogeneous electro-mediated reduction (HEMR) of several organic compounds (cyclohexene, cyclohexanone, acetophenone, benzaldehyde, styrene, linalool, 1,3-cyclohexadiene, citral, trans-4-phenyl-3-buten-2-one, and piperine) was carried out using Fe2+, Ni2+, and [NiII(bpy)]Br2 (bpy=2,2′-bipyridine) as electron mediators. An electrochemical system composed of sacrificial anode (Fe, Ni or Zn), nickel cathode, NaI (0.2 M) as supporting electrolyte in DMF and an undivided cell, was used. A constant current ≤100 mA was applied with a maximum cell potential of 2.0 V. Non-conjugated olefins are not reactive, but ketones may be easily reduced to the respective alcohol. In the case of conjugated olefins and ketones, [NiII(bpy)]Br2 or Ni2+ mediator presented good reactivity and selectivity in most cases. Fe2+ more efficiently mediates the reduction of carbonyl containing systems. Preliminary electroanalytical studies indicate the complexation of the organic substrate by Fe2+ and Ni2+ ions and [NiII(bpy)]Br2 complex.

Electrochemical Pumping of DMF Electrolyte Solutions across Membranes

Electrolysis of (dimethylformamide) (DMF) solutions containing tetraalkylammonium iodide salts and dissolved iodine in a two-compartment cell separated by a Nafion membrane results in transfer of solution volume between the two compartments. The pumping process was reversible and the rate, which ranged from 20 to 50 μL/min, was controlled by the cell current. The volume of solution pumped was significantly greater than what is predicted from the apparent molar volumes of the species involved in the electrolysis and from the charge passed. The additional volume is attributed to migration-assisted solvent flow across the membrane separator. Comparison of pumping results for a series of Nafion materials indicated that the solvent flow was related to the number of solvent molecules per ion-exchange site in the membrane. Pumping occurred with and against small external pressures up to 0.1 atm. Analysis of apparent molar ionic volumes indicates that the electrode reaction, contributes little to the observed volume change. Instead, the pumping is associated almost entirely with the apparent molar ionic volume of tetraalkylammonium ions and migration-assisted flow of DMF. © 2004 The Electrochemical Society. All rights reserved.

Linear correlation of electrochemical reduction potential with substituent effect in a 5-phenyl-1,2-dithiole-3-thione series

A range of 19 different 5-phenyl-1,2-dithiole-3-thiones, meta- or para-substituted, were investigated in a DMF electrolyte at a platinum electrode. In all cases, excepted for the para-nitrophenyl derivative, the reduction appeared as a quasi-reversible process at 90 °C while it was generally irreversible at 20 °C. The redox potential of the quasi-reversible reduction ( E redox), or the peak potential of the irreversible reduction ( E p c ) followed a linear correlation involving the Hammett parameters σ m and σ p related to the phenyl group substituent. Good linear correlation relationships were obtained regardless of the characteristic potential ( E p c or E redox) or the temperature: at 20 °C E p c x (V/Fc +/Fc)=0.20 σ x−1.54 ( r=0.96) and at 90 °C E redox x (V/Fc +/Fc)=0.16 σ x−1.46 ( r=0.97). In the case of strong electron-withdrawing substituents ( para-CN or para-CO 2CH 3) the compounds showed quasi-reversible behaviour even at room temperature.

Electrochemical Detection for Gaseous Vinyl Chloride with a Sputtered Au/Porous Alumina Substrate/Pt Electrode Assembly

A detector with a porous alumina substrate has been developed to monitor vinyl chloride gas in the concentration range of 0.5–4% at room temperature successfully. Several operating variables, including type of supporting electrolyte, applied potential, concentration of supporting electrolyte, and porosity of alumina substrate were investigated to find the highest sensitivity for vinyl chloride sensing. Compared with tetrabutylammonium tetrafluoborate, higher sensitivities were obtained when tetrabutylammonium perchlorate was used as the supporting electrolyte. The highest sensitivity of 70.9 μA%−1 was obtained at −2.1 V (vs. Ag/Ag+) in 50% toluene/50% DMF electrolyte containing 10 mM Bu4NClO4 supporting electrolyte. The sensing current and the sensitivity for vinyl chloride increased significantly with the porosity of the porous alumina substrate.

Study on electroreduction of Eu(III) and electrodeposition of Eu–Co in europium toluenesulfonate+DMF

Europium toluenesulfonate highly soluble in organic solvent was prepared for the first time and was used as the electrolyte in DMF. The composition of its crystalline hydrate was determined as (p-CH3C6H4SO3)3Eu · 7H2O. Cyclic voltammetry and the E–t curve resulting from a current step were used to study the electroreduction of Eu(III) in (p-CH3C6H4SO3)3Eu+DMF. The electrode process of Eu(III) reduced on a Pt electrode occurs in two steps: Eu(III)+e−=Eu(II), Eu(II)+2e−=Eu; the first step is quasi-reversible. The diffusion coefficient of Eu(III) was calculated as 5.8×l0−7 cm2 s−1 at 25°C. A europium film with a bluish violet lustre and a Eu–Co film with black metallic lustre were obtained by potentiostatic electrolysis. SEM, EDAX and XRD were used to analyze the film. The composition of Eu–Co film is 69.4 at.%Co and 30.6 at.%Eu. It adheres firmly to the copper substrate.