DMF In Presence Research Articles

Tailoring the Interfacial Water Structure by Electrolyte Engineering for Selective Electrocatalytic Reduction of Carbon Dioxide

Engineering aqueous electrolytes with low amounts of additives to achieve a tunable CO2 reduction product is an underexplored territory in electrocatalysis. Here, we show the enhancement of the Faradaic efficiency (FE) of CO2 reduction to CO on unmodified polycrystalline gold from ∼67 to ∼94% by the addition of up to 15 mol % of N,N-dimethylformamide (DMF) to an aqueous electrolyte. The role of electrolyte structure modification near the electrode–electrolyte interface was studied using in situ surface-enhanced infrared absorption spectroscopy in attenuated total reflection mode (ATR-SEIRAS). In addition to the expected detection of the adsorbed CO (COad) intermediate present on the Au surface, in both the linearly bonded and bridge-bonded forms, we observed changes in the structure of interfacial water induced by the addition of DMF. The changes in the water stretching band and the DMF carbonyl band indicate an increase in the strongly hydrogen-bonded DMF–water pairs with increasingly negative potential near the interface in the presence of DMF. We hold this interfacial water structure modification by DMF responsible for increasing the CO2RR FE and decreasing the competing hydrogen evolution reaction (HER). Furthermore, the suppression of the HER is observed in other electrolytes and also when platinum was used as an electrode and hence can be a potential method for increasing the product selectivity of complex electrocatalytic reactions.

Improved electrical and mechanical properties of highly stretchable polymeric films prepared by blending DMF with the mixed solution of PEDOT:PSS and PVA

Stretchable conducting films of polymeric composite are prepared by mixing poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with poly(vinyl alcohol) (PVA) in presence of polar organic solvent N,N-dimethylformamide (DMF) and their structural, morphological, and improved electrical and mechanical responses are investigated. In presence of DMF, X-ray diffraction pattern exhibits the shifting of the crystalline peak of PEDOT:PSS/PVA film towards higher diffraction angle and 10 wt% DMF blended film shows highest crystallinity of 52.9%. DMF transforms PEDOT conformation from benzoid to quinoid structure. FTIR and UV–vis spectroscopy confirm the formation of hydrogen bonds among PSS, PVA and DMF components, whereas AFM images show the increase in surface roughness with DMF concentration. The composite films exhibit non-linear current (I) - voltage (V) characteristics which follow the Poole-Frenkel charge transport mechanism. 10 wt% DMF blended film exhibits highest electrical response (nearly 7 times higher at 5 V). At higher DMF concentration, films become highly stretchable and 10 wt% DMF film has elongation at break around 333.0 ± 17% which is almost 2 times higher. With increasing number of loading-unloading cycle, irreversible damage occurs in the film. The optimum concentration of DMF in this polymeric composite is highly effective for its use as a stretchable conducting film.

Synthesis and Spectroscopic Study of Some New 1,2,4-Triazino[5,6-b]indole Derivatives

The Scheme of this work included the synthesis and characterization of new two series of 1,2,4-triazino[5,6-b] indole and 8-bromo-1,2,4-triazino[5,6-b] indole derivatives according to the starting material used. Both, derivatives of 3-thione-1,2,4-triazino[5,6-b] indole and 8-bromo-3-thione-1,2,4-triazino[5,6-b] indole (3a & 3b) were prepared by using Isatin and 5-bromo isatin as a starting material, the new schiff`s bases (5a & 5b) were synthesized by the reaction of hydrazino indole derivatives (4a & 4b) with aromatic aldehydes. Tetracyclic derivatives (7a & 7b) were prepared by the reaction of hydrazino derivatives (4a & 4b) with carbon disulfide in the presence of pyridine. Also 3-(N-phenyl thiocarbamoyl hydrazino)-1,2,4-triazino-[5,6-b] indole, and 8-bromo-3-(N phenyl thiocarbamoyl hydrazino)-1,2,4-triazino-[5,6-b] indole (6a & 6b) were prepared by the reaction of the compound (4a & 4b) with phenyl thio isocyanate in the presence of DMF. Finally, new Mannich bases (9a & 9b) were prepared by the reaction of the new acetylenic indole derivatives (8a & 8b) with paraformaldehyde and secondary amine in the presence of coprous chloride as catalyst.
 These compounds were identified by their melting points and spectral data (IR & UV), and elemental analysis (C,H,N) and thin layer chromatography (TLC) were used.

Effect of cation and anion sizes of additive ionic liquid on the crystal structure of poly(vinylidene fluoride) nanofiber

We investigated the additive ionic liquid (IL) type dependence on the crystal structure of poly(vinylidene fluoride) (PVDF) nanofibers. As additive ILs, we used imidazolium based ILs with different cation and anion sizes. From differential scanning calorimetry (DSC) measurements, we found that there is a proper amount for the additive IL to promote PVDF crystallization, and the proper amount is influenced by the cation size, not by the anion size. In addition, it was found that IL itself inhibited the crystallization, but IL can promote crystallization under the presence of DMF.

Synthesis and Characterization of Biologically active Oxadiazole derivatives

The aryl-substituted oxadiazole motif is present in natural products and in many biologically active compounds. In this present communication, novel substituted oxadiazole derivatives were reported along with their isolation and synthesis by the reaction of 5- phenyl-1,3,4-oxadiazole-2-amine with several aldehydes in the presence of DMF and MK-10 as a catalyst. The compounds were characterized by spectral data such as IR, 1H NMR and 13C NMR.

Synthesis and Characterization of Polymer-anchored Ni(II) Complex

Polystyrene-3-aldehydosalicylate (PSCH2-FSal) reacts with o-aminophenol in presence of DMF and forms PS-FSal-OAP (A). A reacts with mercaptoacetic acid and converts into PS-FSal-OAP-THZ (B) as a result of cyclization. B reacts with nickel(II) acetate salt and forms [PSCH2– FSal-OAP-THZ.Ni(OAc)(DMF)3]. The coordination compound has been characterized by various studies like: FTIR, diffused reflectance spectral studies and magnetic moment measurements. B behaves like a bidentate (OS donor) ligand in this compound. The acetate group shows its monodenticity in this compound. [PSCH2–FSal-OAP-THZ.Ni(OAc)(DMF)3] exhibits an octahedral structure.

A novel asymmetric structured nanocomposite PEO-Cloisite based membrane for salt and dye separation

In this study a novel approach was adopted to couple cloisite functionalised with PEO nanoparticles to modify the polyether sulfone (PES) at low pressure nanofiltration membrane for the removal of salts and dyes from waste water. PES/f-(PEO-Cloisite) nanocomposite membranes were fabricated by phase inversion process in presence of DMF as solvent. The functionalised PEO-Cloisite mixture was characterised by SEM-EDX and the membranes were characterised by hydrophilicity and morphology. The highest water flux of 152.77 Lm−2h−1 was observed for 4.5 wt% of PEO-Cloisite in PES membrane. Contact angle values reduced from 74.3° to 60.9° with the increase in the concentration of PEO-Cloisite and confirmed the increase of hydrophilicity. The membrane performance was tested using model saline and dye solutions by low pressure nanofiltration under longer run mode. This study infers that modification of PES membranes using functionalised PEO-Cloisite increase the membrane stability can be used to alleviate the fouling in the treatment of industrial waste water.

Effect of eggshell/N,N-dimethylformamide (DMF) mixing ratios on the sonochemical production of CaCO3 nanoparticles

Bio-CaCO3 nanoparticles have several applications and have attracted significant attention in current research. N,N-dimethylformamide (DMF) has been proven to be an effective non-volatile solvent for synthesizing bio-CaCO3 nanomaterials from eggshell. However, the optimum ratio of eggshell and DMF need to be specified to achieve maximum nano-CaCO3 production for large-scale purposes. Thus, this work investigated the effect of eggshell/DMF mixing ratios on the production of CaCO3 nanoparticles from the chicken eggshell. The nano-CaCO3 were synthesized via dry milling and then sonication at a frequency of 40 kHz for 6 h in the presence of DMF. The eggshell mass was varied from 0.5 to 20 g per 100 mL of DMF. The synthesized CaCO3 materials were characterized using SEM, TEM, EDX, XRD, and BET surface analysis. The eggshell/DMF ratio was optimized to maximize the production of CaCO3 nanoparticles, and its effect on the size, crystallinity, surface area, and porosity of the CaCO3 particles were discussed. Increasing eggshell/DMF ratio decreased the sonication efficiency with increasing crystallite and particle size. The specific surface area of the synthesized CaCO3 particles decreased with increasing eggshell/DMF ratio. 1 g/100 mL was the optimum or highest ratio to obtain 100% nano-CaCO3. At 1 g/100mL ratio, the bio-CaCO3 contained a crystallite size of 23.08 nm, particle size between 5 and 30 nm and surface area of 47.44 m2 g−1.

Synthesis and characterization of polypyrrole encapsulated formamidinium lead bromide crystals for fluorescence memory recovery

Impressive optical properties of organic–inorganic lead halide perovskite crystals make them suitable for optoelectronic devices. However, these crystals are unstable in water and other polar solvents and quickly lose their fluorescence which cannot be recovered by the addition of non-polar solvents. Fluorescence recovery is absolute necessity for long-term stability of perovskite in optoelectronic devices. Till date, there is no report showing mechanism of fluorescence recovery of organic–inorganic lead halide perovskite crystals. Here, we have reported the synthesis of FAPbBr3/polypyrrole (PPy) composites (FA = Formamidinium) for shedding light on the mechanism of fluorescence recovery in presence of N,N Dimethyl formamide or DMF. We have synthesized FAPbBr3 crystals at room temperature and tuned their band gap from green to blue by varying the amount of surfactant. Similar study was repeated with FAPbBr3/PPy composites, synthesized through in situ polymerization. Encapsulation was found to improve the emission quality and purity of the colour and successfully restored the fluorescence memory which was lost in presence of DMF. The recovery was attributed to resurfacing of PPy in presence of toluene which brought the building blocks of FAPbBr3 crystals back to the co-crystallization domain. In brief, this fundamental finding could pave the future way for achieving long-term stability of perovskite crystals in optoelectronic devices.

Co2 Be a Catalyst? Yes, Evidence from N-Formylation of Aliphatic Amines with Dmf in Presence of Co2

Co2 Be a Catalyst? Yes, Evidence from N-Formylation of Aliphatic Amines with Dmf in Presence of Co2

Synthesis of Some Novel Indoline-2,3-Dione Derivatives and the Influence of Gamma Irradiation on Their Biological Activities

2-(2-oxoindolin-3-ylidene)-N-phenylhydrazinecarbothioamide (4) was synthesized by reaction of 3-hydrazonoindolin-2-one (3) with phenyl isothiocyanate in DMF in presence of potassium hydroxide. Thus, treatment of 4 with the appropriate halo ketones, hydrazonoyl halides, and benzylidene malononitriles afforded thiazolidin-4-one, and thiadiazole derivatives. Moreover, structures of the newly synthesized compounds were elucidated as based of elemental analysis and spectral data. Also, the influence of gamma irradiation on the biological activities of the new compounds was evaluated.

Synthesis, Characterization of New Polytriazole Derivatives from Polyacryloyl chloride and Theoretical with Corrosion Inhibitor Study for Stainless steel in acidic medium

The purpose of the study is to synthesize and characterize a new polytriazole derivative from polyacryloyl chloried, first reaction of polyacryloyl chloride with hydrazine hydrate in the presence of DMF as a solvent to obtained acid hydrazide (1) than reacted with different amide to give poly 1,2,4-triazole derivatives(1a-1c). Newly synthesized compounds were characterized by spectral methods [13C-NMR, 1H-NMR, and FTIR] and calculated some of its physical properties. Also, we worked theoretical study involving calculated the geometric configurations, total energy, dipole moment etc..,. In addition, the inhibition effect of the synthesized compounds (1a-1c) on corrosion of stainless steel in 1M HCl were studied by method of weight loss. The results of weight loss measurements showed that corrosion inhibition efficiency by increasing the concentration of organic inhibitors for stainless steel in 1M HCl solution at 30oC.

Understanding the role of Dimethylformamide as co-solvents in the dissolution of cellulose in ionic liquids: Experimental and theoretical approach

Cellulose has been identified as the most abundant renewable material but however utilization of cellulose is still limited, it does not dissolve in most convectional solvents. This study focusses on cellulose dissolution using ionic liquids (ILs) namely: 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]), 1-allyl-3-methylimidazolium chloride ([AMIM][Cl]) and 1-butyl-3-methylpyridinium chloride ([BMPy][Cl]) with N,N-dimethylformamide (DMF) co-solvent. The solubility of the cellulose was tested in pure ILs as well as in solution of ILs/DMF. Results showed that solubility of the cellulose in ILs greatly enhanced in the presence of DMF. The complete dissolution of cellulose in both the systems such as pure ILs and ILs/DMF was also evident by density (ρ), sound velocity (u) and refractive index (nD) measurements. Furthermore, COSMO-RS analysis was also performed in order to achieve a better understanding of the molecular interactions between the ILs and the co-solvent. In addition to the above theoretical chemistry tools, natural bond orbital (NBO), Fragment molecular orbital (FMO) and chemical reactivity analyses for cellulose molecule was investigated. Theoretical data obtained proved that cellulose molecule is more reactive than glucose. In addition, this study also deals with the regeneration of the cellulose from dissolved solution using deionized water. The regenerated cellulose was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques. It was observed that the cellulose regenerated cellulose from both solvent systems hold excellent mechanical properties.

Synthesis, Characterization and Biological Evaluation of Some Novel Substitute N-(4-(3-Oxomorpholino)phenyl)-2-(4-((phenylamino)methyl)-1H- 1,2,3-triazol-1-yl)-acetamide via Click Chemistry Approach

A novel heterocyclic library were synthesized, characterized and tested for biological evaluation against bacteria and fungus. This novel series of substitute N-(4-(3-oxomorpholino)phenyl)-2-(4- ((phenylamino)-methyl)-1H-1,2,3-triazol-1-yl)acetamide via click chemistry approach in the presence of DMF:H2O:n-BuOH and CuSO4·5H2O in good yield. The title compounds have been synthesized with several structural variations. The synthesized compounds were screened for antimicrobial activity against standard drugs. The structure of synthesized compounds characterized by their spectral (IR, 1H NMR and mass) data. The purity of the synthesized compounds was confirmed by TLC.

Highly regioselective 1,3-dipolar cycloaddition of 3′-O-propargyl guanosine with nitrile oxide: An efficient method for the synthesis of guanosine containing isoxazole moiety

The 1,3-dipolar cycloaddition reaction of 3′-O-propargyl guanosine with various in-situ generated nitrile oxides in the presence of DMF as a solvent is described. It is noteworthy that the reaction is highly regioselective that affords biologically important guanosine containing isoxazole moiety in good yields with high purities.

Tourmaline Nanoparticles Doped Polyvinylidene Fluoride (PVDF) Nanofibers

The aim of this work is to produce tourmaline (TM) doped polyvinylidene fluoride (PVDF) nano-composite fibers. TM-containing PVDF nanofibers were produced via a horizontally located electrospinning unit. N,N-dimethylformamide (DMF) and acetone were used as solvents. The amount of PVDF or PVDF/TM in the polymer solution was 20 wt.%. PVDF was dissolved in DMF in presence of heat by using a magnetic stirrer while TM powder was dispersed in Acetone in absence of heat by using an ultrasonic stirrer. These two solutions were then mixed for TM/PVDF nanocomposite fiber production. Pristine PVDF nanofibers were also electrospun as control samples. Produced nano-surfaces were analyzed under scanning electron microscopy (SEM), Fourier-transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD). Voltage generation capacities were investigated by recording the voltage outputs of samples under an applied rotational impact. The peak voltage produced by the TM doped PVDF nanocomposite fibers was higher than the PVDF nanofibers.

Esterified carboxylic pyrazolone dyes and their in situ CuII/H2O2 catalytic oxidation

In this paper, we report the studies on in situ CuII/H2O2 catalytic oxidation for esterified carboxylic pyrazolone dyes. Our results reveal that two ortho phenolic hydroxyl pyrazolone based heterocyclic dyes can be prepared successfully by treating corresponding esterified carboxylic pyrazolone dyes with Cu(CH3COO)2·H2O/H2O2 or CuCl2·2H2O/H2O2 in the presence of DMF via the Fenton-type reaction. In addition, when Cu(CH3COO)2·H2O and CuCl2·2H2O were used under the similar reaction condition, respectively, copper(II) complexes with distinguishable nuclearities and coordination modes have been obtained. Furthermore, all the compounds have been spectrally compared, where hydrazone to deprotonated and then to hydrazone configurations have been proved before and after forming the copper(II) intermediates and subsequent demetallization. The acquisition of three intermediate copper(II) complexes of esterified carboxylic pyrazolone dyes herein via the Fenton-type reaction is suggested to provide further understanding on the study of such kind of reaction. As far as we know, this is the first study on esterified carboxylic pyrazolone dyes and also the first attempt on the extension of Fenton-type reactions for CuII/H2O2/pyrazolone system.

A novel five-step synthetic route to 1,3,4-oxadiazole derivatives with potent α-glucosidase inhibitory potential and their in silico studies.

A series of new N-aryl/aralkyl derivatives of 2-methyl-2-{5-(4-chlorophenyl)-1,3,4-oxadiazole-2ylthiol}acetamide were synthesized by successive conversions of 4-chlorobenzoic acid (a) into ethyl 4-chlorobenzoate (1), 4-chlorobenzoylhydrazide (2) and 5-(4-chlorophenyl)-1,3,4-oxadiazole-2-thiol (3), respectively. The required array of compounds (6a-n) was obtained by the reaction of 1,3,4-oxadiazole (3) with various electrophiles (5a-n) in the presence of DMF (N,N-dimethylformamide) and sodium hydroxide at room temperature. The structural determination of these compounds was done by infrared, 1 H-NMR (nuclear magnetic resonance), 13 C-NMR, electron ionization mass spectrometry, and high-resolution electron ionization mass spectrometry analyses. All compounds were evaluated for their α-glucosidase inhibitory potential. Compounds 6a, 6c-e, 6g, and 6i were found to be promising inhibitors of α-glucosidase with IC50 values of 81.72 ± 1.18, 52.73 ± 1.16, 62.62 ± 1.15, 56.34 ± 1.17, 86.35 ± 1.17, 52.63 ± 1.16 µM, respectively. Molecular modeling and ADME (absorption, distribution, metabolism, excretion) predictions supported the findings. The current synthesized library of compounds was achieved by utilizing very common raw materials in such a way that the synthesized compounds may prove to be promising drug leads.

Radicals and Ions Formed in Plasma-Treated Organic Solvents: A Mechanistic Investigation to Rationalize the Enhancement of Electrospinnability of Polycaprolactone.

This paper reports and discusses the beneficial effects on the quality of electrospun polycaprolactone nanofibers brought about by pretreatment of the solvent with non-thermal plasma. Chloroform/dimethylformamide 9:1 (CHCl3:DMF 9:1) and pure chloroform were pretreated by a few minute exposure to the plasma generated by an atmospheric pressure plasma jet (APPJ). Interestingly, when pure chloroform was used, the advantages of plasma pretreatment of the solvent were way less pronounced than found with the CHCl3:DMF 9:1 mixture. The chemical modifications induced by the plasma in the solvents were investigated by means of complementary analytical techniques. GC-MS revealed the formation of solvent-derived volatile products, notably tetrachloroethylene (C2Cl4), 1,1,2,2-tetrachloroethane (C2H2Cl4), pentachloroethane (C2HCl5), hexachloroethane (C2Cl6) and, in the case of the mixed solvent, also N-methylformamide (C2H5NO). The chlorinated volatile products are attributed to reactions of ·Cl and Cl-containing methyl radicals and carbenes formed in the plasma-treated solvents. ·Cl and ·CCl3 radicals were detected and identified by EPR spectroscopy analyses. Ion chromatography revealed the presence of Cl−, , and HCOO− (the latter only in the presence of DMF) in the plasma-treated solvents, thus accounting for the observed increased conductivity and acidification of the solvent after plasma treatment. Mechanisms for the formation of these solvent derived products induced by plasma are proposed and discussed. The major role of radicals and ions in the plasma chemistry of chloroform and of the chloroform/dimethylformamide mixture is highlighted. The results provide insight into the interaction of plasma with organic solvents, a field so far little explored but holding promise for interesting applications.

Organic solvent free in situ growth of flower like Co-ZIF microstructures on nickel foam for glucose sensing and supercapacitor applications

Flower like microstructures of cobalt zeolitic imidazolate framework (FLCo-ZIF) was grown on flexible nickel foam (NF) when water was used as a solvent using Co-salt and imidazole as precursors. No such flower like microstructures was formed when ethanol or methanol was used as a solvent. Interestingly, no microstructures were grown on NF in the presence of DMF or DMSO. The microstructure growth was optimized with respect to the mole ratio of 2-methylimidazole (2-MI) and Co salt, solvent and immersion time. The scanning electron microscopy (SEM) images confirmed the formation of FLCo-ZIF on NF with an average framework size of 5 μm from 1:2 mole ratio in water at an immersion time of 3 h. Here, water acted as a green solvent and structure-directing agent to favour Co2+ nuclei to interact with the smaller building units of 2-MI to form FLCo-ZIF microstructures on NF. The cyclic voltammogram of FLCo-ZIF showed two redox waves corresponding to Co and Ni. Further, the FLCo-ZIF fabricated on NF was directly used as a binder free electrocatalyst for glucose oxidation and supercapacitor electrode. When the concentration of glucose increases the amperometric current was increased linearly from 2 μM to 1 mM in 0.1 M NaOH and the limit of detection (LOD) was found to be 0.42 μM (S/N = 3) with a sensitivity of 2.981 mA/(mM cm2). The clinical application of the present method was evaluated by determining glucose in human blood serum samples and the results were validated with the commercial glucometer. Besides, NF modified with FLCo-ZIF was also used for supercapacitor application. It showed a specific capacitance (C) of 87 F g−1 at the current density of 0.5 A g−1 and good stability for 2000 cycles. Thus, the FLCo-ZIF formed on NF from a green solvent shown here is a potential candidate for not only non-enzymatic sensing of glucose but also supercapacitor application.