Search Results (14)

The technology of perovskite solar cells (PSC) is getting close to breaching the consumer market. Yet, one of the current challenges is to reduce the toxicity during their fabrication by reducing the use of the toxic solvents involved in the perovskite fabrication process. A good solubilization of lead halides used in hybrid perovskite preparation is required, and it is only possible with polar solvents. A mixture of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) is the most popular solvent combination for a perovskite precursor solution. DMF is necessary to ensure a good dissolution of lead iodide, but it is also the most toxic solvent. In this paper, we study the replacement of the dimethylformamide with presumably less toxic alternatives, such as N-methyl-2-Pyrrolidone (NMP) and ethyl acetate (EA), for the preparation of the K_0.1FA_0.7MA_0.2PbI_2.8Cl_0.2 (KFAMA) hybrid perovskite. The perovskite thin films were investigated by various characterization techniques: X-ray diffraction, atomic force microscopy, scanning electron microscopy, and UV–vis spectroscopy, while the photovoltaic parameters were determined by measuring the IV curves of the corresponding solar cells. The present study shows that by keeping the same deposition parameters as when only DMF solvent is used, the partial solvent substitution with NMP and EA gives promising results for reducing the toxicity of the fabrication process of KFAMA-based PSCs. Thus, with no specific optimization of the deposition process, and for the maximum possible partial substitution of DMF with NMP and EA solvents, the loss in the power conversion efficiency (PCE) value is only 35% and 18%, respectively, associated with the more structural defects promoted by NMP and EA. Full article

Here, we described the synthesis of novel pyrazole-s-triazine derivatives via an easy one-pot procedure for the reaction of β-dicarbonyl compounds (ethylacetoacetate, 5,5-dimethyl-1,3-cyclohexadione or 1,3-cyclohexadionone) with N,N-dimethylformamide dimethylacetal, followed by addition of 2-hydrazinyl-4,6-disubstituted-s-triazine either in ethanol-acetic acid or neat acetic acid to afford a novel pyrazole and pyrazole-fused cycloalkanone systems. The synthetic protocol proved to be efficient, with a shorter reaction time and high chemical yield with broad substrates. The new pyrazolyl-s-triazine derivatives were tested against the following cell lines: MCF-7 (breast cancer); MDA-MB-231 (triple-negative breast cancer); U-87 MG (glioblastoma); A549 (non-small cell lung cancer); PANC-1 (pancreatic cancer); and human dermal fibroblasts (HDFs). The cell viability assay revealed that most of the s-triazine compounds induced cytotoxicity in all the cell lines tested. However, compounds 7d, 7f and 7c, which all have a piperidine or morpholine moiety with one aniline ring or two aniline rings in their structures, were the most effective. Compounds 7f and 7d showed potent EGFR inhibitory activity with IC₅₀ values of 59.24 and 70.3 nM, respectively, compared to Tamoxifen (IC₅₀ value of 69.1 nM). Compound 7c exhibited moderate activity, with IC₅₀ values of 81.6 nM. Interestingly, hybrids 7d and 7f exerted remarkable PI3K/AKT/mTOR inhibitory activity with 0.66/0.82/0.80 and 0.35/0.56/0.66-fold, respectively, by inhibiting their concentrations to 4.39, 37.3, and 69.3 ng/mL in the 7d-treatment, and to 2.39, 25.34 and 57.6 ng/mL in the 7f-treatment compared to the untreated control. Full article

Short-chain fatty acids (SCFAs), produced by microbes when dietary fiber ferments in the colon, are one of the most studied microbial products despite their volatility and complex matrices, which make analysis challenging. In the current study, we sought to address research gaps by exploring the commonalities and differences between the retention time changes for SCFAs in polar solvents. In one such solvent, dimethyl sulfoxide (DMSO), the retention time of the SCFA acetic acid shows a linear positive correlation with the equal volume increase in the DMSO solvent. We used gas chromatography–mass spectrometry to analyze the retention times of mixed solutions of formic acid, acetic acid, butyric acid, valeric acid, and toluene in the solvents DMSO and water and found that only the retention times of formic acid and acetic acid changed. We further compared the effect of three solvents with similar polarities, DMSO, N-methylpyrrolidone (NMP), and dimethylformamide (DMF), on the retention time of acetic acid and found that it increased in the DMSO–water solution more than in the NMP–water solution and remained unchanged in the DMF–water solution. This finding is consistent with quantum chemical calculations showing that the strength of the hydrogen bond between DMSO and acetic acid is greater than between NMP and acetic acid. Taken together, the chromatographic results and quantum chemical calculations indicate that, in all three solvents, the portion of the molecule with the smallest negative electrostatic potential (red) has high electron density and can easily donate electrons, forming a hydrogen bond with acetic acid. However, the portion with the largest positive electrostatic potential (blue) forms a bond with polyethylene glycol, a column stationary solution with a strong dipole moment, and is adsorbed on the stationary solution in the direction of the dipole moment. Therefore, the retention times of formic acid and acetic acid change under the combined influence of a series of complex intermolecular forces. In the chromatographic column, the outflow rate of DMF is higher than that of acetic acid, and the force of the hydrogen bond between DMF and acetic acid cannot overcome the outflow resistance of acetic acid, so the retention time of the acetic acid in the DMF–water solution does not change. The retention times of butyric acid and valeric acid are unchanged in aprotic polar solvents for the same reason. Full article

The analysis of the fatty acid (FA) profile requires multiple preparation steps, which are lipid extraction followed by derivatization of the FA into a fatty acid methyl ester (FAME). The procedures are time-consuming, and generally require large volumes of sample sizes and solvents. This report proposes a technique for the preparation of FAME from fresh horse mussels without a step of lipid extraction. A rapid in situ derivatization using N,N-dimethylformamide dimethyl acetal (DMF-DMA) methylation followed by alkali-transesterification was examined. In this method, acylglycerols and free fatty acids (medium to long-chain FA) of the sample are targeted to convert into FAME. Direct alkali-transesterification of the fresh sample gave only 58.7% FAME with 12.4% triglyceride and 21.1% FFA. The alkali in situ method showed low conversion efficiency due to the initial sample containing high contents of moisture and FFA (75.11% of the fresh sample and 14.3% of total oil, respectively). The reaction was developed by using two steps in situ derivatization. A 50 mg sample was methylated with 1 mL of DMF-DMA (100 °C, 15 min), followed by transesterified with 10 mL of 1% (w/v) NaOH in methanol (60 °C, 3 min). The conversion into FAME was monitored using size-exclusion HPLC with evaporative light-scattering detection. The column was a 100 Å Phenogel with toluene and 0.25% acetic acid as a mobile phase. The FAME yield of 79.9% with 7.8% triglyceride and 8.5% FFA was obtained. The two steps in situ derivatization gave a promising result with the higher conversion with lower FFA. It is a simple and rapid (less than 20 min) method that requires a low volume of sample and solvent for FAME preparation. However, increasing the conversion efficiency as well as the variety of samples should be further studied. Full article

Series of methyl 3- and 5-(N-Boc-piperidinyl)-1H-pyrazole-4-carboxylates were developed and regioselectively synthesized as novel heterocyclic amino acids in their N-Boc protected ester form for achiral and chiral building blocks. In the first stage of the synthesis, piperidine-4-carboxylic and (R)- and (S)-piperidine-3-carboxylic acids were converted to the corresponding β-keto esters, which were then treated with N,N-dimethylformamide dimethyl acetal. The subsequent reaction of β-enamine diketones with various N-mono-substituted hydrazines afforded the target 5-(N-Boc-piperidinyl)-1H-pyrazole-4-carboxylates as major products, and tautomeric NH-pyrazoles prepared from hydrazine hydrate were further N-alkylated with alkyl halides to give 3-(N-Boc-piperidinyl)-1H-pyrazole-4-carboxylates. The structures of the novel heterocyclic compounds were confirmed by ¹H-, ¹³C-, and ¹⁵N-NMR spectroscopy and HRMS investigation. Full article

Bio-based levulinic acid (LA), furfural (FF), and hydroxymethylfurfural (HMF) represent key chemical intermediates when biorefining biomass resources, i.e., either cellulose, glucose, hexoses, etc. (HMF/LA), or hemicellulose, xylose, and pentose (FF). Despite their importance, their online in situ detection by process analytical technologies (PATs), solubility, and its temperature dependence are seldom available. Herein, we report their solubility and temperature dependence by examining n-hexane, cyclohexane, benzene, toluene, 1,4-dioxane, diethyl ether, dichloromethane, tetrahydrofuran, ethyl acetate, acetone, dimethylformamide, acetonitrile, dimethyl sulfoxide, formic acid, n-butanol, n-propanol, ethanol, methanol, and water. These solvents were selected as they are the most common nonpolar, polar aprotic, and polar protic solvents. Fourier-transform infrared (FTIR) spectroscopy was applied as a fast, accurate, and sensitive method to the examined solutions or mixtures. The latter also enables operando monitoring of the investigated compounds in pressurized reactors. Selected temperatures investigated were chosen, as they are within typical operating ranges. The calculated thermodynamic data are vital for designing biorefinery process intensification, e.g., reaction yield optimization by selective compound extraction. In addition to extracting, upstream or downstream unit operations that can benefit from the results include dissolution, crystallization, and precipitation. Full article

A high-silica chabazite (CHA) type zeolite membrane was prepared on the porous α-Al₂O₃ support tube by the secondary growth of seed particles. The dehydration performances of the membrane were determined using methanol, ethanol, 2-propanol, acetone, acetic acid, methyl ethyl ketone (MEK), tetrahydrofuran (THF), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N-methyl-2-pyrolidone (NMP) at 303–373 K. As a result, the dehydration performances of the membrane were categorized to following three types: (1) 2-propanol, acetone, THF, and MEK; (2) ethanol and acetic acid; and (3) methanol, DMF, and DMSO, and NMP. The adsorption isotherms of water, methanol, ethanol, and 2-propanol were determined to discuss the influences of the organic solvents on the permeation and separation performances of the membrane. For 2-propanol, acetone, MEK, and THF solutions, the high permeation fluxes and separation factors were obtained because of the preferential adsorption of water due to molecular sieving. In contrast, the permeation fluxes and separation factors were relatively low for methanol, DMF, and DMSO, and NMP solutions. The lower dehydration performance for the methanol solution was due to the adsorption of methanol. The permeation fluxes for ethanol and acetic acid solution were ca. 1 kg m⁻² h⁻¹. The significantly low flux was attributed to the similar molecular diameter to the micropore size of CHA-type zeolite. Full article

The ionic liquid (IL) of 1-hexyl-3-methylimidazolium acetate is widely used in chemical and bio-chemical processes. In this work, due to the high viscosity of IL, the promising chemicals (i.e., N, N-dimethylacetamide, N, N-dimethylformamide, and dimethyl sulfoxide) were selected as the additives to lower IL viscosity. The thermophysical properties of density and viscosity for IL with solvents were measured using a digital vibrating U-tube densimeter and an Ubbelohde capillary viscometer from 303.15 to 338.15 K at atmospheric pressure (0.0967 MPa), respectively. The influences of the solvents on the thermophysical properties of ionic liquid were quantitatively studied. Furthermore, based on the measurement values, the derived properties of excess molar volumes, thermal expansion coefficient, and the energy barrier were calculated, and the results showed that the mixture composition had great impact on excess volume change and viscosity. The hard-sphere model was employed to reproduce the viscosity. The infrared spectroscopy was performed to study the chemical structure to further understand the interactions between IL and the solvents. Full article

Available protocols for the synthesis of ketocyanine dyes precursor 2,5-bis((dimethylamino)methylene)cyclopentanone are not straightforward and the reported yields are low to moderate. The important feature in the synthesis of this product through organocatalyzed condensation of cyclopentanone and N,N-Dimethylformamide dimethyl acetal is the removal of methanol produced during the reaction. By studying the reaction profile, in particular the selectivity for the formation of mono- and bis-condensation products, a high yield of the desired product can be obtained through an operationally simple and solvent-free protocol. Full article

Recently, IL/cosolvent systems have generated a lot of interest as cellulose-dissolving solvents and reaction media for various kinds of cellulose modification. In the present study, both 1-allyl-3-methylimidazolium chloride (AmimCl)/dimethyl sulfoxide (DMSO) and AmimCl/N,N-dimethylformamide (DMF) systems were employed to synthesize cellulose acetate by transesterification. Microcrystalline cellulose, 1,8-diazabicyclo[5.4.0]undec-7-ene and isopropenyl acetate were chosen as the raw material, catalyst and acetylation reagent, respectively. The results revealed that DMSO was a suitable cosolvent for the transesterification in the homogeneous solution. Moreover, DMSO had a positive effect on the reaction as the cosolvent under the given conditions and the degree of the substitution of cellulose acetate could be significantly enhanced through increasing the molar ratio of DMSO. The synthesized products were characterized by Fourier transform infrared (FT-IR) spectroscopy, ¹H and ¹³C nuclear magnetic resonance spectroscopy (¹H-NMR and ¹³C-NMR), correlation spectroscopy (COSY), heteronuclear single quantum correlation (HSQC) spectroscopy, and X-ray diffraction (XRD) to confirm the chemical and physical structure of the cellulose acetate generated. The thermal properties were also evaluated using thermogravimetric analysis (TGA)/derivative thermogravimetry (DTG). Full article

The paper presents the potential of an electronic nose technique in the field of fast diagnostics of patients suspected of Chronic Obstructive Pulmonary Disease (COPD). The investigations were performed using a simple electronic nose prototype equipped with a set of six semiconductor sensors manufactured by FIGARO Co. They were aimed at verification of a possibility of differentiation between model reference mixtures with potential COPD markers (N,N-dimethylformamide and N,N-dimethylacetamide). These mixtures contained volatile organic compounds (VOCs) such as acetone, isoprene, carbon disulphide, propan-2-ol, formamide, benzene, toluene, acetonitrile, acetic acid, dimethyl ether, dimethyl sulphide, acrolein, furan, propanol and pyridine, recognized as the components of exhaled air. The model reference mixtures were prepared at three concentration levels—10 ppb, 25 ppb, 50 ppb v/v—of each component, except for the COPD markers. Concentration of the COPD markers in the mixtures was from 0 ppb to 100 ppb v/v. Interpretation of the obtained data employed principal component analysis (PCA). The investigations revealed the usefulness of the electronic device only in the case when the concentration of the COPD markers was twice as high as the concentration of the remaining components of the mixture and for a limited number of basic mixture components. Full article

3-Aroyl and 3-heteroaroyl substituted 3-oxoalkanenitriles were synthesized by the reactions of activated aromatic and hetero-aromatic substances with cyanoacetic acid in the presence of acetic anhydride. As part of studies focusing on the preparation of cyanoacetyl-1-N-methylbenzimidazole, we observed that reaction of N-methyl-benzimidazole with the cyanoanhydride formed by condensation of cyanoacetic acid with acetic anhydride, leads to the formation of 2-(1,3-diacetyl-2,3-dihydro-1H-benzo[d]-imidazol-2-yl)acetonitrile (5), whose structure was confirmed by X-ray crystallographic analysis. 3-Oxoalkanenitriles 3a,b were observed to undergo condensation reactions with dimethylformamide dimethyl acetal (DMFDMA) to afford the corresponding enamino-nitriles, which react with malononitrile to give 2-dialkylaminopyridines through a pathway involving a new, unexpected rearrangement process. Reactions of 3-oxoalkanenitriles with ethyl acetoacetate were found to afford 2-oxopyran-3-carbonitriles, also occurring via this unexpected rearrangement process. Mechanisms to account for both rearrangement reactions are suggested. In addition, reactions of 3-oxoalkanenitriles with acetylacetone in acetic acid in the presence of ammonium acetate result in the formation of pyridine-3-carbonitriles. Finally, upon heating in the presence of zeolite 3-oxoalkanenitriles 3b,c self-trimerized to produce the corresponding aniline derivatives 23b,c. Full article

Condensation of phthalimidoacetone (1) with DMFDMA (N,N-Dimethylformamide dimethyl acetal) has afforded enaminone 2. Refluxing 2 with equimolecular amounts of benzaldehyde and urea in acetic acid afforded a mixture of tetrahydropyrimidine 5 and the dihydropyridine 6. Compound 2 undergoes self-condensation on heating in acetic acid or under microwave irradiation in presence of acidic zeolite to give 1,3,5-triacylbenzene 9. Reacting enaminone 11a with naphthoquinone 15 afforded the naphthofuran 18. The possible formation of the aldehyde 19 was excluded based on an HMQC experiment, which revealed that the carbonyl carbon is not linked to any hydrogen. Full article

2-Thioxopyrimidinyl-5-(N,N-dimethylamino)formamidine (5) and 1,3-diphenyltriazolo[3,4-d]pyrimidinyl-N,N-dimethylformamidine (14) were prepared by condensation of 6-amino-2-thioxo-1,3-dihydropyrimidin-4-one (2) and 7-amino-1,3-diphenyl-1,2,4-triazolo[4,3-a]pyrimidin-4-one (13) with dimethylformamide dimethyl-acetal (DMFDMA). Compound 5 reacts with acetophenone and 2-acetylthiophene to give the 2-thioxo-1,3-dihydropyridino[2,3-d]pyrimidin-4-ones 3a and 3b, respectively. Compounds 3a,b react with hydrazonoyl halides 6,7 to give pyridino[2,3-d]triazolo[4,5-a]pyrimidin-4-ones 11a-d and not the isomeric structures 12a-d. Formamidines of type 14 react with ethyl cyanoacetate, malononitrile and benzoyl acetonitrile to give the 1,3-diphenyl-3a-hydropyridino[2,3-d]1,2,4-triazolo[4,5-a]pyrimidin-4-one derivatives 15a,b and 18, respectively. The structures of the newly synthesized compounds are established on the basis of chemical and spectroscopic evidences as well as their synthesis by alternative methods. Full article