Showing papers on "Acetonitrile published in 2022"

Management of validation of HPLC method for determination of acetylsalicylic acid impurities in a new pharmaceutical product

Abstract: The work mainly focused on a validation of the method for determining the content of salicylic acid and individual unknown impurities in new pharmaceutical product-tablets containing: 75, 100 or 150 mg of acetylsalicylic acid and glycine in the amount of 40 mg for each dosage. The separation of the components was carried out by means of HPLC, using a Waters Symmetry C18 column (4.6 × 250 mm, 5 μm) as the stationary phase. The mobile phase consisted of a mixture of 85% orthophosphoric acid, acetonitrile and purified water (2:400:600 V/V/V). Detection was carried out at a wavelength of 237 nm, with a constant flow rate of 1.0 ml min-1. In order to verify the method, linearity, precision (repeatability and reproducibility), accuracy, specificity, range, robustness, system precision, stability of the test and standard solution, limit of quantification and forced degradation were determined. Validation tests were performed in accordance with ICH (International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use) guidelines. The method was validated successfully. It was confirmed that the method in a tested range of 0.005-0.40% salicylic acid with respect to acetylsalicylic acid content is linear, precise and accurate.

Multi-Component Synthesis of a Buta-1,3-diene-Linked Covalent Organic Framework.

Abstract: We report a multi-component synthetic strategy on a two-dimensional crystalline covalent organic framework (COF) by connecting acetonitrile with aromatic aldehyde and acetaldehyde moieties to form an unprecedented cyano-substituted buta-1,3-diene linkage. Different from most of the COFs that were crystallized from the condensations from two components, the presented COF is generated from two competitive and reversible reactions among three moieties. The buta-1,3-diene COF exhibits remarkable photoactivity with a low exciton binding energy of 44.4 ± 1.5 meV for promoted charge separation, which enables the buta-1,3-diene-linked COF as an efficient photocatalyst for various aerobic oxidation reactions under visible light. Our multi-component synthesis strategy may provide new sights for synthesizing COFs with structural diversity and functional variability that are hard to achieve by traditional COF synthesis.

Synthesis of Seleno-Dibenzocycloheptenones/Spiro[5.5]Trienones by Radical Cyclization of Biaryl Ynones.

Abstract: We report herein an alternative method for the synthesis of seleno-dibenzocycloheptenones and seleno-spiro[5.5]trienones through the radical cyclization of biaryl ynones in the presence of diorganyl diselenides, using Oxone as a green oxidizing agent. The reactions were conducted using acetonitrile as the solvent in a sealed tube at 100 °C. The protocol is operationally simple and scalable, exhibits high regioselectivity, and allows the synthesis of 24 dibenzocycloheptenones/spiro[5.5]trienones in yields of up to 99%, 17 of which are unpublished compounds. Additionally, synthetic transformations of the prepared compounds, such as oxidation and reduction reactions, are demonstrated.

AQbD based green UPLC method to determine mycophenolate mofetil impurities and Identification of degradation products by QToF LCMS

Abstract: We report an ideal method for quantifying impurities in mycophenolate mofetil drug substances and their oral suspension preparations. We developed a systematic and eco-friendly analytical approach utilizing quality by design (QbD) and green chemistry principles. Initially, the critical method parameters (CMPs) were screened using a D-optimal design. The robust final method conditions were optimized using a systematic central composite design (CCD). Through graphical and numerical optimization, the protocol conditions were augmented. The pH of mobile phase buffer (25 mM KH2PO4) (MP-A), initial gradient composition (% MP-A), flow rate (mL min-1), and column oven temperatures (°C) are 4.05, 87, 0.4, and 30, respectively. The best possible separation between the critical pairs was achieved while using the Waters Acquity UPLC BEH C18 (100 × 2.1) mm, 1.7 µm analytical column. A mixture of water and acetonitrile in the ratio of 30:70 (v/v) was used as mobile phase-B for the gradient elution. The analytical method was validated in agreement with ICH and USP guidelines. The specificity results revealed that no peaks interfered with the impurities and MPM. The mean recovery of the impurities ranged between 96.2 and 102.7%, and the linearity results r > 0.999 across the range of LOQ - 150%. The precision results (%RSD) ranged between 0.8 and 4.5%. The degradation products formed during the base-induced degradation were identified as isomers of mycophenolic acid and sorbitol esters using Q-ToF LC-MS and their molecular and fragment ion peaks. The developed method eco-friendliness and greenness were assessed using analytical greenness (AGREE), green analytical procedure index (GAPI), and analytical eco score, and found it is green.

Visible Light-Mediated C(sp2)-H Selenylation of Amino Pyrazole and Amino Uracils in the Presence of Rose Bengal as an Organophotocatalyst.

Abstract: Herein, we report an efficient methodology for the synthesis of alkyl, benzyl, and phenyl selenoethers of aminopyrazoles and aminouracils by C(sp2)-H functionalization in the presence of visible light and Rose Bengal as an organophotocatalyst. The reaction of amino pyrazole/iosothiazole/isoxazole or amino uracils with 0.5 equivalent of diphenyl/dibenzyl/diethyl diselenides in the presence of visible light in acetonitrile medium and a catalytic amount of Rose Bengal provided the corresponding phenyl, benzyl, or ethyl selenoethers in good to very good yields. We have also utilized some of the selenylated aminopyrazoles for the preparation of pyrazole-fused dihydropyrimidines tethered with arylselenoethers by a catalyst-free one-pot three-component reaction. The notable features of this methodology are metal-free reaction conditions, good to very good yields, use of an organic photocatalyst, and wide substrate scope; it is also applicable to gram-scale synthesis and provides selenoethers of medicinally important heterocycles such amio-pyrazole, isoxazole, isothiazole, and uracils.

Solvent and Counteranion Assisted Dynamic Self-Assembly of Molecular Triangles and Tetrahedral Cages.

Abstract: Self-assembly of naked PdII ions separately with newly designed bis(3-pyridyl)benzothiadiazole (L1) and bis(3-pyridyl)thiazolo[5,4-d]thiazole (L2) donors separately, under varying experimental conditions, yielded Pd4L8 (L= L1 or L2) tetrahedral cages and their homologous Pd3L6 (L= L1 or L2) double-walled triangular macrocycles. The resulting assemblies exhibited solvent, temperature, and counteranion induced dynamic equilibrium. Treatment of L1 with Pd(BF4)2 in acetonitrile (ACN) resulted in selective formation of a tetrahedral cage [Pd4(L1)8](BF4)8 (1a), which is in dynamic equilibrium with its homologue triangle [Pd3(L1)6](BF4)6 (2a) in dimethyl sulfoxide (DMSO). On the other hand, similar self-assembly using L2 instead of L1 yielded an equilibrium mixture of tetrahedral cage [Pd4(L2)8](BF4)8 (3a) and triangle [Pd3(L2)6](BF4)6 (4a) forms in both ACN and DMSO. The assembles were characterized by multinuclear NMR and ESI-MS while the structure of the tetrahedral cage (1a) was determined by single crystal X-ray diffraction. Existence of a dynamic equilibrium between the assemblies in solution has been investigated via variable temperature 1H NMR. The equilibrium constant K = ([Pd4L8]3/[Pd3L6]4) was calculated at each experimental temperature and fitted with the Van't Hoff equation to determine the standard enthalpy (ΔH°) and entropy (ΔS°) associated with the interconversion of the double-walled triangle to tetrahedral cage. The thermodynamic feasibility of structural interconversion was analyzed from the change in ΔG°, which suggests favorable conversion of Pd3L6 triangle to Pd4L8 cage at elevated temperature for L1 in DMSO and L2 in ACN. Interestingly, similar self-assembly reactions of L1 and L2 with Pd(NO3)2 instead of Pd(BF4)2 resulted in selective formation of a tetrahedral cage [Pd4(L1)8](NO3)8 (1b) and double-walled triangle [Pd3(L2)6](NO3)6 (4b), respectively.

Sequential and Reversible Phase Transformations in Zero-Dimensional Organic-Inorganic Hybrid Sb-based Halides towards Multiple Emissions.

Abstract: Zero-dimensional (0D) metal halides have drawn increasing attention due to the attractive structure dependent photoluminescence (PL) properties. Here, we report two new 0D organic-inorganic hybrid Sb-based halides, (MTP)6SbBr6Sb2Br9·H2O (MTP = Methyltriphenylphosphonium, crystal 1) and (MTP)2SbBr5 (crystal 2), featuring a reversible structural phase transformation and tunable orange and red emissions upon dehydration and rehydration of H2O molecules. Intriguingly, a subsequent heat treatment further enables the formation of glassy state (MTP)2SbBr5 (glass 3) with near-infrared luminescence, moreover, a sequential reverse phase transformation from glass 3 to crystal 2 and 1 is triggered by acetonitrile and water vapor stepwise. The anti-counterfeiting demo based on the tunable and reversible PL switching is finally achieved and thus the phase structure engineering in 0D metal halides expands their multiple applications in optical fields.

Matrix Effects on Photoluminescence and Oxygen Sensitivity of a Molecular Ruby

Abstract: The molecular ruby analogue [Cr(ddpd)2]3+ (ddpd=N,N’-dimethyl-N,N’-dipyridine-2-ylpyridine-2,6-diamine) exhibits near infrared (NIR) emission with a high photoluminescence (PL) quantum yield ΦPL of 11 % and a lifetime of 898 μs in deaerated water at room temperature. While ligand-based control of the photophysical properties has received much attention, influences of the counter anions and microenvironment are still underexplored. In this study, the luminescence properties of the molecular ruby were systematically examined for the counter anions Cl−, Br−, [BF4]−, [PF6]−, [BPh4]−, and [BArF24]− in acetonitrile (MeCN) solution, in crystals, and embedded into polystyrene nanoparticles (PSNP). Stern-Volmer analyses of the oxygen quenching studies in the intensity and lifetime domain showed the highest oxygen sensitivity of the complexes with the counter anions of [BF4]− and [BArF24]−, which also revealed the longest luminescence lifetimes. Embedding [Cr(ddpd)2][PF6]3 in PSNPs and shielding with poly(vinyl alcohol) yields a strongly NIR-emissive oxygen-insensitive material with a record ΦPL of 15.2 % under ambient conditions.

Development and validation of liquid chromatography method for determination of Ibrutinib in finished dosage forms using quality by design approach

Abstract: A simple, precise, linear, robust, accurate, and stability-indicating liquid chromatography method was developed and validated to determine Ibrutinib in finished solid dosage forms by reversed-phase high-performance liquid chromatography/photodiode array detector. Separation was achieved using a Luna C18 150 mm × 4.6 mm × 3.0 μm with a suitable mobile phase. The mobile phase: A consists of a 10 mM phosphate buffer concentration and 1 mL triethylamine, adjusted to pH 5.6 with a diluted orthophosphoric acid solution and acetonitrile in the ratio of 95:5 v/v to enhance the results. Moreover, mobile phase - B contains 85% of acetonitrile. The optimized chromatographic conditions such as flow rate 1.0 mL/min, injection volume 10 μL, column temperature 40°C, and wavelength 258 nm. The proposed method is significant because it was developed by the Quality by Design approach. All impurities were identified, such as degradation and placebo impurities without interference at principle peak retention time. After development, it has been validated as per current regulatory guidelines. Obtained recovery between 98 and 102% at 50–200% level; linearity found (r2) = 0.9999 from 20 to 200% level; precision results achieved <2.0% relative standard deviation; and the robustness study results are found satisfactory. It's beneficial.

2,3,5,6-Tetrabromo-8-phenyl BODIPY as a fluorometric and colorimetric probe for amines

Abstract: The usability of 2,3,5,6-tetrabromo-8-phenyl BODIPY (BrBDP) for colorimetric/fluorimetric determination, discrimination, and quantification was investigated. The addition of an amine compound to the solution of BrBDP in acetonitrile caused dramatic changes in the photophysical properties and the color of the solution. These observed changes were specific to the structure of the amine, giving the chemodosimeter the ability to distinguish amines based on their structural properties Other tested functional groups (ethanol, phenol, acetone, formaldehyde, DMF, diethyl ether, ethyl acetate, and acetic acid) resulted in minimal or no change in the photophysical properties of the chemodosimeter indicating it to be highly selective. BrBDP-adsorbed TLC plates were shown to be used as test strips for the detection of volatile amines. Biogenic amines released from spoiled chicken meat were detected by this test strip.

Investigations of the reactivity, stability and biological activity of halido (NHC)gold(I) complexes.

Abstract: The significance of the halido ligand (Cl-, Br-, I-) in halido[3-ethyl-4-phenyl-5-(2-methoxypyridin-5-yl)-1-propyl-1,3-dihydro-2H-imidazol-2-ylidene]gold(I) complexes (2-4) in terms of ligand exchange reactions, including the ligand scrambling to the bis[3-ethyl-4-phenyl-5-(2-methoxypyridin-5-yl)-1-propyl-1,3-dihydro-2H-imidazol-2-ylidene]gold(I) complex (5), was evaluated by HPLC in acetonitrile/water = 50:50 (v/v) mixtures. In the presence of 0.9% NaCl, the bromido (NHC)gold(I) complex 3 was immediately transformed into the chlorido (NHC)gold(I) complex 2. The iodido (NHC)gold(I) complex 4 converted under the same conditions during 0.5 h of incubation by 52.83% to 2 and by 8.77% to 5. This proportion remained nearly constant for 72 h. The halido (NHC)gold(I) complexes also reacted very rapidly with 1 eq. of model nucleophiles, e.g., iodide or selenocysteine (Sec). For instance, Sec transformed 3 in the proportion 73.03% to the (NHC)Au(I)Sec complex during 5 min of incubation. This high reactivity against this amino acid, present in the active site of the thioredoxin reductase (TrxR), correlates with the complete inhibition of the isolated TrxR enzyme at 1 μM. Interestingly, in cellular systems (A2780cis cells), even at a 5-fold higher concentration, no increased ROS levels were detected. The concentration required for ROS generation was about 20 μM. Superficially considered, the antiproliferative and antimetabolic activities of the halido (NHC)Au(I) complexes correlate with the reactivity of the Au(I)-X bond (2 < 3 < 4). However, it is very likely that degradation products formed during the incubation in cell culture medium participated in the biological activity. In particular, the high-cytotoxic [(NHC)2Au(I)]+ complex (5) distorts the results.

Dissipative control of the fluorescence of a 1,3-dipyrenyl calix[4]arene in the cone conformation

Abstract: The temporal control (ON/OFF/ON) of the fluorescence of a dichloromethane/acetonitrile 1 : 1 solution of calixarene 3 decorated with two pyrenyl moieties at the upper rim is attained by the addition of CCl3CO2H used as a convenient chemical fuel.

2,3,5,6-Tetrabromo-8-phenyl BODIPY as a fluorometric and colorimetric probe for amines

Abstract: The usability of 2,3,5,6-tetrabromo-8-phenyl BODIPY (BrBDP) for colorimetric/fluorimetric determination, discrimination, and quantification was investigated. The addition of an amine compound to the solution of BrBDP in acetonitrile caused dramatic changes in the photophysical properties and the color of the solution. These observed changes were specific to the structure of the amine, giving the chemodosimeter the ability to distinguish amines based on their structural properties Other tested functional groups (ethanol, phenol, acetone, formaldehyde, DMF, diethyl ether, ethyl acetate, and acetic acid) resulted in minimal or no change in the photophysical properties of the chemodosimeter indicating it to be highly selective. BrBDP-adsorbed TLC plates were shown to be used as test strips for the detection of volatile amines. Biogenic amines released from spoiled chicken meat were detected by this test strip.