Carbon-13 Nuclear Magnetic Resonance Spectroscopy Research Articles

(1E)-1-(2-pyrazinyl)ethanone thiosemicarbazone (PT) as a tyrosinase inhibitor with anti-browning activity: Spectroscopy, DFT and molecular docking studies

In this study, (1E)-1-(2-Pyrazinyl)ethanone thiosemicarbazone (PT) was synthesized and characterized using Fourier-transform infrared (FTIR), ultraviolet-visible (UV–Vis), proton nuclear magnetic resonance (1HNMR ) and carbon-13 nuclear magnetic resonance (13CNMR ) spectroscopy. The vibrational frequencies were analysed using the Vibrational Energy Distribution Analysis (VEDA) program. The chemical properties of PT, including electron density distribution and intramolecular interactions, were characterized using in-silico methods based on Mulliken atomic charges, molecular electrostatic potential (MEP), quantum theory of atoms in molecules and reduced density gradient noncovalent interaction approaches. PT exhibits a significant inhibitory effect on enzymatic browning (6 and 24 h) and tyrosinase enzymes (IC50 = 7.75 μM). Kinetic analysis shows that PT is a mixed-type inhibitor, with respective Km and Vmax values of 0.632 mM and 0.0044 μM/s, and that it forms a reversible enzyme-inhibitor interaction. The PT-tyrosinase interaction was experimentally evaluated based on 1D, second derivatives of 1D, 2D and 3D IR spectroscopy. Furthermore, analysis of absorption, distribution, metabolism, excretions and toxicity properties revealed good physicochemical properties of PT according to the drug scores and Lipinski's Rule of Five. Lastly, the mechanisms of PT against tyrosinase were visualized and supported by means of a molecular docking approach.

Design and Synthesis of Novel Phthalazine Scaffolds Linked to 1,3,4–oxadiazolyl–1,2,3–triazoles as Potent Anticancer Agents: A Computational Docking Analysis

Background and objective: A study on the chemical and biological properties of molecules simultaneously comprising various heterocycles, such as fused 1,3,4–oxadiazole and 1,2,3–triazoles, has been conducted as part of our ongoing research in the field of medicinal and organic chemistry. In the present study, novel 1,3,4-oxadiazoles and 1,2,3-triazoles incorporating a phthalazine ring have been synthesized and evaluated for their anticancer activity and docking analysis. Methods: In this study, we performed ligand–based pharmacophore modeling as a promising design strategy of substituted phthalazin–1(2H)–one–1,3,4–oxadiazole acetamides (4); 1,2,3–triazole–1,3,4–oxadiazolyl)phthalazin-1(2H)-one (5) were synthesized from key intermediate 2-((5-mercapto-1,3,4-oxadiazol-2-yl)methyl)-4-methylphthalazin-1(2H)-one 2. The prepared compounds were characterized by proton and carbon nuclear magnetic resonance spectroscopy, infrared, elemental analysis, and mass spectroscopy. Synthesized scaffolds were screened for their anticancer activity against three cell lines, MCF-7, T-47D, and MDA-MB-231, by MTT assay. The prepared ligands were docked by using the input protocols, like RCSB, AutoDock 4.2, ACD ChemSketch, Open Babel, and SwissADME. Results: The final compound 5f exhibited excellent activity (IC50 = 10.21 ± 2.2, 7.53 ± 0.1 µM) against T-47D and MCF-7 cancer cell lines, respectively, and compounds 4b and 5b showed the highest % growth of inhibition (61.25 ± 0.52, 62.48 ± 0.20 µg/mL) against T-47D and MCF-7 cell lines, which has been found to be equivalent to that reported by the standard cisplatin. The prepared ligand 5f exhibited greatest bonding with amino acids AlaX:191, MetX:193, ValX:196, ThrX:140, PheX:192, TyrX:155, AsnX:90, LysX:159, LeuX:95, and IleX:14, with a docking score of –11.53 Kcal/mol, respectively. These compounds were further evaluated for their ADMET and physicochemical properties by using SwissADME. Conclusion: Phthalazine with 1,3,4–oxadiazole substituents and 1,2,3–triazoles containing 1,3,4–oxadiazole ring displayed excellent anticancer activity; some interesting relationship has also been evidenced between the synthesised structures and their antimicrobial activity and docking studies. In light of all the above findings, it can be concluded that these molecules may serve as lead molecules for further synthetic and biological evaluation.

Synthesis, characterization, crystal structure, in silico and computational studies on a novel Schiff base derived from α-chlorocinnamaldehyde and 4-aminoantipyrine

Schiff base, 4-(((1E,2Z)-2‑chloro-3-phenylallylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (1) was synthesized by condensation reaction of 4-aminoantipyrine and α-chlorocinnamaldehyde. The compound was characterized using Fourier-transform infrared spectroscopy (FT-IR), ultraviolet (UV)-visible spectroscopy, proton and carbon nuclear magnetic resonance spectroscopy (1H/13C NMR) and single-crystal X-ray diffraction analysis (SC-XRD). Density functional theory (DFT) was used to compute molecular parameters and also compared them with experimental data. The X-ray diffraction data revealed that the compound crystallizes as a monoclinic crystal system with a space group of C2/c and Z = 8, and is stabilized by C12–H12⋯O1, and C8–H8A⋯O1 intramolecular hydrogen bonds. The presence of a distinctive azomethine C = N bond length N3-C12 of 1.283(3) Å, and 1640 cm−1 stretching vibration in the FT-IR spectrum are evidence of the formation of a Schiff base. The computational result indicates that the ionization energy (IE), and electron affinity (EA) values for the molecule are 4.025 and 2.110 eV, respectively. The positive value of EA suggests that the addition of an electron to the molecule would be an exothermic process. The evaluated energy is relatively low and is an expression of the ease of electron transfer from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO). Hirsfeld surface map over dnorm and curvedness surface indicated the presence of π-π stacking while the shape factor index suggests donor and acceptor intermolecular CH—π. Analysis of Hirsfeld surfaces concerning the fingerprint indicated a minimal contribution from the de−di pair and reveals H—-H as a major contribution to the Hirsfeld surface. However, the molecular packing did not confirm H—-H as a significant contributor the packing. Docking calculations on the compound showed average theoretical binding energies toward aromatase (–5.99 ± 0.34 kcal/mol) and fibroblast growth factor receptor (FGFR) (–17.57 ± 6.85 kcal/mol), indicating binding interactions with both protein targets.

Probing the relationship between chemical structure and thermal degradation behavior of acetone fractionated kraft lignin

This study reports the relationships between structure and thermal degradation behavior of industrial softwood and hardwood kraft lignin (KL) after acetone fractionation to obtain acetone soluble (AS) and acetone insoluble (AI) fractions with reduced structural polydispersity. The structure and thermal degradation behavior of AS-KL and AI-KL was examined by gel permeation chromatography, Fourier transform infrared, quantitative carbon-13 nuclear magnetic resonance spectroscopy, and thermogravimetric analysis. The results showed that the AS-KL fractions had reduced apparent molecular weight, lower polydispersity, less native wood lignin side chains, greater aromatic hydroxyl groups, and more condensed structures. In contrast, the AI-KL fractions showed substantially larger apparent molecular weight and polydispersity, as well as more aliphatic hydroxyl groups and native lignin side chains. Consequently, AI-KL samples exhibited greater thermal degradation activation energy than those of AS-KL samples because the former fractions had a larger apparent molecular weight as well as more aliphatic OH groups, which facilitated hydrogen bonding between lignin polymers, improving their thermal stability. This finding suggests that acetone fractionation of KL can be used to examine the relationship between structure and thermal degradation of industrial KL. These results also provide important information on the thermal degradation behavior of acetone fractionated products with relevant chemical and physical properties for a specific application, such as raw materials for lignin valorization.

Synthesis and Energetic Properties of N-Substituted 3,4- and 3,5-Dinitropyrazoles.

3,4- and 3,5-Dinitropyrazoles (DNPs) were substituted with acryl and allyl groups on the N1 nitrogen atom, resulting in three novel energetic materials. These compounds are all liquids at room temperature with melting points ranging from -60.2 to -38.6 °C and were fully characterized by high-resolution mass spectrometry, elemental analysis, proton and carbon nuclear magnetic resonance spectroscopy, and Fourier transform infrared spectroscopy. These materials were also tested for electrostatic discharge, friction, and impact sensitivities and then compared to DNP starting materials and to the explosive nitroglycerin (NG). These results indicate that the synthesized compounds are less sensitive to impact compared to NG and have higher thermal stabilities to decomposition.

Evaluation of the Impact of Two Thiadiazole Derivatives on the Dissolution Behavior of Mild Steel in Acidic Environments.

In light of the variety of industrial uses and economic relevance of mild steel, corrosion resistance is a serious topic. Utilization of inhibitors serves as one of the most essential methods for corrosion control. Two thiadiazole compounds, namely, 2-amino-5-(4-bromobenzyl)-1,3,4-thiadiazole (a1) and 2-amino-5-(3-nitrophenyl)-1,3,4-thiadiazole (a2), were synthesized. The structure of the prepared compounds was verified by Fourier transform infrared spectroscopy (FTIR) and proton and carbon-13 nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR). In a 0.50 M H2SO4 solution, the effectiveness of two synthetic thiadiazole derivatives as mild steel corrosion inhibitors were investigated. In this evaluation, various electrochemical methodologies have been utilized, such as potentiodynamic polarization, open circuit potential (OCP), and electrochemical impedance spectroscopy (EIS). The results confirm the efficiency of the inhibition increases by raising concentrations of a1 and a2. The inhibitory behavior was explained by the notion that the adsorption of thiadiazole molecules, a1 and a2, on the surface of mild steel causes a blockage of charge and mass transfer, protecting the mild steel from offensive ions. Furthermore, the synthesized molecules a1 and a2 were analyzed using density functional theory (DFT).

Independent and combined effects of sepiolite and palygorskite on humus spectral properties and heavy metal bioavailability during chicken manure composting

The effects of the independent and combined addition strategies of sepiolite and palygorskite on humification and heavy metals (HMs) during chicken manure composting were evaluated. Results showed that clay mineral addition showed a favorable effect on composting, prolonged the duration of the thermophilic phase (5–9 d) and improved the TN content (14%–38%) compared to CK. Independent strategy enhanced the humification degree in equal measures with the combined strategy. Carbon nuclear magnetic resonance spectroscopy (13C NMR) and fourier transform infrared spectroscopy (FTIR) confirmed that aromatic carbon species increased by 31%–33% during composting process. Excitation–emission matrix (EEM) fluorescence spectroscopy showed that humic acid–like compounds increased by 12%–15%. In addition, the maximum passivation rate of Cr, Mn, Cu, Zn, As, Cd, Pb and Ni were 51.35%, 35.98%, 30.39%, 32.46%, −87.02%, 36.61% and 27.62%, respectively. The independent addition of palygorskite exhibits the most potent effects for most HMs. Pearson correlation analysis indicated that pH and aromatic carbon were the key determinants of the HMs passivation. This study provided preliminary evidence and perspective of the application of clay minerals on the humification and safety of composting.

Design, synthesis, crystal structure, and antimicrobial activities of new quinazoline derivatives containing both the sulfonate ester and piperidinylamide moieties.

To discover more efficient antimicrobial agents in agriculture, a series of new quinazoline derivatives bearing both sulfonate ester and piperidine-4-carboxamide moieties were synthesized and assessed for their antimicrobial effects. All of the target compounds were fully characterized by proton (1 H) nuclear magnetic resonance (NMR), carbon-13 (13 C) NMR, and high-resolution mass spectroscopy (HRMS), and compound III-6 containing a 3-bromophenyl substituent was clearly confirmed via single-crystal X-ray diffraction analysis. The bioassay results indicated that some compounds displayed noticeable inhibitory effects in vitro against Xanthomonas oryzae pv. oryzicola (Xoc). Further measurements of median effective concentration (EC50 ) values showed that compound III-17 bearing a 4-methoxyphenyl group had the best anti-Xoc efficacy (EC50 = 12.4 μg mL-1 ), far better than the commercialized bismerthiazol (77.5 μg mL-1 ). Moreover, this compound also demonstrated good protection and curative activities in vivo against rice bacterial leaf streak caused by Xoc. Compound III-17 had a good potential for further development as a new bactericide for controlling Xoc. © 2023 Society of Chemical Industry.

A novel formaldehyde-free wood adhesive synthesized by straw soda lignin and polyethyleneimine

To eliminate toxic formaldehyde from wood-based panels, a new formaldehyde-free wood adhesive (named OL/PEI adhesive) was synthesized by a reaction of oxidized lignin (OL) and polyethylenimine (PEI) reaction in the presence of sodium periodate. The curing mechanism of the OL/PEI adhesive was clarified by Fourier transform infrared spectroscopy (FTIR) and solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS13C-NMR) spectroscopy. The results showed that the sodium periodate could selectively oxidize wheat straw lignin to produce the ortho-quinone, and then the ortho-quinone in OL could further react with amino groups in PEI to form the OL/PEI adhesive. The as-prepared poplar particleboard was investigated with regard to hot-pressing temperature, the hot-pressing time, the OL/PEI weight ratio, and the dosage of OL/PEI adhesive. Under the optimum conditions, e.g., hot pressing temperature of 180 °C, hot pressing time of 13 min, the OL/PEI weight ratio of 1:1, and the dosage of 10%, OL/PEI adhesive was found to disperse evenly into the voids among the shavings of poplar particleboard, followed by the curing of OL/PEI adhesive using hot-pressing to form tightly bonds between the shavings. The resulting particleboard reached the requirement of mechanical properties (GB/T 4897.3-2003), higher water resistance properties, and better heating resistivity. This study demonstrated a new way to produce a formaldehyde-free wood adhesive with unique properties. This material could replace formaldehyde wood adhesive in wood bonding.

Graphene oxide-doped poly(styrene-co-maleic anhydride) for high-energy supercapacitors

Reliable energy-storage materials that can provide enhanced capacitance with good cycling stability along with improved energy and power densities are exceedingly relevant in the commercial arena to attenuate the prevalent energy shortage. Polymers with structural flexibility and good mechanical and thermal stability can be coupled with carbon-based additives to obtain an electrochemical platform for energy storage without compromising on the required thermal and mechanical attributes. Here, a styrene–maleic anhydride copolymer was modified with a diamine to form a polyimide. The samples were characterized using ultraviolet–visible spectroscopy, carbon-13 (13C) nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, Fourier transform Raman spectroscopy, thermogravimetric analysis, differential scanning calorimetry, Brunauer–Emmett–Teller analysis, scanning electron microscopy, transmission electron microscopy and X-ray diffraction to understand and investigate the spectral, morphological and electrochemical characteristics of the polymer nanocomposites. Efficacious intercalation of graphene oxide resulted in the formation of polymer nanocomposites that can act as excellent supercapacitor electrodes with a high specific capacitance of 700 F/g at 0.5 A/g and an energy and a power density of 129.23 Wh/kg and 5572 W/kg, respectively.

New pyrrolopyridine-based thiazolotriazolesas diabetics inhibitors: enzymatic kinetics andin silico study.

Aim: To synthesizepyrrolopyridine-based thiazolotriazoles as a novel class ofα-amylase and α-glucosidase inhibitors and to determine their enzymatic kinetics. Methodology: Pyrrolopyridine-based thiazolotriazole analogs (1-24) were synthesized and characterized through proton nuclear magnetic resonance, carbon-13nuclear magnetic resonance andhigh-resolution electron ionization mass spectrometry. Results: All synthesized analogs displayed good inhibitory potential of α-amylase and α-glucosidase ranging 17.65-70.7μM and 18.15-71.97μM, respectively, compared with the reference drug, acarbose (11.98μM and 12.79μM). Analog 3 was the most potent among thesynthesized analogs, having α-amylase and α-glucosidase inhibitory activity at17.65 and 18.15μM, respectively. Thestructure-activity relationship and binding modes of interactions between selected analogs were confirmed via docking and enzymatic kinetics studies. The compounds (1-24) were tested for cytotoxicity against the3T3 mouse fibroblast cell line and wereobserved to benontoxic.

Effect of acidification on microscopic properties and pore structure of coal

Acidification is a common method for removing minerals from coal. In this study, four groups of acidification samples were evaluated: raw coal (Raw), hydrofluoric acid (HF), hydrochloric acid (HCl), and mixed HF–HCl acid (Mix) groups. The concentrations of ash and various elements in the sample groups were measured by industrial and elemental analyses. The Mix solution most effectively removed the minerals from coal, with an ash removal fraction of 87.87%. The microscopic characteristics of the four groups were studied using Fourier-transform infrared (FT-IR) and carbon nuclear magnetic resonance spectroscopy (13C NMR). The oxygen-containing functional groups of the coal samples increased after acidification by 76.07%, 14.49%, and 51.06% for the HF, HCl, and Mix groups, respectively. In addition, the content of aliphatic structures decreased during acidification. The adiposity of the Mix, HCl, and HF groups decreased by 16.36%, 8.50%, and 12.73 %, respectively. The results of CO2 and liquid nitrogen adsorption showed that the cumulative pore volume of the HF and Mix groups increased by 24.90% and 21.39%, respectively, while that of the HCl group decreased by 3.23% compared to the Raw group. The changes in the coal microstructures were observed for both micropores and mesopores. The aliphatic content was inversely proportional to the pore volume, whereas some oxygen-containing functional groups enhanced the pore volume. These findings contribute to the body of knowledge related to coal-seam acidification.

Polyurethanes Based on Dicyclohexylmethane 4,4′-Diisocyanate and N-tert-Butyldiethanolamine for Enhancing the Dyeability of Fiber toward Acid Dye

Conventional polyurethane fiber (CPUF) has been widely used in clothes, but it is difficult to color CPUF into a deep hue with acid dyes. In this work, it is proposed that polyurethane is synthesized using dicyclohexylmethane-4,4′-diisocyanate (HMDI) and N-tert-butyldiethanolamine (TBDEA), named poly(HMDI-TBDEA), and is added to a CPUF spinning solution to prepare a modified polyurethane fiber (MPUF) which has an enhanced dyeability toward acid dyes. It is assumed that poly(HMDI-TBDEA) brings tertiary amine groups and tert-butyl groups to MPUF, of which the tertiary amine groups can be protonated under acidic conditions and electrostatically adsorbs anionic ions of acid dyes, and the tert-butyl groups disrupt the ordered arrangement of hard segments in polyurethane to increase the accessible area for acid dyes. The synthesis of poly(HMDI-TBDEA) was validated by proton and carbon nuclear magnetic resonance spectroscopy (1H and 13C NMR) and gel permeation chromatography. MPUF was characterized by differential scanning calorimetry, thermogravimetry, X-ray diffraction, and the tensile test. The study revealed that the addition of poly(HMDI-TBDEA) disrupted the ordered arrangement of the hard segments and strengthened the soft segments but had no obvious influence on the thermal stability. In comparison with CPUF, MPUF exhibited approximately the same elastic recovery, despite a drop in the elongation at break and the break strength. The zeta potential test demonstrated that MPUF might be protonated for enhanced electropositivity under acidic conditions. MPUF displayed superior dyeability than CPUF when dyed with C.I. Acid Orange 7 at pH 3.

A convenient synthesis, characterization and biological evaluation of novel schiff base heterocycles as potential antimicrobial, antitubercular agents and their structural activity relationship

A series of (E)-1-methyl-3-((substituted phenylimino)methyl)quinolin-2(1H)-one schiff bases (3a-j) bearing quinoline moiety synthesized successfully in ethanol by condensation of starting material 1-methyl-2-oxo-1,2-dihydroquinoline-3-carbaldehyde (1) with various substituted anilines (2a-j). The structure of the newly synthesized compounds was confirmed by proton (1H) and carbon (13C) nuclear magnetic resonance spectroscopy, Fourier transformation infrared (FT-IR), Mass spectroscopic study and elemental analysis. The in-vitro antimicrobial activity of the synthesized compounds was undertaken by agar well diffusion method against gram positive bacteria (Bacillus licheniformis and Bacillus cereus) gram negative bacteria (Escherichia coli and Acetobactor sp.) and antifungal activity against (Aspergillus Flavus and Pichnanomala). Further the compounds which shows good activity (3b, 3c, 3d, 3f, 3g and 3j) are screened for in-vitro antitubercular activity by Micro-plate alamar blue assay (MABA) method against mycobacterium tuberculosis H37Rv strain provided important information about activity against these strains. The structure activities of the synthesized compounds were also discussed. Compounds 3a, 3c, 3d, 3f and 3g show good argument with the different substituent attached to the phenyl ring.

Synthesis of Piperine-Based Ester Derivatives with Diverse Aromatic Rings and Their Agricultural Bioactivities against Tetranychus cinnabarinus Boisduval, Aphis citricola Van der Goot, and Eriosoma lanigerum Hausmann.

Exploration of plant secondary metabolites or by using them as leads for development of new pesticides has become one of the focal research topics nowadays. Herein, a series of new ester derivatives of piperine were prepared via the Vilsmeier−Haack−Arnold (VHA) reaction, and their structures were characterized by infrared spectroscopy (IR), melting point (mp), proton nuclear magnetic resonance spectroscopy (1H NMR), and carbon nuclear magnetic resonance spectroscopy (13C NMR). Notably, the steric configurations of compounds 6 and 7 were confirmed by single-crystal analysis. Against T. cinnabarinus, compounds 9 and 11 exhibited 47.6- and 45.4-fold more pronounced acaricidal activity than piperine. In particular, compounds 9 and 11 also showed 2.6-fold control efficiency on the fifth day of piperine. In addition, compound 6 (>10−fold higher than piperine) displayed the most potent aphicidal activity against A. citricola. Furthermore, some derivatives showed good aphicidal activities against E. lanigerum. Moreover, the effects of compounds on the cuticles of T. cinnabarinus were investigated by the scanning electron microscope (SEM) imaging method. This study will pave the way for future high value added application of piperine and its derivatives as botanical pesticides.

SYNTHESIS AND ANTIMALARIAL EVALUATION OF 1-(2,4- DIMETHOXYPHENYL)-3-(4-TRIFLUORO METHYL-PHENYL) PROPAN-2-ENE-1- ONE

Malaria is one of the most serious health problems worldwide and Its treatment has been compromised by drug resistance. Chalcones represent an important chemical scaffold with promising antimalarial activity. A chalcone derivative; 1(2,4dimethoxyphenyl)-3-(4-trifluoro methyl-phenyl) propan-2-ene-1-one (Compound P21) was synthesized by modified ClaisenSchmidt condensation reaction. The structure of compound P21 was established using Fourier transform infrared (FT-IR), proton and carbon-13 nuclear magnetic resonance (NMR) spectroscopy, and also mass spectrometry (MS). The compound was screened for in-vivo antimalarial activity in mice infected with P berghii parasite, using curative model. Compound P21 displayed appreciable activity (66% parasitaemia suppression) comparable to that of chloroquine (5 mg kg-1) at a dose of 175mg kg-1 in the curative test (p<0.05). The present finding suggests that compound P21 is a promising antimalarial compound and is a candidate for further optimization and evaluation.

Synthesis and Antioxidant Evaluation of Few Heterocyclic Derivatives

A series of novel heterocyclic derivatives [A1-A7] have been synthesized by the alkylation reaction of the (SH, NH, OH) of various heterocyclic (oxadiazole, thiadiazole,4-hydroxy coumarin and benzothiazole) with chloro acetone or 2-bromoacetophenone. The resulting percentage yield of synthesized compound was relatively (69-85%). The producing compounds have been identified by infrared radiation (IR), proton nuclear magnetic resonance (1H-NMR), Carbon-13 nuclear magnetic resonance (13C-NMR) spectroscopy, and the quantities of various physical properties (melting point, crystal shape, and color). The synthesized derivatives were examined for their antioxidant activities.

New solvent-free method for isolating ellagic acid from sulphite spent liquor

Ellagic acid (EA) is a plant polyphenol with wide potential in biomedical (e.g., anti-inflammatory, neuroprotective, and anti-melanogenic, among others) and technical applications such as copolymers, chelating reagents, ion-exchange resins and materials for electrochemical devices. Upon acid sulphite pulping of Eucalyptus wood, EA is partially dissolved in the spent liquor and adsorbed on the resulting pulp. In this work, a new solvent-free eco-friendly method for isolating EA from sulphite spent liquor and alkali extract of unbleached sulphite pulp is proposed. EA was recovered from sulphite pulping streams via crystallization from acidified solutions under preselected conditions (80 °C, 24 h, glass container and surface-to-volume ratio >1.0). The crystals obtained were washed with acidified water to reduce concomitants and increased EA purity from ca. 55–70% (w/w) to ca. 85–95% (w/w). The main contaminants of raw EA crystals were carbohydrates (ca. 15%), lignin (ca. 22%), lipophilic extractives (ca. 5%) and ash (ca. 3%). The obtained fractions were characterized by liquid and solid-state carbon nuclear magnetic resonance spectroscopy, mass spectrometry and wide-angle X-ray scattering, being the latter used to assess the crystalline structure. The purity of EA from sulphite spent liquor was much higher than that of the acidified alkaline extract of unbleached sulphite pulp obtained in the sulphite pulp purification step.

A new strategy for direct solution electrospinning of phosphorylated poly(vinyl chloride)/polyethyleneimine blend in alcohol media

Phosphorylated poly(vinyl chloride) (PPVC)/polyethyleneimine (PEI)-based nanofibers were produced via electrospinning in their blended solutions for the first time. For this purpose, PVC was partially converted into PVC-N3 and the PVC-N3 is then reacted with bis(diethoxyphosphoryl) acetylene (BDPA) via metal-free azide–alkyne 1,3-dipolar cycloaddition reaction to achieve the alcohol-soluble PPVC. PPVC and PEI solutions at certain concentrations prepared in methanol were electrospun from a single syringe at 90/10 and 85/15 vol ratios without phase separation. The accuracy of the modifications conducted on PVC was proven by Fourier-transform infrared (FT-IR), proton and carbon nuclear magnetic resonance (1H NMR and 13C NMR) spectroscopies and gel permeation chromatography (GPC), respectively. The achieved nanofibers and their intermediates were characterized by scanning electron microscope (SEM), water contact angle (WCA) measurement, thermogravimetric (TGA) and differential scanning calorimetry (DSC) analyses.The blood interaction of PPVC-PEI was evaluated through hemolysis and platelet activation assay, since most of the biomedical applications of PVC derivatives have close contact with blood. The results showed that PPVC-PEI nanofibers provide a safer surface for platelet with lower hemolytic activity compared to PPVC nanofibers. Therefore, PPVC-PEI-based electrospun nanofibers obtained by such an effective strategy exhibited a promising perspective for scientists in various biomedical purposes.

Synthesis and Theoretical Calculations of Benzoic Acid-Based New Mono Azo Dye

This study describes the synthesis, characterization and theoretical calculation of 3,5-dihydroxy-2-(naphthalen-2-yldiazenyl) benzoic acid. The synthesized compound was obtained through efficient synthetic route using 2-Naphthylamine and 3,5-dihydroxybenzoic acid as starting materials and characterized by various spectroscopic techniques such as Fouirer Transform Infrared Spectroscopy (FTIR), Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR), Carbon Nuclear Magnetic Resonance Spectroscopy (13C-NMR), Ultraviolet–visible spectroscopy (UV-Vis). All theoretical calculation was performed with Density Functional Theory (DFT). Optimized molecular structure, vibrational spectra, NMR chemical shift values, frontier molecular orbitals, bond lengths (Å), bond angles (°) and Molecular Electrostatic Potential (MEP) diagram of molecule were calculated using the 6-311G(d,p) basis set. It has been observed that the results obtained from the experimental and theoretical calculations support each other and were in harmony.