Ethanol Solution Research Articles

Monomeric and Dimeric Boron (III) Subphthalocyanines Functionalized with 4-Hydroxy-Benzoic Acid as Potential Photosensitizers and Photocatalysts in Sulfoxidation.

Axial modification of boron (III) subphthalocyanine bromides with 4-hydroxy-benzoic acid successfully led to the formation of the macrocycles with anchored 4-carboxyphenoxy group [RsPcPHBA] (R=tBu, H) in the axial position and to a new dimer [sPcPHBAsPc] as minor product. Tri-tert-butyl and unsubstituted subphthalocyanines bearing benzoate ([tBusPcBA], [sPcBA]), phenoxy-group ([tBusPcOPh], [sPcOPh])) in the axial position, have been also investigated as well as control sPcs. All compounds were characterized by NMR, IR, UV-Vis and mass spectrometry. The electrochemical properties were studied using cyclic voltammetry (CV) and square wave voltammetry (SWV). Singlet oxygen generation was systematically measured for all synthesized [RsPcX] by kinetic method of chemical trap decomposition (DPBF) and by determination of phosphorescence of singlet oxygen (at 1270 nm). Axially modified subphthalocyanines exhibit high quantum yields of singlet oxygen (1O2) generation (0.47-0.62). The observed exceptional photostability in oxygen-saturated ethanol or toluene solutions and high 1O2 quantum yields allows to use [tBusPcPHBA] as photocatalysts of selective oxidative transformations of organic sulfides to sulfoxides. Loading the catalyst to 9.7 ⋅ 10-2 mol % made it possible to achieve complete conversion of the substrate (TON up to 1700).

The Effect of Ethanol on Rotator Cuff Repairs in a Rodent Model

BackgroundAlcohol consumption is a significant risk factor for both the occurrence and severity of rotator cuff tears. However, there is limited supporting evidence to suggest alcohol use is associated with suboptimal outcomes following operative repair of rotator cuff tears. Rat shoulders have been demonstrated as consistent and reliable models for studying rotator cuff disease. Hypothesis/PurposePerioperative alcohol exposure will negatively impact biomechanical and histologic properties of surgically repaired rotator cuffs in rats. MethodsRats were randomized to receive a 20% ethanol or isocaloric control solution as their primary source of drinking water. A tenotomy of the supraspinatus tendon from bone was performed surgically and then immediately repaired with a transosseous technique. Following surgery, rats were continued on the same exposure solution until animals were humanely euthanized at 7, 14, or 21 days postoperatively. The surgically-repaired shoulders underwent biomechanical testing to assess load to failure and failure strain. Histological evaluation of tendon-to-bone healing was performed by a blinded pathologist using a qualitative grading system. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) on total RNA from tendon-to-bone interface tissue was performed to quantify the mRNA expression of Type I & III collagen, and transforming growth factor-beta 1 (TGF-B1) & 3 (TGF-B3) at the repair site. ResultsBiomechanical testing showed that repaired shoulder constructs in rats exposed to ethanol had significantly lower load to failure at 7 days postop relative to repairs in rats exposed to a control solution. No other biomechanical parameters or time points reached statistical significance. TGF-B3 mRNA expression was found in significantly higher quantities at the repair sites of rats exposed to ethanol at 7 days postop relative to control rat repair sites. No other time points or factors reached statistical significance. No significant differences were identified amongst time points or groups at the healing tendon-to-bone interface. ConclusionAlcohol exposure significantly decreases biomechanical load to failure of rotator cuff repairs in the early postoperative period in rat models. In the later postoperative period, alcohol exposure was not associated with a decrease in biomechanical load to failure compared to controls. Additionally, rats exposed to ethanol have significantly higher TGF-B3 expression at repair sites on postoperative day 7. This data suggests that ethanol consumption does deleteriously affect rotator cuff and bone healing. Future study is needed to validate the clinical significance of these findings in humans.

ANTIMICROBIAL, ANTIOXIDANT AND CYTOTOXICITY STUDY OF Cu(II), Zn(II), Ni(II), AND Zr(IV) COMPLEXES CONTAINING O, N DONOR SCHIFF BASE LIGAND

Objective: The aim of the research is to synthesize and characterize Cu(II), Zn(II), Ni(II), and Zr(IV) complexes with a Schiff base ligand, and evaluate their antibacterial and antioxidant properties. Methods: The ligand was synthesized by refluxing salicylaldehyde with o-phenylenediamine in ethanol, forming a yellow-orange product. The complexation reaction involved stirring ethanolic solutions of Zn(II), Cu(II), Ni(II), or Zr(IV) salts with a Schiff base ligand. Thermal decomposition of Zn(II), Cu(II), Ni(II), and Zr(IV) complexes was analyzed under nitrogen, heating at 30 °C/min, measuring weight loss from ambient temperature to 800 °C. The antibacterial activity, antioxidant properties, and cytotoxicity of the synthesized compounds wereexamined using reported methods. Results: Cu(II), Zn(II), Ni(II), and Zr(IV) complexes with a Schiff base ligand were synthesized. Analyzed through Fourier-transform infrared spectroscopy (FTIR), Ultraviolet-visible (UV-vis) and physiochemical tests and confirmed the structures. Magnetic susceptibility and electronic spectra suggested geometries, supported by thermogravimetric data. Antibacterial tests revealed complexes had higher activity than ligands, and also showed antioxidant properties. Conclusion: Cu(II), Zn(II), Ni(II), and Zr(IV) Schiff base complexes were synthesized, showing tetrahedral or square planar geometries. They exhibited thermal stability and strong antibacterial activity, outperforming the ligand alone.

Enhanced hydrophobic properties, wear and corrosion resistance of plasma electrolyte oxidation coatings on AZ31B magnesium alloys with addition of TiO2 nanoparticles

Nanocomposite coatings were fabricated on AZ31B magnesium alloy by means of plasma electrolyte oxidation (PEO) with the addition of TiO2 nanoparticles into the alkaline electrolyte, followed by low surface energy modification in the ethanol solution of lauric acid. The dual-layered nanocomposite PEO coatings composed of MgO, Mg2SiO4, anatase-TiO2, rutile-TiO2, and Mg2TiO4 were formed, and the TiO2 nanoparticles incorporated into the PEO coatings via both inertia and reactive modes. Besides, the penetration and adsorption of TiO2 nanoparticles created a distribution gradient in the coating thickness direction. The wear rate of the PEO coatings with TiO2 nanoparticles in 4 g/L was approximately 82 % lower than that of the bare substrate and approximately 39 % lower than that of the PEO coatings without TiO2 addition, respectively. The enhancement in wear resistance was due to the synergistic effect of the lower coefficient of friction (COF), the higher microhardness and the denser microstructure with finer micropores and less microcracks on the coatings than that of the TiO2-free coatings. Besides, the hydrophobic property was enhanced for the low surface energy modified PEO coatings with the addition of TiO2 nanoparticles in the electrolyte. Moreover, a significant enhancement in the corrosion resistance was achieved for the PEO coating with the addition of TiO2 nanoparticles in 4 g/L. It exhibited a higher corrosion inhibition efficiency and a lower corrosion rate than that in other concentrations and without TiO2 addition. The improvement in anti-corrosion property was originated from the formation of phases including TiO2 and Mg2TiO4 in the coating, and denser microstructure with better hydrophobic properties for the PEO coatings with TiO2 nanoparticles in 4 g/L compared with that in other concentrations. Accordingly, the hydrophobic, wear-resistant and corrosion-resistant PEO coatings with TiO2 nanoparticles exhibited significant advantages in the field of Mg alloys protection.

Changes in morphometric indicators of liver blood vessels under conditions of long-term ethanol exposure

Hyperdynamic splanchnic blood circulation is an important component of portal hypertension syndrome, which develops under conditions of chronic alcoholic hepatitis. Angiogenesis caused by alcohol consumption contributes to the development of splanchnic hyperemia and the development of portal-systemic collaterals. The purpose of the study is to study the morphometric indicators of the vascular bed of the liver of rats under the conditions of chronic alcoholic hepatitis modeling. Experiments were performed on 30 white, sexually mature male Wistar rats weighing 180–220 g. The animals were divided into 2 groups: I (control group) contained 6 rats; II – 24 rats that modeled chronic alcoholic hepatitis by the method of forced intermittent alcoholization for 5 days, with a repeat after two days by intraperitoneal injection of a 16.5% ethanol solution in a 5.0% glucose solution, at the rate of 4 ml/kg of body weight. Animals were removed from the experiment on days 35, 42, 49, and 56 by taking blood from the right ventricle of the heart under thiopental anesthesia. On the 35th day of simulation of chronic alcoholic hepatitis, the inner diameter of central veins, lobular arterioles and interlobular veins increased, and interlobular arteries and lobular venules decreased compared to the control. On the 42nd day of simulation of chronic alcoholic hepatitis, the internal diameter of central veins, lobular arterioles and interlobular veins increased, and interlobular arteries decreased compared to the control. On the 49th day of simulation of chronic alcoholic hepatitis, the inner diameter of the central veins, lobular arterioles, and interlobular veins increased, and the interlobular arteries decreased compared to the control. On the 56th day of simulation of chronic alcoholic hepatitis, the inner diameter of the central veins and lobular arterioles increased, and the interlobular arteries and lobular venules decreased compared to the control. Keywords: arteries, veins, arterioles, venules, sinusoidal capillaries.

Composite photocatalysts g-C<SUB>3</SUB>N<SUB>4</SUB>/TiO<SUB>2</SUB> for hydrogen production and dye decomposition

The photocatalytic activity of the g-C3N4 /TiO2 composite samples in the processes of dye (methylene blue) decomposition and hydrogen evolution from an aqueous ethanol solution under the action of visible radiation (400 nm) has been studied. A new original method for the synthesis of the g-C3N4 /TiO2 composite by depositing g-C3N4 /TiO2 to TiO2 nanoparticles during sol-gel synthesis is proposed. The synthesized photocatalysts were characterized by X-ray diffraction, low-temperature gas adsorption, X-ray photoelectron spectroscopy, high-resolution transmission microscopy, and diffuse reflectance spectroscopy in the UV and visible regions. The maximum activity in the hydrogen evolution reaction was 1.3 mmol h–1, which exceeds the rate of hydrogen evolution on the unmodified g-C3N4 and TiO2 samples.

Enzymatic-Assisted Recovery of Antioxidants from Chicory and Fennel by-Products

AbstractThe work was aimed to evaluate the antioxidant extraction efficiency of enzymatic-assisted extractions, alone or combined with sonication, applied to chicory and fennel by-products. Three enzymatic preparations were tested: enzyme mix 1, made of pectinlyase, polygalacturonase, pectinesterase, and arabinase; enzyme mix 2, composed of pectinlyase, cellulase, and acid proteas; xylanase. They were applied alone or coupled with a successive sonication performed according to the following conditions: 100 g/L; 45 °C; 40 min; 72 W. The results were compared with those of a solid-liquid extraction performed with a 70% ethanolic solution whose conditions were previously optimized to maximize the extraction of antioxidants from the specific matrix (chicory: 60–180 min, antioxidant content 6.15 ± 0.20 mg/g dm; fennel: 60–90 min, antioxidant content 7.60 ± 0.70 mg/g dm). Concerning chicory by-products, the three enzymatic treatments coupled with ultrasounds allowed the obtainment of extracts having approximately the same amounts of antioxidants than the conventional extraction (6.10–6.22 mg/g dm). Regarding fennel, all the enzymatic-assisted extractions (coupled or not with ultrasounds) gave lower antioxidant concentrations than the hydroalcoholic extraction. Enzymatic extraction and sonication significantly influenced type and quantity of phenolics in the extracts, highlighted that compounds other than phenolics contributed to their antioxidant properties.

A pH-Responsive Hydrogel for the Oral Delivery of Ursolic Acid: A Pentacyclic Triterpenoid Phytochemical.

In this study, poly(HEMA-PEGxMEM-IA) hydrogels were prepared by radical copolymerization of poly(ethylene glycol) methyl ether methacrylate (PEGxMEM), 2-hydroxyethyl methacrylate (HEMA), and itaconic acid (IA). The reaction was carried out in ethanolic solution using N,N'-methylenebisacrylamide (MBA) as a crosslinking agent and 1-hydroxycyclohexyl phenyl ketone (HCPK) as a photo-initiator. The poly(HEMA-PEGxMEM-IA) hydrogels (HGx) were evaluated as a delivery system for ursolic acid (UA), a phytochemical extracted from the plant Clinopodium revolutum, "flor de arena". The hydrogels were characterized by Fourier-transform infrared spectroscopy (FTIR-ATR), Raman spectroscopy, X-Ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The swelling behavior was studied in buffer solutions from pH 2 to 10, specifically at pH 2.2 (gastric environment) and 7.4 (intestinal environment). It was found that the hydrogels studied showed sensitivity to pH. At pH 2.2, the degree of swelling for HG5 and HG9 hydrogels was 0.45 and 0.93 (g water/g hydrogel), respectively. At pH 7.4, the degree of swelling for HG5 and HG9 hydrogels was 1.97 and 2.64 (g water/g hydrogel), respectively. The SEM images show the variation in pore size as a function of pH, and the UA crystals in the pores of the hydrogels can also be observed. The in vitro UA release data best fit the Korsmeyer-Peppas kinetic model and the diffusion exponent indicates that the release mechanism is governed by Fickian diffusion.

Measurement of ethanol concentration for monitoring the solvent exchange during the alcogel preparation

A crucial and time-consuming stage in aerogel production is the solvent exchange process for alcogel formation. This process involves multiple steps, exposing the hydrogel to ethanol solutions with increasing concentration until the equilibrium in each step. Currently, the determination of contact time between phases (hydrogel and liquid solution) is either arbitrary or based on prior studies. However, considering the unique physicochemical characteristics of each system, as well as the solid-liquid interactions and the liquid diffusion within the matrix, the required time may vary. Monitoring this step can lead to a reduction in the time needed for alcogel production and the optimization of the entire process. The refractive index serves as a tool to assess ethanol concentration in the liquid solution over time, providing immediate information about the status of the solvent exchange. Alongside, differential scanning calorimetry can be employed to evaluate ethanol content in the alcogel (solid phase), confirming the attainment of equilibrium between phases.•This research introduces a technique for monitoring solvent exchange.•Refractive index measurement of the liquid solvent offers immediate concentration information into the status of the solvent exchange.•Differential scanning calorimetry is applicable for measuring the ethanol content within the alcogel and validating refractive index findings.

Red‐Emitting Pyrazole Azo Hydrazone and Its Metal Complexes for Photophysical Probing, Latent Fingerprints, Anti‐counterfeiting, and Biological Studies

ABSTRACTThe present paper discusses the synthesis of unprecedented red‐emitting mono‐azo compound pyrazole azo fluorescent tag (PAFT) by a diazotization method, followed by an electrophilic substitution reaction. Further, the metal complex of PAFT is also prepared by refluxing the ethanolic solution of the ligand with the corresponding metal (RuCl3 and C4H6CuO4.H2O) salts under suitable experimental conditions. The synthesized fluorophore PAFT displays intense fluorescence in the aggregate state and has excellent qualities, including high purity, low cost, eco‐friendliness, and good photostability. These unique characteristics of PAFT led to the development of new fluorescence‐based technology for the in situ viewing of latent fingerprints. Various spectroscopic and analytical techniques are used to confirm the structural characteristics of the synthesized compounds, including UV–Vis, FT‐IR, (1H) NMR, HRMS, TGA, VSM, ESR, and powder XRD methods. The potency of the antibacterial activity of the compounds was evaluated. The results revealed that compound PAFT and [Ru(PAFT)Cl3] H2O showed excellent sensitivity at 0.8 μL/mL against the Gram‐positive bacteria Staphylococcus aureus.

A shifted ratio spectrum strategy for effective subtraction of fluorescence interference in Raman spectra.

Raman spectroscopy is an important technique for analyzing the chemical composition of samples in many fields. A severe challenge often encountered in Raman measurements is the presence of a concurrent fluorescence background, especially in biological samples. In order to obtain accurate Raman spectra, the fluorescence background must be subtracted from the original Raman spectra. We proposed a shifted ratio spectrum method to subtract the strong fluorescence background from the original Raman spectrum. First, the original Raman spectrum is divided into multiple regions according to the spectral shape of the shifted ratio spectra, and then, Gaussian fitting is performed in each region. The fitting results are stitched together in order to obtain the complete fluorescence background. Finally, this fluorescence background is subtracted from the original spectrum to obtain a pure Raman spectrum. This method can accurately subtract the fluorescence background of Rhodamine 6G (R6G)/ethanol solution and serum. This highlights the great potential of this method for applications in both biological and non-biological samples.

A soft processing technology for the extraction of cellulose from plant residues and agri-food wastes

In this study, cellulose was extracted from giant cane (GC), Posidonia oceanica seagrass (PO), coffee silverskin (CS), and brewer's spent grain (BSG) as alternatives to conventional sources of cellulose. The extraction protocol involved three steps: i) hemicellulose and lignin removal through alkaline hydrolysis in a 5% (w/v) NaOH solution (solid-to-liquid ratio = 1:100 g/mL, T = 25 °C, t = 2 h, ω = 300 rpm), ii) removal of organic compounds and ashes through a 95% (v/v) ethanol solution (solid-to-liquid ratio = 1:25 g/mL, T = 25 °C, t = 0.5 h, ω = 500 rpm), and iii) double bleaching in a 1% (w/v) acidic (pH = 4) NaClO2 solution (solid-to-liquid ratio = 1:50 g/mL, T = 90 °C, t = 1.5 h, ω = 500 rpm). Yield, purity, crystallinity degree, and morphology of cellulose extracted through a soft-chemical cascade process were assessed by gravimetric, infrared (FT-IR), nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses. Averaged cellulose extraction yields of 36.4, 38.6, 23.1, and 22.2% for GC, PO, CS, and BSG were obtained, respectively. All cellulose samples had high purity, though lower than the ultra-pure bacterial cellulose, which was due to the slight contamination from unremoved hemicellulose and lignin residues. Cellulose samples exhibited similar chemical features and the typical fibril-like morphology of microcrystalline cellulose (6–13 μm in width). The versatility of the proposed extraction procedure supports the sustainable conversion of low-cost organic biomasses to valuable products with manifold industrial applications (e.g., food packaging).

Ultrasound-promoted synthesis of polysubstituted imidazole-linked benzoxazole derivatives and the investigation of their optical properties

A rapid and efficient synthesis of novel hybrid imidazole-benzoxazole derivatives is described under ultrasound irradiation. These reactions were carried out through a cyclization reaction of polysubstituted imidazole-based o-aminophenols and various benzoic acids in polyphosphoric acid. The starting o-amiophenols were synthesized from corresponding o-nitrophenols using Fe powder in EtOH and acetic acid. o-Nitrophenol derivatives were synthesized from related phenols by employing HNO3 in acetic acid. Structures of the newly obtained products were confirmed by spectral and analytical data. The optical properties of the products were investigated via UV–Vis absorption and fluorescent emission spectroscopy in dilute ethanol solution.

Preparation, Characterization, In Vitro Biological Evaluation, DFT Calculations, and Molecular Docking Investigations of 1H-Imidazole-2-Carboxylic acid and Histidine-Based Mixed-Ligand Complexes.

Mixed-ligand complexes incorporating 1H-Imidazole-2-Carboxylic acid (IMCA) and Histidine (LHIS) show promise for biomedical and biotechnological applications. This study synthesizes and characterizes FeIMCALHIS, CoIMCALHIS, and NiIMCALHIS coordination compounds using metal chloride salts (FeCl3.6H2O, CoCl2.6H2O, NiCl2.6H2O) in ethanolic solutions. The complexes are characterized by spectroscopic methods (IR, UV-vis, and mass spectra), elemental analysis, conductivity, magnetic, and thermal analysis. Molar conductivity indicates their non-electrolytic nature. UV-vis spectra reveal absorption bands with pathochromic shifts, and electronic spectra show characteristic metal-ligand transitions, indicating their structural configuration and coordination geometry. 3D geometry optimization shows six-coordination around Fe(III) and Co(II) in FeIMCALHIS and CoIMCALHIS, and four-coordination around Ni(II) in NiIMCALHIS. Analysis of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) suggests decreased electron donation ability upon coordination. Electronic structure parameters (HOMO, LUMO, ionization potential, energy gap, electron affinity, chemical potentials, and electronegativity) provide further insights into stability and reactivity. The metal complexes exhibit enhanced antimicrobial, antioxidant, and anti-inflammatory activity compared to individual ligands, with FeIMCALHIS showing notable antimicrobial activity. Molecular docking analysis reveals strong binding interactions with target proteins, highlighting their potential therapeutic applications.

Analysis of the composition of Brazilian black soybean seeds and mathematical modelling of intermittent drying and extraction of antioxidant compounds using fractional calculus

AbstractThe present study aims to analyze the composition of black soybean seeds, evaluate the intermittent drying of black soybean seeds by fractional calculus, optimize the extraction conditions of the antioxidant compounds by varying the solvent ratio and the extraction time, fit traditional models of extraction kinetics, and compare with the fractional order model. Regarding the oil content, it is analyzed that black soybeans have a high lipid content (18.86%), an oil source of interest for research and industrial applications. Regarding drying, it was found that the first order model cannot be used to describe the kinetics of intermittent drying for black soybean seeds and the best kinetic fits were obtained with the Page and fractional order models, which can be applied in simulations of drying and dryer designs. Regarding the extraction process, ethanol/water 45/55 (v/v) solvent proportion obtained the highest antioxidant compound content during 1 h of extraction. So and MacDonald's and hyperbolic kinetic models presented the best fitting to experimental data. About the fractional order model, it is found that for extraction conditions with more significant amounts of water in the ethanolic solution, the α value obtained is less than 1, resulting in the phenomenon of subdiffusion. For the extraction condition with a low amount of water in the ethanolic solution, the α value was greater than 1, depicting a superdiffusion process.

Nanofilament organization in highly tough fibers based on lamin proteins

The escalating plastic pollution crisis necessitates sustainable alternatives, and one promising solution involves replacing petroleum-based polymers with fibrous proteins. This study focused on the recombinant production of intracellular fibrous proteins, specifically Caenorhabditis elegans lamin (Ce-lamin). Ce-lamins spontaneously organize within the cell nucleus, forming a network of nanofilaments. This intricate structure serves as an active layer that responds dynamically to mechanical strain and stress. Herein, we investigated the arrangement of nanofilaments into nanofibrils within wet-spun Ce-lamin fibers using alcoholic solutions as coagulants. Our goal was to understand their structural and mechanical properties, particularly in comparison with those produced with solutions containing Ca+2 ions, which typically result in the formation of nanofibrils with a collagen-like pattern. The introduction of ethanol solutions significantly altered this pattern, likely through rearrangement of the nanofilaments. Nevertheless, the resulting fibers exhibited superior toughness and strain, outperforming various synthetic fibers. The significance of the nanofilament structure in enhancing fiber toughness was emphasized through both the secondary structure transition during stretching and the influence of the Q159K point mutation. This study improves our understanding of the structural and mechanical aspects of Ce-lamin fibers, paving the way for the development of eco-friendly and high-quality fibers suitable for various applications, including medical implants and composite materials.

High Salt-Resistant Urethanase Degrades Ethyl Carbamate in Soy Sauce.

Urethanase is a promising biocatalyst for degrading carcinogen ethyl carbamate (EC) in fermented foods. However, their vulnerability to high ethanol and/or salt and acidic conditions severely limits their applications. In this study, a novel urethanase from Alicyclobacillus pomorum (ApUH) was successfully discovered using a database search. ApUH shares 49.4% sequence identity with the reported amino acid sequences. It belongs to the Amidase Signature family and has a conserved "K-S-S" catalytic triad and the characteristic "GGSS" motif. The purified enzyme overexpressed in Escherichia coli exhibits a high EC affinity (Km, 0.306 mM) and broad pH tolerance (pH 4.0-9.0), with an optimum pH 7.0. Enzyme activity remained at 58% in 12% (w/v) NaCl, and 80% in 10% (v/v) ethanol or after 1 h treatment with the same ethanol solution at 37 °C. ApUH has no hydrolytic activity toward urea. Under 30 °C, the purified enzyme (200 U/L) degraded about 15.4 and 43.1% of the EC in soy sauce samples (pH 5.0, 6.0), respectively, in 5 h. Furthermore, the enzyme also showed high activity toward the class 2A carcinogen acrylamide in foods. These attractive properties indicate their potential applications in the food industry.

Benzo[6,7]cyclohepta[1,2-d]pyrazolo[1,5-a]pyrimidines: Regioselective synthesis of a Novel Ring System, DFT-based NMR prediction, local reactivity indexes, and MEP analysis

Novel benzo[6,7]cyclohepta[1,2-d]pyrazolo[1,5-a]pyrimidines were prepared as a new ring system utilizing a regioselective protocol. A mixture of the appropriate 3,5-diamino-1H-pyrazoles and benzosuberone-based enones in ethanolic potassium hydroxide solution was heated at reflux for 5 h to produce the novel benzosuberone-fused pyrazolo[1,5-a]pyrimidines in 87–94 % yields. Both spectral data as well as elemental analyses were used to establish the structure of the novel products. Theoretical calculation of chemical shifts of NMR spectra is a powerful tool in analyzing experimental spectra for known substrates as well as elucidating the chemical structure for unknown ones. Using the DFT-GIAO approach under the B3LYP and mPW1PW91 functions, as well as a variety of basis sets, including 6–31G(d,p), 6–31+G(d), 6–311G(d), 6–311+G(d,p), 6–311++G-(d,p), and 6–311+G(2d,p), the chemical shifts of 1H- and 13C NMR in DMSO were calculated. The results that are most similar to the experimental observations are obtained from the computation of the chemical shift values under the 6–31G(d,p) or 6–31+G(d,p) basis sets and mPW1PW91 when using the multistranded approach. By identifying the preferred regions for electrophilic and nucleophilic attack, DFT-based FMO, global descriptors, local reactivity indexes, and MEP mapping were applied at the B3LYP function using the 6–31+G(d,p) basis set to provide additional insight into the regioselectivity in the desired reaction as well as the plausible mechanism for the formation of new products.

Anti-corrosion and anti-icing properties of superhydrophobic laser-textured aluminum surfaces

Superhydrophobic surfaces have favorable properties in simultaneously reducing the negative effects of corrosion and ice accumulation. In this study, laser-texturing was employed as a facile and environmentally friendly surface method to prepare a surface with hierarchical roughness for subsequent grafting by immersion in an ethanol solution containing 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-10). Various analytical techniques were utilized to assess the characteristics of the laser-textured aluminum surfaces before and after grafting, such as a contact profilometer, optical tensiometer, scanning electron microscope with energy-dispersive spectroscope, and X-ray photoelectron spectroscope. These methods were used to evaluate surface roughness, wettability, morphology, and composition. The corrosion properties were evaluated through potentiodynamic and impedance measurements in a dilute Harrison's solution (DHS) composed of 0.35 wt% (NH4)2SO4 + 0.05 wt% NaCl. Additionally, freezing delay tests at various surface temperatures were performed to assess the surface's ability to prevent the freezing of water droplets on the treated surface. The laser-textured aluminum surface, featuring micro/nanostructures and a grafted nanoscopic perfluoroalkyl silane film, exhibited outstanding superhydrophobicity and enhanced corrosion protection. The developed surface has been shown to significantly delay the onset of ice nucleation and extend the freezing delay.

Molecular interaction studies of L-proline in water and ethanol at different temperatures using dielectric relaxation, refractive index and DFT methods

The complex dielectric permittivity of L-Proline in water and ethanol solutions with molar concentrations ranging from 0.025 M to 0.15 M was measured by open-ended coaxial probe technique. The measurements were carried out across a frequency span of 0.02 < ν/GHz < 20 and temperatures varying from 298.15 K to 323.15 K. The densities (ρ) and refractive index (nD ) of the L-proline in aqueous and ethanol solutions were also determined to provide insights into the solute-solvent interactions in the system. The Havriliak-Negami equation was employed to compute the dielectric relaxation time of the mixtures. The relaxation time of L-Proline in an ethanol medium was found to be higher than that of L-Proline in an aqueous medium due to the greater degree of self-association of ethanol molecules. Additionally, the relaxation time of the mixtures lengthened with rising molar concentration, which is attributed to the presence of hydrogen bonds among L-Proline and aqueous/ethanol molecules. The strength of the hydrogen bond interaction of L-Proline in both mediums was calculated using single-point energy calculations employing IEFPCM/PCM solvation models through DFT/B3LYP and MP2 approaches with a 6-311 G ++ (d, p) basis set. The results were correlated with the hydrogen bond strength, Gibbs’ free energy of activation parameter, and dipole-dipole interactions. Communicated by Ramaswamy H. Sarma