UV Spectra Research Articles

Supersaturation Behavior: Investigation of Polymers Impact on Nucleation Kinetic Profile for Rationalizing the Polymeric Precipitation Inhibitors.

Although nucleation kinetic data is quite important for the concept of supersaturation behavior, its part in rationalizing the crystallization inhibitor has not been well understood. This study aimed to investigate the nucleation kinetic profile of Dextromethorphan HBr (as an ideal drug, BCS-II) by measuring liquid-liquid phase segregation, nucleation induction time, and Metastable Zone width. Surfeit action was examined by a superfluity assay of the drug. The concentration was scrutinized by light scattering techniques (UV spectrum (novel method) and Fluorometer (CL 53)). The drug induction time was 20 min without polymer and 90 and 110 min with polymers, such as HPMC K15M and Xanthan Gum, respectively. Therefore, the order of the polymer's ability to inhibit nucleation was Xanthan Gum > HPMC K15M in the medium (7.4 pH). Similarly, the drug induction time was 30 min without polymer and 20, 110, and 90 min with polymers, such as Sodium CMC, HPMC K15M, and Xanthan Gum, respectively. Therefore, the order of the polymer's ability to inhibit nucleation was HPMC K15M > Xanthan Gum > Sodium CMC in SIFsp (6.8 pH), which synchronizes the polymer's potentiality to interdict the drug precipitation. The HPMC K15M and xanthan Gum showed the best crystallization inhibitor effect for the maintenance of superfluity conditions till the drug absorption time. The xanthan gum is based on the "glider" concept, and this shows the novelty of this preliminary research. The screening methodology used for rationalizing the best polymers used in the superfluity formulations development successfully.

Glycation modification of protein hydrolysate from channel catfish (Ictalurus Punetaus) viscera to mitigate undesirable flavor: Unraveling structure and flavor characteristics

To investigate the impacts of glycation modification on the structure and flavor of fish viscera-derived protein hydrolysates, channel catfish viscera was utilized and hydrolyzed by Flavourzyme, followed by glycation with glucosamine, xylose, ribose and glucose, respectively. The structural characteristics, taste and odor of glycated products were evaluated. The results revealed that glycation led to an increase in peptides (<1 kDa) and a decrease in peptide fraction (>5 kDa). UV and fluorescence spectra indicated a gradual rise in absorbance and fluorescence intensity. Glucosamine-induced glycation significantly mitigated bitterness, while enhancing saltiness and umami. GC–MS/MS analysis revealed that glycation led to reduced undesirable odor, and formation of aromatic compounds. LC-MS/MS identified Arg and Lys as the main modification sites. Interestingly, aldehydes were found to modify peptides via carbonyl-amine reaction, leading to decreased fishy odor. The present study contributes to flavor improvement of fish viscera-derived peptides through glycation and high-value utilization of fish viscera.

Enantioselective complexation of protonated tyrosine by a chiral crown-ether: the nature of the Hydrogen bonds makes the difference.

The complexes formed between (18-crown-6)-tetracarboxylic acid, denoted as 18C6TA, and the two enantiomers of protonated tyrosine, L- and D-Tyr, are studied in a cryogenic ion trap by combining mass spectrometry, laser spectroscopy, and DFT calculations. Both UV and IR photodissociation spectra indicate the formation of multiple isomers for each complex, some of them interconverting upon IR irradiation. Conformer-selective vibrational spectroscopy reveals that all structures involve an internally hydrogen-bonded folded structure of the crown ether. The complexes formed with L-Tyr involve two NH…O interactions with the ether oxygen atoms,and two hydrogen bonds to the crown ether carboxylic function, one from the NH group and the other from the COOH group of tyrosine. TheD-Tyr complexesshow more conformational mobility: two out of the three lowest energy conformers observed are tripodal, with three NH…O interactions between the amino acid ammonium and the crown ether oxygens. An additional conformer shows only one NH…O interaction, but has two interactions involving one of the cavity COOH moieties, one with the NH and one with the phenol OH. The increased calculated stability of the complex made from (-) 18C6TA and L-Tyr parallels its higher abundance in the mass spectrum of an isotopically labelled racemic mixture.

Probing Aromaticity with Supersonic Jet Spectroscopy: A Case Study on Furan, Thiophene, and Selenophene.

Aromaticity is a century-old concept that is even introduced in high school textbooks. However, the determination of the order of aromaticity of molecules as simple as furan, thiophene, and selenophene is still challenging. This work describes how different theoretical and experimental methods posit different aromaticity orders. To benchmark the theoretical results and arrive at a conclusion, mass-selective electronic and vibrational spectroscopy of these five-membered heterocycles under isolated supersonic-jet-cooled conditions was necessary. Since the aromaticity order can be unveiled from the magnitude of the electron density in the ring, we used hydrogen bonding as a probe. The experimental results revealed that selenophene forms the strongest π-hydrogen bond, suggesting that selenophene is the most aromatic, followed by thiophene and furan. It is concluded that gauge-including magnetically induced currents (GIMIC) and relative 1H and 13C NMR chemical shifts are better parameters to determine the aromaticity order in a similar class of molecules.

Green Hydrothermal Synthesis of Gallic Acid Carbon Dots: Characterization and Cytotoxic Effects on Colorectal Cancer Cell Line.

Colorectal cancer remains a leading cause of cancer-related deaths worldwide, necessitating the development of novel therapeutic approaches. Carbon dots (CDs) have emerged as promising nanoparticles for biomedical applications due to their unique properties. Gallic acid (GA), a known anticancer agent, is effective against various tumor types. This study explores the potential of gallic acid-derived carbon dots (GA-CDs) as an innovative anticancer agent against HCT-116 colorectal cancer cells, focusing on apoptosis signaling pathways. GA-CDs were synthesized using a one-pot hydrothermal method. Characterization was conducted using transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, and ultraviolet-visible (UV-Vis) absorption spectroscopy. The cytotoxicity of GA and GA-CDs on HCT-116 cells was evaluated using the MTT assay at various concentrations over 24 and 48 hours. Cellular uptake was assessed via fluorescence microscopy, and apoptosis was analyzed using acridine orange/propidium iodide (AO/PI) staining. Total RNA extraction followed by complementary DNA (cDNA) synthesis via RT-PCR was performed, and real time-PCR (Q-PCR) was conducted to examine the expression of apoptosis-related genes Caspase-3, Bax, and Bcl-2. Characterization confirmed the successful synthesis of spherical GA-CDs. GA-CDs exhibited dose- and time-dependent cytotoxicity, with IC50 values of 88.55 µg/mL for GA-CDs and 192.2 µg/mL for GA after 24 hours. Fluorescence microscopy confirmed the efficient uptake of GA-CDs by HCT-116 cells. AO/PI staining showed a significant increase in apoptotic cell numbers after treatment with GA-CDs. Q-PCR analysis revealed overexpression of Caspase-3 and Bax genes in GA-CD-treated cells, though no significant changes were observed in the expression of Bcl-2 or the Bax/Bcl-2 ratio. GA-CDs demonstrated potent anticancer properties by inducing apoptosis and reducing cell viability in HCT-116 cells. These findings suggest the potential of GA-CDs as a novel therapeutic agent for colorectal cancer treatment, warranting further investigation into their mechanism of action and in vivo efficacy.

Gram-Scale, One-Pot Synthesis of a Cofacial Porphyrin Bridged by Ortho-xylene as a Scaffold for Dinuclear Architectures.

Herein, we report the reaction between four 1,2-dibromoxylenes and two tetra-3-pyridylporphyrins for the formation of a cofacial porphyrin core spanned by dipyridinium xylene moieties. The metal-free organic nanocage (oNC) was synthesized in one twenty-four h step at a gram-scale with a 91.5% yield. The free base oNC was subsequently metalated with cobalt(II) (Co-oNC), copper(II) (Cu-oNC), and nickel(II) (Ni-oNC) ions to furnish dinuclear complexes that were characterized by mix of mass spectrometry, NMR, EPR, electronic absorption spectroscopy, and for Co-oNC, single-crystal X-ray diffraction. Cofacial cobalt porphyrins are often active as catalysts for the Oxygen Reduction Reaction. Under heterogeneous conditions in water, Co-oNC was 83% selective for the electrocatalytic 4 e-/4 H+ reduction of O2 to H2O, matching homogeneous experiments which revealed consistent selectivity for H2O (88%). This oNC core offers significant advantages over prisms formed by coordination-driven self-assembly: the dipyridnium-xylene coupling can furnish over 1 g of material in a single synthesis and the tethering motif is robust, maintaining a cofacial architecture in acidic and basic solutions. We envision this approach may be generalized to other bis-bromobenzyl building blocks, providing a means to tune metal-metal separation and other structural and electronic properties.

The Effect of Hydrodynamic Cavitation on the Structural and Functional Properties of Soy Protein Isolate–Lignan/Stilbene Polyphenol Conjugates

In this study, hydrodynamic cavitation technology was utilized to prepare conjugates of soy protein isolate (SPI) with polyphenols, including resveratrol (RA) and polydatin (PD) from the stilbene category, as well as arctiin (AC) and magnolol (MN) from the lignan category. To investigate the effects of hydrodynamic cavitation treatment on the interactions between SPI and these polyphenols, the polyphenol binding capacity with SPI was measured and the changes in the exposed sulfhydryl and free amino contents were analyzed. Various methods, including ultraviolet–visible spectroscopy, fluorescence spectroscopy, Fourier transform infrared spectroscopy, and circular dichroism spectroscopy, were also used to characterize the structural properties of the SPI–polyphenol conjugates. The results showed that compared to untreated SPI, SPI treated with hydrodynamic cavitation exposed more active groups, facilitating a greater binding capacity with the polyphenols. After the hydrodynamic cavitation treatment, the ultraviolet–visible absorption of the SPI–polyphenol conjugates increased while the fluorescence intensity decreased. Additionally, the content of exposed sulfhydryl and free amino groups declined, and changes in the secondary structure were observed, characterized by an increase in the α-helix and random coil content accompanied by a decrease in the β-sheet and β-turn content. Furthermore, the SPI–polyphenol conjugates treated with hydrodynamic cavitation demonstrated improved emulsifying characteristics and antioxidant activity. As a result, hydrodynamic cavitation could be identified as an innovative technique for the preparation of protein–phenolic conjugates.

In vitro inhibitory effect of berberine against rotavirus combined with its antioxidant, anti-inflammatory, and cytotoxicity activities.

Although berberine (BBR) is well known as a traditional medicine used in treatment of gastrointestinal diseases, its potent against viral gastroenteritis has not been specifically reported. This study aims to investigate the antiviral activity of BBR against rotavirus and evaluate its cytotoxicity and pharmacological efficacies, including antioxidant and anti-inflammatory activities in vitro. Using ultraviolet-visible absorption spectroscopy, the saturation concentration of BBR was determined as 2261 µg/mL, indicating that BBR is a poor water-soluble compound. The inhibition rate of NO production of BBR solution at a concentration of 238 µg/mL was similar to that of Cardamonin 0.3 µM with a cell viability of 92,46±0.35%, revealing the anti-inflammatory activity of BBR. The cytotoxicity of BBR solution depended on its concentration, whereby the 50% cytotoxicity concentration (CC50) of BBR after 96 h exposure was 664 µg/mL. Investigation of cytopathic effects (CPE) of MA104 cells treated with BBR and BBR-incubated rotavirus indicates that BBR could effectively inhibit the replication of rotavirus. CPEs were not observed in the cells inoculated with rotavirus (100TCID50) which was pre-incubated with BBR for 96 hours at BBR concentration of 283 µg/mL. Therefore, the study provides reliable results to demonstrate the ability of BBR to inhibit the replication of rotavirus.

Eco-friendly four spectrophotometric approaches for the simultaneous determination of the recently FDA-approved combination, bupivacaine and meloxicam in pharmaceutical dosage forms

In this study, bupivacaine (BUP) and meloxicam (MLX) were simultaneously assayed in their co-formulated ampoules without interference using four affordable, sensitive, and eco-friendly spectrophotometric methods. The assay of MLX at 359.3 nm over the concentration range of 1.0–15.0 µg/mL was accomplished using a direct UV-spectrophotometric method (Method I) without interference from BUP. However, there was a significant overlap between the spectra of BUP and MLX, making it difficult to determine BUP directly from the UV spectrum. Therefore, various UV-based techniques, including second derivative spectrophotometry (Method II), ratio subtraction method (Method III), and absorption factor method (Method IV), were used to determine BUP over the concentration range of 5.0–80.0 µg/mL. The proposed methods could simultaneously determine the studied drugs with a challenging ratio of 33.3:1.0 (BUP: MLX), which increases the importance of the current study. The proposed methods were applied to estimate the studied drugs in commercial ampoules with high % recoveries and low %RSD values. The excellent eco-friendliness of the developed methods was demonstrated using GAPI and AGREE metrics. The developed methods were validated according to ICHQ2(R2) guidelines. The proposed methods can be better suited for the routine analysis of BUP and MLX in their fixed-dose combination with high selectivity.

Probing photochemical dynamics using electronic vs vibrational sum-frequency spectroscopy: The case of the hydrated electron at the water/air interface.

Photo-dynamics can proceed differently at the water/air interface compared to in the respective bulk phases. Second-order non-linear spectroscopy is capable of selectively probing the dynamics of species in such an environment. However, certain conclusions drawn from vibrational and electronic sum-frequency generation spectroscopies do not agree as is the case for the formation and structure of hydrated electrons at the interface. This Perspective aims to highlight these apparent discrepancies, how they can be reconciled, suggests how the two techniques complement one another, and outline the value of performing both techniques on the same system.

Optical properties of carbon dots generated in liquid by pulsed IR laser at 1064 nm

Biocompatible carbon dots (CDs) have been synthesized by the laser ablation of graphite and vegetable carbon (charcoal) placed in a phosphate-buffered saline (PBS) solution. The carbon nanoparticles are produced by a pulsed IR laser beam, operating at 1064 nm, 100 mJ energy, and 3 ns pulse duration, interacting with the carbon matrix placed in the liquid at a 0.2 Hz repetition rate. The ablation rate, in terms of removed carbon mass per laser shot, was evaluated to be about 75.8 ng/pulse and 758 ng/pulse for graphite and charcoal, respectively. Optical and electronic microscopy, UV-Vis spectroscopy, and luminescence measurements were employed to evince the CDs dispersion through its photoluminescence emission. The UV excitation at a 365 nm wavelength induces CDs luminescence in the visible region, as a result of electron transition, at a wavelength band depending on the laser spot size, i.e., of the laser fluence. CDs luminescence emission obtained from charcoal is independent of the laser fluence, showing a major emission peak around 475 nm and a secondary emission peak at 515 nm. CDs luminescence emission obtained from graphite depends on the laser fluence, showing a minor wavelength band, around 474 nm, at high laser fluences and a major wavelength band, around 670 nm, at low laser fluence. The CDs luminescence of the produced biocompatible solution finds many applications in the bio-medical field, as will be presented and discussed.

Impact of Fe3+ and Al3+ co-doping on the structure, optical properties, and antibacterial activities of ZnO nanoparticles

Understanding the potential role of nanoparticles (NPs) in the global antibiotic resistance threat is essential. This study focuses on the potential antibacterial applications of Zn1−2x(Fe, Al)xO (x = 0.0, 0.02, 0.035, 0.05, and 0.065) NPs synthesized using the citrate–nitrate solution combustion method. The synthesized NPs were characterized using XRD, FESEM, FTIR, UV–Vis, and PL spectroscopies. Their antibacterial performance was assessed using the standard disc diffusion method. The synthesized NPs exhibited a single-phase hexagonal wurtzite structure (P63mc space group), with crystallite sizes ranging from 8.5 to 19.74 nm, which decreased with increasing dopant concentration. Incorporation of Fe3+ and Al3+ significantly altered key parameters of ZnO NPs, including lattice constant, bond length, dislocation density, and microstrain. Furthermore, FESEM revealed the formation of relatively spherical grains with sizes ranging from 28.42 to 56.54 nm. FTIR confirmed the presence of metal–oxygen bonds, and changes in optical properties of ZnO NPs were observed in the UV and PL spectra due to the dopants. The direct optical band gap energies ranged from 3.29 eV to 3.43 eV, indicating a notable effect of doping. Incorporating Fe3+ and Al3+ into Zn1−2x(Fe, Al)xO led to a substantial enhancement in antibacterial efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), increasing the zones of inhibition (ZOI) (at a concentration of 33.33 mg/mL) from 14.14 mm to 16.14 mm and from 17.14 mm to 19.18 mm, respectively. Among all samples, Zn0.96Fe0.02Al0.02O NPs exhibited outstanding antibacterial activity, with ZOIs of 16.14 mm and 19.18 mm against S. aureus and E. coli, respectively. This study also suggests enhanced antibacterial mechanisms for the Zn0.96Fe0.02Al0.02O NPs.

Photocatalytic degradation of methylene blue dye by ZnO nanoparticle thin films, using Sol–gel technique and UV laser irradiation

The focus of the current work is the study of the effect of the photo-catalytic activity of ZnO nanoparticles. The photocatalytic destruction of methylene blue dye, a common water contaminant, was used to assess the photocatalytic efficiency of the ZnO nanoparticles from its aqueous solution by using ZnO nanoparticles thin film under UV light and laser irradiation. Sol–gel methods prepared ZnO nanoparticle thin films. X-ray diffraction and a field-emitted scanning electron microscope were utilized to examine the structure of the produced ZnO nanoparticles. An extended characterization by laser-based fluorescence and UV–visible spectroscopic techniques. The effects of operational parameters such as photo-catalyst load and contact time on photocatalytic degradation of methylene blue were investigated. The recent study’s findings showed that irradiation with a UV laser increases with power density 25 µW/cm2, the photo-catalytic rate. The UV spectra show decay for the band at 664nm decreased and the concentration of M.B. in monomer form decayed to 26% of the original concentration in 24 h, while the band at 612 which is related to the dimer M.B. molecules was not affected. The laser irradiation did the same for monomer M.B. molecules in only 3 h, while the dimer decreased to 28% of its original concentration. The reaction mechanism has been discussed by molecular modelling. Quantum mechanical calculations at B3LYP/6-311g(d,p) level indicated that methylene blue changed from dimers to monomers in the existence of ZnO. The current results present a method for degrading M.B. not only in wastewater but also in the industrial waste scale.

Crystal Structures and Biological Profiles of Novel Tridentate Schiff Bases Nickel (II) Complexes

ABSTRACTNovel bioactive ternary nickel (II) complexes, [Ni(5BrSal‐Phe)(phen)] (1) and [Ni(5BrSal‐Tyr)(phen)] (2) (5BrSal‐Tyr: Schiff base derived from 5‐bromosalicylaldehyde and L‐tyrosine, 5BrSal‐Phe: Schiff base derived from 5‐bromosalicylaldehyde and L‐phenylalanine, phen: 1,10‐phenanthroline), have been synthesized and characterized by electronic absorption spectroscopy, CHN, FTIR, ESI‐MS and X‐ray crystallography techniques. Interaction of the complexes with biomolecules (calf thymus DNA (CT‐DNA) and bovine serum albumin (BSA)) has been investigated by electronic absorption and fluorescence spectroscopy. The results show that the complexes can bind to CT‐DNA via a minor groove binding mode. Moreover, the fluorescence quenching mechanism between the complexes and BSA is a static quenching process. The antiproliferative activities of the complexes against breast cancer cells (MCF‐7 and MDA‐MB‐231) and healthy breast epithelial cells (MCF‐10A) were investigated. The complex 2 was found to have promising antiproliferative activity in selected cell line, with lower IC50 values than cisplatin. Molecular docking studies suggest that the complexes may serve as potential chemotherapeutic agents. These complexes have been observed to interact with various targets within cells, including the epidermal growth factor receptor (EGFR), bovine serum albumin (BSA), and B‐DNA. Analyses indicate that these interactions are supported not only by conventional hydrogen bonds but also van der Waals forces and π‐π interactions. Additionally, determining binding constants and regions enhances our understanding of how the complexes interact with target molecules. The results emphasize the importance of the complexes in cancer therapy by highlighting the necessity of understanding their molecular‐level interactions with targets.

Spectroscopic Detection and Theoretical Description of Spin‐Crossover Effect in Co(II)‐terpyridine System

AbstractSpin‐crossover (SCO) effect on octahedral Co(II) centers is much rarer and less known than in the case of Fe(II) complexes, although it is no less promising for the development of fundamental research, sophisticated memories, and sensors. The representative compound [Co(terpy)2]I2 ⋅ 2H2O (terpy=2,2′:6′,2′′‐terpyridine) was synthesized, and its physicochemical properties were studied both experimentally and theoretically. Magnetic experiments revealed a very gradual SCO between a low‐spin state (SCo(II)‐LS=1/2) and a high‐spin state (SCo(II)‐HS=3/2) for the pristine sample and an abrupt SCO with a narrow thermal hysteresis around 130 K for the desolvated sample. Moreover, temperature‐dependent vibrational and electronic spectroscopy were employed to track the evolution of spectroscopic features related to SCO and desolvation processes. Additionally, quantum chemical calculations were utilized to determine the electronic structure, molecular orbitals, and vibrations for different spin states at various temperatures, offering a more comprehensive understanding of the compound's spectroscopic and magnetic behaviors. These extensive investigations provide valuable insights into Co(II)‐based SCO materials and their theoretical underpinnings, paving the way for the application of their thermometric properties.

Synthesis and characterization of Ag-decorated ZnO/MgO nanocomposite using a novel phyto-assisted biomimetic approach for anti-microbial and anti-biofilm applications

The synthesis of nanoparticles using plant extracts presents an innovative alternative to traditional chemical or physical methods. Natural nanoparticle synthesis using plant extracts has several advantages over traditional methods, including less reliance on synthetic chemicals, a reduced environmental impact, the potential to synthesize unique nanoparticle characteristics, and the production of biocompatible and biodegradable materials. This strategy is a sustainable and effective alternative. The antimicrobial activity of Ag-decorated ZnO/MgO from the leaves extract of Polygonum chinensis has been demonstrated in the present work. UV–vis, XRD, FTIR, and SEM-EDX were used to assess the bio-synthesized nanocomposite after the effective synthesis of Ag-decorated ZnO/MgO nanocomposite. The UV spectrum of the synthesized Ag-decorated ZnO/MgO nanocomposite showed a peak at 225 nm, with a band gap energy of 4.30 eV. The nanocomposite was confirmed with irregular flakes-like structure with range in size from 70 to 150 nm using SEM analysis. Standardized tests used in antimicrobial analysis were used to investigate the antimicrobial activity of Ag-decorated ZnO/MgO nanocomposite against various microorganisms. Biofilm inhibition studies confirmed the nanocomposite’s inhibitory effect on various bacteria. The findings indicated that Ag-decorated ZnO/MgO nanocomposite is a promising antimicrobial and antifilm agent.

Molecular and morphofunctional bases of development of the horse multiple congenital eye anomalies with the silver gene presence on the example of the &lt;i&gt;Soviet draft&lt;/i&gt; breed

The article concretizes clinical data on the molecular and morphofunctional foundations of the development of multiple congenital eye abnormalities (MСOA) linked to the silver gene, using the example of the Soviet heavy-duty horse breed. Recommendations for owners on their maintenance and medical support and work with them are provided. The study was conducted on the basis of data from the VNIIK breeding center for the specified horse breed, genetic testing and ophthalmological examination. The focus group included 26 horses of the Soviet heavy-duty breed, examined for the presence of the silver gene. The results of the study showed that horses of the Soviet heavy-duty breed should undergo genetic testing for the presence of a silver gene in the genotype. However, the presence of MCOA linked to the silver gene is not an indication for the culling of horses due to the status of this breed as endangered, if it is necessary to select a mate for mating without genetic abnormalities so that they do not spread during uncontrolled crossing. Regular observation of an ophthalmologist and strict implementation of his recommendations are necessary to prevent the development of infectious complications and rapid progression of the disease with the onset of blindness. Horses homozygous for the silver gene should be kept in conditions that limit the possibility of injury to the eyeballs, including secondary damage to eye structures by the UV spectrum of solar radiation, for which translucent/opaque masks or sunglasses should be used. Working on homozygous horses with partial or complete loss of vision is potentially dangerous and possible only if a number of conditions are met and the owner is ready to bear legal responsibility for possible consequences.

Rational design of ZnO/SrTiO3 S-scheme heterojunction for photo-enhanced piezocatalytic hydrogen production

Photopiezocatalysis have been frequently investigated for hydrogen evolution reactions in recent years. Herein, ZnO, SrTiO3 and ZnO/SrTiO3 S-scheme heterojunction were investigated for photo/piezocatalytic hydrogen production. Piezocatalytic hydrogen production under ultrasonic vibration by using ZnO, SrTiO3 and ZnO/SrTiO3 was obtained as 270 µmol g-1h−1, 200 µmol g-1h−1 and 1265 µmol g-1h−1, respectively. In addition, ZnO/SrTiO3 S-scheme heterojunction showed 2200 µmol g-1h−1 photopiezocatalytic hydrogen production under simultaneous exposure to white LED light and ultrasonic sound. ZnO/SrTiO3 heterojunction displayed significantly higher hydrogen production rate due to the decreased charge recombination, increased charge transfer with strong piezoelectric polarization and internal electrical field. The piezoelectric effect of ZnO/SrTiO3 heterojunction is also confirmed by piezoresponse force microscope technique with butterfly and phase hysteresis loops. Also, piezoelectric coefficient of ZnO/SrTiO3 found about 2-folds higher than those of their pristine forms. Electron transfer and reaction mechanism of ZnO/SrTiO3 and activity differences are confirmed by advanced optical and electrochemical techniques such as diffuse reflectance spectroscopy, electronic impedance spectroscopy, Mott-Schottky calculation and chronoamperometry. The whole electrochemical measurements have been performed with or without mechanical stress and light irradiation, which signify their band bending properties, electron transfer mechanism and catalytic activities.

Isolation, Purification, and Antioxidant Activity of Polyphenols from Cynanchum auriculatum Royle ex Wight

Cynanchum auriculatum Royle ex Wight (CA) is a traditional medicinal and edible plant in China. This study aimed to isolate and characterize the phenolic compounds of C. auriculatum to identify its main antioxidant constituents. Polyphenols were extracted using an ultrasound-assisted ethanol extraction method, followed by partitioning with ethyl acetate. The ethyl acetate extract was then purified through thin-layer chromatography, silica gel column chromatography, and reverse-phase silica gel column chromatography. Three monomeric compounds—cynandione A (I), 2,5-dihydroxyacetophenone (II), and radix piperacanthone (III)—were identified through their physical and chemical properties, UV and IR spectra, and liquid chromatography–mass spectrometry (LC-MS/MS). Vitamin C (VC) and 2,4-dihydroxyacetophenone were used as controls to evaluate the antioxidant potential of the two most abundant monomers. Antioxidant assays demonstrated that 2,5-dihydroxyacetophenone and cynandione A exhibited strong antioxidant activity at lower concentrations, whereas 2,4-dihydroxyacetophenone showed significantly weaker activity. Furthermore, cynandione A displayed superior cellular antioxidant activity compared to 2,5-dihydroxyacetophenone, indicating its potential as a promising bioactive compound. In conclusion, this study provides valuable insights into the phenolic composition of C. auriculatum and highlights cynandione A as a key antioxidant, paving the way for future research on its therapeutic applications.

Organometallic Ru(III) Catalysts for α-Alkylation of Carbonyl Compounds using Alcohols: Mechanistic Insights via Detection of Key Intermediates.

Three novel cyclometalated ruthenium complexes ([Ru.L(9)] [Ru.L(10)] and [Ru.L(11)]) featuring azo functionalities were synthesized and characterized using a variety of spectroscopic techniques, namely FT-IR, electronic absorption spectroscopy, and ESI-MS. Representative solid-state structures of the acquired complexes were determined through X-ray crystallography. These complexes were evidenced to be efficient catalysts for the synthesis of various α-alkylated compounds utilizing simple acetophenone derivatives with easily affordable and economically viable alcohols, which were isolated and characterized via 1H and 13C NMR spectroscopy. The optimum reaction conditions were found by employing toluene as solvent, potassium tert-butoxide as base at 115 oC temperature utilizing 0.8 mol% of catalyst [Ru.L(10)]. The yield of the desired compounds found to be in the range of 83 - 97%. Additionally, mass spectrometry provided insights into the in-situ generated ruthenium hydride and ruthenium alkoxy intermediates, shedding light on the catalytic mechanism.