UV Spectroscopy Research Articles

Enhanced photocatalytic performance of (Mg, Cu) Dual-Doped ZnS nanosheets for Solar-Driven water treatment and embedded with PVA polymer membrane for reusability

Photocatalysis uses semiconductor materials to solar energy effectively purify to water by eliminating pollutants. Organic Dye degradation serves as a standard to assess the photocatalytic effects of the materials. In this study Mg, Cu dual-doped ZnS nanosheets were synthesized using the coprecipitation method. The impact of the concentration on the structural, morphology, optical, and degradation efficiency was investigated with XRD, XPS, TEM with EDAX, and UV spectroscopy. The pure ZnS and Zn0.98-xCu0.02MgxS (x = 0, 0.01, 0.02) (ZCM1, ZCM2, ZCM3, and ZCM4) nanosheets, exhibited cubic structure with high phase purity. The average crystalline size was calculated as 1.66, 1.60, 1.45, and 1.47 nm for the ZCM1, ZCM2, ZCM3, and ZCM4 nanosheets, respectively. TEM analysis revealed the presence of crumpled nanosheets. The bandgap of the ZCM1, ZCM2, ZCM3, and ZCM4 nanosheets were 3.99, 3.78, 4.03, and 4.09 eV respectively. This study investigated the photocatalytic activity of crystal violet dye when exposed to natural sunlight irradiation. Notably, ZCM3 nanosheets exhibited a high degradation rate of 99 % over 120 min under sunlight. Furthermore, the proposed dye degradation mechanism, effect of dosage, effect of dye variation, reusability, scavenging activity, and hemolytic activity were comprehensively discussed. The nanosheets embedded with the Polyvinyl alcohol (PVA) polymer membrane for reusability.

DFT and Monte Carlo simulation studies of potential corrosion inhibition properties of some basic heterocyclic compounds

ABSTRACT This study utilises a combination of density functional theory (DFT) approach, 6-31G (d, p) basis set, and Monte Carlo (MC) simulations. The goal is to understand the relationship between the structure and properties of heterocyclic inhibitors and how they interact with Fe (110) surfaces. Furan, pyrrole, thiophene, pyridine, pyridazine, pyrimidine, indole, benzofuran, carbazole, quinolone, isoquinoline, and imidazole are the chemicals that were looked at in this study. The DFT calculations provide important insights into various properties of the inhibitors, such as molecular structure, dipole moments, electrostatic potential maps, Reduced Density Gradient (RDG), UV spectroscopy, and thermal characteristics. Carbazole has the smallest energy difference (4.789 eV) and the highest softness (0.209 eV−1), It also has the most chemical activity, Furthermore, the Monte Carlo models demonstrate that these derivatives have favourable adsorption energies on the Fe (110) surface. Among them, carbazole shows significant inhibitory potential. The study confirms that the carbazole compound with the biggest negative adsorption energy (−95.495) actually has the smallest energy difference and fits with the MC simulation for adsorption on Fe (110) when it is not charged. Carbazole has much stronger adsorption than oxazole, showing how the structure of a molecule affects how well an inhibitor works.

Plasma synthesis and characteristics of nanocomposite coatings based on PVA and chitosan with incorporated nanoparticles for the healing of skin wounds

This study investigated the impact of new composites based on PVA and chitosan on wound healing in mice. Metal or metal oxide nanoparticles were synthesized without reagents by creating an impulse discharge between metal electrodes in a polymer dispersion. Polymer composites and coatings were then prepared using these nanoparticles. The composites were analyzed using various techniques, including UV spectroscopy, X-ray diffraction, scanning and transmittance electron microscopy, and infrared spectroscopy. The maximum concentration of nanoparticles in the composite was 3.5%. The average diameter of the nanoparticles was approximately 50-60 nm. The inclusion of Ag and ZnO nanoparticles accelerated the healing process by approximately 25%.

An Estimation of Baricitinib by AQbD-driven UV Spectrophotometry Development and Validation Process

Background: Baricitinib (BCTB) is a novel Janus Kinase (JAK) 1 and 2 inhibitor used in the therapy of rheumatoid arthritis, approved by the “Food and Drug Administration” in 2018. It has significant dose-dependent effectiveness and severe side effects. Thus, it is crucial to figure out its concentration in developed dosage forms. The literature search revealed that there has only been one UV spectroscopy technique documented up to this point. Methanol was chosen as the detection medium in this approach, which is not comparable with plasma or serum. As a result, the preliminary research suggested developing a UV spectroscopic approach that can estimate BCTB concentration and compare it to its concentration in the plasma or serum. Thus, in the proposed method, 7.4 pH phosphate buffer was selected as a mobile phase. Aim: Using the Analytical Quality by Design (AQbD) methodology, a simple, robust spectrophotometric method for the detection of BCTB in API form and Niosomes drug delivery system is designed and assessed. Methods: In the AQbD approach, a face-centered CCD design of Design Expert 13 software was used to evaluate two critical method variables: scanning speed and sampling interval. The design space suitability was confirmed by standard error and overlay plots. The 2-D contour and 3-D response surface plots were used to forecast the relationship between the response variable and predictor variables. Results: Baricitinib displays an absorption maximum at 249.40 nm in saline phosphate buffer pH 7.4. The distinguished linearity of the method was obtained over a concentration of 5–30 µg/ml with a correlation coefficient (R2 ) value of 0.998. BCTB % assay was found to be near 99 %. Intraday and Interday precision were found to have % RSDs of 0.067–0.488 and 0.146–0.942, respectively. Conclusion: The established spectrophotometric technique was observed to be precise as per ICH revised guidelines ICH Q2 (R1) and Q14 for analytical method validation. Our findings are instructional for the future design and development of safe and reliable therapeutic dosage forms of BCTB for rheumatoid arthritis.

Greenness assessment of a molecularly imprinted polymeric sensor based on a bio-inspired polymer

Methyldopa, a synthesized dopamine substitute with phenolic, amine, and carboxylic groups, was used to create a selective molecular imprinted polymer (MIP) for detecting formoterol fumarate dihydrate (FFD), a long-acting beta2-agonist for asthma and COPD. The bio-inspired polymer (MD) was electro-grafted onto a pencil graphite electrode (PGE) using cyclic voltammetry in a phosphate buffer (pH 6.5). An indirect method involving a redox probe (ferrocyanide/ferricyanide) and differential pulse voltammetry measured FFD binding to the MIP’s 3D cavities. The sensor showed a linear response range from 1 × 10⁻⁹ M to 2 × 10⁻¹⁰ M, with a detection limit of 1.7 × 10⁻¹¹ M. The polymethyldopa (PMD) and FFD interaction was assessed by UV spectroscopy, and the method was validated per ICH guidelines. Green analytical approaches, including RGB and GAPI, were also implemented. The goal was to use advances in molecularly imprinted polymers to develop a more precise and selective electrochemical sensor for FFD quantification.

Biofabricated silver nanoparticles from Calotropis procera: A potential antimicrobial solution against pathogenic bacteria

Calotropis procera has the potential as a traditional medicinal plant that offers a diverse array of healing treatments. It was used in conventional medicine to remedy several ailments, including diarrhea and snakebites. This study examines the antibacterial properties of silver nanoparticles derived from the floral and latex components of C. procera. The nanoparticles were tested for their effectiveness against Gram-negative and Gram-positive bacterial strains. For characterization, the synthesized nanoparticles underwent thorough analysis using UV spectroscopy, fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). After the reduction process, the FTIR analysis revealed that some functional biomolecules found in plants form a coating on the nanoparticles, serving as organic agents that stabilize the nanoparticles. The size of nanoparticles analyzed with SEM falls in the 30 to 130 nm range. Furthermore, the synthesized silver nanoparticles were tested as antimicrobial agents against Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa, well-known microorganisms that can produce ulceration phases and severe health consequences. After a comprehensive examination, it was found that the silver nanoparticles have significant antibacterial effectiveness, particularly against S. aureus, a primary bacterium responsible for causing different ailments. The remarkable antibacterial efficacy of the silver nanoparticles synthesized in an environment-friendly manner underscores its potential applications in combating the evolution of antibiotic-resistant strains.

Study of Luminescence Phenomena of Tb (III) Containing Fluroquinoline for Application in Optoelectronic Devices.

This study presents a series of six vivid green Tb(III) complexes, denoted by the general formula [Tb(L)3.secondary sensitizers], where L represents 1-cyclopropyl-7-(4-ethylpiperazin-1-yl)-6-fluoro-4-oxoquinoline-3-carboxylic acid and secondary sensitizers consist of heterocyclic N-donor aromatic systems. The synthesis of these complexes were achieved through a solvent-assisted grinding method, and their characterization involved various techniques such as CHN analysis, FTIR, NMR, UV, XRD, and NIR spectroscopy. These analyses confirmed the successful synthesis of complexes with coordination between the quinoline moiety and the metal ion. Photoluminescence studies were conducted in solid and solution phases, revealing excellent luminescence properties. The bright green color emitted by the complexes upon exposure to UV rays was attributed to the hypersensitive 5D4 → 7F5 transition. J-O analysis indicated an asymmetrical coordination environment around in the complexes. Additionally, various radiative properties (Ared, Anred, η, βexp, σs) and band gap values were determined, highlighting the potential applications of these complexes in diverse optoelectronic fields. Chromaticity evaluation demonstrated high color purity in both solid and solution phases. Furthermore, the CCT value identified the solid complexes as a cool light source. Overall, the analyses supported the exceptional luminosity of synthesized complexes, positioning them as promising luminescent materials for a wide range of devices.

Efficient Extraction and Analysis of Wheat Straw Lignin by Response Surface Methodology

To enhance the high-value utilization of straw waste and achieve efficient lignin extraction, wheat straw was selected as the feedstock for investigating the effects of reaction temperature, reaction time, solid–liquid ratio, and formic acid concentration on lignin yield using a formic acid/acetic acid solvent system. A single-factor experimental design was initially employed, followed by optimization using the response surface methodology. Additionally, a kinetic model was developed to describe lignin extraction kinetics in the formic acid/acetic acid system. The structural characteristics and thermal stability of the extracted lignin were analyzed via FTIR, UV spectroscopy, and TGA. The findings indicate that increasing reaction temperature, reaction time, solid–liquid ratio, and formic acid content all significantly enhanced lignin extraction yield from wheat straw, with the primary influencing factors being reaction temperature > solid–liquid ratio > reaction time > formic acid content. The optimal extraction conditions were identified at a reaction temperature of 90 °C, a reaction time of 3.5 h, a solid–liquid ratio of 1:16.5, and a formic acid content of 86.2 wt.%, yielding a lignin content of 79.83%. The analytical results demonstrated that the extracted lignin preserved the structural integrity of the original lignin and exhibited good thermal stability.

Zein and 3-Aminophenyl Boronic Acid Conjugated Polyvinylpyrrolidone Polymer Blend: Electrospinning, Characterization, and Mucoadhesive Drug Delivery.

The era of mucoadhesive polymers has advanced to the next generation, focusing on targeted adhesion of chemical functional groups with mucosa. This work aims to develop boronic acid functionalized polymers, which could facilitate reversible binding with the mucin in the mucosa. Pendant groups of boronic acid were conjugated on the chains of polyvinylpyrrolidone (PVP) via C═N bonding. The evidence from FTIR spectroscopy, XPS analysis, and UV spectroscopy has been used for the confirmation of the chemical conjugation of 3-aminophenyl boronic acid (APBA) to PVP. Boronate ester formation is a pH-dependent process. High pKa values of APBA preferably cause the binding of trigonal-shaped boronic acid with sialic acid groups of mucin. Boronic acid moieties additionally benefited in mucoadhesion in comparison to PVP alone, which is a result of the formation of a five-membered boronate ester complex. The presence of boronic acid moieties enhanced the force of adhesion on porcine buccal mucosal tissue from 13.12 ± 1.52 to 19.04 ± 1.97 g force. Specific binding of the polymer to the mucosal surface caused prolonged adhesion of the polymer to the mucosal surface. A polymer blend of boronic acid functionalized PVP and zein has been explored for its potential for mucoadhesive delivery of propranolol hydrochloride.

Utilization of Tea Polyphenols as Color Developers in Reversible Thermochromic Dyes for Thermosensitive Color Change and Enhanced Functionality of Polyester Fabrics

Thermochromic textiles possess the capability to indicate ambient temperature through color changes, enabling real-time temperature monitoring and providing temperature warnings for body heat management. In this study, three thermochromic dyes—blue, red, and yellow—were synthesized using crystalline violet lactone (CVL), 6′-(diethylamino)-1′,3′-dimethyl-fluoran (DDF), and 3′,6′-dimethoxyfluoran (DOF) as leuco dyes, respectively, with biomass tea polyphenol serving as the color developer and tetradecanol as the phase change material. The chemical structures of these dyes were characterized using UV spectroscopy, infrared spectroscopy, Raman spectroscopy and 1H NMR. The thermochromic mechanisms were investigated, revealing that the binding bonds between the leuco dyes and the color developer broke and reorganized with temperature changes, imparting reversible thermochromic property. Polyester fabrics were dyed using an impregnation method to produce three reversible thermochromic fabrics in blue, red, and yellow. The structure and properties of these fabrics were analyzed, showing a significant increase in the UPF value from 26.3 to approximately 100, indicating enhanced UV resistance. Water contact angle measurements revealed that the contact angle of undyed polyester fabrics was 139°, while that of dyed polyester fabrics decreased by about 40°, indicating improved hydrophilicity. Additionally, the fabric inductive static tester showed that the static voltage half-life of dyed polyester fabric was less than 1 s, demonstrating a significant antistatic effect. Infrared thermal imaging results indicated that during the warming and cooling process, the thermochromic polyester fabric exhibited specific energy storage and insulation effects at 38 °C, close to the human body temperature. This study presented a novel approach to developing smart color-changing textiles using biomass-derived thermochromic dyes, offering diverse materials for personal thermal management, and intelligent insulation applications.

ZIF‐8 as Potential Vector for Enhanced Target Delivery of Sulfathiazole for the Treatment of Bovine Ruminal Acidosis

The aim of this paper is enlarging the potential use of ZIF‐8 MOF as drug delivery system (DDS) for antimicrobial molecules, in particular for sulfathiazole, to be employed for the treatment of Subacute Ruminal Acidosis (SARA) in dairy cows. We therefore optimized (from milligrams to grams) the synthesis methodology for ZIF‐8 MOF, moving from organic solvents to aqueous solution, deeply characterizing the prepared material with X‐ray diffraction (XRD), surface area analyses (BET), electron microscopy (SEM), and thermogravimetric analyses (TGA). Once proved that the synthesis is also reproducible, we tested the stability of the material at physiological and acid pH, controlling material stability over time by checking their crystallinity with XRD. We then optimized sulfathiazole entrapment method to obtain the best material, checking the effective loading with UV‐vis spectroscopy. Afterwards, we checked the effective entrapment vs physical mixture by means of XRD, SEM and ATR‐MIR spectroscopy. Finally we tested the pH‐responsive drug release by dialyzing the sulfathiazole@ZIF‐8 by UV spectroscopy on the dialysis solution, confirming the strong pH‐dependence of release time of sulfathiazole.

Next-Generation BiOCl/MXene Nanocomposites: Optimized for Dye Removal and Supercapacitor Applications.

The study focuses on the development of an efficient and sustainable solution for synthetic dye degradation through the hydrothermal synthesis of BiOCl and BiOCl/MXene heterostructures. Structural and compositional properties were analyzed by using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS) techniques. A significant reduction in the band gap of BiOCl/MXene to 2.97 eV from 3.62 eV for BiOCl was observed via UV spectroscopy, leading to enhanced photocatalysis with 89% degradation efficiency in just 12 min. The mechanism involved and reactive species were confirmed by LC-HRMS and radical trapping tests, while ICP-MS verified metal content in water before and after degradation. Additionally, the nanocomposite demonstrated a specific capacitance of 431.24 F g-1 at a current density of 1 mA cm-2, with an excellent capacitance retention of 94.35% after 2000 cycles. This study highlights BiOCl/MXene as a promising material for both photodegradation and supercapacitor applications.

Aurelia aurita jellyfish collagen: Recovery properties

Wound and burn healing is a complex physiological process that can be facilitated by medications based on marine collagen. In this regard, biomass of the Aurelia aurita jellyfish is a promising alternative source of medical collagen. As the global incidence of burns and wounds continues to grow, new healing methods have become a relevant area of medical science. This study featured acetic acid as a means of marine collagen extraction from A. aurita biomass. The physical and chemical properties of jellyfish collagen were determined gravimetrically and included such indicators as water solubility and water holding capacity. The molecular weight was defined by gel electrophoresis. The spectral studies relied on the method of UV spectroscopy. The regenerative experiments included such parameters as cytotoxicity, antioxidant properties, adhesion, and wound healing rate, as well as a quantitative PCR analysis. The optimal conditions for maximal collagen yield were as follows: 0.5 M acetic acid and 48 h extraction time. However, the collagen yield was very low (≤ 0.0185%). The high water holding capacity showed good prospects for A. aurita collagen to be used as hemostatic sponge. The acid-soluble collagen sample had a molecular weight of 100–115 kDa, which made it possible to classify it as type I. A. aurita jellyfish collagen revealed no cytotoxic properties; it had no effect on adhesion, migration, and proliferation of keratinocytes, neither did it affect the expression of cell differentiation markers. The wound healing model proved that the marine collagen had regenerative properties as it was able to increase the wound healing rate by 24.5%. Therefore, collagen extracted from the biomass of A. aurita jellyfish d emonstrated good p rospects for cosmetology and regenerative medicine.

Nanotherapy for Cancer and Biological Activities of Green Synthesized AgNPs Using Aqueous Saussurea costus Leaves and Roots Extracts.

Background/Objectives: Nanoparticles derived from medicinal plants are gaining attention for their diverse biological activities and potential therapeutic applications. Methods: This study explored the antioxidant, anti-inflammatory, anti-tumoral, and antimicrobial properties of green synthesized silver nanoparticles (AgNPs) using the aqueous leaf and root extracts of Saussurea costus (S. costus). The physicochemical characterizations of both biosynthesized AgNPs using the aqueous leaf extract (L-AgNPs) and root extract (R-AgNPs) were examined using UV spectroscopy, fluorescence spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, dynamic light scattering, and Fourier-transform infrared spectroscopy. The antioxidant activity measured using ABTS, DPPH, and FRAP assays showed that AgNPs, particularly from roots, had higher activity than aqueous extracts, attributed to phenolic compounds acting as capping and antioxidant agents. Results: Enzyme inhibition studies indicated that AgNPs exhibited remarkable anti-inflammatory effects, inhibiting COX-1, 5-LOX, and secreted PLA2 enzymes by over 99% at 120 µg/mL, comparable to standard drugs. The anti-tumoral effects were evaluated on the human cancer cell lines HCT-116, LoVo, and MDA-MB-231, with AgNPs inhibiting cell proliferation dose-dependently and IC50 values between 42 and 60 µg/mL, demonstrating greater potency than extracts. The AgNPs also showed enhanced antimicrobial activities against various microbial strains, with IC50 values as low as 14 µg/mL, which could be linked to nanoparticle interactions with microbial cell membranes, causing structural damage and cell death. Conclusions: These findings suggest that S. costus-derived AgNPs are promising natural, biodegradable agents for various biological applications and potential new therapeutic agents, necessitating further research to explore their mechanisms and applications.

Optical sensing and nonlinear optical properties of Cr-doped MoO3/PEDOT:PSS Nanocomposites

In this study, we observed a negative UV photoresponse that switched to a positive photoresponse in Cr-doped MoO3/PEDOT:PSS nanocomposite films(NCF) prepared via drop-casting. MoO3 and Cr-doped MoO3 were synthesized using a hot oil bath co-precipitation method, combined with PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate)), and coated onto flexible OHP sheets. The open aperture z-scan method investigated the nonlinear optical properties of NCF on the glass substrate. The films were characterized by X-ray diffraction, scanning electron microscopic (SEM), UV–Vis spectroscopy, and Fourier Transformed Infrared (FTIR). Chromium doping caused minor changes in lattice parameters, crystalline size, and microstrain. UV spectroscopy revealed an increase in bandgap with higher Cr–MoO3 concentrations. The photoresponse of different Cr–MoO3 concentrations showed an initial current decrease under UV light, but the photoresponse became positive beyond a threshold and continued to improve. Nonlinear optical studies indicated saturable absorption in the nanocomposite. This work enhances our understanding of Cr-doped MoO3/PEDOT:PSS nanocomposites, contributing to advancements in flexible UV photodetectors and nonlinear optical applications.

Unveiling the power of g-C3N4@CR composite photocatalyst in simulated solar light-assisted degradation of fast green dye and nitrophenol

A novel and efficient method has been developed for synthesizing the g-C3N4@CR composite using a simple mingling and heating technique. This method involves the decoration of one-dimensional carmine (CR) onto graphitic carbon nitride (g-C3N4). The light-harvesting composites produced through this process underwent characterization using various spectroscopic techniques, including UV, XRD, FT-IR, Raman, and XPS spectroscopy. To assess the photocatalytic activity of the g-C3N4@CR Composite, its degradation efficiency was investigated by examining its performance in degrading fast green and nitrophenol dyes under outdoor solar light irradiation. The mechanism of degradation for these dyes by the newly designed g-C3N4@CR composite was elucidated through degradation kinetics analysis, involving the determination of parameters such as half-life time, rate constant, and degradation efficiency.

Core-shell nanomaterials based on La2FeCrO6 coated with metal oxides for optical applications

In this research work, the preparation of core/shell nanoparticles comprising La2FeCrO6 (LFCO) as the core was accompanied by the choice of ZnO and CuO as different shells. Structural and optical characteristics were investigated for the LFCO (core) relative to La2FeCrO6/ZnO and La2FeCrO6/CuO core/shell NPs. x-ray diffraction analyses reveal the conformation of core/shell structures within average crystallite sizes of 22.46 nm and 25.03 nm. Raman spectroscopy and Fourier-transform infrared spectroscopy (FTIR) were performed to provide fundamental information about the vibrational modes and the functional groups of core/shell NPs, respectively. x-ray photoelectron spectroscopy (XPS) detects the electronic states of the constituent elements of the core/shell nanostructures, including lanthanum, iron, chromium, oxygen, zinc, and copper. Optical characteristics have been extensively analyzed using UV spectroscopy. The energy gap (Eg) was determined by utilizing both Tauc and Derivation of Absorbance Spectrum Fitting (DASF) methods. LFCO/ZnO and LFCO/CuO core/shell NPs exhibit a direct optical transition, similar to that of the core LFCO NPs, with a decrease in band gap value from 3.4 eV for the core to 3.3 eV and 3.18 eV for LFCO/ZnO and LFCO/CuO core/shell NPs respectively. The enhanced transparency of core/shell NPs, particularly at longer wavelengths, is evident from the decrease in refractive index (n) compared to that of the core (LFCO) NPs. This decrease is attributed to the encapsulation of LFCO with either ZnO or CuO NPs. The samples exhibit a decline in both linear and non-linear optical susceptibilities with respect to the square of photon energy. The LFCO/CuO sample shows excellent results in the photocatalytic degradation of aqueous organic dyes, considering it a promising candidate for wastewater treatment and the removal of organic pollutants.

UV-induced E/Z isomerization of the electron-rich pyrrole ring containing diketoenols: Theoretical and experimental study

The Knoevenagel reaction of 2-acetyl-1,3-indandione, dehydroacetic acid, 3-acetyl-4-hydroxy-coumarin and acetyl-barbituric acid with pyrrol-2-carbaldehyde affords 2-(1-hydroxy-3-(1H-pyrrol-2-yl)allylidene)-1H-indene-1,3(2H)-dione 5, 3-(3-(1H-pyrrol-2-yl)acryloyl)-4-hydroxy-6-methyl-2H-pyran-2-one 6, 3-(3-(1H-pyrrol-2-yl)acryloyl)-4-hydroxy-2H-chromen-2-one 7 and 5-(1-hydroxy-3-(1H-pyrrol-2-yl)allylidene)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione 8. The UV-induced E→Z isomerization, intra and intermolecular H-bonding is studied by NMR, IR, UV spectroscopy and theoretical calculations. The driving force for the E→Z isomerization is the formation of a bifurcate O–H⋯O⋯H–N hydrogen bond in the latter. The position of the E⇆Z equilibrium strongly depends on the solvent (CH2Cl2, acetone, EtOH, DMSO). According to QTAIM analysis, the formed OH⋯O bonds are strong or moderate in energy (from 7.6 to 10.2 kcal/mol), while the NH⋯O bonds are weak (from 4.8 to 6.4 kcal/mol).

Synergistic corrosion inhibition of 4-hydroxypyridine and halogen ions: Insights from interfacial nonlinear spectroscopy.

4-Hydroxypiridine (4-HPy) is a green chemistry corrosion inhibitor for low-carbon steel, valued for its environmental compatibility and low toxicity. Despite lower initial effectiveness than 4-mercapto/4-aminopyridine, 4-HPy's performance is markedly enhanced by halogen ions. By employing second harmonic generation (SHG) spectroscopy combined with electrochemical methods, Raman spectroscopy, atomic force microscopy, x-ray photoelectron spectroscopy, and in situ UV spectroscopy, this study elucidates the synergistic enhancement mechanism of 4-HPy with Cl-, Br-, and I- in 0.5 mol/L HCl solution. Time-dependent SHG measurements showed a two-step process of rapid adsorption and subsequent orientation change, with a proposed mechanism to interpret the temporal changes in SHG intensity. Deducing the adsorption kinetic equations and their application to the experimental data yields the adsorption rate (kad) and orientation change rate (Kre). Halogens reduce the orientation angle of 4-HPy, facilitating its adsorption on the substrate surface and effectively inhibiting corrosion via distinct mechanisms. Cl- and Br- ions primarily adsorb onto the metal surface, forming an adsorption film that not only enhances the subsequent adsorption of 4-HPy but also provides a protective effect for the metal surface. Conversely, I- forms mainly complexes with 4-HPy in solution, co-adsorbs onto the metal surface, and demonstrates a significant synergistic effect. This study revealed the synergistic efficacy hierarchy among halogen ions, with the order 4HPy + NaCl < 4HPy + NaBr < 4HPy + NaI. This study enhances our molecular-level understanding of the synergistic mechanism between halogen ions and corrosion inhibitors and provides valuable insights for designing and developing effective corrosion inhibitors.

Bioactive Formulation and Bulk Allopurinol and Lycopene Estimation by UV Spectroscopy

Background: This study developed a UV spectrophotometric method for quantifying allopurinol and lycopene in both bulk and dosage forms, aiming for simplicity and practicality. Materials and Methods: The method was developed and validated using methanol and lyco-pene in phosphate buffer saline at various pH levels (7.4, 6.8, 1.2, 5.5). Validation parameters included linearity, accuracy, precision, limit of quantification (LOQ), and limit of detection (LOD) according to ICH standards. Results: The method demonstrated high sensitivity and linearity over a concentration range of 4-20 μg/ml, adhering to Beer's law. The LOQ and LOD were 2–18 μg/ml and 2–6 μg/ml, re-spectively. Optimal absorbance wavelengths were 251 nm for lycopene and 471 nm for allopu-rinol. Calibration curves showed a high correlation coefficient (0.9994), indicating a strong lin-ear relationship. Conclusion: The developed UV spectrophotometric method is effective, interference-free, and suitable for routine quality control, providing reliable measurements for allopurinol and lyco-pene.