UV-Vis Spectrophotometric Measurements Research Articles

Synthesis, physicochemical, optical, thermal and TD-DFT of (E)-N′-((9-ethyl-9H-carbazol-3-yl)-methylene)-4-methyl-benzene-sulfonohydrazide (ECMMBSH): Naked eye and colorimetric Cu2+ ion chemosensor

Benzene-sulfonohydrazide (ECMMBSH) Schiff base has been made available in an excellent yield via reflux dehydrate of 4-methylbenzene-sulfonohydrazide with 9-ethyl-9H-carbazole-3-carbaldehyde in EtOH. The synthesis of the ECMMBSH was monitored via two main spectroscopic techniques FT-IR and UV–vis tools; ECMMBSH was characterized via MS, 1H NMR, FT-IR, CHN-EA, TG/DTG, EDX, and UV–vis., analysis. Moreover, DFT-optimized, Molecular Electrostatic Potential (MEP) and MAC/NPA-charge models were performed for ECMMBSH. The HOMO/LUMO and Density of State (DOS) calculated energy levels were compared to Tuac experimental optical energy gap values in methanol. Additionally, the TD-DFT and UV–vis. experimental absorption behavior was matched under the same condition. Moreover, the chemo-sensation effect of the ECMMBSH towered Cu2+ ions via complexation was evaluated by naked eye in addition to the UV–vis spectrophotometric measurements.

Curve fitting and linearization of UV–Vis spectrophotometric measurements to estimate yeast in inoculum preparation

The counting of microorganisms is essential in the area of microbiology, especially in the preparation of inoculum. The main methods for obtaining inoculum are McFarland standard, Neubauer chamber, and plate count. However, the visual comparison is subjective while the counting in the chamber and the plating are technically time-consuming. For this reason, our article aims to correlate the absorbance of the spectrophotometer in the visible ultraviolet region (UV–Vis) with the cell counting in the Neubauer chamber. This study used suspensions of Candida spp. measured at three wavelengths (530, 600, and 700 nm) and counting in a Neubauer chamber. In the next step, curves were adjusted with different polynomials using absorbances and counts. The two best polynomial curve fittings were the Saturation Growth Rate (SGR) and Morgan-Mercer-Flodin (MMF). Therefore, the polynomials were linearized and a direct correlation between absorbance and the number of cells was made. The proposed method proved to be more accurate (5 ± 0.5 × 106) than the comparison with the McFarland turbidity (1–5 x 106) and more practical than plate counting. Predicting the number of cells by UV–Vis is an alternative that reduces the uncertainty of the cell count interval for inoculum preparation.

Effect of O2, N2, Ar, and Ar/O2 Plasma Treatment on Optical Properties of Polyaniline Films

In the current work, improvement of the optical properties of Polyaniline (PAni) films was investigated using cold plasma technique. Samples were treated with different gases including argon (Ar), oxygen (O2), nitrogen (N2) and Ar/O2 mixture using low-pressure dc glow discharge. Films of about 300 nm were fabricated by simple deposition of polyaniline suspension in toluene on glass slides. UV-Vis spectrophotometric measurements of the prepared films showed that plasma treatment resulted in a significant increase in the optical band gap of the films. Plasma treatment was found to increase the band gap energies range from (1.7–1.98 eV) of the untreated films to 1.8-2.42 eV of the treated ones. Exposure to oxygen plasma was found to alter the chemical composition of the films and thus, resulting in a high transmission (over 85%) of the peak centred at 550 nm. This increases the photoelectric performance of the plasma treated polyaniline films

Deposition time and annealing effects on morphological and optical properties of ZnS thin films prepared by chemical bath deposition

Abstract Nanocrystalline zinc sulfide (ZnS) thin films are prepared on glass substrates by chemical bath deposition (CBD) method using aqueous solutions of zinc chloride, thiourea ammonium hydroxide along with non-toxic complexing agent tri-sodium citrate in alkaline medium at 80 °C. The deposition time and annealing effects on the optical and morphological properties are studied. The morphological, compositional, and optical properties of the films are investigated by scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDAX) and UV-Vis spectroscopy. SEM micrographs exhibit uniform surface coverage. UV-Vis (300 nm to 800 nm) spectrophotometric measurements show transparency of the films (transmittance ranging from 69 % to 81 %), with a direct allowed energy band gap in the range of 3.87 eV to 4.03 eV. After thermal annealing at 500 °C for 120 min, the transmittance increases up to 87 %.

Modulation of surface tension and rheological behavior of methyl cellulose – Amino acid based surfactant mixture by hydrophobic drug rifampicin: An insight into drug stabilization and pH-responsive release

The interaction of Methyl Cellulose (MC) with amino acid-based anionic surfactants viz. sodium lauryl sarcosinate (SLS) and sodium stearyl sarcosinate (SSS) having different hydrophobic chain lengths but the same head group has been investigated using surface tension, rheological and UV–Vis spectrophotometric measurements. The effect of poorly water-soluble drug Rifampicin (Rif) on the physicochemical and rheological properties of the MC-surfactant system was also elucidated. The tensiometric profiles of the two systems (MC + SLS & MC + SSS) indicated that the Critical Aggregation Concentrations (CACs) are further reduced in presence of Rif while as the Critical Micelle Concentrations (CMCs) remain more or less constant. The oscillatory rheological experiments revealed that the gelation is highly dependent upon the applied frequency and concentration of the surfactants. Moreover, the viscoelasticity of the polymer-surfactant system is greatly modulated by the presence of Rif molecules which tend to decrease the viscoelasticity of the MC + SSS system more than that of MC + SLS system till the CAC. The kinetic stability of Rif w.r.t. oxidation with H2O2 in MC and MC-surfactant systems revealed that the polymer-surfactant systems were able to stabilize and protect the drug more than individual polymer or surfactant systems. The systems were also investigated for drug (Rif) release at pHs 7.4 and 4.0 in which diffusion predominant release was observed at pH 7.4 while at pH 4.0, the release was controlled by both diffusion and relaxation phenomenon. These experimental findings could be important for modulating the use of polymer-surfactant systems for enhancing the drug stability and their application in pH-responsive drug release.

Study of metal-amino acid [Cr(III)-Trp]2+ complex and ninhydrin reaction: role of gemini micellar solution on rate constant

In this article, the study of metal-amino acid complex and ninhydrin reaction was examined in gemini micellar solution using a UV-visible spectrophotometric measurement. The role of varying amounts of gemini micellar systems on rate constant of the study was investigated. Initially, rate constant (k ψ) enhances, below cmc and levelling-off areas are, then, noticed up to 400 × 10−5 mol dm−3. Later, gemini offers a third region of fast enhancement k ψ above 400 × 10−5 mol dm−3. Gemini surfactant series provided more efficient implications on the study than pure water and their monomeric traditional surfactant system. The values of rate constant, k ψ, were determined under a set of different experimental reaction situations with the help of a computer-based procedure. Such unfamiliar behaviour developed by gemini micellar solutions was treated by pseudo-phase model of micellar activity. An electrical conductometric measurement was employed to measure critical micellar concentration (cmc) of pure gemini micellar solutions and mixed systems. Several activation parameters were also determined by Eyring’s equation and different constants. Data obtained confirmed that lower values of activation enthalpy (ΔH #) with large negative activation entropy (ΔS #) were attained in gemini than aqueous. A plausible reaction mechanism of the study has been discussed and proposed.

Ultraviolet-B-induced changes on phenolic compounds, antioxidant capacity and HPLC profile of in vitro-grown plant materials in Echium orientale L

The application of UV-B radiation is effective stress factor for the biosynthesis and accumulation of valuable plant secondary metabolites. The effect of UV-B irradiation on phenolic compounds, total flavonoid and phenolic contents and antioxidant activity of in vitro grown Echium orientale L. shoots and calli were investigated in current study. For this purpose, phenolic compounds (rosmarinic acid, chlorogenic acid, ferulic acid and quercetin) were determined by High Performance Liquid Chromatography (HPLC) analysis while antioxidant activity, total phenolic and flavonoid contents were evaluated by UV–vis spectrophotometric measurements. The results showed that callus extracts contained higher amount of total phenolics and flavonoids and the phenolic compounds than shoot extracts of E. orientale. Besides, the results revealed that the phenolic compounds, especially rosmarinic acid and quercetin, increased in shoot and callus extracts of E. orientale which were harvested one week later after UV-B treatment when compared with the control. The results also showed that UV-B irradiation increased the antioxidant activity and total flavonoid content in both plant samples which were harvested one week later after UV-B treatment. However, the total phenolic content increased in callus extracts which were harvested immediately after UV-B irradiation.

Chemical bath deposition of aluminum doped zinc sulfide thin films using non-toxic complexing agent: Effect of aluminum doping on optical and electrical properties

Zinc sulfide (ZnS) and aluminum doped zinc sulfide (ZnS:Al) thin films have been prepared by chemical bath deposition onto glass substrates at 85 °C using non-toxic complexing agents by varying the Al concentration between 0 wt. % and 18 wt. %. The ZnS and ZnS:Al thin films exhibited a hexagonal wurtzite crystal structure and showed (008) preferential orientation. The Field Emission Scanning Electron Microscope (FESEM) images of the film showed that the glass substrate was nicely covered by compact and dense mosaic like nanostructures. The elemental composition of ZnS and ZnS:Al thin films was measured by energy dispersive x-ray spectroscopy. X-ray photoelectron spectroscopy (XPS) demonstrates the doping of Al into ZnS. From the XPS spectra, the binding energy (BE) values were observed to shift toward the lower BE side for increasing aluminum content. Raman spectra were obtained for the undoped and Al doped ZnS films, which exhibit first-order phonon modes at 328.33 cm−1 and 341.66 cm−1 for the A1/E1 longitudinal optical phonons, and the bands at 253.33 cm−1 and 263.33 cm−1 revealed longitudinal optical phonon–plasmon coupled modes. UV–visible spectrophotometric measurement showed that approximately 70%–80% transmission happened in the visible to near infrared region, with a direct allowed bandgap in the range of 3.52 eV–3.76 eV. A maximum transmittance of 80% was observed for 6 wt. % Al doped ZnS thin films, and the absorption edge shifted toward the blue spectrum region. ZnS and ZnS:Al thin films showed n-type electrical conductivity with carrier concentrations varying from 1.55 × 1017/cm3 to 3.13 × 1017/cm3. Resistivity of the ZnS:Al thin films was decreased with the increase in Al concentration.

Spectro-electrochemical characterization and quantification of Rutin in aqueous media.

From UV-Vis spectrophotometric measurements the acidity constants of Rutin in aqueous media, at 25 °C and 0.1 M ionic strength, were determined as: pK1 = 4.392 ± 0.167, pK2 = 7.130 ± 0.050, pK3 = 8.661 ± 0.042 and pK4 = 12.354 ± 0.020 and the molar absorptivity coefficients of all the Rutin pH-dependent species were reported as a function of wavelength. Furthermore, the electrochemical behavior of Rutin at neutral pH was investigated using a bare carbon paste electrode, CPE. It was found that both: Rutin electrochemical oxidation and reduction are reversible, adsorption-controlled processes, involving 2 electron transfers. Moreover, the bare CPE was used for the electrochemical quantification of Rutin in neutral aqueous media, displaying the following features: (1.078 ± 0.440) μM, (3.594 ± 0.400) μM and (0.308 ± 0.014) μA μM-1 for the detection and quantification limits and sensitivity, respectively, within the 1-11 μM linear range. Meanwhile the spectrophotometric method displayed the following analytical features: (3.385 ± 1.318) μM, (11.283 ± 3.114) μM and (0.0120 ± 0.0001) AU μM-1 for the detection and quantification limits and sensitivity, respectively within the 11-110 μM linear range. In like manner, the bare CPE is also shown as a robust electrochemical sensor that allows Rutin quantification even in the presence of ascorbic acid, commonly found in Rutin samples.

Deposition time and annealing effects on morphological and optical properties of ZnS thin films prepared by chemical bath deposition

Abstract Nanocrystalline zinc sulfide thin films were prepared on glass substrates by chemical bath deposition method using aqueous solutions of zinc chloride, thiourea ammonium hydroxide along with non-toxic complexing agent trisodium citrate in alkaline medium at 80 °C. The effect of deposition time and annealing on the properties of ZnS thin films was investigated by X-ray diffraction, scanning electron microscopy, optical transmittance spectroscopy and four-point probe method. The X-ray diffraction analysis showed that the samples exhibited cubic sphalerite structure with preferential orientation along 〈2 0 0〉 direction. Scanning electron microscopy micrographs revealed uniform surface coverage, UV-Vis (300 nm to 800 nm) spectrophotometric measurements showed transparency of the films (transmittance ranging from 69 % to 81 %), with a direct allowed energy band gap in the range of 3.87 eV to 4.03 eV. After thermal annealing at 500 °C for 120 min, the transmittance increased up to 87 %. Moreover, the electrical conductivity of the deposited films increased with increasing of the deposition time from 0.35 × 10−4 Ω·cm−1 to 2.7 × 10−4 Ω·cm−1.

Spectrophotometric Determination of Lacosamide in Bulk Drug and Oral Dosage Formulation

A simple, rapid, cost effective and extractive UV-Vis spectrophotometric method has been developed for the determination of Lacosamide (LA) in bulk drug and pharmaceutical formulation. It was based on UV-Vis spectrophotometric measurements in which the drug reacts chromogenic reagent 4-Chloro-7-nitrobenzo-2-oxa-1,3-diazole in alkaline medium and give stable pale yellow colored complex which exhibits absorption maximum at 420 nm. Beer’s law was obeyed in the concentration range of 0.04 - 40 μg /ml. This method was tested and validated for various parameters according to ICH guidelines. The proposed method was successfully applied for the determination of LA in oral formulation. The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation < 2 %). As it is simple, cheap and less time consuming, it can be suitably applied for the estimation of LA in dosage forms in quality control labs.

Spectrophotometric Determination of Apixaban in Bulk Drug and Oral Dosage Formulation

A simple, rapid, cost effective and extractive UV-Vis spectrophotometric method has been developed for the determination of Apixaban (AP) in bulk drug and pharmaceutical formulation. It was based on UV-Vis spectrophotometric measurements in which the drug reacts chromogenic reagent (N-(1-napthyl) ethylene diamine dihydrochloride solution) in acidic medium and give stable pale yellow colored complex which exhibits absorption maximum at 680 nm. Beer’s law was obeyed in the concentration range of 5 - 50 μg /ml. This method was tested and validated for various parameters according to ICH guidelines. The proposed method was successfully applied for the determination of AP in oral formulation. The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation < 2 %). As it is simple, cheap and less time consuming, it can be suitably applied for the estimation of LA in dosage forms in quality control labs.

Spectrophotometric Determination of Rufinamide in Bulk Drug and Oral Dosage Formulation

A simple, rapid, cost effective and extractive UV-Vis spectrophotometric method has been developed for the determination of Rufinamide(RFM) in bulk drug and pharmaceutical formulation. It was based on UV-Vis spectrophotometric measurements in which the drug made a complex with ?-naphthol in alkaline medium and give stable pale yellow colored complex which exhibits absorption maximum at 540 nm. Beer’s law was obeyed in the concentration range of 2 - 24 ?g /ml. This method was tested and validated for various parameters according to ICH guidelines. The proposed method was successfully applied for the determination of RFM in oral formulation. The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation < 2 %). As it is simple, cheap and less time consuming, it can be suitably applied for the estimation of RFM in dosage forms in quality control labs.

Spectrophotometric determination of Rivaroxaban in bulk drug and oral dosage formulation

A simple, rapid, cost effective and extractive UV-Vis spectrophotometric method has been developed for the determination of Rivaroxaban (RIV) in bulk drug and pharmaceutical formulation. It was based on UV-Vis spectrophotometric measurements in which the drug made a complex with bromocresol green dye (BCG) in acidic medium and give stable pale yellow colored complex which exhibits absorption maximum at 416 nm. Beer’s law was obeyed in the concentration range of 2 - 40 ?g /ml. This method was tested and validated for various parameters according to ICH guidelines. The proposed method was successfully applied for the determination of RIV in oral formulation. The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation < 2 %). As it is simple, cheap and less time consuming, it can be suitably applied for the estimation of RIV in dosage forms in quality control labs.

Determination of kinetic parameters of the enzymatic reaction between soybean peroxidase and natural antioxidants using chemometric tools

The oxidation of eugenol, isoeugenol and vanillin natural antioxidants catalyzed by the soybean peroxidase enzyme was studied using uv–vis spectroscopy. An experimental design was used to optimize the different variables. The multivariate curve resolution method was used to obtain the profiles of antioxidant absorbance’s as a function of time due to uv–vis absorption bands of both antioxidants and the enzymatic reaction product/s show a strong overlap. From these results, apparent Michaelis-Menten constants as well as the kinetic parameters k1 and k3 involved in the catalytic cycle of peroxidases were calculated. The antioxidant apparent acidity constants were also determined at different pH’s from uv–vis spectrophotometric measurements. Values of k1 were (0.6 ± 0.1) × 105 M−1 s−1, (2.0 ± 0.2) × 105 M−1 s−1 and (7.0 ± 0.5) × 106 M−1 s−1 and k3 (4.0 ± 0.2) × 105 M−1 s−1, (6.0 ± 0.6) × 105 M−1 s−1 and (6.0 ± 0.9) × 106 M−1 s−1 for eugenol, isoeugenol and vanillin, respectively.

Electrochemical, spectroscopic and theoretical studies on redox speciation of neptunium with phenylphosphonic acid

Neptunium (Np) is a key element of concern for the safety aspects regarding the reprocessing and handling of spent nuclear fuel owing to its long half life (t1/2 = 2.14 × 106 years). Np can exist in several oxidation states in aquatic environments depending on the surrounding conditions in which it exists. The +5 oxidation state of Np as NpO2+ is the most stable and least binding moiety that can migrate in aquatic arena to far away positions from its source of origin. Humic acids, which are omnipresent in aquifers, are the major source of binding for the actinides including Np to facilitate their migration and transportation phenomenon. Probing the systematic knowledge of neptunium (Np), such as, speciation and coordination as function of its oxidation states in presence of chelating agents is essential aspect of its solution chemistry. The present study aimed at investigating the redox and complexation of Np with phenylphosphonic acid (PhPO3H2) (PPA) as mimic for binding of aromatic phosphorus functionalities in humic substances by using electrochemical and UV–Visible absorption spectroscopy and density functional calculations. The cyclic voltammetric measurement indicates the complexation of both oxidation states (V & VI) of Np with [PhPO3]2−. The presence and stability region (via Eh-pH plot) of new species of Np-PhPO3 in two different oxidation states (V & VI) in aqueous solution at varying physicochemical conditions are identified. The kinetics for reduction of Np complexes in different oxidation states are explored by evaluation of heterogeneous electron-transfer kinetic (D0, ko and α) parameters by cyclic voltammetric results. The spectral parameters, namely λmax and its molal extinction coefficient (ε) are obtained from UV–Visible spectrophotometric measurements and are found to be 988.2 nm and 302 ± 8 mol−1 L cm−1 respectively. The electrochemical as well as UV–Visible spectrophotometric measurements showed the formation of 1:1 complex only and the stability constant (logβ) obtained for the same from both the methods found to be in agreement with each other. Density Functional Theory (DFT) calculations are carried out to optimize the geometries of Np-PhPO3 complex for the Np in +5 and +6 oxidation states with [PhPO3]2− in mono and bidentate mode to identify the most probable coordination mode for complex formation.

Influence of nickel incorporation on structural, optical and electrical characteristics of SILAR synthesized CuO thin films

In this report, we have primarily studied the influence of nickel (Ni) incorporation on ac electrical conductivity, dielectric relaxation mechanism and impedance spectroscopy characteristics of copper oxide (CuO) thin films synthesized by successive ion layer adsorption and reaction (SILAR) technique. The materials has been characterized using X-ray diffraction and UV–VIS spectrophotometric measurements. Reduction in grain size in doped films up to a certain extent of doping (tentatively 6%) were confirmed from XRD analysis, beyond which there is a reverse tendency. Increase in band gap in doped films were observed up to 6% doping level which could be associated with enhanced carrier density in doped films. Impedance spectroscopy analysis confirmed enhancement of ac conductivity and dielectric constant for doped samples. The results are useful for capacitive application of the films. Beyond 6% doping level, AC conductivity and dielectric constant shows a reverse tendency indicating reduced density of charge carriers. Nyquist plot shows contribution of both grain and grain boundary towards total resistance and capacitance. Imaginary part of complex modulus and imaginary part of complex impedance was used to find the migration/activation energy to electrical conduction process. Nearly identical result was obtained from relaxation frequency/relaxation time approach suggesting hopping mechanism of charge carriers.

Bifunctional 3-hydroxy-4-pyridinones as effective aluminium chelators: synthesis, solution equilibrium studies and in vivo evaluation

This paper reports the results on the study of a set of synthesized bifunctional 3-hydroxy-4-pyridinones chelators as potential aluminium sequestering agents. They were N-functionalized with alkyl-amino, -carboxylic and –(amino-carboxylic) groups, envisaging the improvement of the Al3+ sequestering capacity, in comparison with the marketed chelating drug deferiprone. The main focus of this work was given to the assessment of their binding ability towards Al3+, which was studied by potentiometric and UV–Vis spectrophotometric measurements carried out at T = 298.15 K. The speciation models were characterized by AlpLqHr(3p+r−qz) species with different stoichiometry. Depending on ligand side-chain structures and on their thermodynamic properties, different trends of stability was found. Furthermore, the sequestering ability of the ligands towards Al3+ was investigated by the calculation of pL0.5 values at different experimental conditions. These results clearly indicate that the presence of amino-carboxylic groups in the ligands increases the sequestering ability towards Al3+. The in silico evaluation of pharmacokinetic descriptors indicated no violation to the Lipinski's rule and drug-likeness properties. Furthermore, the in vivo bioassays on a model of metal-overload mice showed for three investigated ligands a higher metal-sequestering capacity than for the chelating drug deferiprone, thus suggesting their potential interest as Al-chelating drug candidates.

Interaction of a Surface-Active Ionic Liquid with an Antidepressant Drug: Micellization and Spectroscopic Studies

The interaction of the antidepressant drug nortriptyline hydrochloride (NOT) with the surface-active ionic liquid (SAIL), 1-decyl-3-methylimidazolium chloride, [C10mim][Cl], has been studied using multiple techniques, including conductometric titration, tensiometric, fluorometric, dynamic light scattering and UV–visible spectrophotometric measurements. There is a significant decrease in the cmc of SAIL on the addition of the drug NOT, indicating adsorption of drug molecules in the outer portion of the micelle. In the present study, the values of the packing parameter, P, lie in the range of 0–0.3, which suggests that the micelles formed are spherical in nature. More negative values of the standard Gibbs energy of adsorption, $$ \Delta G_{\text{ad}}^{ \circ } $$ , compared to $$ \Delta G_{\text{m}}^{ \circ } $$ support our contention that adsorption of SAIL on the air-solution interface is relatively more favorable than its micellization in the presence of NOT. Fluorescence and DLS studies indicate that the aggregation number, Nagg, and hydrodynamic radius of SAIL increase with increase in concentration of NOT. The UV–visible spectroscopic study confirms the formation of a new complex between SAIL and NOT; this is also supported by the negative Gibbs energy of complexation.

Modification of surface morphology of sputtered AZO films with the variation of the oxygen

Al doped Zinc Oxide (AZO) thin films were deposited on glass substrates using DC magnetron sputtering method at different oxygen argon gas ratio. Effects of oxygen gas concentration ratio on structural, electrical and optical properties of the deposited AZO thin films were investigated by X-ray diffraction (XRD), atomic force microscope (AFM), Hall effect, ellipsometry and UV–visible spectrophotometer measurements. Results established that the films have strong c-axis orientation perpendicular to the substrate surface and exhibit better crystallinity as oxygen argon ratio increases. The lowest resistivity of 4.83 × 10−4 Ω-cm was obtained without using oxygen in the gas mixture. The average optical transmission increased from 73% to 80% in the wavelength range of 350–1100 nm and ultraviolet absorption edge shifts toward longer wavelength with the increase of oxygen argon ratio. Higher value of refractive index and a strong orange-red deep level emission was spotted in AZO thin films deposited with higher O2/Ar ratio.