Showed Absorption Maxima Research Articles

Two Different Emissions of (2Z)-2-(4-Bromophenyl)-3-[4-(dimethylamino)phenyl]prop-2-enenitrile Due to Crystal Habit and Size: Synthesis, Optical, and Supramolecular Characterization

Optical and X-ray diffraction characterizations of crystals I and II of (2Z)-2-(4-bromophenyl)-3-[4-(dimethylamino)phenyl]prop-2-enenitrile (Z-4-BrPhDMAPhACN) are reported. I and II belong to the same monoclinic space group and have nearly identical unit-cell dimensions [I: a = 11.0169(2); b = 6.02041(11); c = 21.8541(4); (β) 98.4082(18). II: a = 11.0475(6); b = 6.0273(3); c = 21.8533(11); (β) 98.315(5)]. Crystals I and II were formed under different conditions and have different crystal habits and colors: crystals I are yellow blocks, whereas crystals II are small, orange needles. I and II show absorption maxima (λabs) in solution at 404 nm and emission (λem) maxima at 501 nm (I) and at 502 nm (II). However, their emission maxima are different in the solid state: I shows an emission at 512 nm and a shoulder at 534 nm, whereas II exhibits a λem maximum at 582 nm. The differences in solid-state photoluminescence were attributed to variations in the crystal morphology and to the crystal habit and size. Both...

A comprehensive physicochemical, thermal, and spectroscopic characterization of zinc (II) chloride using X-ray diffraction, particle size distribution, differential scanning calorimetry, thermogravimetric analysis/differential thermogravimetric analysis, ultraviolet-visible, and Fourier transform-infrared spectroscopy.

Objective:Zinc chloride is an important inorganic compound used as a source of zinc and has other numerous industrial applications. Unfortunately, it lacks reliable and accurate physicochemical, thermal, and spectral characterization information altogether. Hence, the authors tried to explore in-depth characterization of zinc chloride using the modern analytical technique.Materials and Methods:The analysis of zinc chloride was performed using powder X-ray diffraction (PXRD), particle size distribution, differential scanning calorimetry (DSC), thermogravimetric analysis/differential thermogravimetric analysis (TGA/DTG), ultraviolet-visible spectroscopy (UV-vis), and Fourier transform-infrared (FT-IR) analytical techniques.Results:The PXRD patterns showed well-defined, narrow, sharp, and the significant peaks. The crystallite size was found in the range of 14.70–55.40 nm and showed average crystallite size of 41.34 nm. The average particle size was found to be of 1.123 (d10), 3.025 (d50), and 6.712 (d90) μm and average surface area of 2.71 m2/g. The span and relative span values were 5.849 μm and 1.93, respectively. The DSC thermogram showed a small endothermic inflation at 308.10°C with the latent heat (ΔH) of fusion 28.52 J/g. An exothermic reaction was observed at 449.32°C with the ΔH of decomposition 66.10 J/g. The TGA revealed two steps of the thermal degradation and lost 8.207 and 89.72% of weight in the first and second step of degradation, respectively. Similarly, the DTG analysis disclosed Tmax at 508.21°C. The UV-vis spectrum showed absorbance maxima at 197.60 nm (λmax), and FT-IR spectrum showed a peak at 511/cm might be due to the Zn–Cl stretching.Conclusions:These in-depth, comprehensive data would be very much useful in all stages of nutraceuticals/pharmaceuticals formulation research and development and other industrial applications.

SYNTHESIS AND CHARACTERISATION OF SILVER NANOPARTICLES USING VERNONIA CINEREA AQUEOUS EXTRACT AND THEIR CYTOTOXICITY ACTIVITY AGAINST KASUMI-1 CELL LINE

Green synthesis is preferable for the synthesis of silver nanoparticles (AgNPs) due to its rapid and reliable process. Previous studies have demonstrated that active compounds present in Vernonia cinerea (V. cinerea) are responsible for bioreduction during synthesis of AgNPs. Hence, in this present study, aqueous extract of V. cinerea was used to synthesise AgNPs. The V. cinerea aqueous extract was added to AgNO3 solution (25 mL, 50 mL and 100 mL) to produce mixture with ratio of 1:5, 1:10 and 1:20. The formation of V. cinerea-AgNPs was monitored for colour changes, and characterised by UV-Vis spectroscopy, transmission electron microscopy (TEM) and zeta potential analyses. The UV-Vis spectrum of V. cinerea-AgNPs showed absorption maxima at 450 nm while TEM images showed that the V. cinerea-AgNPs were spherical in shape with an average size of 15.29 nm. The zeta value of synthesised V. cinerea-AgNPs was – 29.50 mV with a peak area of 100 % intensity. The cytotoxicity of V. cinerea-AgNPs were tested in vitro on Kasumi-1 cells using MTS assay. The MTS assay revealed that the V. cinerea-AgNPs with the concentration of 31.25 mg/mL at 72 hr produced highest cytotoxicity effects on Kasumi-1 cells. These results indicate that AgNPs can be biologically synthesised from V. cinerea and has potential to be used as an anticancer agents on acute myeloid leukaemia cell line

Naked eye and spectrophotometric detection of chromogenic insecticide in aquaculture using amine functionalized gold nanoparticles in the presence of major interferents

Detection of a chromogenic insecticide, malachite green (MG) using 3,5-diamino-1,2,4-triazole capped gold nanoparticles (DAT-AuNPs) by both naked eye and spectrophotometry was described in this paper. The DAT-AuNPs were prepared by wet chemical method and show absorption maximum at 518nm. The zeta potential of DAT-AuNPs was found to be −39.9mV, suggesting that one of the amine groups of DAT adsorbed on the surface of AuNPs and the other amine group stabilizes the AuNPs from aggregation. The wine red color DAT-AuNPs changes to violet while adding 25μM MG whereas the absorption band at 518nm was increased and shifted towards longer wavelength. However, addition of 70μM MG leads to the aggregation of DAT-AuNPs. This is due to strong electrostatic interaction between ammonium ion of MG and the free amine group of DAT. Based on the color change and shift in SPR band, 25 and 5μM MG can be easily detected by naked eye and spectrophotometry. The DAT-AuNPs show high selectivity towards MG even in the presence of 5000-fold higher concentrations of common interferents. The practical application was successfully demonstrated by determining MG in fish farm water.

Insect Gut Bacteria: A Novel Source for Siderophore Production

Insect gut microbial community is known to produce biotechnologically important products. Present study is focussed on isolation of bacteria and screening of siderophore producing strains of Sathrophyllia femorata collected from Western Ghats region near Pune, Maharashtra, India (19°20′N and 73°47′E). Total 207 bacteria were isolated from gut of 2 different specimens (DM and EM) of grasshopper belonging to S. femorata. Out of 207 bacterial isolates, 166 (79 %) isolates produced siderophore during their submerged growth in iron deficient succinic acid medium. Among these, 24 isolates produced copious amount of siderophore and hence selected for further study. Further analysis of these isolates showed absorption maxima either at 240 or at 250 nm depending on type of siderophore. Molecular identification of these siderophore producing bacteria based on 16S rRNA gene sequencing confirms their affiliation to 37 species representing 19 genera. Dominance of phylum Proteobacteria followed by Firmicutes was observed. Among 19 genera, gammaproteobacteria like Acinetobacter, Klebsiella and Pseudomonas showed abundance over other genera like Serratia, Stenotrophomonas and Yokenella. Some of these bacteria have been used in plant growth promotion and as biocontrol agents against insect pests of plants. Siderophore producing bacteria having insecticidal activity against the insect pests promoting plant growth can serve as green bioinoculants for sustainable agriculture.

Label-free colorimetric detection of Cr(VI) in aqueous systems based on flower shaped silver nanoparticles

We herein report a green method to synthesize flower shaped silver nanoparticles (AgNPs) by employing 3,4-dihydroxyphenylalanine (L-dopa), as the reducing and capping agent for detection of Cr(VI) to the ppm level in aqueous systems. Stable nanoparticles were obtained in the alkaline medium and showed absorption maxima at 417nm. Aggregation induced detection of Cr(VI) provides a highly selective and sensitive method with a detection limit of 0.01ppm. Aggregation causes a dramatic color change of nanoparticles solution from dark yellow to reddish brown. The interaction between nanoparticles and metal ions characterized by ultraviolet-visible (UV−Vis) spectroscopy, Fourier transform-infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and zeta potential analyses. The applicability of this detection method was validated through the presence of other heavy metal ions in the detection system. The findings in this work might lead to developing a very efficient nanoparticles aggregation based colorimetric sensor for chromium, keeping in view of its stability, simplicity, reproducibility, and low cost.

Investigating the Energy Transfer from Dye Molecules to DNA Stabilized Au Nanoparticles.

Double-stranded DNA stabilized gold nanoparticles (Au NPs) are synthesized by chemical reduction method and characterized with different spectroscopic techniques such as UV-Visible absorption, Fourier transform infrared (FTIR), & circular-dichroism (CD) as well as transmission electron microscopy (TEM). These NPs show absorption maximum at 520nm and size of most of the particles are of the order of 3.5±1.0nm. These Au NPs show crystalline nature as confirmed from electron diffraction pattern. The effect of formation of Au NPs on the macromolecule has been studied using infrared and circular dichroism spectroscopy. Formation of NPs causes conformational changes in the DNA molecules. These Au NPs are further used as resonant energy acceptor of fluorescence emission from dye molecules (Rhodamine 6G). The fluorescence intensity of Rhodamine 6G (R6G) is quenched in presence of Au NPs. The effect of DNA molecules on the fluorescence quenching and the rate of energy transfer from R6G molecules to Au NPs have been explored.

Effect of hexyl substituent groups on photophysical and electrochemical properties of the poly[(9,9‐Dioctyluorene)−2,7‐diyl‐alt‐(4,7‐bis (3‐Hexylthien‐5‐Yl)−2,1,3‐Benzothiadiazole)−2′,2″‐diyl

ABSTRACTThe effect of the presence of hexyl group in thiophene on the photophysical and electrochemical properties of poly[(9,9‐dioctyluorene)−2,7‐diyl‐alt‐(4,7‐bis(3‐hexylthien‐5‐yl)−2,1,3‐benzothiadiazole)−2′,2″‐diyl] (F8TBT) is investigated. The copolymers present electron donor–acceptor architecture and are synthesized by Suzuki coupling reaction. The UV/Vis spectra show absorption maximum in the wavelength range of blue and orange, which are associated with different segments of the polymer backbone. Addition of hexyl substituent groups has a positive effect on the molar absorptivity and increases the emission and absorption intensities due to fluorene and thiophene‐benzothiadiazole‐thiophene (TBT) units, although an increment in the bandgap is observed. Cyclic voltammetry study of the polymer films reveal irreversible reduction and oxidation processes of the TBT units in the polymer chain and the HOMO and LUMO energy levels suggest ambipolar character for the polymers, while the electrochemical bandgaps are consistent with the absorbance measurements. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1975–1982

Characterization of Triangular Gold Nanoparticles Using Aloe arborescens Leaf Extract: A Green Synthesis Approach

Herein, the authors show the use of the Aloe arborescens leaf extract for green synthesis of gold nanoparticles in water at room temperature under very mild conditions. The synthesis of the gold nanoparticles was complete in several minutes, and no extra stabilizing or capping agents were necessary. The size of the nanoparticles could be controlled by varying the concentration of the leaf extract. The silver nanoparticles and reaction process were characterized by UV-vis spectrometer, Fourier transform infrared spectroscopy, and transmission electron microscopy. The UV-visible spectra of synthesized nanoparticles showed absorption maxima at 540 nm. Transmission electron microscopy images confirm that the nanoparticles are spherical and triangular in shape.

Green synthesis and characterization of monodispersed silver nanoparticles obtained using oak fruit bark extract and their antibacterial activity

Green synthesis of silver nanoparticles (Ag NPs) has been achieved using oak fruit bark extract as a reducing, capping and stabilizing agent. The biosynthesized Ag NPs were characterized using various techniques. UV–visible spectrum of prepared silver colloidal solution showed absorption maximum at 433 nm. X‐ray diffraction and transmission electron microscopy analysis revealed that Ag NPs have a face‐centred cubic structure being spherical in shape with an average particle size of 20–25 nm. The toxicity of the Ag NPs was tested on bacterial species such as Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli by comparison based on diameter of inhibition zone in disc diffusion tests and minimum inhibitory concentration and minimum bactericidal concentration of NPs dispersed in liquid cultures. The antimicrobial activity of Ag NPs was greater towards Gram‐positive bacteria (S. aureus and B. subtilis) compared to Gram‐negative bacteria as determined using standard Kirby–Bauer disc diffusion assay and serial dilution. Copyright © 2016 John Wiley & Sons, Ltd.

Spectrofluorimetric and Spectrophotometric Determination of Irbesartan and Bisoprolol hemifumarate independently in their Tablets

Sensitive, simple and rapid spectrofluorimetric and spectrophotometric methods were developed for the determination of Irbesartan (IRB) and Bisoprolol hemifumarate (BPH) in their tablets dosage form. Both methodologies are based on charge transfer reaction between the studied drugs and 7-Chloro-4-nitrobenzen-2-oxa-1, 3-diazole NBD-Cl. The developed orange products were measured in the appropriate solvent fluorometrically at 534 and 538 nm after excitation at 465 and 470 nm for IRB and BPH, respectively. The fluorescence–concentration plots were rectilinear over the range of 2.5–8 μg/mL for IRB and 6–16 μg/mL for BPH with lower detection limits of 0.18 and 0.39 μg/mL and a lower quantification limit of 0.55 and 1.17 μg/mL for IRB and BPH, respectively. The spectrophotometric method is based on measuring the orange colored products which were developed upon charge transfer complex formation between the studied drugs and (NBD-Cl) in organic media. This showed absorption maxima at 476 nm and 479 nm for IRB and BPH, respectively. The absorbance–concentration plots were rectilinear over the range of 20–90 μg/mL for IRB and 40–160 μg/mL for BPH with lower detection limits of 1.37 and 3.98 μg/mL and lower quantification limits of 4.17 and 12.06 μg/mL for IRB and BPH, respectively. Both methods were successfully applied to the analysis of the two selected drugs. The current study showed that the results were in good agreement with the reference methods.

Extractive Spectrophotometric Methods for determination of Prasugrel Hydrochloride in Pharmaceutical Formulations using some Acidic Triphenylmethane Dyes

Three simple and sensitive extractive spectrophotometric methods have been described for the assay of ondansetron hydrochloride either in pure form or in pharmaceutical formulations. The developed methods involve formation of coloured chloroform extractable ion-pair complexes of the drug with bromothymol blue (BTB), bromophenol blue (BPB) and bromocresol green (BCG) in acidic medium. The extracted complexes showed absorbance maxima at 419 nm for all three methods. Beer’s law is obeyed in the concentration ranges 2.5-25, 2.5.0-25 and 3.5-22.5 µg/ml with BTB, BPB and BCG respectively. The effect of concentration of dye, pH, and interference of excipients have been studied and optimized. The limits of detection and quantification have been determined for three methods. All the three methods have been validated as per the guidelines of ICH. The methods have been applied to the determination of drug in commercial tablets and results of analysis were validated statistically through recovery studies.

Method Development and Validation for Simultaneous Estimation of Rizatriptan Benzoate and Naproxen Sodium by UV Spectrophotometric Method

A Simple, validated, accurate and precise simultaneous UV Spectrophotometric method has been developed for the simultaneous estimation of Rizatriptan Benzoate (RIZ) and Naproxen Sodium (NAP) in pharmaceutical dosage form. Rizatriptan Benzoate exhibits absorption maximum at 282.9nm and Naproxen Sodium shows absorption maximum at 261.8nm in methanol. The Beer's law obeyed the concentration range of 5–30μg/ml for RIZ and NAP. Mean recovery of 100.25% for RIZ and 99.2%5 for NAP respectively signifies the accuracy of the method. This method can be used for the routine simultaneous estimation of RIZ and NAP in pharmaceutical dosage forms.

Synthesis and electroluminescence characterization of a new aluminum complex, [8-hydroxyquinoline] bis [2, 2'bipyridine] aluminum Al(Bpy)2q

We have synthesized and characterized a new electroluminescent material, [8-hydroxyquinoline] bis [2,2'bipyridine] aluminum. A solution of this material Al(Bpy)2q in toluene showed absorption maxima at 380 nm, which was attributed to the moderate energy (π–π*) transitions of the aromatic rings. The photoluminescence spectrum of Al(Bpy)2q in the toluene solution showed a peak at 518 nm. This material shows thermal stability up to 300 °C. The structure of the device is ITO/F4-TCNQ (1 nm)/α-NPD (35 nm)/Al(Bpy)2q (35 nm)/ BCP (6 nm)/Alq3 (28 nm)/LiF (1 nm)/Al (150 nm). This device exhibited a luminescence peak at 515 nm (CIE coordinates, x = 0.32, y = 0.49). The maximum luminescence of the device was 214 cd/m2 at 21 V. The maximum current efficiency of OLED was 0.12 cd/A at 13 V and the maximum power efficiency was 0.03 lm/W at 10 V.

Synthesis and characterization of new photoluminescent material tris (2-methyl 8-hydroxy quinoline) europium Eu(mq)3

A new photoluminescence material, namely tris (2-methyl 8-hydroxy quinoline) europium Eu(mq)3 has been synthesized and characterized by different techniques. The prepared material Eu(mq)3 was characterized for structural, thermal and photoluminescence analysis. Structural analysis of this material was done by fourier transformed infrared spectroscopy (FTIR) and mass spectroscopy. Thermal analysis of this material was done by thermal gravimetric analysis (TGA) which shows thermal stability up to 230°C. Absorption and emission spectra of the material was measured by UV-visible spectroscopy and photoluminescence spectroscopy. Solution of this material in ethanol showed absorption maxima at 300nm which may be attributed due to (π-π*) transitions. The photoluminescence spectrum of Eu(mq)3 in ethanol showed most intense peak at 430 nm. The time resolved photoluminescence spectra of this material Eu(mq)3 showed one life time component which was 1.4ns.

Development and Validation of UV Spectrophotometric Method for Estimation of Benfotiamine in Bulk and Dosage Form

A simple, rapid, precise and economical spectrophotometric method has been developed for quantitative analysis of Benfotiamine (BEN) in Pharmaceutical formulations. The method is developed using water as a solvent. The stock solution of BEN was prepared in water and small quantity of conc. HCl was added to dissolve the drug completely. Subsequent dilution has been done in water. The standard solution of BEN showed absorption maxima at 245 nm. The drug obeyed Beer-Lambert's law in the concentration range of 4–24 μg/mL with Regression coefficient 0.9990 at 245 nm. The overall % recovery was found to be 99.72 at 245, which reflect that the method is free from interference of the impurities and other additives used in tablet formulation. Relative standard deviations of absorbance from six measurements was always found to be less than 2%. The results of analysis have been validated as per ICH (Q1B, 1996, Q2 R1, 1996) guidelines. The wavelength can be adopted in routine spectroscopic analysis of BEN in tablet dosage form.

Development and validation spectroscopic methods for the determination of lomefloxacin in bulk and pharmaceutical formulations

Four simple, sensitive spectrophotometric and spectrofluorimetric methods (A-D) for the determination of antibacterial drug lomefloxacin (LMFX) in pharmaceutical formulations have been developed. Method A is based on formation of ternary complex between Pd(II), eosin and LMFX in the presence of methyl cellulose as surfactant and acetate-HCl buffer pH 4.0. Spectrophotometrically, under the optimum conditions, the ternary complex showed absorption maximum at 530 nm. Methods B and C are based on redox reaction between LMFX and KMnO4 in acid and alkaline media. In indirect spectrophotometry method B the drug solution is treated with a known excess of KMnO4 in H2SO4 medium and subsequent determination of unreacted oxidant by reacting it with safronine O in the same medium at λmax = 520 nm. Direct spectrophotometry method C involves treating the alkaline solution of LMFX with KMnO4 and measuring the bluish green product at 604 nm. Method D is based on the chelation of LMFX with Zr(IV) to produce fluorescent chelate. At the optimum reaction conditions, the drug-metal chelate showed excitation maxima at 280 nm and emission maxima at 443 nm. The optimum experimental parameters for the reactions have been studied. The validity of the described procedures was assessed. Statistical analysis of the results has been carried out revealing high accuracy and good precision. The proposed methods were successfully applied for the determination of the selected drug in pharmaceutical preparations with good recoveries.

UV Spectrophotometric Method for the Estimation of Roflumilast in Human Serum

Ultra violet spectrophotometric method for the estimation roflumilast in spiked human serium. The present study was spectrophotometric estimation of roflumilast in spiked human serum is based on measurement at the maximum wavelength 248 nm using 0.2M Hcl as a solvent. The roflumilast stock solution was prepared with distilled water to produse calibration curve. The standard solution of roflumilast shows absorption maxima at 248 nm. The roflumilast obeyed beer lamberts law in the concentration range of 40-88μg/ml with regression 0.9987 at 248nm. The overall percentage recovery of roflumilast was found to be 99.52% which reflects that the method was free from the interference. The % RSD values of intra day and inter day precision was found to be 0.031 and 0. 046% respectively, which is less than 2 and hence this method is precise. The values of LOD and LOQ were found to be 0.783 and 2.375 μg/ml, respectively and it indicates this method was sensitive.

Determination of persulphates using N,N-diethyl-p-phenylenediamine as colorimetric reagent: Oxidative coloration and degradation of the reagent without bactericidal effect in water

Determination of persulphate is important in persulphate based advanced oxidation process (AOP). Potassium iodide (KI) based iodometry has been the conventional method for determination of persulphate. Recently, determination of persulphate by decolorization of organic pollutants via cobalt ion activated persulphate was reported. Here, we have studied the oxidative coloration of N,N-diethyl-p-phenylenediamine (DPD) by persulphates such as peroxydisulphate (PDS) and peroxymonosulphate (PMS). At room temperature, oxidation of DPD by these persulphates generated pink colored solution that showed absorption maximum at 510 and 551nm. Importantly, the absorption at 510 and 551nm increased linearly on increasing the concentration of persulphate, and linear calibration graphs were obtained with PDS and PMS concentrations in the range between 10μM and 100μM for quantitative analysis of persulphate. Determination of persulphates by the oxidative coloration of DPD was in good agreement with those determined by KI based conventional iodometric titration. Importantly, after analysis, the pink colored oxidized DPD waste solution was rapidly degraded by heat (80°C) activated persulphate. Additionally, DPD, oxidized pink colored DPD waste solution left over after analysis, showed no bactericidal effect towards Escherichia coli, a common bacterium. Moreover, the colorless solution obtained after the degradation of pink oxidized DPD wastes by thermal activation of persulphate also showed no bactericidal effect towards E. coli. Degradation of DPD by persulphate activation, as well as the absence of bactericidal effect by DPD and its wastes, supports that the proposed DPD method for persulphate determination is environment friendly. Thus, the study highlights DPD as a potential colorimetric reagent for the spectrophotometric determination of both PDS and PMS that are commonly used for persulphate based AOP.

Low‐Band‐Gap BODIPY Conjugated Copolymers for Sensing Volatile Organic Compounds

Conjugated polymers with strong photophysical properties are used in many applications. A homopolymer (P1) and five new low band gap copolymers based on 4,4'-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) and acceptors 3,6-dithienyldiketopyrrolopyrrole (P2), phthalimide (P3), benzotriazole (P4), 4,7-dithienyl[1,2,3]triazolo[4,5g]quinoxaline (P5), and 2,5-dithienylthieno[3,4-b]pyrazine (P6) were prepared by means of Sonogashira polymerization. The characterization of polymers by using (1) H NMR, absorption, and emission spectroscopy is discussed. All polymers with high molecular weights (Mn ) of 16 000 to 89 000 g mol(-1) showed absorption maxima in the deep-red region (λ=630-760 nm) in solution and exhibited significant redshifts (up to 70 nm) in thin films. Polymers P2, P5, and P6 showed narrow optical band gaps of 1.38, 1.35, and 1.38 eV, respectively, which are significantly lower than that of P1 (1.63 eV). The HOMO and LUMO energy levels of the polymers were calculated by using cyclic voltammetry measurements. The LUMO energy levels of BODIPY-based alternating copolymers were independent of the acceptors; this suggests that the major factor that tunes the LUMO energy levels of the polymers could be the BODIPY core. All polymers showed selective and reproducible detection of volatile organic solvents, such as toluene and benzene, which could be used for developing sensors.