Absorption Spectra Of Solutions Research Articles

Innovative NSAID dosage forms: lornoxicam suppositories and their standardization

The article presents the studies on the development of a method for the quantitative determination of lornoxime in suppositories using UV spectrophotometry. The optical densities of the test solutions were recorded at a wavelength of 375 nm. The absorption spectra of standard solutions of lornoxicam, as well as of tested solutions of suppositories were obtained. The relative standard deviation was 2.31%.

The Influence of Iron Ions on Optical Brighteners and Their Application to Cotton Fabrics.

The influence of iron ions at concentrations of 0.2, 0.5, and 1.0 g/L on optical brighteners of the groups stilbene and biphenyl in solution and on cotton fabric was investigated. Both groups of optical brighteners are intended for detergent formulations. The influence of iron ions was studied by absorption and fluorescence spectra in solution and by whiteness degree, identifying color differences using CIEL*a*b* coordinates and Ultraviolet Protection Factor (UPF) of cotton fabrics. The obtained results in solutions and cotton fabrics showed different behavior of optical brighteners stilbene and biphenyl in the presence of iron. Stilbene compounds with metal ions produced new species capable of absorbing in the UV-B region of the spectrum. A biphenyl compound in combination with iron had no effect on the absorption properties. Both optical brighteners were influenced by iron ions in the sense of fluorescence quenching. The influence of iron ions in single- and two-bath treatments of cotton fabrics after one cycle on whiteness degree and UPF was negligible.

Study of the Effect of Solvent Polarity on Transitions of Absorption and Fluorescence Spectrum of a Erythrosine Dye

In this paper, the absorption and fluorescence spectra of Erythrosine dye laser liquid solution dissolved with acetone and ethanol solution were studied in different concentrations (10-3, 10-4, 10-4 M). The results showed an increase in absorption and fluorescence intensity by increasing polarity of the solvent. Some of the linear optical properties of the prepared models were also studied. The results showed an increase in the absorbance, linear refractive index, and linear absorption coefficient with an increase in solvent polarity and the molar concentration against a decrease in the permeability value, as well as the quantitative production efficiency was calculated based on the results of the absorption spectra and fluoridation. The Purpose of the search Study the effect of solvent polarity on both absorption and fluorescence spectra, and on linear and electrical optical properties. Keywords: Erythrosine Laser dye, absorption, fluorescence spectra and Polar solvents (acetone and ethanol).

Reversible isomerization of metal nanoclusters induced by intermolecular interaction

Reversible isomerization of metal nanoclusters induced by intermolecular interaction

Manifestation of the dynamics of ultrafast photoprocesses in the transient absorption spectra of diflavonoid solutions

Herein, using the femtosecond absorption spectroscopy method, the dynamics of the nonstationary induced absorption spectra of diflavonoid 3,7-dihydroxy-2,8-di(4-methoxyphenyl)-4H, 6H-pyrano[3,2-g]chromene-4,6-dione (DFV) in solvents of different polarities is studied. It is found that the rapid transformation of the transient absorption spectra of DFV in time is due to the processes of intramolecular protons transfer in excited singlet states. For a nonpolar solvent, two protons are transferred in two stages. Initially, during the sub-picosecond times, a form with a single transferred proton is formed from the Frank-Condon state. From this transition state, in a time range of about 9 ps, the second proton is transferred and the two proton transfer tautomer with a high quantum yield of fluorescence ~0.66 is formed, which has the gain band in the transient absorption spectra. For the polar solvent dimethylformamide only the short-lived form with a single proton transferred is formed also during the subpicosecond times practically the same ones as for the nonpolar solution and has a lifetime of about 20 ps. The polarity of the medium, which affects the formation of a set of the “closed” and “open” forms of DFV in the ground state, differing in relative positions in the space of hydroxyl and carbonyl groups, largely determines the mechanism of the intramolecular proton transfer process in the DFV molecule, which consists in the sequential transfer of two protons in a non-polar solvent to form a fluorescent long-lived tautomer and the transfer of one proton in polar solvents to form a short-lived non-fluorescent form.

Investigation of the Characteristic of Solution‐Processed Tetraphenyldibenzoperiflanthene (DBP) Film and Its Application on Organic Photovoltaic Cells

Solution‐processed tetraphenyldibenzoperiflanthene (DBP) films are prepared with three popular solvents, including chroloform (CF), chrolobenzene (CB), and dichrolobenzene (ODCB). The absorption and photoluminescence (PL) spectra of the DBP solution and DBP film are investigated. The absorption spectra between the DBP film and DBP solution are similar, whereas the PL spectrum shape of the DBP film and DBP solution is completely different, originating from the DBP molecular aggregation in the film, causing conjugate expansion, which results in dimer luminescence. The DBP donor layer at 32 nm prepared from solvent of CF, CB, and ODCB achieves a power conversion efficiency (PCE) of 1.42%, 0.88%, and 0.48%, respectively. The annealing temperature and DBP thickness are optimized; the 32 nm‐thick active layer annealed at 50 °C achieves the highest performance. The CF‐DBP film represents an interpenetrating network morphology, slightly higher roughness and hole mobility, which may be the main contribution to the relatively higher photocurrent than the CB‐DBP and ODCB‐DBP devices. Herein, a simple guidance for preparing solution‐processed DBP films is provided and simultaneously its application on organic photovoltaic cells (OPVs) is expanded.

Chromatic Conductive Polymer Nanocomposites of Poly (p-Phenylene Ethynylene)s and Single-Walled Carbon Nanotubes

We report on dispersions and thin films of chromatic conductive nanocomposites of poly(p-phenylene ethynylene)s (PPEs) and single-walled carbon nanotubes (SWNTs) generated via solution mixing. The linear, conjugated PPEs with dialkyl- and dialkyloxy-side chain groups are shown to debundle and disperse high concentration (up to 2.5 mg/mL) SWNTs in various organic solvents. The solubilization of SWNTs and PPE wrapping is accompanied with the change in the solution color. Ultraviolet visible absorption spectra of nanocomposite solutions demonstrate a new absorption peak at a higher wavelength, supporting the observed chromatism. Fluorescence spectra of nanocomposite solutions display significant quenching of the fluorescence intensity and the Stern–Volmer model is used to analyze fluorescence quenching. Electron microscopy of the chromatic solid films of high mass fraction PPE/SWNT nanocomposites obtained by vacuum filtration reveals the debundled SWNTs in the PPE matrix. The tensile strength and Young’s modulus of these PPE/SWNT nanocomposite films are as high as 150 MPa and 15 GPa, respectively. The composite films exhibit remarkably high conductivities, ranging from ~1000 S/m to ~10,000 S/m for 10 wt% and 60 wt% SWNT nanocomposites, respectively.

Optical characterization and effects of iodine vapor & gaseous HCl adsorption investigation of novel synthesized organic dye based on thieno[2,3-b]thiophene

Comparison of the absorption spectra of the ethanolic solution (3 ppm) of some diethyl 3,4-diaminothieno[2,3-b]thiophene-2,5-dicarboxylate (TT amino ester) derivatives has revealed that the azo dye derivative compound 4 manifests smaller band gap and higher absorption maximum close to solar maximum wavelength. Very good adhesive thin films to glass substrates of the azo dye compound 4 have been successfully prepared by thermal evaporation technique. The optical spectral analysis of such compound film revealed three absorption transitions corresponding to the optical gap, the electron transition between impurity levels in band gap and the fundamental band gap (HOMO to LUMO π→π* transitions). Absorption, dielectric and dispersion parameters have been determined for as- deposited and gas treated films and discussed. This film manifested a fast response and high sensitivity toward iodine vapor with a reasonable recovery time indicating a reversibility of iodine adsorption process. In contrast, the film illustrated slow response and weak sensitivity toward HCl gas with irreversible adsorption process. Besides, the azo dye compound 4 solution manifests strong emissive properties that recommend it as promising candidate for fluorescence sensors.

Effect of non-peripheral fluorosubstitution on the structure of metal phthalocyanines and their films

In this work, we study crystal structures and thin films of tetrasubstituted metal phthalocyanines with fluorine substituents in non-peripheral positions, MPcF4-np (M = Cu(II), Co(II), Pd(II), Fe(II), Pb(II), VO). The effect of fluorosubstitution in non-peripheral positions of the phthalocyanine macrocycle on the structure of single crystals and thin films, and intermolecular interactions is elucidated and compared with that of other fluorinated phthalocyanine derivatives. MPcF4-np (M = Cu(II), Pd(II), Fe(II)) are isostructural and crystallize in the monoclinic P21/c space group, while CoPcF4-np forms two polymorphs (P21 and P21/c). Monoclinic PbPcF4-np (P21/n) is packed in chains along the c axis, in which one PbPcF4-np molecule is oriented “up” and two neighboring molecules face “down”. Two triclinic (P-1) phases were obtained for VOPcF4-np. For the better visualization and comparison of intermolecular contacts in different MPcF4-np, the analysis of Hirshfeld surfaces (HS) was carried out. All investigated MPcF4-np derivatives form thin films with a strong preferred orientation. The effect of the positions of F-substituents on the electronic absorption spectra of MPcF4 solutions and thin films is also discussed.

New 3-Ethynylaryl Coumarin-Based Dyes for DSSC Applications: Synthesis, Spectroscopic Properties, and Theoretical Calculations.

A set of 3-ethynylaryl coumarin dyes with mono, bithiophenes and the fused variant, thieno [3,2-b] thiophene, as well as an alkylated benzotriazole unit were prepared and tested for dye-sensitized solar cells (DSSCs). For comparison purposes, the variation of the substitution pattern at the coumarin unit was analyzed with the natural product 6,7-dihydroxycoumarin (Esculetin) as well as 5,7-dihydroxycomarin in the case of the bithiophene dye. Crucial steps for extension of the conjugated system involved Sonogashira reaction yielding highly fluorescent molecules. Spectroscopic characterization showed that the extension of conjugation via the alkynyl bridge resulted in a strong red-shift of absorption and emission spectra (in solution) of approximately 73–79 nm and 52–89 nm, respectively, relative to 6,7-dimethoxy-4-methylcoumarin (λabs = 341 nm and λem = 410 nm). Theoretical density functional theory (DFT) calculations show that the Lowest Unoccupied Molecular Orbital (LUMO) is mostly centered in the cyanoacrylic anchor unit, corroborating the high intramolecular charge transfer (ICT) character of the electronic transition. Photovoltaic performance evaluation reveals that the thieno [3,2-b] thiophene unit present in dye 8 leads to the best sensitizer of the set, with a conversion efficiency (η = 2.00%), best VOC (367 mV) and second best Jsc (9.28 mA·cm−2), surpassed only by dye 9b (Jsc = 10.19 mA·cm−2). This high photocurrent value can be attributed to increased donor ability of the 5,7-dimethoxy unit when compared to the 6,7 equivalent (9b).

Characterization of tracers for two-color laser-induced fluorescence thermometry of liquid-phase temperature in ethanol, 2-ethylhexanoic-acid/ethanol mixtures, 1-butanol, and o-xylene.

The fluorescence spectra of dye solutions change their spectral signature with temperature. This effect is frequently used for temperature imaging in liquids and sprays based on two-color laser-induced fluorescence (2cLIF) measurements by simultaneously detecting the fluorescence intensity in two separate wavelength channels resulting in a temperature-sensitive ratio. In this work, we recorded temperature-dependent absorption and fluorescence spectra of solutions of five laser dyes (coumarin 152, coumarin 153, rhodamine B, pyrromethene 597, and DCM) dissolved in ethanol, a 35/65 vol.% mixture of ethanol/2-ethylhexanoic acid, ethanol/hexamethylsiloxane, o-xylene, and 1-butanol to investigate their potential as temperature tracers in evaporating and burning sprays. The dissolved tracers were excited at either 266, 355, and 532 nm (depending on the tracer) for temperatures between 296 and 393 K (depending on the solvent) and for concentrations ranging between 0.1 and 10 mg/l. Absorption and fluorescence spectra of the tracers were investigated for their temperature dependence, the magnitude of signal re-absorption, the impact of different solvents, and varying two-component solvent compositions. Based on the measured fluorescence spectra, the tracers were analyzed for their 2cLIF temperature sensitivity in the respective solvents. Coumarin 152 showed for single-component solvents the overall best spectroscopic properties for our specific measurement situation related to temperature imaging measurements in spray-flame synthesis of nanoparticles as demonstrated previously in ethanol spray flames [Exp. Fluids61, 77 (2020)10.1007/s00348-020-2909-9].

Dithienothiazine Copolymers – Synthesis and Electronic Properties of Novel Redox-Active Fluorescent Polymers

Dithienothiazine copolymers are efficiently obtained by Suzuki polymerization or in situ lithiation–Negishi polymerization in good to excellent yields. Gel permeation chromatography was applied to characterize the dispersities and degrees of polymerization of these novel materials. Thermogravimetric analysis shows that the copolymers are stable towards side-chain cleavage up to 200 °C. The materials are deep red to black amorphous solids or resins and their absorption and emission spectra in solution reveal broad absorption bands in the visible and orange to deep red luminescence upon UV excitation. According to the optical band gaps these novel copolymers qualify as a new class of low band gap organic semiconductors.

Production of Zinc and Copper as Nanoparticles by Green Synthesis Using Pseudomonas fluorescens.

<b>Background and Objective:</b> Nanoparticles with a little size to an enormous surface (1-100 nm) have expected clinical, mechanical and agricultural applications. This study aimed to produce nano Zinc Oxide (ZnO) and nano Copper Oxide (CuO) particles by green synthesis. <b>Materials and Methods:</b> Two strains of <i>Pseudomonas fluorescens</i> i.e., PSI and PSII, both cell culture supernatants and cell pellets from the two strains were examined separately in CuSO<sub>4</sub> or ZnSO<sub>4</sub> solutions. The supernatants from both strains produced color changes in both solutions referring to the formation of nano CuO or ZnO particles. The solutions were examined for nano-particle characteristics using UV-spectroscopy, particle size and morphology were tested using a scanning electron microscope and transmission electron microscopy. <b>Results:</b> UV-Vis absorption spectrum of solutions at a wavelength range 200-800 nm exhibits a distinct absorption peak in the region of 238-331 and at 303-366 nm for CuO or ZnO NPs, respectively. Absorption bands and the characteristic Surface Plasmon Resonance (SPR) spectra confirm the existence of CuO and ZnO NPs. SEM analysis micrographs indicated that CuO NPs were formed as spherical particles, while the exact shape of ZnO NPs could be identified as oval aggregates. <b>Conclusion:</b> Changes of color occurred in both solutions of two strains referring to the formation of nano CuO or ZnO particles.

Naked eye colorimetric detection of fluoride through TiO2 NPs/CQDs based detector

Fluoride (F−) occurs naturally in a soil, air and water as commonly found element in earth crusts. Almost 200 million populations worldwide and approximately 60 million in India are facing F− contamination problem. Therefore, development of low-cost and highly sensitive colorimetric detector for F− ions using carbon quantum dots (CQDs) and metal salts is required. For this, CQDs were synthesized using flower waste from temples by green method and further characterized. CQDs-TiO2 complex solution color changes from green to black on addition of F− ions due to exchange of F− ions with hydroxyl ions of the solution. Absorption spectrum of CQDs-TiO2 complex solution depicts change in spectral graph on adding F− ions with the appearance of new band at approx. 550 nm. The color spectral as a function of F− ions concentration gave a linear response in the range of 2–8 ppm (R2 = 0.9808). The color change can be observed at 2 ppm after incubation of 5 min by naked eye. Developed colorimetric detector shows high selectivity with other ions (Cl−, Br−, I− and H2PO4−). The F− ion detection was done in different water samples collected from districts of Haryana using developed detector. The developed colorimetric detector allows wide range of F− sensing for water sample even at every low concentration i.e 2 ppm.

The Plasmon Effects of AgNPs on Wave Guide Consisting of Polymers Mixed with Rhodamine Dyes

In this research, the optical properties refractive index, absorption spectrum, and fluorescence spectrum of solutions of different concentrations have been studied in order to prepare thin films to obtain an efficient waveguide. A wave guide consisting of three layers has been prepared in which the middle layer has a relatively higher refractive index than the upper and lower layers. This optical wave guide was prepared by using different solutions of two concentrations of poly vinyl pyrrolidone (PVP) & poly vinyl alcohol (PVA) polymers. Different concentrations of the rhodamine pigments RhB & Rh6G were prepared. It is added to the middle layer of the optical wave guide in order to raise its refractive index first and to obtain a laser profit. The practical results have proven that there are specific concentrations of polymers and dyes that can be used to obtain wave guides that have the ability to transmit and amplify the input signal and operate within certain wavelengths. The PVA + RhB(10-4M) model showed the best laser emission performance and the PVA + Rh6G (10-5M) model showed the best signal transmission performance. Finally, the plasmon effect is clearly appears when we added the AgNPs on our samples it’s effecting on threshold pumping and increase the efficiency of wave guide.

Terahertz, infrared and Raman absorption spectra of tyrosine enantiomers and racemic compound

The application of terahertz (THz)-based techniques in biomolecule study is very promising but still in its infancy. In the present work, we employed THz time-domain spectroscopy (THz-TDS) and THz time-domain attenuated total reflection (THz-TD-ATR) spectroscopy to investigate the properties of tyrosine (Tyr) enantiomers (L- and D-Tyr) and racemate (DL-Tyr) in solid state and aqueous solutions, respectively. THz absorption spectra of solid L- and D-Tyr show similar absorption spectra with peaks at 0.95, 1.92, 2.06 and 2.60 THz, which are obviously different from the spectrum of DL-Tyr with peaks at 1.5, 2.15 and 2.40 THz. In contrast, although THz absorption spectra of L-Tyr solution and D-Tyr solution are similar and different from the spectrum of DL-Tyr solution, both of them have no observable peaks. Interestingly, it was found that the solution containing equal amounts of L- and D-Tyr has a similar spectrum as that of DL-Tyr solution, as far as the mass concentrations of the two types of solutions are kept the same. On other hand, solid L-, D- and DL-Tyr were also investigated with infrared spectroscopy and Raman spectroscopy, respectively. The results show that the spectra of L- and D-Tyr can be regarded the same but they are slightly different from the spectrum of DL-Tyr. With the aid of principal component analysis (PCA), the difference between L-/D-Tyr and DL-Tyr can be confirmed without any ambiguity. Overall, this work systematically interrogated and evaluated the performance of THz-based techniques in the detection of the chirality of tyrosine.

Terahertz spectral nondestructive detection of amino acid molecules in aqueous solution

Only in liquid environment can most biomolecules maintain their biological activity, the realization of terahertz (THz) spectrum detection of water-bearing biomolecules has an important application value for the research of the function and structure of active biomolecules and non-invasive biomedical detection. In this paper, by using the THz radiation source generated by LiNbO3 light rectification, and combing with the local electric field enhancement effect of the flared gradient parallel flat waveguide, we have built a THz time domain spectral measurement system that can detect the trace amounts of living cells and aqueous biomolecules, which can implement THz spectral detection of 4-aminobenzoic acid and glutamic acid in solution. The results show that 4-aminobenzoic acid and glutamic acid in aqueous solution have obvious and unique characteristic absorption peaks in the frequency band of 0.1–2.0 THz when the effect of water on THz wave absorption is removed. The acquisition of characteristic absorption spectrum of amino acid aqueous solution in THz frequency band lays a foundation for the detection of active biological macromolecules or tissues.

Hydration of the Zwitterionic and Protonated Forms of Glycine Betaine Probed by Soft X-ray Emission Spectroscopy Coupled with Chemometrics.

Soft X-ray absorption and emission spectra of glycine betaine (GB) have been measured at the O K-edge in neutral and strongly acidic solutions. The absorption spectra of the neutral solutions have a resonance peak at 532.6 eV, assigned to the transition to the π* orbital, whereas in the acidic solutions, the peak is shifted by -0.3 eV. The emission spectra taken as a function of the GB concentration have been analyzed by means of a modified classical least-squares regression method to obtain the hydration number of the solute. The analysis is successful when the emission spectra have been acquired at the energy of a slightly detuned resonance, giving 28 and 24 as the minimum values for the zwitterionic and protonated GB, respectively. The number of 28 accords with the reported values for the number of water molecules in the first hydration layer of the zwitterion and is greater than that obtained by other experimental techniques. The obtained numbers are used to discuss the hydration structure of GB with the aid of ab initio molecular orbital calculations. The hydration structure of the protonated form of GB is explored for the first time.

Synthesize of CdS nanoparticles using liquid-gas method

In this paper, Cadmium Sulfide (CdS) nanoparticles (NPs) was synthesized using Liquid-Gas method. After CdCl2 mixed with surfactant in liquid phase, the mixture was exposed to S2 gas from brimstone. The solution changes color to yellow which means that the CdS NPs semiconductor has been formed. It was approved by the blue-shifted of the absorption spectra of CdS colloid solution then the size (radius) of CdS NPs would be determined by using the Efros equation. The radius yielded was about 2 nm. FTIR result also confirmed the CdS bond at 509 cm−1.

The effect of relative humidity on CaCl2 nanoparticles studied by soft X-ray absorption spectroscopy.

Ca- and Cl-containing nanoparticles are common in atmosphere, originating for example from desert dust and sea water. The properties and effects on atmospheric processes of these aerosol particles depend on the relative humidity (RH) as they are often both hygroscopic and deliquescent. We present here a study of surface structure of free-flying CaCl2 nanoparticles (CaCl2-NPs) in the 100 nm size regime prepared at different humidity levels (RH: 11–85%). We also created mixed nanoparticles by aerosolizing a solution of CaCl2 and phenylalanine (Phe), which is a hydrophobic amino acid present in atmosphere. Information of hydration state of CaCl2-NPs and production of mixed CaCl2 + Phe nanoparticles was obtained using soft X-ray absorption spectroscopy (XAS) at Ca 2p, Cl 2p, C 1s, and O 1s edges. We also report Ca 2p and Cl 2p X-ray absorption spectra of an aqueous CaCl2 solution. The O 1s X-ray absorption spectra measured from hydrated CaCl2-NPs resemble liquid-like water spectrum, which is heavily influenced by the presence of ions. Core level spectra of Ca2+ and Cl− ions do not show a clear dependence of % RH, indicating that the first coordination shell remains similar in all measured hydrated CaCl2-NPs, but they differ from aqueous solution and solid CaCl2.