FT-IR Spectral Investigations Research Articles

Surface functionalization of core-shell QDs for solar photovoltaic and anti-cancer applications

We undertook this present study; a simple and straight forward approach is developed to achieve CdSe/ZnS core-shell quantum dots by hydrothermal method and change the different hydrazine hydrate concentrations. As prepared QDs were characterized by high-throughput techniques and are tested for cytotoxicity activity against breast cancer cell line (MDA-MB-231) and testing in to sensitized solar cells (QDSSC) respectively. Further, the results study also revealed that, CdSe/ZnS QDs display unique tunable size, which is evidenced by transmission electron microscopic studies and optical properties (UV-Visible) studies. Moreover, FT-IR spectral investigations provide information about the interaction of trisodium citrate and hydrazine hydrate role in the surface functionalization and found plausible reason. The hydrazine hydrate modified CdSe/ZnS QDs (CZT-10) show an impressive anticancer activity in breast cancer cells and photovoltaic efficiency. This study open new avenues to find vital play on development of nanomaterial in the field of energy and environment application.

Behavior of lysozyme within ionic liquid-in-water microemulsions

Ionic liquids (ILs) and IL-based microemulsions are of immense importance due to their broader application potential in various interdisciplinary research areas such as, synthesis, catalysis, biochemical processes, pharmaceutics, and material science. In this manuscript, we have studied the behavior of an antimicrobial enzyme lysozyme within IL-in-water (IL/W) microemulsions formed by hydrophobic IL 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6] in nonionic surfactant Brij-35 solution. It is noteworthy that the fluorophores and chromophoric responses clearly indicate significant changes in the micropolarity and microviscosity within aqueous Brij-35 micellar solution in the presence of IL [bmim][PF6] forming microemulsions. DLS shows the size of these nanostructures formed are of 6–8 nm range. IL-lysozyme interactions within the IL/W microemulsions were studied using UV–Vis, steady-state and time-resolved fluorescence and FT-IR spectral investigations. Increase in Brij-35 concentration increases the lysozyme fluorescence intensity in absence of the IL, whereas increase in IL concentration within the IL/W microemulsions results in gradual decrease in the lysozyme fluorescence intensity as a results of IL-lysozyme binding. Both steady-state and time-resolve fluorescence results suggest fluorescence quenching of lysozyme in presence of IL [bmim][PF6] within both aqueous solution and Brij-35 IL/W microemulsions. Further, electrochemical response from cyclic voltammetric studies also confirms the binding of lysozyme with IL [bmim][PF6]. FTIR spectral responses show that lysozyme remains stable within the IL/W microemulsions amid IL-lysozyme binding observed from UV–Vis and fluorescence studies.

Growth and study of 4-sulfobenzenaminium potassium dihydrogenphosphate for mechanical, dielectric and photonics applications

Abstract This article describes the growth and characterization of 4-sulfobenzenaminium potassium hydrogen phosphate (SPH) sulphanilic acid with potassium dihydrogen phosphate (KDP) doped semi-organic single crystals. The crystal was grown by the slow evaporation method. Examination of the crystalline nature of the sample was carried out by single crystal X-ray diffraction and it confirmed that the sample crystallizes in orthorhombic structure in the centrosymmetric space group P212121. The optical transmittance behavior was tested by UV-Vis spectral analysis. FT-IR spectral investigations have been carried out to indicate the presence of functional groups. The chemical structure of the compound was established by 1H and 13C NMR spectra. The SHG efficiency of the powdered SPH crystal is around 1.7 times that of pure KDP. The grown crystal was stable up to 270 °C as observed from TGA and DTA curves. The microhardness test was carried out to study the load dependency of hardness. The result of this study indicates that SPH crystal is a malleable material. From the hardness values, the stiffness constant and yield strength were calculated. The dielectric response of the novel crystal was studied in the frequency range of 50 Hz to 5 MHz at various temperatures. By employing FE-SEM, the surface morphology and the particle size of the crystal were assessed.

Surface chemical and selective flocculation studies on iron oxide and silica suspensions in the presence of xanthan gum

The changes in the surface chemical properties of iron oxide and silica suspensions consequent to the addition of xanthan gum were studied. The adsorption density of xanthan gum for iron oxide was found to be maximum at pH ~ 2, whereas almost nil adsorption was found for silica throughout the pH range investigated. The isoelectric points (i.e.p.) of iron oxide and silica were found to be located at pH ~ 8.4 and presumably less than pH 2 respectively. The addition of xanthan gum shifted the i.e.p. of iron oxide towards more acidic pH values, in proportion with the concentration of xanthan gum added, with a concomitant change in the zeta potentials to more electronegative or less electropositive values. The maximum flocculation of iron oxide (98%) was observed in the wide pH regime of 2–9 with the optimum dosage of xanthan gum (20–50 ppm). The electrokinetic and flocculation characteristics of the silica were not altered much by the addition of xanthan gum, akin to the adsorption result. FTIR spectral investigations provide evidence in support of hydrogen bonding and chemical interaction forces between iron oxide and xanthan gum. Maximum separation efficiency of 65% for iron oxide-silica mixture was observed in selective flocculation tests.

A new class semi-organic nonlinear optical materials: Mono(4-sulfo benzene aminium) tri nickel(II) bis(dihydrogen phosphate) for photonic applications

This article is discussing the growth of a new class semi-organic nonlinear crystal (4-sulfo benzene aminium) tri nickel(II) bis(dihydrogen phosphate) (4-STNBDHP) grown by slow evaporation solution growth technique at ambient temperature. The purity of the crystal was achieved by recrystallization and the size of the crystal is 3 × 3 × 7 mm3. It was harvested over the period of 85 days. The solubility of the 4-STNBDHP crystal is done at different temperatures from 30 °C to 80 °C in steps of 10 °C. Lattice parameters, obtained from the result of single crystal X-ray diffraction study, indicate that the grown crystal is an orthorhombic crystal. FTIR spectral investigations indicated the formation of bonds like N–H⋯O, O⋯Ni–O and Ni–O–P and these bonds are arising because of doping. The UV–visible spectrum demonstrates that the grown crystals are transparent and an absorption peak at 768 nm indicates the presence of Ni2+ ions. TGA/DTA investigations were made to study the decomposition of the title compound. Nonlinear optical (NLO) efficiency of the crystal was tested through second harmonic generation efficiency test. Photoluminescence study shows the green light emission. The microhardness analysis confirms that the grown crystal belongs to the soft material. From tis study, the mechanical properties such as stiffness constant (C11), yield strength (δy), hardness (Hv), and hardening coefficient (n) were calculated. The dielectric constant (ε), dielectric loss (ε′), imaginary dielectric constant (ε″), AC conductivity (σac) and Cole-Cole graphs were plotted. From this study, it is concluded that the 4-STNBDHP shows higher conduction at a higher temperature and at low frequency. The elemental analysis was carried out by energy dispersive X-ray analysis and it confirms the presence of the different elements in the 4-STNBDHP crystal.

Visible‐Light‐Active Mixed‐Valent Copper‐Ion‐Coordinated 2,5‐Dimercapto‐1,3,4‐thiadiazole‐Based p‐Type Metallopolymer

AbstractVisible‐light‐active coordination metallopolymer and metal‐organic frameworks have gained substantial attention in recent years, owing to their tunable electronic properties. Herein, we present a novel copper‐ion‐containing metallopolymer, which exhibits visible‐light absorption and p‐type photoelectrochemical behavior. The functional thiadiazole‐based metallopolymer thin films were prepared by using both chemical and electrochemical methods on fluorine‐doped tin oxide substrates. XPS, Raman, and FTIR spectral investigations evidence the presence of Cu(II), Cu(I), Cu−S, and disulfide (S−S)2− linkages in the polymeric network. The swift photoresponses, repeatable photovoltage of approximately 55 mV with zero applied current, and high photocurrent values at different bias potentials (ca. 24 μA cm−2 @ −0.6 V vs. Ag/AgCl in 0.1 KCl) in acidic electrolytes (0.5 M H2SO4) suggest that this metallopolymer as an acid‐stable p‐type photocathode material. In contrast, the electropolymerized non‐metallated polymers exhibit n‐type photoactivity. Photoelectrochemical sensing studies reveal the analyte‐induced reduction in photoactivity.

Optical and infrared spectral investigations of cadmium zinc phosphate glasses doped with WO3 or MoO3 before and after subjecting to gamma irradiation

Optical and FTIR spectral investigations of prepared undoped and WO3-or MoO3-doped glasses from ZnO-CdO-P2O5 glassy system were carried out before and after irradiation with a dose of 8 Mrad (= 8 × 104 Gy). The optical spectrum of the undoped glass reveals strong UV absorption band due to trace ferric ions present as trace impurity within the chemicals. The WO3 or MoO3-doped glasses show additional UV–visible bands due to the dominance presence of the low valence states of the two transition metal (TM) ions (M3+, M4+, M5+). Gamma irradiation extends and increases the UV absorption due to suggested photochemical reactions of ferrous iron present as impurity to react with positive holes during the irradiation process to transfer to additional ferric ions possessing their absorption in the UV region. The TM-doped glasses show some shielding behavior in almost the persistence of the visible spectra due to the TM ions. FTIR spectral bands are related to phosphate groups (mainly Q2 and Q3 units) in accordance with the high content of P2O5 (70 mol%). The effects of dopant ions on the IR spectra are limited due to the low percent (0.25 to 0.75 g/100 g) and their presence in modifying positions. Gamma irradiation decreases the intensity of some IR bands due to OH, water vibrations present mainly in terminal sites.

Efficacies of sodium nitrite and sodium citrate\u2013zinc acetate mixture to inhibit steel rebar corrosion in simulated concrete interstitial solution contaminated with NaCl

Investigations were carried out to compare the effectiveness of compounds such as sodium nitrite, trisodium citrate (TSC) and TSC–zinc acetate to inhibit the corrosion of steel rebar in simulated concrete interstitial solution contaminated with chloride and to explain the mechanism of corrosion inhibition on reinforcing steel by these systems. Inhibition efficiency of these systems was studied by electrochemical techniques such as potentiodynamic polarization and half cell potential measurements. Electronic spectral studies of simulated pore solution and FT-IR spectral investigations of the film deposited on steel surface were carried out for understanding the mechanism of corrosion inhibition. Microscopic surface analysis was conducted to obtain the surface morphological behaviour of steel rebar. TSC alone was not exhibited good corrosion inhibition at very low and high concentrations according to electrochemical studies. However, in the presence of zinc acetate, corrosion protection efficiency of TSC increased appreciably. When comparing with sodium nitrite, TSC in the presence and absence of zinc acetate displayed good corrosion inhibition efficiency. Among a number of samples, TSC 100 ppm-zinc acetate 50 ppm combination showed maximum corrosion inhibition efficiency on steel rebar in simulated concrete interstitial solution.

Nonlinear optical properties of Ag@SiO2 core-shell nanoparticles investigated by continuous wave He-Ne laser

A facile one step synthesis approach for preparing Ag@SiO2 core-shell nanoparticles was reported and its third-order nonlinear optical analysis was discussed. The linear optical behaviour of the synthesized core-shell structured Ag@SiO2 nanoparticles was studied by UV-vis spectral analysis. The red shifting of the surface plasmon resonance peak affirmed the core-shell structure of the products. The surface functionality of the product was probed by the FTIR spectral investigations and the results revealed that silica networks formed an outer shell covering Ag nanoparticles. The crystallinity and chemical composition of the products are analyzed by powder XRD pattern and confirmed that the crystallinity of Ag nanoparticles was not affected by the formation of the amorphous SiO2 shell. The particle size, morphology and the formation of uniform SiO2 shell over the Ag core are visualized by the TEM analysis. Moreover, the optical nonlinearity of the Ag and Ag@SiO2 core-shell nanoparticles is examined by z-scan technique using continuous wave He-Ne laser which showed interesting optical nonlinearity and exhibited switching behaviour from reverse saturated absorption to saturated absorption, which could be useful for numerous photonic applications like, Q-switching and optical limiting.

Optical, FTIR and ESR Spectral Investigations of Tungsten Ions in Barium Phosphate Host Glass and Effects of Gamma Irradiation

Tungsten oxide (0.25 – 3% WO3) doped barium phosphate glasses were prepared by the conventional melting annealing procedure. Spectroscopic FTIR infrared and ESR measurements were applied at 0 and 10 Mrad doses of gamma irradiations. The UV-Visible spectrum of the base glass consists of distinct ultraviolet peaks that can be correlated with trace ferric (Fe3+ ions) impurities. UV-Visible absorption spectra of WO3 – doped glasses show similar ultraviolet absorption as the base glass and a very broad visible band settled at about 720 nm and with the high content sample (3% WO3) two peaks are identified at 602 and 790 nm on the very broad visible absorption band. These additional broad band accompanied by the bluish color to the samples support the assumption of the formation or presence of pentavalent tungsten ions because of the reducing nature of the phosphate host glass. Gamma irradiation produces some extension of the UV absorption of the undoped glass spectrum accompanied by the generation of an induced visible broad band centered at 520 nm. These extra induced changes are related to some photochemical reactions leading to the partial oxidation of some ferrous ions to ferric ions through the radiation effect. The induced broad visible band is assumed to be related to the formation of phosphorus oxygen hole centers (POHC) or nonbridging oxygen hole centers (NBOHC) from interaction of gamma rays on the phosphate network. Gamma irradiation of WO3 doped glasses reveals the increase of the intensity of the very broad band and in the high content sample (3% WO3), a new induced band is generated at about 411 nm. These changes are assumed to be related to some photochemical reactions involving the conversion of some W6+ ions to W5+ ions by capturing electrons or by photo-reduction of W6+ ions to W4+ ions and thus imparting the additional peak at 411 nm. FTIR results of the studied glasses reveal the appearance of vibrational modes due to phosphate network groups mainly of metaphosphate units or P–O–P linkages as the response of the chemical composition 50% BaO – 50% P2O5. The infrared results of the radiative samples have no notable changes due to compactness of the phosphate with noticeable amount of heavy Ba2+ ions which seem to retard the passage of liberated electrons or positive holes during the irradiation process and thus the network structure remains unaffected. ESR spectra of WO3 – doped glasses reveal distinct signals due to the unpaired pentavalent ions which are stable towards irradiation due to the existence of a high content of the heavy Ba2+ ions which block the passage of negative and positive holes during irradiation.

Surface chemical properties and selective flocculation studies on alumina and silica suspensions in the presence of xanthan gum

The changes in the surface chemical properties of alumina and silica suspensions consequent to the addition of xanthan gum were studied. The adsorption density of xanthan gum for alumina was found to be maximum at pH 2, whereas nil adsorption was found for silica throughout the pH investigated. The isoelectric points (i.e.p.) of alumina and silica were found to be located at pH 9.1 and presumably less than pH 2 respectively. The addition of xanthan gum shifted the i.e.p. of alumina towards more acidic pH values, in proportion with the concentration of xanthan gum added, with a concomitant change in the zeta potentials to more electronegative or less electropositive values. The addition of xanthan gum beyond a certain concentration (>50ppm), increases the flocculation of alumina suspension to a higher value (∼92%), in the pH range of 2–9. The electrokinetic and flocculation characteristics of the silica were not altered much by the addition of xanthan gum, akin to the adsorption result. FTIR spectral investigations provide evidence in support of hydrogen bonding and chemical interaction forces between alumina and xanthan gum. Maximum separation efficiency of ∼93% for alumina-silica synthetic mixture was observed in selective flocculation tests.

Raman and Ftir Spectral Investigations of Twinned M(IO3)2 (M = Mn, Ni, Co, AND Zn) Crystals

Raman and infrared spectra of twinned M(IO3)2 (M = Mn, Ni, Co, and Zn) crystals are recorded and the observed bands are assigned in terms of vibrations of the IO6 octahedron. The IO6 octahedra in Mn(IO3)2 and Zn(IO3)2 are comparatively more distorted than those of Co(IO3)2 and β-Ni(IO3)2. The Iν1/Iν5 ratio of Mn(IO3)2 is higher compared to other compounds, and its linear polarizability is more than that of angular polarizability. The noncentrosymmetric space group of the title compounds is confirmed by the coincidence of the majority of IR and Raman bands, and the compounds giving intense Raman bands are expected to give better SHG efficiency.

Comparative evaluation of natural and acid-modified layered mineral materials as rimifon-carriers using UV/VIS, FTIR, and equilibrium sorption study

AbstractThe encapsulation of rimifon on natural (NZ) and acid-modified (AMZ) zeolites was investigated by UV/VIS, FTIR, and equilibrium sorption studies in aqueous medium. The UV/VIS and FTIR spectral investigations provided data on the nature and characteristics of the drug–zeolite complexes. The probable host–guest interactions during rimifon encapsulation in AMZ include van der Waals interactions, as well as H-bonds established between the O-atom from the carbonyl (>C=O) group and N-pyridine/N-hydrazine atoms in rimifon and zeolite OH-groups. The maximum experimental equilibrium sorption capacity of AMZ (qmax = 7.17 mg/g) was approximately 24 times higher than that of NZ. Baudu and Fritz–Schlunder isotherms almost overlapped and seemed to be the best-fitting models with regard to the experimental equilibrium data of rimifon sorption on AMZ. The unique properties of AMZ and the established high extend of rimifon encapsulation proved the possibility of its successful application as rimifon-carrier for en...

Investigation on growth, structure and characterization of succinate salt of 8-hydroxyquinoline: An organic NLO crystal

8-Hydroxyquinolinium succinate (8-HQSU) has been synthesized and single crystals were grown from ethanol solvent by employing the technique of slow evaporation at room temperature. The structure of the grown crystal has been elucidated by single crystal X-ray diffraction analysis. It reveals that 8-HQSU crystallizes in monoclinic system with non-centro symmetric space group P21. FTIR, 1H and 13C NMR spectral investigations have been carried out to identify the vibrational modes of various functional groups and placement of proton and carbon in the 8-HQSU compound, respectively. UV–vis–NIR transmission spectrum shows the cutoff wavelength around 357nm. In addition, a photoluminescence spectral analysis was carried out for 8-HQSU crystals. The thermal properties of crystals were evaluated from TGA and DTA techniques and the crystal was found to be stable up to 145°C. The dielectric studies show that the dielectric constant and dielectric loss decrease exponentially with frequency at different temperatures. Photoconductivity studies were carried out on the grown crystals it reveals the positive photo conducting nature. Powder second harmonic generation property of the crystal was confirmed by Kurtz and Perry powder SHG technique and it is found to be 1.3 times greater than that of KDP.

EPR, optical and physical properties of chromium ions in CdO–SrO–B2O3–SiO2 (CdSBSi) glasses

Chromium ions doped 10CdO–(20−x) SrO–50B2O3–20SiO2 (x=0.5, 1.0, 1.5, 2.0, 2.5mol%) (CdSBSi) glasses have been studied by using Electron Paramagnetic Resonance (EPR) and optical absorption techniques at room temperature. Powder XRD pattern of all the samples confirms amorphous nature of the glass. The low field spectral line of the EPR spectrum of chromium ions in CdSBSi glass is attributed to isolated Cr3+ ions and the high field spectral line is assigned for exchange of coupled pairs Cr3+ ions in all these glasses. The optical absorption spectra of Cr3+ ions in these glasses shows single broad band characteristic of Cr3+ ions in near octahedral symmetry. From this optical absorption spectral data the crystal field parameter (Dq) is evaluated from ultraviolet absorption edges, the optical band gap and Urbach energies are evaluated. The results assert that the optical band gap energy values are depended quite sensitively on added chromium content. The FT-IR spectral investigations of chromium ion doped glasses exhibits characteristic vibrations of BO3 units. Several physical parameters are also evaluated for these glasses with respect to the composition.

The ‘partial resonance’ of the ring in the NLO crystal melaminium formate: Study using vibrational spectra, DFT, HOMO–LUMO and MESP mapping

The molecular geometry and vibrational spectral investigations of melaminium formate, a potential material known for toxicity and NLO activity, has been performed. The FT IR and FT Raman spectral investigations of melaminium formate is performed aided by the computed spectra of melaminium formate, triazine, melamine, melaminium and formate ion, along with bond orders and PED, computed using the density functional method (B3LYP) with 6-31G(d) basis set and XRD data, to reveal intermolecular interactions of amino groups with neighbor formula units in the crystal, intramolecular H⋯H repulsion of amino group hydrogen with protonating hydrogen, consequent loss of resonance in the melaminium ring, restriction of resonance to N3C1N1 moiety leading to special type resonance of the ring and the resonance structure of CO2 group of formate ion. The 3D matrix of hyperpolarizability tensor components has been computed to quantify NLO activity of melamine, melaminium and melaminium formate and the hyperpolarizability enhancement is analyzed using computed plots of HOMO and LUMO orbitals. A new mechanism of proton transfer responsible for NLO activity has been suggested, based on anomalous IR spectral bands in the high wavenumber region. The computed MEP contour maps have been used to analyze the interaction of melaminium and formate ions in the crystal.

Optical absorption, ESR, FT-IR spectral studies of iron ions in lead oxyfluoro silicate glasses

Melt quenching technique is used for the preparation of lead oxyfluoro silicate glasses containing iron ions. Optical absorption, ESR, FT-IR spectral investigations are carried out to study local structure in glass network. The optical absorption spectra contains three optical absorption bands in visible – NIR regions. The ESR spectra exhibit resonance signals at g=9.4, 4.2 and 2.0. The resonances at g=9.4 and 4.2 are attributed to Fe3+ ions in rhombic and axial symmetry sites, respectively. The g=2.0 resonance signal is due to dipolar interaction. The optical absorption together with ESR measurements suggested that iron ions are dominant presence in the trivalent state. The FT-IR spectral analysis indicates a gradual transformation of iron ions from tetrahedral sites to octahedral sites as the concentration of Fe2O3 is increased in the glass matrix. The physical parameters like density, refractive index, interionic distance along with spectroscopic parameters are measured for these glasses.

Mixed alkali effect and optical properties of Ni 2+ doped 20ZnO + xLi 2O + (30 − x)Na 2O + 50B 2O 3 glasses

Optical and physical properties of Ni 2+ doped 20ZnO + xLi 2O + (30 − x)Na 2O + 50B 2O 3 (5 ≤ x ≤ 25) glasses are carried out at room temperature. Powder XRD pattern of all the glass samples confirms the amorphous nature. Several physical parameters are evaluated for all the glasses with respect to the composition. The optical absorption spectra confirm the site symmetry of the Ni 2+ doped glasses are near octahedral. Crystal field and inter-electronic repulsion parameters are also evaluated. It is interesting to observe that the optical band gap and Urbach energies exhibit the mixed alkali effect. The FT-IR spectral investigations of Ni 2+ doped glasses exhibit characteristic vibrations of BO 3 and BO 4 units.

Electronic, Raman and FT-IR spectral investigations of the charge transfer interactions between ketoconazole and povidone drugs with iodine

The interaction between ketoconazole and povidone drugs with iodine was found to proceed through initial formation of a charge transfer (CT) complex as an intermediate. The stoichiometry of the complex was found to be 1:1 in the case of povidone–iodine system and 1:2 in the case of ketoconazole–iodine system and the same was confirmed by thermal (TGA/DSC) studies. The formation of I 3 − species was confirmed by electronic and laser Raman spectra. The three peaks appeared in Raman spectra, of the isolated adducts corresponds to ν as(I–I), ν s(I–I) and δ(I 3 −), confirmed the presence of asymmetric I 3 − ion. The rate of the interaction has been measured as a function of time and solvent. The pseudo-first-order rate constants at various temperatures for the interactions were measured and the activation parameters (ΔG #, ΔS # and ΔH #) were computed. Based on the spectral and spectrokinetic evidences a mechanism involving the formation of a polar intermediate and its conversion to the final product has been proposed and discussed.

Low potential electrosyntheses of free-standing polyfluorene films in boron trifluoride diethyl etherate

High quality free-standing polyfluorene (PFe) films were synthesized electrochemically by direct anodic oxidation of fluorene in pure boron trifluoride diethyl etherate (BFEE) on stainless steel sheet. The oxidation potential of fluorene in this medium was measured to be only 1.1 V versus SCE, which was much lower than that determined in acetonitrile + 0.1 mol L −1 TBATFB. PFe films obtained from this medium showed good electrochemical behavior, good thermal stability with conductivity of 0.25 S cm −1, indicating that BFEE is a better medium than acetonitrile for the electrosyntheses of PFe films. FTIR and 1H NMR spectral investigations indicated that the polymerization of fluorene occurred mainly at 2, 7 position. As-formed PFe films can be partly dissolved in acetone, acetonitrile, tetrahydrofuran, etc.