Absorption Bands In IR Spectra Research Articles

Tuning the dielectric and structural properties of erbium substitution on cobalt ferrites

Spinel ferrites having the composition CoErxFe2-xO4(x = 0.0, 0.01, 0.02, 0.03, 0.04, 0.05) was synthesized through micro emulsion method. To study the structural, IR spectra, morphology and composition and electrical properties of these spinel ferrites, the characterization of samples was done by XRD, FTIR, SEM and Dielectric properties respectively. Spinel ferrites XRD patterns revealed that the structure was crystallite and single phase. By doping the rare earth metal Erbium, it was shown that there were variations in lattice parameters. The range of Crystallite size was in 19- 25nm which was calculated by Scherer formula. FTIR recorded the IR spectra, the absorption bands of IR spectra revealed that all samples were spinel ferrites. SEM also confirmed the shape of the particle and grain size that is found to be in agreement with the XRD data, it also showed monotony in the morphology. Real and imaginary parts of impedance Z՛ and Z″ in the frequency range of 1MHz to 3 GHz was plotted. The results show that the impedance decreases with increasing frequency. In order to determine the grain effect, the real and imaginary parts electrical modulus was plotted with increasing Erbium substitution. The effect of frequency in high frequency region gives the variation in electrical modulus. Furthermore, real and imaginary parts of dielectric constant were plotted as a function of frequency. The results show the significant effect in the high frequency region. Also the same behavior was observed in case of tangent loss. Ac conductivity was determined showing the increasing trend with increasing frequency. Excellent dielectric properties suggest that Er3+ has significant effects for the application of high frequency devices.

Influence of surface tension on the characteristics of FTIR spectra on the example of saliva

The aim of this work was to test the hypothesis about the effect of surface tension of biological fluids on the characteristics of IR spectra using saliva as an example. The study involved 100 volunteers without clinically significant diseases. Saliva samples were collected from all participants, a parallel determination of surface tension, biochemical composition was carried out, and IR spectra were obtained. Comparison of the results was carried out using cluster analysis, principal component analysis and correlation analysis. The existence of a relationship between the characteristics of absorption bands in IR spectra and surface tension has been established using saliva as an example. It is shown that, first, a change in the surface tension affects the shift of the absorption bands in the spectra, while the intensity and area of ​​the corresponding absorption bands change to a lesser extent. Combinations of the characteristics of the IR spectra have been revealed that provide the maximum correlation relationship with both the total volumetric content of surfactants and their adsorption activity. Correlations with total surfactant content include absorption band characteristics corresponding to proteins, lipids and phospholipids. Whereas the adsorption activity of surfactants correlates mainly with the absorption bands of proteins in saliva. The revealed patterns are substantiated taking into account the biochemical composition of saliva, depending on the surface tension.

SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL STUDIES OF NI (II) COMPLEXES WITH SCHIFF BASE CO-LIGAND DERIVED FROM 5,6-DIAMINO-1,10-PHENANTHROLINE AND BENZENE-1,4-DICARBALDEHYDE

The Schiff base (PDB) was synthesized by refluxing ethanolic solution of 5,6-diamino-1,10-phenanthroline with Benzene-1,4-dicarbaldehyde for 3 hours. Similarly the complexes were synthesized by refluxing equimolar solution of PDB with [Ni(phen)2Cl2] and [Ni(bpy)2Cl2] for 5 hours each and characterized by FTIR, UV-visible, Mass and Elemental Analysis. The absorption band in IR spectrum of PDB at 1593 cm-1 was assigned to C=N stretching frequency which was shifted to 1550 cm-1 and 1549 cm-1 in the spectra of [Ni(phen)2PDB](PF6)2 and [Ni(bpy)2PDB](PF6)2 respectively. The new absorption bands at 721 cm-1 and 754 cm-1 in the spectra of both complexes were due to M-N coordinate bond. The UV- visible absorption band at 390 nm was due to p®p* transitions for azomethine. The low energy band at 450 nm for both complexes is due to MLCT Ni(dp) ®PDB(p*) transition. The molecular ion peak (M)+ in the mass spectra for PDB and the complexes were observed at 443 m/z, 984.75 m/z and 940.95 m/z respectively. The compounds were evaluated for antimicrobial activities, by well diffusion method against bacteria using agar nutrient as the medium and fungi using potato dextrose agar as medium. The free Schiff base has low activity compared to the complexes with inhibition zone between 4.0 mm to 6.6 mm whereas the complexes ranges from 7.5 mm to 11.2 mm.

Influence of erbium on the structural, optical and magnetic properties of sol–gel Ce: YIG films

Sol–gel Y2.8-xCe0.2Er x Fe5O12 (x = 0.0, 0.2, 0. 4, 0.6, 0.8 and 1.0) nanofilms were successfully prepared for their potential use in nonreciprocal magneto-optical devices, such as isolators and circulators. The effect of Er-doped Ce-substituted yttrium iron garnet (Ce:YIG) was investigated using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), UV–vis spectrophotometry and vibrating sample magnetometry (VSM). Analysis of the diffractograms indicated a cubic garnet structure and the incorporation of the Er3+ ions into the Ce: YIG. The absorption bands in IR spectra revealed the fingerprint of the YIG structure in the obtained films. The optical transparency of the Er-doped Ce:YIG samples was above 98% in the visible and near infrared region wavelengths. All samples were soft ferrimagnetic films, as indicated by their hysteresis loops and low magnetic coercivity fields (~50 Oe). As more erbium ions were introduced, the saturation magnetisation decreased and the magnetic coercivity increased. These findings suggest that Er-doped Ce:YIG films may have a promising role in magneto-optical applications.

Characteristics of the surface chemistry of linden pyrochar after removal of labile organic matter

The changes of chemical properties of the pyrochar surface were studied in the laboratory experiment that simulated pedogenic transformation of pyrochar under the influence of soil biota. The native pyrochar samples were obtained by pyrolysis of linden wood residues at the temperature of 250°C, 450°C and 650°C. Their modified samples were obtained by removing an easily degradable pool of organic substances that can be used by microorganisms during the first months after application to the soil. In low-temperature linden pyrochar (250°C and 450°C) dominated carboxylic and phenolic surface groups, in high-temperature (650°C) - lactonic groups. After removal of readily decomposable organic substances the acidity of the phenolic and lactonic groups in pyrochar of low-temperature pyrolysis sharply decreased. Characteristic feature of all studied samples is the presence in IR spectra of absorption bands of gyroxyl, carbonyl, methylene groups and organosilicon polymers. The feature of IR spectra of linden pyrochar (250°C and 450°C) is the presence of absorption bands of the stretching vibrations of the tertiary alcohols and phenols C-O group.

DFT analysis of the structure and IR spectrum of potassium salt of diphenylsulfophthalide – A model compound for polydiphenylenesulfophthalide salts

Experimental IR spectra of crystalline dried and non-dried potassium diphenylsulfophthalide (TAC-K) as a model compound for polymeric salts are presented. DFT analysis (B3LYP/6-311G(d,p)) of the structure and IR spectra of a series of compounds similar in structure to TAC-K as well as their dimers indicates that the sulfonate group environment strongly affects the positions of absorption bands (ABs) of vibrations of SO bonds and demonstrates that information on the exact structure of ion clusters is needed for reliable and unambiguous assignment of the ABs in experimental IR spectra of real sulfonate ion containing systems to particular vibrational modes. Various ways of metal ion coordination with sulfonate ion, as well as their reflection in IR spectra of model compounds, are considered and discussed. Using TAC-K as an example, the effect of an intramolecular hydrogen bond on the vibrational modes of sulfonate group and hydroxy group is considered. The effect of ion aggregation on the shape of the IR spectrum of TAC-K is analyzed for an energetically favorable dimer of this salt as an example. Based on a combination of calculated, literature and reference data, a number of ABs in the IR spectra of TAC-K have been tentatively assigned. In particular, the bands in the region of 3230–3180 cm−1 have been assigned to ν(OH); those at 1240-1160 cm−1, to νas(SO3−); the AB at 1080 cm−1, to νs(SO3−); that at 616 cm−1, to δ(oop)s(SO3−); and that at 570 cm−1, to δ(ip)as(SO3−).

Effect of ion interactions on the IR spectrum of benzenesulfonate ion. Restoration of sulfonate ion symmetry in sodium benzenesulfonate dimer

Literature data concerning the assignment of IR spectra of benzenesulfonate salts that serve as model compounds for aromatic sulfonate-containing ionomers and polyelectrolytes have been analyzed. The structures and IR spectra of free benzenesulfonate ion and its potassium and sodium salts have been calculated in B3LYP/6-311G(d,p) approximation. The bidentate coordination of counter-ions is energetically favorable for isolated ion pairs. In this coordination, the symmetry of sulfonate ion changes noticeably, which manifests itself as strong splitting of calculated vibrational modes of asymmetric stretching vibrations of SO bonds, Δνas(SO3) = 154 cm−1 (K) and 180 cm−1 (Na). For sodium benzenesulfonate it is thermodynamically favorable to form a dimer (ΔG° = −37.6 kcal/mol) in which the joint effects of monodentate and bidentate coordinated Na cations result in equalization of SO bond lengths and thus a considerable restoration of C3V symmetry of the sulfonate ion. The IR spectrum of the dimer in which Δνas(SO3) splitting is considerably smaller much better matches the experimental spectrum than the spectrum of an isolated ion pair. The major absorption bands in the IR spectrum of sodium benzenesulfonate have been assigned to theoretical vibrational modes of the dimer and, based on visualization of modes, to vibrations of certain bonds in the anion. In particular, the bands at 1200 and 1186 cm−1 have been assigned to νas(SO3), that at 1049 cm−1 to νs(SO3), and those at 628 and 572 cm−1 to δ(oop)s(SO3), and δ(ip)as(SO3), respectively. The strong effect of sulfonate ion environment on the positions of the absorption bands of stretching vibrations of SO bonds makes it necessary to obtain data on exact structures of ion clusters for reliable assignment of absorption bands in experimental IR spectra of real sulfonate-containing systems.

FT-IR and computer modeling study of hydrogen bonding in N-alkyl acrylamide–toluene binary mixtures

Degree of hydrogen bonding driven self-association of N-(n-butyl)acrylamide, N-(n-octyl)acrylamide, N-(sec-octyl)acrylamide and N-(tert-octyl)acrylamide in toluene was investigated using IR spectroscopy and computer modeling methods.Consistent results were demonstrated in the treatment of the Amide-I (νC=O), Amide-II (δN−H and νC−N) and Amide-A (νN−H) absorption bands in IR spectra. Thus, the content of non-bonded (free) amide groups decreases from 83–98% to 8–20% and the content of linear polyassociates increases to 80–90% with an increase in monomer concentration from 0.5 wt% to 50 wt%. The content of cyclic dimers was equal to the value between 5 and 10% regardless of the initial monomer concentration. Dependences of the association degree and the content of the linear polyassociates on the concentration were found to be similar for all of the studied amides.

Structural and magnetic study of Al3+ doped Ni0.75Zn0.25Fe2−xAlxO4 nanoferrites

Nanostructured Al3+ doped Ni0.75Zn0.25Fe2−xAlxO4 (x=0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) ferrites were synthesized via the wet chemical method. X-ray diffraction, transmission electron microscopy, and magnetization measurements have been used to investigate the structural and magnetic properties of spinel ferrites calcined at 950°C. With the doping of Al3+, the particle size of Ni0.75Zn0.25Fe2−xAlxO4 first increased to 47nm at x=0.4 and then decreased down to 37nm at x=1. The main two absorption bands in IR spectra were observed around 600cm−1 and 400cm−1 corresponding to stretching vibration of tetrahedral and octahedral group Fe3+–O2−. Saturation magnetization and hyperfine field values decreased linearly with Al3+ due to magnetic dilution and the relative strengths of Fe–O–Me (Me=Fe, Ni, Zn, and Al) superexchanges. The coercive field showed an inverse dependence on ferrite particle size with minimum value of 82Oe for x=0.4. A continuous drop in Curie temperature was observed with the Al3+ substitution. From the Mossbauer spectral analysis and X-ray diffraction analysis, it is deduced that Al3+ for x<0.4 has no obvious preference for either tetrahedral or octahedral site but has a greater preference for the B site for x>0.4. In nutshell the study presents detailed structural and magnetic, and Mossbauer analysis of Ni0.75Zn0.25Fe2−xAlxO4 ferrites.

Preparation of chalcogenide glasses of As–S, Ge–S, Ge–Se systems from monoisotopic elements

As2S3, GeS3, GeSe4 glasses have been prepared from monoisotopic (isotopically enriched) arsenic, germanium, sulfur and selenium. Impurity composition was investigated; IR-spectra and glass transition temperature of prepared glasses were measured as compared with glass samples from the elements of natural isotopic composition. It is shown that the change in isotopic composition of glass leads to the expected shift in resonance absorption bands in IR-spectra by ~1–8cm−1 as compared with the samples of natural isotopic composition. Optical fibers were fabricated from As2S3.26 glass with natS and 32S. Great difference in optical losses in glass of natural and isotopically enriched composition is due to a different degree of purity of the used sulfur.

Syntheses and characterization of new tetraazamacrocyclic copper(II) complexes as a dual functional mimic enzyme (catalase and superoxide dismutase)

A series of macrocyclic complexes, [Cu(TAAP)]X2, X = ClO4 and CH3COO; [Cu(TAAP)X]X, X = NO3, Cl, and Br, have been synthesized by self-condensation of 5-amino-3-methyl-l-phenylpyrazole-4-carbaldehyde (AMPC) in the presence of copper(II). Elemental analyses and conductivity measurements confirm the stoichiometry of the ligand and complexes, while the characteristic absorption bands in IR spectra confirmed the formation of ligand framework around copper. Square-pyramidal and square-planar stereochemistries have been proposed for the five-coordinate (nitrato and halogeno) and four-coordinate (perchlorate and acetate) complexes. The electrochemical properties and thermal behaviors have been studied by cyclic voltammetry and TGA. Mimetics of antioxidant enzymes such as superoxide dismutase (SOD) and catalase demonstrated that there is a correlation between the observed redox properties and the SOD and catalase biomimetic catalytic activities of the copper(II) complexes.

Manifestation of enol–enol tautomerism in IR spectra of 2-acetylcyclopentanone-d1

IR spectroscopy was used to show that 2-acetylcyclopentanone (2-ACPN) exists in solutions of aprotic organic solvents as a mixture of three tautomeric forms. Assignments of absorption bands in IR spectra of 2-ACPN and its deuterated analog 2-ACPN-d1 were made based on calculations of normal mode frequencies by a B3LYP/6-311++(2 d,2p) method for the gas phase and taking into account the influence of aprotic solvents in the framework of a polarizable continuum model (PCM). The enol–enol tautomeric equilibrium constant was evaluated for 2-ACPN-d1 in solutions of the aprotic solvents. The content of the diketo form of 2-ACPN was shown to depend strongly on the solvent polarity and increased with it.

Infrared spectra of brassinolide and castasterone steroid phytohormones and their 24-epi derivatives

Absorption bands in IR spectra of brassinolide, castasterone, and their 24-epi derivatives in the frequency range 3800-1000 cm -1 have been interpreted. A number of spectral features distinguishing brassinolide from castasterone have been found. The conducted analysis shows that the structural differences manifest themselves in IR spectra of the investigated brassinosteroids in the region of stretching vibrations of CO-H, C=O, C-OH, C-O-C, CH 3 , CH 2 , and CH groups. The main distinctions in IR spectra of brassinolides and castasterones are due to the B ring structure.All hydroxyl groups of brassinosteroids pressed in KBr are included in hydrogen bonds. Broad bands attributed to associated OH groups are observed in the IR spectra. Two possible kinds of hydrogen bonding exist. IR spectra of diluted solutions of the studied brassinosteroids contain two bands caused by vibrations of free hydroxyls and those associated by intramolecular hydrogen bonds.A fraction of the C=O groups of brassinosteroids pressed in KBr remains free. High-frequency bands in solid-state IR spectra are due to vibrations of free C=O groups whereas low-frequency bands are attributed to stretching vibrations of associated groups. The lack of low-frequency bands in solution spectra proves that the C=O⋅⋅⋅H-O hydrogen bond is intermolecular rather than intramolecular. Vibrational frequencies of brassinolide C=O groups are higher than the corresponding frequencies for castasterones because of the influence of oxygen in the seven-membered B ring.

Utilization of carboxymethyl cellulose based on bean hulls as chelating agent. Synthesis, characterization and biological activity

Binary and ternary complexes of Ni 2+, Cu 2+, Ag + and UO 2 2+ with the prepared carboxymethyl cellulose in its sodium salt (P-NaCMC) and pyridine (py) as secondary ligand have been prepared. Probable structures of the binary and ternary complexes were inferred via elemental analysis, spectral data (IR, mass and solid reflectance) as well as magnetic susceptibility measurements, thermal and XRPD analysis. The change in the selected vibrational absorption bands in IR spectrum of P-NaCMC upon coordination with metal ions investigates the coordination mode of P-NaCMC to be the two vicinal uncarboxylated diol groups (2- and 3-hydroxyl groups) of the glucopyranose rings in addition to the carbonyl oxygen atom of the carboxylate group while the coordination mode of pyridine ligand is the ring nitrogen. The mass spectra confirmed the proposed structure of the synthesized compounds. The solid reflectance spectral data and magnetic moment measurements suggest the geometrical structures for the metal complexes. Thermal studies suggest a mechanism for degradation of P-NaCMC and its metal complexes as function of temperature supporting the chelation modes. Also, the activation thermodynamic parameters, such as, Δ E *, Δ H *, Δ S * and Δ G * for the different thermal decomposition steps of P-NaCMC and its metal complexes were calculated. Antimicrobial activities of P-NaCMC and its binary and ternary complexes were studied against S. aureus and S. pyogenes (Gram-positive bacteria), P. phaseolicola and P. fluorescens (Gram-negative bacteria) and the fungi; F. oxysporum and A. fumigates using agar disc diffusion method. The results showed that all the metal complexes, especially Cu 2+ ternary complex have higher antibacterial and antifungal activities than P-NaCMC.

Phase transformations in LnF 3–(Ln, Zr)–ZrF 4 systems, where Ln = Sm, Eu, Tm, Yb

Phase transformations in LnF 3–(Ln, Zr)–ZrF 4 systems (where Ln = Sm, Eu, Tm, Yb) in the temperature range 700–900 °C have been investigated by chemical and X-ray phase analyses, UV and IR spectroscopy. Synthesis conditions of nonstoichiometric samarium, europium, ytterbium and thulium fluorides, which are products of interaction between LnF 3 and Ln and original substances for the preparation of compounds such as LnZrF 6 are given. The crystal lattice of the fluorozirconates obtained is similar to the Yb 27F 64 superstructure. Thulium fluorozirconate (TmZrF 6), whose structure is indexed as the Tm 13F 32− δ superstructure of hexagonal system, is an exception. For all compounds obtained, the lattice parameters have been calculated and the absorption bands of IR spectra have been interpreted.

Interpretation of IR spectra of epoxysaccharides based on the theoretical calculation of frequencies and intensities of normal vibrations

A detailed assignment of absorption bands in IR spectra of methyl 3,4-anhydro-α-D-talo-hexapyranoside and methyl 2,3-anhydro-4-deoxy-α-D-ribo-hexapyranoside is first made based on the complete calculation of frequencies and absolute intensities of normal vibrations of molecules and their comparison with the corresponding experimental values. The effect of the epoxy group on the bands characteristic of the pyranose ring is analyzed. The charactericity of spectral features of oxymethyl substitution for the hydroxyl group and the oxirane ring is studied.

Method for assigning absorption bands in IR spectra of polyatomic molecules with respect to internal vibrational coordinates

A method is proposed for assigning absorption bands in IR spectra of polyatomic molecules. An algorithm is developed and a Fortran program is written based on this method. The method is illustrated for the example of the toluene molecule.

Neutron irradiation and post-irradiation annealing of rutile (TiO2−x ): effect on hydrogen incorporation and optical absorption

Neutron irradiation and post-irradiation annealing under oxidising and reducing conditions have been used to investigate H incorporation in, and the optical properties of, reduced (TiO2−x ) rutile. Optical absorption in rutile is mainly due to a Ti3+ Ti4+ intervalence charge transfer effect. The main mechanism for H incorporation in rutile involves interstitial H not coupled to other defects, which has important implications for the rate of H diffusion, and possibly also on the electrical properties of rutile. Additional minor OH absorption bands in IR spectra indicate that a small amount of interstitial H is coupled to defects such as Ti3+ on the main octahedral site, and indicates that more than one H incorporation mechanism may operate. Concentration of oxygen vacancies has a controlling influence on the H affinity of rutile.

Spectral and energy characteristics of dioxybenzenes

In the approximation for the valence force field with quantum-chemical estimation of the intensities of the absorption bands of IR spectra, calculation of the main spectral-structural and energy characteristics of dioxy-benzenes is performed. This made it possible to suggest energetically more favorable conformations and assign the frequencies of normal vibrations to individual types of symmetry.

Accuracy in Calculating the Intensities of the Absorption Bands in IR Spectra by Direct Quantum-Chemical Methods

To obtain information on the accuracy of quantum-chemical computations of the integral intensities of the absorption bands in IR spectra, calculations were performed by the density functional and ab initio methods for a number of polyatomic molecules that include the atoms of halogens, sulfur, phosphorus, etc. The results are compared with quantitative experimental data. A sufficient scatter in the calculated and experimental values has been found, but statistical processing of the results by the bootstrap method has revealed a regular deviation that can be partially compensated for by the coordinate scaling method.