IR Spectroscopic Studies Research Articles

Investigation of the adsorption properties of the sorbent obtained in the process of modification of clinoptilothite in the purification of natural gas from sulfur compounds

The study of the possibility of using modified clinoptilolite as an adsorbent and the adsorption properties of zeolite in the purification of natural gas supplied to gas processing plants from sulfur compounds contained in it is an urgent task. In the experimental study, the adsorbent fraction was chosen as 0.5÷1.0 mm, density - 0.8 g/cm3, adsorbent layer height - 600 mm. Optimal conditions are selected in such a way that the pressure in the experimental process is 0.2-5.0 MPa, the amount of mercaptans in the purified natural gas is 50÷400 mg/nm3, the temperature is 20÷25°C, the gas flow rate is 0.2÷250°C. 0.25 m/s. Experiments IR spectroscopic studies were carried out on a NikoletIS-10 IR spectrometer in the frequency range 400-5000cm-1. The phase composition was studied using a 2DPHASER Bruker X-ray analyzer (CuKa - radiation, 2nd, 20-80 degrees). Electron microscopic images were taken under a Hitachi TM-3000 microscope. Elemental analysis was performed at Oxford Science. The intensity and accuracy of desorption of sulfur compounds adsorbed on clinoptilolite at 250°C, the same results were obtained on NaX zeolite at 320°C. The catalytic activity of regeneration of clinoptilolite at lower temperatures than that of NaX zeolite, although small, made it possible to minimize the decomposition of mercaptans. The purpose of this work is to study the adsorption properties of the sorbent obtained in the process of modifying clinoptilotite during the purification of natural gas from sulfur compounds.

Ir Spectroscopy Studies of the Textile Materials Structures With Natural Dyes

The scientific study examines the functional groups of the oregano shell dye for dyeing textile materials , the expansion of color capabilities and capabilities capable of resisting microorganisms . The aim of the study is to create a natural additive to save resources , environmentally friendly , natural coloring products , easy to manufacture and use manufacturing technology . Extraction of the walnut shell is necessary when dyeing and finishing fabrics and textiles . At the present stage , it is relevant to obtain and study natural dyes for textile materials . The use of natural dyes will improve the hygienic properties of products and increase the environmental friendliness of the finishing process . Thanks to the active extraction of natural dyes and expanded color shades , the possibilities of introducing natural dyes into the textile industry in the future are high . This is due to the fact that the raw material base is extensive , and the compliance of natural dyes with international environmental standards , as well as one of the priorities provided for by the strategy , is the rational use of natural raw materials . IR spectroscopic studies of textile materials using the developed dyes were carried out in the work . To improve the quality of dyeing and chemical properties , various modifying components were added to the dyes . The use of the resulting coloring agent in the dyeing of textile fibers will replace the import of synthetic textile dyes .

Structural, morphological and photocatalytic properties of TiO2 obtained by thermolytic decomposition of the [Ti(OH2)6]3+•3Cl¯ aquacomplex

Thermolytic decomposition in a chloride-acid medium of a titanium aquacomplex precursor solution [Ti(OH2)6]3+•3Cl¯ as a result of its boiling at a temperature of (110-114) 0С is accompanied by precursor hydrolysis and the formation of hydrate molecules Ti(OH)3Cl•2Н2О, which, as a result of condensation, provide the formation of rutile ТіО2 with rod-shaped particles (30-80) nm long and (8-20) nm in diameter, combined into flower-shaped associates with a diameter of (200-280) nm. IR spectroscopic studies of the precursor hydrolysis products and the synthesized oxide material show that the geometric parameters of ТіО5Cl octahedra of Ti(OH)3Cl •2Н2О hydrate molecules are close to those of ТіО6 octahedra of ТіО2 rutile. The average Ti-O interatomic distance of octahedra of titanium-containing hydrate molecules is a kind of template that directs the process of ТіО2 crystallization towards the formation of rutile. Rutile ТіО2 nanopowder synthesized in this way is an effective photocatalyst for the photooxidation of organic dyes in an aqueous medium by UV radiation. The photocatalytic activity of the synthesized rutile ТіО2 was determined by neutralization of Congo Red (CR) dye dissolved in an aqueous medium. The effectiveness of TiO2 was studied by examining the effect of TiO2 amount and Н2О2 concentration. It has been established that complete bleaching of the dye is achieved in just 10 minutes of UV irradiation at a photocatalyst concentration of 1.5 g/L, an Н2О2 concentration of 5 mM, and an initial CR dye concentration of 5 mg/L, at reaction rate constant of 2.1959 min-1.

The study of intermolecular interactions in [Bmim][PF6] + 1-octyl-2-pyrrolidone binary mixtures from volumetric, acoustic, optical and spectroscopic measurements

Under 101.3 kPa pressure, the densities, speeds of sound, and refractive indices of [Bmim][PF6] + 1-octyl-2-pyrrolidone mixtures were determined experimentally over the whole composition range and at 303.15 to 323.15 K. The excess molar volumes (VmE), excess values of partial molar volumes (V¯mE), partial molar volumes at infinite dilution (V¯mE,∞), excess values of isentropic compressibility (KsE), speeds of sound (uE) and isobaric thermal expansion coefficient (αPE) have been calculated using these experimental data. The Redlich–Kister polynomial equation has been adequately fitted to the computed data. Intermolecular interactions between like and unlike molecules have been interpreted using the experimental and computed data. The Prigogine–Flory–Patterson theory of excess molar volume and IR spectroscopic studies supported the conclusions drawn from volumetric and acoustic properties.

IR-spectroscopic study of complex formation of nitrogen oxides (NO, N2O) with strong Lewis acid sites and the reactivity of adsorbed species in CO and CH4 oxidation

The formation of complexes and transformations of nitrogen oxides (NO, N2O) on strong Lewis acid sites of HZSM-5, H[Ga]ZSM-5, ZnO/HZSM-5 zeolites and dealuminated mordenites was investigated by diffuse-reflectance IR spectroscopy. Adsorbed N2O that is formed by disproportionation of NO is capable of oxidizing CO and CH4 molecules to CO2. The behaviour of strong Lewis acid sites in zeolites and cationic forms of zeolites in the NO disproportionation and CO or CH4 oxidation was comparatively studied.

ВИВЧЕННЯ ЗМІНИ ЕКСПЛУАТАЦІЙНИХ ВЛАСТИВОСТЕЙ НАПІВСИНТЕТИЧНОЇ МОТОРНОЇ ОЛИВИ ELF EVOLUTION 700 STI ПІСЛЯ ВИКОРИСТАННЯ У БЕНЗИНОВОМУ ДВИГУНІ

The paper describes the results of research on changes in the performance of fresh and used semi- synthetic motor oil ELF Evolution 700 STI for gasoline engines of cars. The change of physicochemical properties of fresh and used semi-synthetic motor oil before and after its use in a gasoline engine has been studied. The results of derivatographic and IR spectroscopic studies of these oils are presented. The composition of the inorganic part of the studied semi-synthetic oils was determined by the method of X-ray fluorescence research.

Highly Active Bimetallic Single-Atom Alloy PdAg Catalysts on Cerium-Containing Supports in the Hydrogenation of Alkynes to Alkenes

A study of a series of single-atom-alloy catalysts Pd1Ag3/Al2O3, Pd1Ag3/CeO2–Al2O3, and Pd1Ag3/CeO2–ZrO2 in the selective hydrogenation of diphenylacetylene (DPA) showed a significant (five-fold) increase in activity for the PdAg3/CeO2–ZrO2 sample in comparison with that of Pd1Ag3/Al2O3. It was especially noted that the increase in activity was not accompanied by a decrease in the selectivity for the target product. This catalytic behavior can be explained by two factors: (1) a more than twofold increase in the dispersity of the PdAg3/CeO2–ZrO2 catalyst and (2) a change in the electronic state of the nanoparticles, as determined from the results of an IR-spectroscopic study of adsorbed CO. The retention of the high selectivity of the synthesized catalysts indicated the stability of the structure of Pd1 monoatomic sites in the catalysts prepared by deposition on Ce-containing supports, which was also confirmed by the IR spectroscopy of adsorbed CO. The experimental results indicate that Ce-containing supports are promising for the synthesis of catalysts for the selective hydrogenation of substituted alkynes.

Self‐Healable Metallogels for Selective Dye Adsorption

AbstractThe low molecular weight gelator, disodium L‐(3,5‐di‐tert‐butyl‐2‐hydroxy‐benzyl)amino aspartic acid (Na2HL), has been used to prepare three metal‐organic hydrogels (metallogel) with the metal ions Ni2+ (MOG 1), Co2+ (MOG 2), and VO2+ (MOG 3). The gels have been prepared by mixing the aqueous solutions (0.5 mL) of the Na2HL(0.01 to 0.05 mmol) and M(CH3COO)2⋅4H2O {M=Ni or Co} or VO(SO)4⋅H2O (0.01 to 0.05 mmol). The gels have been characterized by IR spectroscopic studies, MALDI TOF spectrometry and various microscopic studies. All the gels are multi‐responsive in nature to different external stimuli, and among them, MOG 1 and MOG‐2 show the self‐healable property indicating a strong metal‐ligand interaction and hydrogen bonding interactions in the gel network. The thixotropic behavior and viscoelastic nature of the self‐healable metallogels have been confirmed by time dependent step‐strain experiment at room temperature. It was observed that MOG 1 shows rapid and more efficient selective dye adsorption of cationic dyes, rhodamine B (RhB) {61.7 mg g−1}, and malachite green (MG) {15.3 mg g−1} from mixtures of cationic, anionic dyes, and neutral dyes. MOG 2 also selectively adsorb cationic dyes from the mixture of dyes. The gel, MOG 3, selectively degrades fluorescein (FL) dye.

A new lipophilic cationic rhodamine-based chemosensor for detection of Al(III)/Cu(II) and intracellular pH change and its application as a smartphone-assisted sensor in water sample analysis

A new probe, RTPP was prepared by condensation of rhodamine B hydrazide with (3-formyl-4-hydroxybenzyl)triphenylphosphonium chloride. The structure of sensor RTPP was elucidated using spectroscopic methods and single crystal X-ray diffraction. Colourless and non-fluorescence sensor RTPP solution turns pink in the presence of Cu2+ and showed orange fluorescence enhancement in the presence of Al3+. Cation recognition performance and binding mechanisms of the probe were studied through UV, fluorescence, IR, MS, and NMR spectroscopic studies; where the results revealed that sensor RTPP has a high affinity towards Al3+/Cu2+ with the limit of detection down to at least 10-7 M. The developed system was applicable for tracing Cu2+ through colorimetric method in two selected water samples with satisfactory results. More significantly, “naked-eye” detection of Cu2+ using RTPP has been effectively incorporated with a smartphone RGBColorDetector application to make it suitable for on-site qualitative and quantitative colorimetric investigation. In addition, RTPP can act as a sensor for detecting acidic pH change in HCT 116 human colorectal carcinoma cell line through fluorescence response.

Dynamics of hydrogen bond reorganization in the S1(ππ*) state of 9-Anthracenecarboxaldehyde

Effect of solvent polarity and hydrogen bonding interaction on the excited state dynamics of 9-Anthracenecarboxaldehyde (9-ACD) have been investigated using steady state and time-resolved electronic and vibrational spectroscopic techniques. Photophysical properties and dynamics of the excited states are seen to be more sensitive to intermolecular hydrogen bonding ability of the solvent, rather than its polarity. FTIR studies reveal formation of complexes with the protic solvents via formation of conventional hydrogen bond at the carbonyl site of 9-ACD molecule. In strong hydrogen bond donating solvents, namely, 2, 2, 2-trifuoroethanol (TFE) and 1, 1, 1, 3, 3, 3-hexafluoroisopropanol (HFIP), nearly all the molecules of 9-ACD in solution remain engaged in complex formation leaving insignificant number of molecules remaining free in solution. In aprotic solvents, the S1 state is short-lived (the lifetime is only a few tens of ps) and intersystem crossing (ISC) is the major deactivation pathway (the triplet yield is near unity). However, in strong hydrogen bond donating solvents, the S1 state lifetime is long (a few ns) because the deactivation pathway for the S1 state via the triplet manifold is blocked. Both the ultrafast time-resolved electronic and vibrational spectroscopy studies in TFE and HFIP reveal that hydrogen bond reorganization process following photoexcitation of the hydrogen bonded complex is the only relaxation process undergone by the S1 state in sub-100 ps time domain. However, the time-resolved IR (TRIR) spectroscopy studies further reveal the possibility of formation of aromatic π- hydrogen bonding and reorganization of the hydrogen bond at this site makes the major contribution towards the S1 state relaxation process in strong hydrogen bond donating solvents.

IR spectroscopic study of the hydrogen bond network in the water–3-amino-1-propanol system and its comparison with the spatial network of hydrogen bonds in the water–monoethanolamine system

IR spectroscopy was used to explore the water–3-amino-1-propanol (3AP) system in the range of 400–4000 cm-1. Based on the stretching vibrations of OH, NH2 and CH groups and skeletal bending vibrations of 3AP it was concluded that mixed spatial networks are formed in the water–3AP system that predominate at medium 3AP concentrations. The obtained results are similar to the IR spectroscopic data for the water–monoethanolamine system, viz., the networks of both amino alcohols are incorporated into the spatial

IR-Spectroscopic Study of the Content of Water and Hydrogen Defects in Industrial Quartz Types of Karelia (Russia)

IR-Spectroscopic Study of the Content of Water and Hydrogen Defects in Industrial Quartz Types of Karelia (Russia)

Catalyst-free crosslinked sustainable functional silicones by supramolecular interactions

Supramolecular full silicone networks are built on the basis of siloxane polymers with low content of amino (6.4 or 9.8 mol%), and carboxyl (14.9 mo%) groups. Alternatively, the carboxyl groups involved are attached to a polyhedral silsesquioxane cage (i.e., octakis(2-carboxymethylene-thioethyl)silsesquioxane), POSS-COOH, which have also been found to play a filler role. Networks substantiated as free-standing films through the development of physical interactions between polar groups forming transverse bridges between chains were analyzed structurally by IR analysis, but also in a more original way by fluorimetric approach, and evaluated in terms of thermal, mechanical, electrical properties and their suitability as biointerfaces. It has been found that these properties are strongly dependent and can be adjusted by the content and the ratio between the two types of polar groups (-NH2 and -COOH), as well as by the substrate to which the carboxyl groups are attached (polysiloxane or POSS). Being elastomers crosslinked by supramolecular interactions, it was necessary to evaluate their reversibility, for which, temperature-dependent IR and dielectric spectroscopy studies were performed. The reflection of this reversibility in the self-healing capacity of the material in the film and solvoplasticity in solvents with different polarities and media that mimic biological fluids was highlighted supporting the sustainability of these materials obtained in the absence of any catalyst.

COORDINATION POLYMER OF STRONTIUM (II) BASED ON PHTHALIC ACID AND PYRAZINE ADDUCT

The coordination polymer of Sr (II), with the chemical formula of {SrL1 (L2)0.5·(H2O)0.36}n (L1 = phthalic acid anion and L2 = pyrazine), have been synthesized by the interaction of sodium phthalate with a water-soluble strontium salt and pyrazine in the aqueous medium with further evaporation of an aqueous solution and characterized by IR spectroscopic, elemental, single-crystal X-ray diffraction and thermal analysis. The results of XRD analysis showed that the synthesis product has a single-phase and is well-identified by means: 12.73; 11.41; 9.04 showing that the unit cell parameters of this compound are approximately equal to a = 12.74, b = 11.41, and c = 9.04 Å. IR spectroscopic studies showed that phthalate anion in polymer acts as a chelate and bridging ligand. Thermographic analysis showed that the polymer is stable up to a temperature of ̴ 2000С

IR-SPECTROSCOPIC STUDY OF WATER AND HYDROGEN DEFECTS IN INDUSTRIAL QUARTZ TYPES OF KARELIA (RUSSIA)

The results of an IR spectroscopic study of the content of water and hydrogen defects in hydrothermal and pegmatite quartz from quartz-vein occurrences in Karelia (North-West Russia), considered as a promising source of high-purity quartz raw materials, are presented. It is shown that the main amount of water in the analyzed quartz is in molecular form, and OH groups associated with aluminum, lithium, and boron trace elements in the quartz lattice are also identified. Granular quartz with the lowest content of molecular water and OH-groups is the most preferred for use as a high-purity quartz raw material.

Computational and Experimental Investigations of 7-(4-nitrophenyl)benzo [6,7]chromeno[3,2-e]pyrido[1,2-a]pyrimidin-6(7h)-one

Acstract:In-silico studies are used for the prediction of the properties of several novel materials using the computer simulation technique. The present study describes the complete description of the molecular vibrations and electronic features of the title compound by this technique. 7-(4-nitrophenyl)benzo[6, 7]chromeno[3,2-e]pyrido[1,2-a]pyrimidin-6(7H)-one was prepared by the multicomponent reaction of 2H-pyrido[1,2-a]pyrimidine-2,4(3H)-dione, 2-naphthol and p-nitrobenzaldehyde. The structure of the compound was confirmed by UV, IR, NMR (1H, 13C), and mass spectroscopic studies. The compound was further subjected to quantum chemical calculations at the level of Hartree-Fock (HF) method using Lan2DZ basis set to compute polarizability, hyperpolarizabilities, AIM approach, Natural bond orbital analysis, complete vibrational assignments, Mulliken charges, spectral analysis and HOMO-LUMO energies.

Cl–···H–N Interaction Assisted Addition of Sulfonamides to Enol Ethers: Synthesis of 2-Deoxy and 2,6-Dideoxy Sulfonamido Glycosides

AbstractThe strained/frustrated electrostatic interactions between the ion pair of TTBPy+X– increases the reactivity in both the ions, resulting in the activation of a third molecule like sulfonamides (aromatic/­aliphatic) via hydrogen bonding. This intriguing weak-interactions-based reactivity has been utilized to develop an organocatalytic synthesis of 2-deoxy-sulfonamido-glycosides from glycals. The sulfonamidoglycosylation of glycals using a catalytic amount of 2,4,6-tri-tert-butylpyridinium salts proceeded stereoselectively to provide N-glycosides in good to high yields. This process was demonstrated with l-rhamnal and d-galactal. Besides, IR spectroscopic studies explain that the hindered protonated pyridine cannot behave as a cationic Brønsted acid as is generally perceived.

Unexpected formation of two different coordination polymers from the reaction of Zn(HCOO)2·2H2O with 1,2-bis(4-pyridyl)ethylene

Zn(HCOO)2·2H2O reacts with 1,2-bis(4-pyridyl)ethylene (bpe) yielding two new coordination polymers [Zn4(HCOO)8(bpe)2(H2O)]∞ (1) and [Zn2(HCOO)4(bpe)]∞ (2) which were structurally characterized by IR spectroscopy and single crystal X-ray diffraction study. The hydrate species 1 is a 3D polymer where four different zinc sites are present, the first of them, four-coordinated, being linked by three bridging formate and one bridging bpe, the second six-coordinated, with a ZnNO5 coordination environment, almost regular, due to three bridging formate groups and one monodentate formate, one water molecule and one bpe. The third zinc center in 1 is always tetrahedral with three bridging formate ligands and one bridging bpe whereas the fourth Zn site is coordinated by five bridging formate ligands and one bridging bpe. The anhydrous species 2, obtained upon recrystallisation from DMF at 278 K is a zig-zag 1D polymer with a tetrahedral N2O2 zinc coordination environment due to two monodentate formate groups and two bridging bpe. Thermal analysis of 1 show a weight loss due to water elimination followed by formate and bpe decomposition, whereas in the case of 2 only a decomposition between 210 and 240 °C was observed.

Synthesis and Emergent Photophysical Properties of Diketopyrrolopyrrole-Based Supramolecular Self-Assembly.

Diketopyrrolopyrrole (DPP)-based molecular semiconductors exhibit intriguing optical and charge transport properties. Herein, we rationally design a series of electronically identical but structurally distinct Hamilton receptor (HR)-based supramolecular assembly of DPP. The HR endows supramolecular assemblies via hydrogen bonding with enhanced structural ordering and excitonic couplings. The mechanism of supramolecular self-assembly was probed by diffusion ordered spectroscopy (DOSY) nuclear magnetic resonance (NMR) and solid-state IR spectroscopy studies. We investigated the morphology of self-assembly, photophysical and electrochemical properties and compared them with the identical DPP molecular structures without HRs. The microstructure of self-assembly was probed with atomic force microscopy in thin films. Subsequently, the influence of solid-state packing was studied by single-crystal X-ray diffraction. The single-crystal structure of HR-TDPP-C20 reveals slipped stack arrangements between the two neighboring chromophores with π–π stacking distance and slip angle of 3.55 Å and 35.4°, respectively. Notably, the slight torsional angle of 1° between thiophene and lactam rings and small π–π stacking distance suggest a significant intermolecular coupling between thiophene (D) and lactam (A) rings. This intramolecular coupling between two π–π chromophore stacks manifests in their optical properties. In this manuscript, we report rational design and synthesis of supramolecular self-assembly of DPP with a collection of compelling structural and optical properties.

Metal complexes of azo compounds: Synthesis, characterization, molecular modeling and degradation study by gamma radiation

The Fe(III), Co(II) and Cu(II) complexes of three azo compounds namely, 2-(phenylazo)-1-naphtllol (Sudan I) (HL1) a, 4-(phenylazo)-1-naphthol (HL2) b and 2,4-bis(phenylazo)-1-naphthol (HL3) c were prepared and characterized on the basis of their elemental analysis, molar conductance, UV–VIS and FT IR spectroscopic studies. Besides, density functional theory (DFT) computations were conducted to study structures and energetics of the ligands and their complexes. Molecular Electrostatic Potential was also calculated by the DFT method and predicts the most reactive part in the molecule. The isolated complexes are found to have the formulas [Cu(L1)2] a1, [Co(L1)2] a2, [Fe(L1)3] a3, [Cu(HL2)2Cl2].H2O b1, [Co(HL2)(NO3)2].H2O b2, [Fe(HL2)Cl3].H2O b3, [Cu(HL3)Cl2].H2O c1, [Co(HL3)(NO3)2].H2O c2 and [Fe(HL3)Cl3].H2O c3. The IR result showed that the ligand a was chelated with the metal ions in a monobasic bidentate manner, with NO donor sites of the azo nitrogen and the deprotonated phenolic oxygen. While the ligand c was chelated with the metal centers in a neutral bidentate manner and the ligand b was bound with the metal ions as a neutral monodentate donor by azo nitrogen atom. The molecular docking results indicated that the ligands HL1a, HL2b and HL3c may possess significant anti-inflammatory activity. Gamma irradiation of variable concentrations of the ligand solutions HL1a and its complexes [Cu(L1)2] a1, [Co(L1)2] a2 and [Fe(L1)3] a3 was investigated. The color bleaching of the dyes solutions was increase gradually with increasing absorbed dose in the dose range of 3, 5 and 10 kGy.