IR Spectroscopic Methods Research Articles

Green Synthesis and Characterisation of Ag2O and Ag2O-Ce3+ nanoparticles

Nanoparticles are usually defined as particles of matter that are between 1 and 100 nm in diameter. Silver oxide nanoparticles have a wide range of applications and they are usually used as sensors, catalysts, optical probes, and in the medicinal field. Nanoparticles of undoped and cerium-doped silver oxide nanoparticles are synthesized using the combustion method while using the latex of jackfruit as fuel (Green synthesis). Crystalline properties and optical properties of the samples were determined using the X-ray diffraction method, UV-visible spectroscopy method, IR spectroscopy method, Scanning electron microscope, and particle analysis. Average particle size was determined by X-ray diffraction method, functional groups were determined by using IR spectroscopy, and the concentration of functional groups was determined by UV-visible spectroscopy. This characterization could be used to study the difference between undoped silver oxide nanoparticles and cerium-doped silver oxide nanoparticles.

Polydimethylsiloxanes with Grafted Dibenzoylmethanatoboron Difluoride: Synthesis and Properties.

A method for the preparation of polydimethylsiloxanes with grafted methoxy-substituted dibenzoylmethanatoboron difluoride has been described. The structures of prepared polymers were confirmed using NMR, IR spectroscopy and gel permeation chromatography methods. Their thermal properties were investigated using thermal gravimetric analysis, differential scanning calorimetry and thermomechanical analysis. The prepared polymers had good thermal (Td5% up to 393 °C) and thermo-oxidative (Td5% = 413 °C) stability. The polymers started to transit in a viscous flow state at about 40 °C (for 3 a) and at about 20 °C (for 3 b). The viscoelastic characteristics of prepared polymers were determined in the sinusoidal oscillating vibrations mode. It was shown that the studied polymers at low frequencies at room temperature are viscoelastic fluids (G′ < G″). Increasing the frequency led to inversion (crossover) of dependences G′ and G″, which indicated the transition of polymers from viscous to elastomeric behavior characteristics, and the beginning of the formation of a physical network. Optical properties were studied using electron absorption, steady-state and time-resolved fluorescence spectroscopy. It was shown that intramolecular H-dimers exist in the ground state. The polymers studied had a bright fluorescence in the solution and in the solid state, consisting of bands of monomer and excimer emission. Thermally-activated delayed fluorescence was observed in the solution and the solid state. The prepared polymers possess intriguing properties that make them useful as optical materials, sensors or imaging agents.

Studying the Structure of a Cement Composite Modified by Hydrothermal SiO2 Nanoparticles and MCNTs by the IR-Spectroscopy Method

Studying the Structure of a Cement Composite Modified by Hydrothermal SiO2 Nanoparticles and MCNTs by the IR-Spectroscopy Method

New anti-inflammatory and non-cytotoxic metabolites of methylstenbolone obtained by microbial transformation

A synthetic anabolic–androgenic steroid, methylstenbolone (1), was structurally transformed into a series of nine analogues, 2,17α-dimethyl-7α,17β-dihydroxy-5α-androst-1-en-3-one (2), 2,17α-dimethyl-15β,17β-dihydroxy-5α-androst-1-en-3-one (3), 2,17α-dimethyl-6α,9α,17β-trihydroxy-5α-androst-1-en-3-one (4), 2-methyl-17β-hydroxy-17α-(hydroxymethyl)-5α-androst-1-en-3-one (5), 2-methyl-11β,17β-dihydroxy-17α-(hydroxymethyl)-5α-androst-1-en-3-one (6), 2-methyl-17β-hydroxy-17α-(hydroxymethyl)-5α-androst-1-en-3,6-dione (7), 2-methyl-17β-hydroxy-17α-(hydroxymethyl)-5β-androst-1-en-3,6-dione (8), 2,17α-dimethyl-7β,17β-dihydroxy-5α-androst-1-en-3-one (9), and 2,17α-dimethyl-12β,17β-hydroxy-5α-androst-1-en-3,7-dione (10) by fungal cell suspension cultures, Macrophomina phaseolina and Cunninghamella blakesleeana for the first time. Among those, compounds 2–4 and 6–10 were identified as new. Herein, spectral data of metabolite 5 was reported for the first time. Their structures were elucidated by NMR, MS, UV, and IR spectroscopic methods. Substrate 1 (IC50 10.1 ± 0.3 µg/mL) was identified as a potent anti-inflammatory agent against nitric oxide (NO) production. Its transformed products 3 (IC50 as 27.8 ± 1.1 µg/mL) and 9 (26.9 ± 0.4 µg/mL) displayed good inhibition. Compounds 2 (IC50 = 45.9 ± 0.8 µg/mL) and 6 (IC50 = 36.6 ± 1.2 µg/mL) were also active moderately against NO production, in comparison to standard LNMMA (IC50 = 24.2 ± 0.8 µg/mL). Cytotoxicity assay showed 1 was active to cancer cell line MCF7 (IC50 = 12.26 ± 0.35 µg/mL), compared to the standard Doxorubicin having IC50 as 1.25 ± 0.11 µg/mL. However, it is also toxic to human normal cell line (BJ) with IC50 as 8.69 ± 0.02 µg/mL. More importantly, all transformed products are non-cytotoxic on BJ. Therefore, biotransformation can be an efficient approach to reduce the toxicity of methylstenbolone.

Study into the hydrolysis of polyhexamethylene guanidine hydrochloride

The development of new preparations for managing skin lesions is a task requiring a complex research approach. Thus, one promising direction consists in the creation of new bases for wound-healing drugs for external application. Chemical compounds that can be used as such bases include polymeric hydrogels, representing spatially cross-linked macromolecules that swell in a solvent. This property provides an opportunity to load hydrogels with drugs of both synthetic and herbal origin. A search for a gel-forming polymer acting not only as a drug carrier, but also as a healing agent presents a relevant research task. In a previous work, the authors obtained polyhexamethylene guanidine hydrochloride hydrogels by crosslinking terminal amino groups with formaldehyde. The conducted studies of the wound-healing capacity of the obtained hydrogels and compositions on their basis confirmed their comparability with such widely-used agents, as levomecol, bepanthene, etc. In addition, the obtained compositions were found to exhibit their own activity. Therefore, hydrogels based on polyhexamethylene guanidine hydrochloride can be used as a promising platform for drug design. In this work, the destruction products released during hydrolysis of the hydrogel under study were investigated. IR and UV spectroscopy methods were applied to evaluate the concentration of hydrogel destruction products over time. A mechanism of hydrogel destruction yielding the initial polyhexamethylene guanidine hydrochloride and formaldehyde in a gem-diol form is proposed.

Selective Destruction of Soluble Polyurethaneimide as Novel Approach for Fabrication of Insoluble Polyimide Films.

Polymeric coatings and membranes with extended stability toward a wide range of organic solvents are practical for application in harsh environments; on the other hand, such stability makes their processing quite difficult. In this work, we propose a novel method for the fabrication of films based on non-soluble polymers. The film is made from the solution of block copolymer containing both soluble and insoluble blocks followed by selective decomposition of soluble blocks. To prove this concept, we synthesized copolymer [(imide)n-(polyurethane)]m, in which the imide blocks were combined with polyurethane blocks based on polycaprolactone. By selective hydrolysis of urethane blocks in the presence of acid, it was possible to obtain the insoluble polyimide film for the first time. It was shown that the combination of thermal and acid treatment allowed almost complete removal of urethane blocks from the initial copolymer chains. IR spectroscopy, TGA, DSC and DMA methods were used to study the evaluation of the structure and properties of polymeric material as a result of thermal oxidation and hydrolysis by acid. It was shown that the polymeric films obtained by controlled decomposition were not soluble in aprotic solvent, such as dimethylformamide, n-methylpyrrolidone and dimethyl sulfoxide, and showed very close similarity to the homopolymer consisting of the same imide monomer, poly-(4,4′oxydiphenylene)pyromellitimide, confirming the feasibility of the proposed concept and its perspectives for fabrication of organic solvent-resistant membranes.

SYNTHESIS AND RESEARCH OF THE NEW POLYURETHANE UREAS THAT CONTAINE 1,8-DIAMINO-3,6-DIOXAOCTANE AS EXTENDER OF MACROCHAINE

A number of polyurethane ureas (PUUs) containing 1,8-diamino-3,6-dioxooctane (DOODA) in their structure as a macrochain extender were synthesized with a different molar ratio of 4,4'-diaminodiphenylmethane (DADPh) to DOODA as 30:70; 50:50; 70:30. Synthesized polymers are elastic, transparent films with a thickness of 0.3 mm. According to the results of physical and mechanical tests, the tensile strength of the synthesized PUUs is in the range of (0.7-2.0) MPa, and the relative elongation at break is in the range of (73.9-584.7)%. The best physical and mechanical characteristics have the polymer synthesized with a ratio of DADPh:DOODA as 0.3:0.7 with a tensile strength of 2.0 MPa and a relative elongation of 522%. The formation of PUUs was confirmed by the method of IR-spectroscopy. Thermophysical properties synthesized by DSC, TGA methods were studied. It was established that the glass transition temperature (Tg) in a number of synthesized PUUs with DOODA is in the range from (minus) 18.50 °C to (minus) 34.52 °C. An increase in the content of 1,8-Diamino-3,6-dioxaoctane in the PUUs structure leads to a decrease in Tg and a slight increase in ΔCp during the second heating. According to the TGA, the heat resistance characteristics of the synthesized PUUs depend on the content of DOODA. When entering the structure of the PUUs DOODA, a decrease of the temperature of the start of the decomposition (T0) and the temperature of the maximal speed of the decomposition (Tmax), which is non-linear nature. T0 of the synthesized PUUs is in the range (275.16-289.8)°C and is accompanied by a slight loss of mass (0.007-0.093)%. Synthesized PUUs are heat-resistant to a temperature of 275.16 °C, which makes it possible to carry out dry sterilization of samples without changing their characteristics. Synthesized PUUs are promising materials for the immobilization of medicinal substances for further use in medicine.

Distinguishing Anionic Species That Are Intercalated in Layered Double Hydroxides from Those Bound to Their Surface: A Comparative IR Study

Guest molecules in layered double hydroxides (LDHs) may be located both on the surface and in the interlayer gallery. In this work, a comparative study of various IR spectroscopic methods coupled with X-ray diffraction (XRD) is presented, which makes it possible to distinguish between the two possibilities. During the experimental work, first, CaAl-LDHs intercalated with nitrate/carbonate ions were transformed to d-gluconate- and benzoate-containing solids. Depending on the initial interlayer ion, the organic molecules may end up between the layers and/or on the surface of the LDH. The IR spectra of the specimens were recorded by using four different techniques, which are different in their penetration depth (photoacoustic spectroscopy (PAS), attenuated total reflectance (ATR), diffuse reflectance IR spectroscopy (DRIFTS), and wide angle diffuse reflectance (WA-DRIFTS)). By comparing the spectra obtained, the anionic species that are surface adsorbed to LDHs were proven to be distinguishable from those intercalated in the interlayer gallery. PAS spectra are shown to provide information about interlamellar and bulk compounds. The screening of the surface species could be performed using the WA-DRIFTS technique, while ATR and DRIFTS are capable of detecting both the surface and the bulk anions residing in the top few layers.

Aging analysis of textured water-repellent coatings under ultraviolet radiation and water

The object of research in this work is a coating based on styrene butyl methacrylate binder and calcium carbonate modified with stearic acid. The existing problem is that the stability of the properties of superhydrophobic coatings when interacting with environmental factors – ultraviolet radiation, water vapor or dynamic action of water is limited. Establishing the relationship between the change in the chemical composition and texture of structured water-repellent surfaces under the influence of environmental factors is an essential step towards creating a stability model for such coatings. The work carried out is aimed at establishing the nature of the loss of water repellency of textured organo-mineral coatings under exposure to ultraviolet radiation in the UV-A range and water. UV resistance testing was performed in accordance with ASTM D 4329. The surface texture was examined using electron microscopy. The study of the change in chemical composition was performed using the IR spectroscopy method. As a result, it was shown that, under UV radiation, the most vulnerable component of organo-mineral coatings consisting of styrene-butyl methacrylate polymer and calcium carbonate modified with stearic acid is the polymer matrix, the oxidation of which leads to surface hydrophilization. The action of water in both static and dynamic modes leads to the loss of the upper layer of microparticles which forms the structure. It was found that in the surface layer of the polymer, upon irradiation with ultraviolet, the formation of polar carboxyl groups occurs at the initial stages of irradiation, which is accompanied by noticeable hydrophilization. Based on the obtained results, one of the ways to increase the resistance of additive water-repellent coatings to environmental factors can be the use of polymers that are more resistant to UV radiation. An alternative way is to use the optimization of the interfacial contact, which will ensure the slowing down of the loss of texture elements in the water environment.

Thermal transformations of bismuth (III) tartrates

The processes of oxidative thermolysis of bismuth tartrates [Bi(NO3)(C4H4O6)]·3H2O and BiC4H3O6·H2O precipitated from bismuth nitrate solutions was studied by the methods of X-ray diffraction, thermal analysis, IR spectroscopy and chemical analysis. The staging of thermal transformation processes was determined. Morphological studies of initial precursors and the final products of their thermal transformations were carried out. The expediency of obtaining fine-crystal powders of the tetragonal bismuth oxide modification β-Bi2O3 with uniform sized particles by oxidative thermolysis of BiC4H3O6∙H2O was shown.

Synthesis and study of properties of polyazomethines based on carbamide and aromatic dialdehydes

New polyazomethines were synthesized by low-temperature polycondensation of urea and aromatic dialdehydes. The optimal conditions for the process of obtaining polyazomethines have been determined. The structure of the obtained polyazomethines was determined by IR spectroscopy and elemental analysis methods. The synthesized polyazomethines are partially crystalline, highly soluble and fusible materials. It was established that the synthesized polyazomethines have an increased thermal stability, which depends on the structure of the initial aromatic dialdehyde. It was found that polyazomethine based on carbamide and 4,4’-diform yldiphenoxyterephthalate melts, exhibiting liquid crystalline properties. It was shown that the obtained polyazomethines are fiber and film-forming materials.

Investigation of the properties and technologies of epoxy asphalt concrete preparation with the addition of fiber from fly ash of thermal power plants

Slowly curingepoxy asphalt concrete has high physical properties and low sensitivity to temperature changes, which allows ituse as a road surface on a rigid base. However, a negative property of epoxy asphalt concrete is the ability to gain strength over a long period of operation. The epoxy-asphalt concrete really gains its initial strength in a relatively short time, but the feature of classic epoxy asphalt concrete is their subsequent set of strength, which in winter at negative temperatures can lead to the destruction of the matrix during movement and negatively affect the performance of both the road and the cars. To solve this problem, optimum types of modifying additives for changing bitumen properties and their possible use in epoxy asphalt concrete were considered. Changes in the structure of bitumen with fibre were investigated by the IR spectroscopy method; the dependence of bitumen penetration on temperature, as well as the mide and the amount of additives, influencing the bitumen plasticity were studied. Adhesive characteristics of bitumen at different temperatures were also determined. A directed change in the properties of bitumen in asphalt concrete is the most effective way to increase the performance and durability of road surfaces.

Self-assembling cobalt(II) porphyrin - fullero [60]pyrrolidine triads. Synthesis and spectral properties in the ground and excited state

Meso‑4-Trifluoromethylphenyl substituted cobalt(II)porphin, CoT(CF3P)P, and its coordination 1: 2 complex (triad) with 1-N-methyl-2-(pyridin-4-yl)-3,4-fullero [60]pyrrolidine, (PyC60)2CoT(CF3P)P, were firstly synthesized and the properties of their molecular solutions were studied. The chemical structure of CoT(CF3P)P and triad was fully confirmed by the UV–vis, IR and 1H NMR spectroscopy and mass spectrometry methods. The triad formation mechanism as the two-step equilibrium characterized by equilibrium constant K1 (5.89 ± 1.50) × 104 M−1 and K2 (7.40 ± 1.66) × 105 M−1 was revealed. Using femtosecond pump-probe spectroscopy measurements, the photoinduced electron transfer in the synthesized triad was described. The excited state lifetime of the precursors, CoTPP, CoT(CF3P)P and the charge separated state lifetime of (PyC60)2CoT(CF3P)P compared with unsubstituted (PyC60)2CoTPP were determined. It was established that the CF3 groups in the porphyrin periphery slightly change the CoTPP/CoT(CF3P)P excited state lifetime and the electron transfer rate constant in the correspondent triads.

Investigations of the Influence of Nano-Admixtures on Early Hydration and Selected Properties of Calcium Aluminate Cement Paste.

In this work, the hydration of calcium aluminate cement (CAC, Al2O3 ≥ 70%) paste with nano admixtures (0, 0.05%, 0.1% and 0.2%) of nano-silica (NS) and carbon nano-cones (NC) when W/CAC = 0.35 was investigated. The methods of calorimetry, thermal analysis, X-ray diffraction (XRD), IR spectroscopy, and scanning electron microscopy (SEM) were used. In addition, the physical and mechanical properties of hardened cement pastes were determined after 3 days of hardening. NS was found to shorten the induction period of CAC hydration and accelerate the time of the secondary heat release effect, especially in the specimens with the highest NS content. The incorporation of NC (up to 0.2%) slows down the hydration process. After 3 days of hydration, the formation of hydration products, such as C2AH8, CAH10, C3AH6 and AH3 hydrates, was observed in CAC pastes, however, the quantitative compositions were different depending on the kind of nano admixture and its amount. SEM results obtained show differences in the effect of NS and NC on the formation of the structure of cement paste during its hardening. Significant changes in CAC paste microstructure were caused by the addition of NS and NC admixtures. Compressive strength was found to increase with the increase of NS and the optimal NS content was found to be 0.10 wt.%. The modification of the cement paste with an NS admixture results in a higher amount of hydrates, lower total porosity, and a higher amount of the smallest pores in the microstructure of the sample. NS and NC influence the hydration behaviour of CAC in different ways, which causes characteristic changes in the microstructure and properties of hardened samples.

Rapid Quantitation of Adulterants in Premium Marine Oils by Raman and IR Spectroscopy: A Data Fusion Approach.

This study uses Raman and IR spectroscopic methods for the detection of adulterants in marine oils. These techniques are used individually and as low-level fused spectroscopic data sets. We used cod liver oil (CLO) and salmon oil (SO) as the valuable marine oils mixed with common adulterants, such as palm oil (PO), omega-3 concentrates in ethyl ester form (O3C), and generic fish oil (FO). We showed that support vector machines (SVM) can classify the adulterant present in both CLO and SO samples. Furthermore, partial least squares regression (PLSR) may be used to quantify the adulterants present. For example, PO and O3C adulterated samples could be detected with a RMSEP value less than 4%. However, the FO adulterant was more difficult to quantify because of its compositional similarity to CLO and SO. In general, data fusion improved the RMSEP for PO and O3C detection. This shows that Raman and IR spectroscopy can be used in concert to provide a useful analytical test for common adulterants in CLO and SO.

Review of phytochemical and some biological activity of &lt;i&gt;Leptopyrum fumarioides&lt;/i&gt; (L.) Reichenb.

The phytochemical study of Leptopyrum fumarioides started in 2011 and since then 14 volatile compounds have been identified by GC-MS. 7 flavonoids and 4 alkaloids have been isolated and 2 of them have been recognized as new natural compounds. The structures of the natural products have been determined and ascertained by MS, as well as IR, 1D NMR and 2D NMR spectroscopic methods. The antioxidant, antimutagenic, antiproliferative, hepatoprotective, immunomodulatory, and anticancer activity of Leptopyrum fumarioides extracts and some isolated pure compounds were examined. The new alkaloids leptopyrine (3) and leptofumarine (4) were identified. Leptopyrine (3) is a new type of dimer alkaloid of benzylisoquinoline and simple isoquinoline with imine nitrogen. Leptofumarine (4) is the first example of aporphine and benzylisoquinoline alkaloid with two ether bridges which have head-to-head and tail-to-tail coupling. This review clearly shows that the phytochemical study of plant species is just beginning and requires more detailed and comprehensive study.

SYNTHESIS AND STUDY OF PEROXOSOLVATES OF SULFATES OF ELEMENTS OF THE SECOND GROUP

Continuing previous similar research, the ability of sulfates of elements of the second group – magnesium, calcium and zinc, to produce peroxosolvates, the methods for their preparation, as well as their properties have been studied. It has been shown that these sulfates are able to produce peroxosolvates with different molar ratios: MgSO4‧H2O2, CaSO4‧0.04H2O2, ZnSO4‧0.05H2O2. The authenticity, composition and nature of the obtained peroxosolvates have been elucidated by the methods of X-ray and IR spectroscopy. Quantitative data on the decomposition of hydrogen peroxide in dry peroxosolvates of magnesium and zinc sulfates were calculated.

Material composition and processing technology for quartz-kaolin rocks of the Khodzhakul deposit

This paper describes the material composition and processing technology for quartz sand isolated from the quartz-kaolin rock of the Khodzhakul deposit group located in the Republic of Uzbekistan. The chemical, mineral, and grain-size compositions have been studied for the quartz-kaolin rocks and a processing technology has been developed for the resulting sand. Material composition of the sand was established by X-ray phase analysis after calcination at 900&ndash;1350 &deg;C, as well as using chemical and IR spectroscopic analysis methods. The effect of dilution of the kaolin suspension isolated by decantation has been studied. According to the research results, the best processing values are observed when using Uniflok flocculant and sodium phosphate solution as the dispersant at a ratio of 1.0 : 1.0. An 8-EVSV-16/100 electromagnetic separator was used to study the additional processing of quartz sand in an electromagnetic field. Electromagnetic treatment of the quartz product allows removing up to 78.6 % of iron impurities. Based on the results obtained, a process flow was proposed for the extraction and separation of quartz sand from the original rocks and its additional processing. This process includes hydraulic extraction of the raw materials, primary classification in hydrocyclones, quartz flocculation and washing of kaolin slimes, drying of the quartz product, and dry electromagnetic separation using a roller separator. The process includes process water circulation. The quartz sand obtained using this technology contains 97.8 wt% of SiO2, less than 0.05 wt% of Fe2O3, and 1.20 wt% of Al2O3. The quartz product with the specified composition may be used for the manufacture of colorless transparent glass.

Mercury(II)-complex with 5-methyl-1,3,4-thiadiazole-2-thiol: kinetic studies of hydrogen storage

Mixed ligand mercury(II) complexes of 2-meracpto-5-methyl-1,3,4-thiazdiazole (HmtzS) and phosphines or diamines having the general formulae [Hg(mtsZ)2(diphos)] {diphos = 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,4-bis(diphenylphosphino)butane (dppe), 1,1′-bis(diphenylphosphino)ferrocene (dppf)}, [Hg(mtsZ)2(PPh3)2] and [Hg(mtsZ)2(diamine)] {diamine = bipyridyl (Bipy) or 1,10-phenthroline (Phen), were successfully synthesized by simple mixing method. The complexes were characterized by elemental analysis, molar conductivity, IR and NMR (1H, 13C and 31P) spectroscopic methods. The mtzS− ligand was coordinated through the sulfur atom of thiol group, whereas the diphosphine or diamine ligands bonded as bidentate chelating ligand to afford tetrahedral environment around the Hg(II) ions. Moreover, the complex [Hg(mtsZ)2] was used in order to study its ability to store hydrogen. The results of hydrogen isotherm at different temperatures prove that [Hg(mtsZ)2] was able to store 0.8 wt% at a pressure of 80 bar 77 K. Furthermore, the kinetic study of hydrogen storage was studied and the kinetic study was carried out using the Langmuir. Moreover, the adsorption kinetic results revealed that hydrogen storage in [Hg(mtsZ)2] follow the pseudo-second-order model with coefficient regression equal to 0.99.

The study of synthesis of asymmetric heptyloctyl ester of adipinic acid via IR spectroscopy

The reaction of the synthesis of asymmetric compound ester of adipinic acid via IR spectroscopy method is studied. To research the process of obtaining mono- and diesters, the samples were taken each hour and their IR specters made. The process was observed by the decrease of the optic density of carbonyl groups of acid and by the increase of optical density of forming carbonyl groups of compound ester with additional reaction time. The interpretation of the main absorption bands in the specters of studied compounds is provided. Moreover, the physical-chemical and viscous-temperature characteristics of obtained compound were studied. Thus, analyzing IR specters and the data of changing optical density of С=О connection both as an acid and compound ester due to the synthesis time in studied samples, we can make a conclusion that the duration of reaction of the synthesis of mono- and diesters comprises 3 and 4 hours correspondingly.