FTIR Spectroscopy Research Articles

Prediction of pea composites physicochemical traits and techno-functionalities using FTIR spectroscopy

This study aimed to test the feasibility of applying FTIR spectroscopy in order to create models that can predict quality attributes of pea composites. FTIR spectroscopy data were captured from three types of samples namely pea flour (PF), pea concentrate (PC) and pea isolate (PI). The FTIR spectral data along with partial least square (PLS) regression were used to build predictive models for physicochemical (moisture content, protein content, starch content, fiber content, bulk density, color), structural (particle size distribution, surface openings, fractal dimension), thermal (denaturization temperature, enthalpy), and techno-functional traits (water holding capacity, foaming capacity, foam stability, solubility, least gelation concentration) of pea composites. The FTIR spectra were subjected to different spectral pretreatment where 2nd derivative pretreatment provided the most suitable model for prediction of the studied parameters. The values of pea composite's traits determined through non-destructive FTIR spectroscopy coupled with partial least squares regression analysis, were very closed to the values obtained by the destructive standard methods. Performance (correlation, root mean square error) of the developed models were attribute-specific. For most of the studied attributes, correlation coefficient (r) were higher than 0.82 in the calibration step, and 0.71 in the prediction step. Pea composites have shown distinctive functionalities both as individual entity and in formulating meat analogs. Overall, it could be recommended that FTIR spectroscopy could be used in pea processing industry for developing robust models, to non-destructively assess the pea composite's properties and techno-functionalities.

Temperature effects on ribbon characteristics in soft gelatin capsule manufacture

In the manufacture of soft gelatin capsules using a rotary-die encapsulation machine, the formation of ribbons at the cooling drums and their subsequent mechanical performance are key attributes for a smooth machinability. In this paper we present the results of a comprehensive investigation of the intricate impact of the cooling drum temperature in the range between 5 and 25 °C on the mechanical and the microstructural properties of a highly concentrated gelatin formulation (40% w/w) typically used in soft capsule manufacture.The study demonstrates that the temperature at the cooling drums strongly affects the gelation kinetics, the gel elasticity and the tensile strength of the ribbons. The temperature correlates linearly with the storage modulus G′ under low shear deformation, i.e. the lower the temperature of the gel, the higher the gel elasticity. A reverse linear relationship was found for the temperature-dependent ultimate tensile strength (UTS) of the gelatin ribbons, i.e. a higher drum temperature leads to a higher UTS. This inverse effect of the ageing temperature on G′ and UTS can be explained by temperature-induced microstructural differences within the gel network, as indicated by FTIR spectroscopy and Differential Scanning Calorimetry (DSC) measurements. Lower ageing temperatures result in a higher number of triple helical junction zones with fewer and/or weaker hydrogen bonds, which translate into a higher gel elasticity under low shear deformation, but a lower resilience of the ribbons against rupture in tensile testing. At higher temperatures, fewer but longer and/or more thermostable triple helical links in the gel network enhance the stability of the ribbons against tensile stress.In summary, the results clearly reveal that a detailed understanding of the complex relationship between the drum temperature, the gel network structure and the mechanical properties of gelatin ribbons is essential for process optimization.

Functionalized Magnetic Fe3O4 Nanoparticles for Targeted Methotrexate Delivery in Ovarian Cancer Therapy.

Magnetic Fe3O4 nanoparticles (MNPs) functionalized with (3-aminopropylo)trietoksysilan (APTES) or N-carboxymethylchitosan (CMC) were proposed as nanocarriers of methotrexate (MTX) to target ovarian cancer cell lines. The successful functionalization of the obtained nanostructures was confirmed by FT-IR spectroscopy. The nanoparticles were characterized by transmission electron spectroscopy (TEM) and dynamic light scattering (DLS) techniques. Their potential zeta, magnetization, and hyperthermic properties were also explored. MTX was conjugated with the nanocarriers by ionic bonds or by amide bonds. The drug release kinetics were examined at different pH and temperatures. The MTT assay showed no toxicity of the MNPs[APTES] and MNPs[CMC]. Finally, the cytotoxicity of the nanostructures with MTX attached towards the ovarian cancer cells was measured. The sensitivity and resistance to methotrexate was determined in simplistic 2D and spheroid 3D conditions. The cytotoxicity tests of the tested nanostructures showed similar values for inhibiting the proliferation of ovarian cancer cells as methotrexate in its free form. Conjugating MTX with nanoparticles allows the drug to be directed to the target site using an external magnetic field, reducing overall toxicity. Combining this approach with hyperthermia could enhance the therapeutic effect in vivo compared to free MTX, though further research on advanced 3D models is needed.

Physicochemical and bioactive characterization of pink guava pulp microcapsules prepared by freeze-drying using coffee mucilage as a wall material

This study investigated the potential of coffee mucilage (CM), a readily available coffee industry byproduct, as a wall material for the microencapsulation of pink guava pulp via freeze-drying (FD). Microcapsules with varying wall compositions incorporating powdered coffee mucilage, maltodextrin (MD), or a combination of both (FD-CM/MD) were developed and characterized using techniques such as FT-IR spectroscopy, SEM, TGA/DSC, and zeta potential analysis. The retention of bioactive compounds was assessed using total phenolic content, antioxidant capacity and carotenoid analyses. Results revealed that the incorporation of powdered coffee mucilage significantly influenced the physicochemical properties of the microcapsules, resulting in larger particle sizes and less rough surface morphologies compared with maltodextrin-based formulations. Notably, FD-CM microcapsules exhibited a thermal stability (Tg ≈ 50 °C) and retention total polyphenols of 30.19 ± 5.26 mg GAE/g dry weight (DW) and carotenoids of 5.50 ± 0.29 mg β-carotene/100 g DW, which can be attributed to the protective effects and inherent antioxidant capacity of 91.85 ± 9.93 μmol Trolox Equivalents/g DW in the coffee mucilage matrix. While influencing the color attributes, all microcapsule formulations retained a commercially appealing (hab = 79.80 ± 0.06) red-yellow hue. This study demonstrated the potential of powdered coffee mucilage as a sustainable and effective encapsulating wall material for enhancing the stability and bioavailability of bioactive compounds in food products.

Structural, optical, and morphological properties of PVC-BaTiO3 nanocomposite films

This work aims to fabricate barium titanate (BaTiO3) nanoparticles and study the effect of adding different contents of BaTiO3 nanoparticles on the structural, optical, and electrical properties of PVC polymer matrices. The PVC/BaTiO3 nanocomposite films were characterized by X-ray diffraction, FT-IR spectroscopy, and SEM. In addition, dielectric properties were studied within the frequency range of 0.1 KHz–6 MHZ. The XRD analysis reveals an amorphous nature of pure PVC with two characteristic peaks at 2θ = 17.09° and 2θ = 23.25°, and it reveals that BaTiO3 has sharp and narrow peaks. In PVC/BaTiO3 nanocomposite films, all XRD peaks of BaTiO3 appeared in all the samples with an increase in the average particle size from ∼46 nm to 55 nm. There is no shift of IR position in PVC bands, but the decreased intensity of some bands suggests complexation between PVC and BaTiO3. The UV–visible absorption spectrum of pure PVC has a band at λ = 278 nm. This band was shifted to 252 nm after adding BaTiO3 content. UV–visible transmission spectra demonstrate a decrease in the transmittance as an increase of BaTiO3 content from 89.23 % for pure PVC to 5.23 % for 0.1 wt% of BaTiO3. The values of the optical bandgap decrease with increasing BaTiO3 contents due to defect formation in PVC matrices. The optical parameters of the prepared nanocomposite films were also enhanced. The AC conductivity shows an increase with both frequency and BaTiO3 concentration, leading to enhanced movement of charge carriers and relaxation of interface polarization.

Non-stoichiometric protic ionic liquids for efficient carbon dioxide capture and subsequent conversion under mild conditions

Protic ionic liquids (PILs) have emerged as innovative solvents with significant potential for CO2 capture and transformation, presenting a sustainable alternative to conventional methods which often involve energy-intensive processes or environmentally detrimental chemicals. Herein, a novel strategy for CO2 capture and conversion at mild conditions using non-stoichiometric protic ionic liquids (NPILs) was demonstrated for the first time. These NPILs, employed as sorbents, solvents, and catalysts, were composed of imidazole (Im) and 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) in various ratios. Correlations between the mole ratio of DBU/Im and physicochemical properties such as viscosity, conductivity, thermal stability, and the distribution of neutral and ionic species were systematically investigated. Effects of the absorption temperature and CO2 partial pressure on the absorption capacity were also studied. Different absorption mechanisms, including carbonate and carbamate pathways, were analyzed using FT-IR and NMR spectroscopy. Moreover, the fixed CO2 could be catalytically converted to quinazoline-2,4(1H,3H)-diones under exceptionally mild reaction conditions (1 atm, 50 °C, metal-free process). A plausible reaction mechanism involving simultaneous CO2 activation and substrate activation for the transformation of CO2 into quinazoline-2,4(1H,3H)-diones was verified through NMR spectra. It is believed that the new insights into the CO2 mechanism will facilitate the rational design of functional ionic liquids for CO2 capture, utilization, and storage in the future.

Biomimetic fiber/hydrogel composite scaffolds based on chitosan hydrogel and surface modified PCL chopped-microfibers

Hydrogel/fiber composites have received wide attention as tissue engineering scaffolds due to the outstanding properties of fibers and hydrogels. In the current research, a hydrogel/fiber composite scaffold was made based on chitosan-modified polycaprolactone (PCL) microfibers and chitosan hydrogel as a binder. The presence of chitosan as a modifier on the surface of fibers and as a binder between fibers can create scaffolds with excellent structural and mechanical properties. To this end, the three-dimensional microfibers were first functionalized with amine groups. Then, the chitosan chains were attached to the fibers by an aldehyde coupling agent and Schiff base reaction. FTIR and Raman spectroscopies corroborated that chitosan was successfully immobilized on PCL fibers. Chitosan-modified fibers were molded with chitosan solutions of various concentrations and the prepared composite scaffolds were stabilized using ionic crosslinking. The obtained composites represented a porous 3D structure with highly interconnected pores. The compressive modulus increased by 19 and 2.7 folds and the tensile modulus was augmented by 28 and 4 folds, in respective dry and swollen states with increasing hydrogel concentration from 0.1 to 1 %. Hydrogel/fiber composites were able to preserve cell viability, and increasing the hydrogel proportion increased adhesion, proliferation and penetration of cells into the scaffold.

Thiazole-derived pyrazin-2-carbohydrazide chemosensors: Colorimetric & photoluminescent detection of silver ions for theoretical, environmental, and cell imaging

In this work, a simple and versatile chemosensor receptor TZPYZ was synthesized through the combination of thiazole with pyrazine-2-carbohydrazide, resulting in a confirmed chemical structure via various analytical techniques including FT-IR, 1H, and 13C Nuclear Magnetic Resonance Spectroscopy, as well as High-Resolution Mass Spectroscopy analysis. TZPYZ exhibits specific colorimetric and photoluminescent responses to Ag+ ions in a solvent solution consisting of DMSO and H2O (7:3, v/v). Upon addition of Ag+ ions, noticeable changes in absorption spectra occur, resulting in a visible color change from pale yellow to blue. Additionally, an enhanced emission intensity with wavelength at 523 nm, when excited at 410 nm. Notably, TZPYZ demonstrated exceptional selectivity for Ag+ ions over other metal cations, achieving a detection limit (LOD) of 10.6 × 10−9 M and 6.74 × 10−9 M and using the UV–visible & photoluminescent titration method. Interference studies indicated minimal disruption from other metal ions on emission at 523 nm, highlighting TZPYZ discerning capability for Ag+ ions. With a binding affinity of 3.622 × 10−11 M−1, TZPYZ proved effective in detecting Ag+ ions across various water samples, showcasing its practical utility. The mechanism of interaction between TZPYZ and Ag+ ions was investigated using various experimental techniques, including Job’s plot, Benesi-Hildebrand investigations, 1H NMR, and HRMS analysis. Test strips coated with TZPYZ showed selective detection of Ag+ ions, indicating its potential for on-site applications. Furthermore, DFT computations provided insights into the structural and electronic properties of TZPYZ and its complex with Ag+ ions, further elucidating the binding mechanism and stability of the complex. In addition, TZPYZ demonstrated compatibility with biological systems, as fluorescence imaging tests on MCF-7 breast cancer cells confirmed both its non-cytotoxic nature and its proficiency in detecting intracellular silver ions. Based on these findings, TZPYZ is highlighted as a highly sensitive and selective chemosensor for Ag+ ions, with promising applications in environmental analysis and bioimaging.

Synthetic V(V)-peroxido-zwitterionic species catalyze benzene oxidation under mild reaction conditions

A series of dinuclear complexes were synthesized, involving vanadium with N-methylglycine (sarcosine)/N,N’-dimethylglycine in aqueous media and H2O2, capable of exerting catalytic activity. Specifically, the ternary V(V) tetraperoxido dinuclear species (NH4)2[V2O2(O2)4(CH3NH2CH2COO)] (symmetric conformer) (1), (NH4)2[V2O2(O2)4(CH3NH2CH2COO)] (asymmetric conformer) (2), K2(Η2Ο)[V2O2(O2)4(CH3NH2CH2COO)] . H2O (3) (asymmetric conformer), and K2(Η2Ο)2[V2O2(O2)4{(CH3)2NHCH2COO)}] (4) (asymmetric conformer) were synthetically isolated in crystalline form. Compounds 1 and 2 are the same, whilst with profound conformational differences exemplified through pH-specific chemistries. The new materials 1–4 were characterized by elemental analysis, FT-IR, Raman, NMR, and UV–Visible spectroscopy, cyclic voltammetry, thermogravimetric analysis (TGA-DTG), and X-ray crystallography. Further support of the spectroscopic and structural profile was achieved through Bond Valence Sum (BVS) and Hirshfeld molecular mapping calculations. In all of the studied compounds, pH appears to be a crucial factor in the synthesis and isolation. The physicochemical characterization of the hybrid materials justified further use of compound 3 as a potential hydroxylation catalyst of benzene under a variable set of mild reaction conditions. The products of the catalytic reaction systems investigated were identified and quantified by gas chromatography–mass spectrometry (GC-MS) and gas chromatography–flame ionization detection (GC-FID), respectively. The results a) exemplify the involvement of the hybrid dinuclear vanadium compounds in the pursued benzene transformations, and b) distinctly demonstrate the structural and chemical characteristics justifying the emergence of catalytic action of vanadium under mild conditions (40 °C) in reactions toward organic substrates (e.g. benzene) as the basis for the pursuit of selective industrial applications, affording readily available useful compounds.

Synthesis of pyrazole and pyrazoline derivatives of β-ionone: Exploring anti-inflammatory potential, cytotoxicity, and molecular docking insights

In the present paper, pyrazole and pyrazoline derivatives of β-ionone were synthesized. The protocol involved intramolecular oxidative C–H amination of hydrazone to yield corresponding pyrazole in moderate to good yields. Another methodology comprising of condensation of hydrazine hydrochloride with β-ionone in methanol leading to pyrazoline and its oxidative dehydrogenation using hypervalent iodine reagent to synthesize pyrazole is also achieved. One pot methodology for synthesis of pyrazole is also developed by refluxing the hydrazine hydrochloride with β-ionone in acetic acid. The structures of the synthesized compounds were elucidated using 1H NMR, 13C NMR, FTIR and mass spectrometry. All the pyrazole and pyrazoline derivatives were subjected to bovine serum albumin assay for in-vitro anti-inflammatory activity and all the compounds exhibited good to excellent activity. Compounds containing bromo and sulfonamide group exhibited inhibition rates of 87.36 % and 85.82 %, respectively, at a concentration of 0.5 mg/mL, surpassing the efficacy of the standard drug celecoxib (81.67 %). Further, cytotoxicity of the compounds was also evaluated against VERO cell line and all the compounds exhibited the cytotoxic values almost similar to the standard. Molecular docking was performed to study binding affinity of the potent compounds i. e bromo bearing pyrazole and sulfonamide bearing pyrazoline into the crystal structure of COX-II enzyme (PDB ID: 3LN1) at celecoxib binding site to determine the binding energy and interactions.

Adaptability to the environment of protease by secondary structure changes and application to enzyme-selective hydrolysis

The reactions involving enzymes are significantly influenced by various environmental factors. Clarity of how the activity and structure of proteases impact their function is crucial for more efficient application of enzymes as a tool. The impact of temperature, pH, and ionic strength on changes in protease activity, secondary structure, and protein conformation during enzymatic hydrolysis were investigated in this study. The enzymatic activity and secondary structure of acid-base protease were found to undergo significant modifications under different physical conditions, as demonstrated by UV spectrophotometry and FTIR spectroscopy analysis. Specifically, variations in α-helix and β-fold content were observed to correlate with changes in enzyme activity. Molecular simulation analysis revealed that physical conditions have varying effects on the protease, particularly influencing enzyme activity and secondary structure. Evaluation of the proteases indicated alterations in both enzyme activity and structure. This treatment selectively hydrolyzed β-lactoglobulin and reduced sensitization. These findings offer novel perspectives on the functionalities and regulatory mechanisms of proteases, as well as potential industrial applications.

Chemical modification of marigold (Tagetes erecta) dye via diazo-coupling reaction for enhanced dyeing on polyester: A sustainable approach

Plant-derived natural extracts contain large amounts of polyphenolic compounds, presenting opportunities for chemical modification. The present study deals with the extraction of dye from Marigold (Tagetes erecta), a widely cultivated and commercially utilised flower, using water as an extraction medium followed by its chemical modification for sustainable synthesis of yellow dye and dyeing of polyester fabric. Phytochemical analysis and FTIR spectroscopy of the natural dye extract from Marigold flowers indicated the presence of polyphenolic flavonoids. The water-extracted natural dye was subsequently chemically modified with aniline, a primary aryl amine, via diazotisation and coupling reactions to yield a semi-synthetic natural dye with a 1.2 ± 0.3 g yield. The major constituents in the marigold natural extract and the Modified Marigold Extract (MME) dye were characterised using High-Resolution Liquid Chromatography-Mass Spectrometry (LC-HRMS). The marigold water extract contained a high concentration of Gossypetin 8-Glucoside, a yellow-coloured flavonoid compound with a mass-to-charge ratio (m/z) of 480.0904. LC-HRMS analysis further confirmed the presence of a constituent (m/z 424.0485) in the MME dye, corresponding to the predicted mass of chemically modified Gossypetin 8-Glucoside. The MME dye was subsequently employed for dyeing polyester fabric, exhibiting maximum colour strength at 10 % shade under acidic condition. The dyeing performances of the MME-dyed fabrics were evaluated in terms of fastness and post-dyeing strength. This study demonstrates a unique and novel approach to develop a yellow semi-synthetic natural dye, emphasising its potential utility for polyester dyeing.

Oxygen vacancy modulated optical and dielectric properties of photoactive γ-Fe2WO6

Ferrite compounds have gained scientific attention for their multifunctional attributes. This investigation explores the structural, optical, dielectric and conductivity properties of polycrystalline γ-Fe2WO6 synthesized by the solid state route. The X-ray diffraction confirmed the orthorhombic structure and single-phase formation, while the electron microscopy showed uniform distribution of dense micrometer-sized grains in γ-Fe2WO6. The FTIR spectroscopy analysis validated the presence of active stretching and bending modes, signifying oxygen anion vibration at both Fe and W sites. The simultaneous presence of Fe2+ and Fe3+ ions in the matrix, as confirmed by X-ray photoelectron spectroscopy (XPS), results in an augmented optical energy band gap and contributes to dielectric permittivity due to the charge carrier hopping mechanism between the trap sites. The compound manifests semiconductor attributes, evident in its indirect optical band gap measuring 1.7 eV. It is observed that the compound has effectively degraded the Methylene Blue (MB) under the visible light within 40 min with a degradation efficiency up to 63 %. The material's electrical conductivity, follows the Jonscher's power law, signifies its semiconductor nature and adheres to the Small Polaron tunneling model for charge conduction between neighboring sites. The impedance (Z′) curves exhibit dielectric relaxation (≤ 10 kHz) with a similar activation energy to the dc conductivity study. The activation energy, determined from both the impedance and conductivity analyses, indicates a connection with the migration of oxygen vacancies within the material. Our observation reveals the presence of oxygen vacancies, which possibly act as in-gap electron traps, enhancing the correlated optical and ac conductivity properties, making it an appealing material for diverse multifunctional applications.

Inclusion complexes of α-cyclodextrin with p-aminobenzoic acid and nicotinic acid: Crystal structure, DSC and IR spectroscopy analysis in solid state and 1H NMR and ITC calorimetric studies of complexation in solutions

In this work, inclusion complexes of α-cyclodextrin with p-aminobenzoic acid (PABA) and nicotinic acid (NIK) were studied. Solid-state complexes were obtained and studied with single-crystal X-ray diffraction, powder X-ray diffraction, differential scanning calorimetry, and FT-IR spectroscopy. Additionally, the formation of complexes was studied in aqueous solutions with isothermal titration calorimetry and 1H NMR spectroscopy in DMSO‑d6 solutions. Single crystal studies, FT-IR spectroscopy and powder diffraction confirmed the inclusion of PABA and NIK inside the cyclodextrin cavity. From the results of the isothermal titration calorimetry, the stoichiometry (n) and standard thermodynamic functions (ΔH, ΔG, ΔS) of complexation, as well as binding constants (K) for the formed complexes were calculated. The obtained results confirmed the thermodynamically spontaneous formation of complexes in exothermic reactions. Furthermore, the results obtained were compared for complexes of PABA/NIK acids with β-cyclodextrin. A database survey of α-cyclodextrin complexes with different benzoic acids available in the CSD database was performed.

Calcium Acetate Drug Produced from Rapana venosa Invasive Gastropod Shells: Green Process Control Assisted by Raman Technology.

The highly demanded calcium acetate (Ca(CH3COO)2) for biomedicine and various industries constantly requires green and low-cost methods of synthesis. In the present work, a sustainable approach to produce Ca(CH3COO)2 is reported as a proof of concept, processing for the first time as a starting material the worldwide highly abundant Rapana venosa shells, which is a neglected biogenic waste with high economical potential due to the rich mineral and organic pigmentary content. A green synthesis involving an eco-friendly acetic acid has been optimized at room temperature, without any additional energy consumption, and the resulting saturated Ca(CH3COO)2 solution was further slowly evaporated in three stages to obtain white Ca(CH3COO)2 crystalline powder, without impurity traces. Raman spectroscopy provided efficient structural information for every step of the process control, during demineralization as well as end product validation. Yields as high as 87.5% of highly pure Ca(CH3COO)2 mass have been achieved from raw R. venosa shells, proving the uniqueness and economic viability of the method. X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDX), and Fourier-Transform IR spectroscopy (FTIR) analyses validated the final product identity, hydration status, crystalline morphology, and composition. The purity of the resulting product suggests a high valorization potential of the abundant R. venosa shell in the context of the blue bioeconomy and offers a cleaner and efficient method of Ca(CH3COO)2 production with important applications in relevant industries.

SnO2-TiO2 materials for photocatalytic degradation of cationic dye under UV and visible light and a chitosan composite film investigation

The possibility of SnO2 incorporation and immobilization as films forming composites opens new perspectives for TiO2 to profit visible light and to facilitate the photocatalytic process, respectively. In this study, 0 %, 1 % and 10 % wt. of SnO2 was incorporated into TiO2 (SnO2-TiO2) by coprecipitation in a sol-gel method by ammonia addition, followed for calcination at 500 °C. The photocatalysts were characterized by N2 adsorption-desorption, FTIR spectroscopy, XRD Rietveld refinement, TG-DTG, SEM-EDS, DRS and elemental analysis. The performance of all solids was evaluated in the photocatalytic degradation of the cationic dye methylene blue in aqueous phase, under visible and UV irradiation, at 25 °C for 2 h. The results showed that the incorporation of Sn into TiO2 improved the textural properties and decreased the bandgap. All solids presented only TiO2 typical diffractograms, with anatase as the main phase, but catalyst with 10 % SnO2 presented also brookite phase, inferring that Sn atoms were incorporated into TiO2 structure, corroborated by MEV results. All tin-based photocatalysts show high activity under UV and visible light, with the 10 % SnO2 material reaching 83 % and 88 % degradation after 2 h under UV and visible radiation, respectively. This material was tested as an immobilized film, achieving 14 % of decolorization, and the reuse was also evaluated. Our investigation demonstrates that SnO2-TiO2 catalysts could be used to decompose a dye under UV and Visible light as powder in a batch reactor and immobilized as a composite film with chitosan, that opens new perspectives to facilitate the application using solar light.

A New Type of Acidic OH-Groups in the LTL Zeolite

Acidic properties of ion-exchanged LTL zeolites have been studied using FTIR spectroscopy, complemented by X-ray powder diffraction, SEM-EDX, XRF and N2 physisorption. Infrared spectra of the ion-exchanged zeolites show the presence of two intense bands of the bridging OH-groups: a narrow band at ~3640 cm−1 that is attributed to Si(OH)Al groups freely vibrating in 12 MR and a broad, intense band at ~3250 cm−1 that is assigned to bridging OH groups forming hydrogen bond with neighbouring oxygen atoms, e.g., in six-membered rings. The former can be selectively removed by caesium or rubidium cations with up to 3 Cs+ or Rb+ per unit cell readily ion-exchanged into the LTL zeolite, replacing an equivalent number of acidic OH-groups or K+ cations within the structure. The cation migration of the larger cation, evaluated by the Rietveld refinement method, occurs mostly via the main 12 MR channels. By contrast, less than 1 Li+ or Na+ cation per unit cell can be introduced under similar conditions. Accordingly, the concentration of Si(OH)Al groups in back-exchanged NH4-K-LTL with smaller cations (Li+, Na+) does not differ considerably from the concentration of Brønsted acid sites in the original NH4-K-LTL. Lower concentrations of acid sites have been detected in the samples back-exchanged with Cs+, Rb+ and K+. In addition, the acidic properties of NH4-LTL samples have been compared with a structurally related NH4-MAZ zeolite.

Synthesis, characterization and DFT study of Ti(IV) phthalocyanines with quinoline groups.

The synthesis, characterization, and electronic properties of 4-((7-methoxyquinolin-4-yl)oxy), 4-(quinolin-2-ylthio), and 4-((7-(trifluoromethyl)quinolin-4-yl)thio) peripherally substituted oxo-titanium phthalocyanines are described for the first time. The structures of the compounds were determined by UV-Vis, FTIR, 1H NMR, and MALDI-TOF mass spectrometry. Electronic spectra and molecular and electronic properties of compounds were calculated by Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) methods. Solvent effects on the electronic, geometric, and reactivity properties of the compounds were also investigated. Global and local reactivity indices and Molecular Electrostatic Potential surfaces of compounds were calculated. The reactivities and electronic structures of molecules vary depending on the solvent and substituents. It has been found that the synthesized compounds can be used for different purposes such as dye-sensitized solar cells and photodynamic therapy applications.

Experimental and theoretical investigation of CO2 solubility in amine-based deep eutectic solvents

Deep eutectic solvents (DESs) have appealed increasing research interest across various scientific and industrial applications, notably in relation to efforts in CO2 capture. This study presents a novel series of DESs were synthesized on the basis of monoethanolamine (MEA) and N-methyldiethanolamine (MDEA) as hydrogen bond donors with tetrabutylammonium bromide (TBAB) and tetrabutylphosphine bromide (TBPB) salt as hydrogen bond acceptors. A gas solubility measurement experimental system based on pressure drop method has been established to evaluate the solubility of CO2 in amine-based deep eutectic solvents. The evaluation was performed over a temperature range of 303.15 to 323.15 K and a pressure range of 100 to 1000 kPa. The results indicated that as the molar ratio of hydrogen bond donors increases, the solubility of CO2 in DESs increases, while it was found to be less affected by the hydrogen bond acceptor. Of these, the solubility of CO2 is strongest at a 1:10 molar ratio of TBAB and MEA. The nuclear magnetic resonance spectroscopy spectra (NMR) and FTIR spectroscopy revealed that the MEA-based DES mixture primarily exhibited chemical absorption of CO2, while the MDEA-based DES predominantly showed physical dissolution of CO2. In addition, it was observed that both temperature and pressure significantly influenced the CO2 solubility, and a successful correlation was developed using different semi-empirical models.

Isothiocyanate-Based Microemulsions Loaded into Biocompatible Hydrogels as Innovative Biofumigants for Agricultural Soils.

Biofumigation was proposed as an alternative to synthetic pesticides for the disinfection of agricultural soils, in view of the biocidal effect of isothiocyanates (ITCs) released by some vegetal species, like Brassicaceae. However, biofumigation also presents limitations; thus, a novel and viable alternative could be the direct introduction of ITCs into agricultural soils as components loaded into biodegradable hydrogels. Thus, in this work, ITCs-based microemulsions were developed, which can be loaded into porous polymer-based hydrogel beads based on sodium alginate (ALG) or sodium carboxymethyl cellulose (CMC). Three ITCs (ethyl, phenyl, and allyl isothiocyanate) and three different surfactants (sodium dodecylsulfate, Brij 35, and Tween 80) were considered. The optimal system was characterized with attenuated ATR-FTIR spectroscopy and differential scanning calorimetry to study how the microemulsion/gels interaction affects the gel properties, such as the equilibrium water content or free water index. Finally, loading and release profiles were studied by means of UV-Vis spectrophotometry. It was found that CMC hydrogel beads showed a slightly more efficient profile of micelles' release in water with respect to ALG beads. For this reason, and due to the enhanced contribution of Fe(III) to their biocidal properties, CMC-based hydrogels are the most promising in view of the application on real agricultural soils.