Fourier Transform IR Analysis Research Articles

Exploring the Effectiveness of Carboxymethylated and Crosslinked Albizia procera Gum in Diltiazem Hydrochloride Matrix Tablets: A Comparative Analysis.

This study investigates the efficacy of modified Albizia procera gum as a release-retardant polymer in Diltiazem hydrochloride (DIL) matrix tablets. Carboxymethylated Albizia procera gum (CAP) and ionically crosslinked carboxymethylated Albizia procera gum (Ca-CAP) were utilized, with Ca-CAP synthesized via crosslinking CAP with calcium ions (Ca2+) using calcium chloride (CaCl2). Fourier Transform (FT) IR analysis affirmed polymer compatibility, while differential scanning calorimetry (DSC) and X-ray diffraction (XRD) assessed thermal behavior and crystallinity, respectively. Zeta potential analysis explored surface charge and electrostatic interactions, while rheology examined flow and viscoelastic properties. Swelling and erosion kinetics provided insights into water penetration and stability. CAP's carboxymethyl groups (-CH2-COO-) heightened divalent cation reactivity, and crosslinking with CaCl2 produced Ca-CAP through -CH2-COO- and Ca2+ interactions. Structural similarities between the polymers were revealed by FTIR, with slight differences. DSC indicated modified thermal behavior in Ca-CAP, while Zeta potential analysis showcased negative charges, with Ca-CAP exhibiting lower negativity. XRD highlighted increased crystallinity in Ca-CAP due to calcium crosslinking. Minimal impact on RBC properties was observed with both polymers compared to the positive control as water for injection (WFI). Ca-CAP exhibited improved viscosity, strength, controlled swelling, and erosion, allowing prolonged drug release compared to CAP. Stability studies confirmed consistent six-month drug release, emphasizing Ca-CAP's potential as a stable, sustained drug delivery system over CAP. Robustness and accelerated stability tests supported these findings, underscoring the promise of Ca-CAP in controlled drug release applications.

Characterization of Theabrownins Prepared From Tea Polyphenols by Enzymatic and Chemical Oxidation and Their Inhibitory Effect on Colon Cancer Cells.

Theabrownins (TBs) are prepared from dark tea and contain a large number of complex heterogeneous components, such as carbohydrates, proteins, and flavonoids, which are difficult to remove. In addition, some toxic and harmful extraction solvents are used to purify TBs. These obstacles hinder the utilization and industrialization of TBs. In this study, tea polyphenols were used as substrates and polyphenol oxidase and sodium bicarbonate (NaHCO3) were used successively to prepare theabrownins (TBs-E). The UV-visible characteristic absorption peaks of the TBs-E were located at 203 and 270 nm and Fourier-transform IR analysis showed that they were polymerized phenolic substances containing the hydroxy and carboxyl groups. The TBs-E aqueous solution was negatively charged and the absolute values of the zeta potential increased with increasing pH. A storage experiment showed that TBs-E were more stable at pH 7.0 and in low-temperature environments around 25°C. HT-29 human colon cancer cells were used to evaluate the biological activity of TBs-E through 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di- phenytetrazoliumromide (MTT), H&E staining, propidium iodide immunofluorescent staining, flow cytometry, and real-time PCR assays. The TBs-E significantly inhibited cell growth and caused late apoptosis, particularly at the dose of 500 μg/ml. The TBs-E markedly reduced the expression of antioxidant enzyme genes and increased the generation of reactive oxygen species to break the redox balance, which may have led to cell damage and death. These results will promote research and industrialization of TBs.

Cationic UV‐curing of epoxidized cardanol derivatives

AbstractThis paper demonstrates the high reactivity and potentiality of bio‐renewably obtained cardanol‐based epoxy monomers as well as the possibility of tuning the final thermomechanical properties by changing either the epoxy content or the chemical structure of the starting photocurable resin. The reactivity of the cardanol monomers towards the cationic UV‐curing process was investigated by Fourier transform IR analysis and it was shown that a high epoxy group conversion was achieved. Furthermore, the thermomechanical properties were investigated on crosslinked films by means of DSC and dynamic thermomechanical analysis. © 2020 Society of Chemical Industry

A Metal-Free Donor-Acceptor Covalent Organic Framework Photocatalyst for Visible-Light-Driven Reduction of CO2 with H2 O.

Visible-light-driven CO2 reduction to valuable chemicals without sacrificial agents and cocatalysts remains challenging, especially for metal-free photocatalytic systems. Herein, a novel donor-acceptor (D-A) covalent organic framework (CT-COF) was constructed by the Schiff-base reaction of carbazole-triazine based D-A monomers and possessed a suitable energy band structure, strong visible-light-harvesting, and abundant nitrogen sites. CT-COF as a metal-free photocatalyst could reduce CO2 with gaseous H2 O to CO as the main carbonaceous product with approximately stoichiometric O2 evolution under visible-light irradiation and without cocatalyst. The CO evolution rate (102.7 μmol g-1 h-1 ) was 68.5 times that of g-C3 N4 under the same conditions. In situ Fourier-transform (FT)IR analysis indicated that CT-COF could adsorb and activate the CO2 and H2 O molecules and that COOH* species may be a key intermediate. DFT calculations suggested that nitrogen atoms in the triazine rings may be photocatalytically active sites.

One-pot combustion synthesis of nickel oxide and hematite: From simple coordination compounds to high purity metal oxide nanoparticles

This work is the first report of a very simple and fast one-pot synthesis of nickel oxide (NiO) and hematite (?-Fe2O3) nanoparticles by thermal decomposition of transition metal aqua complexes with camphor sulfonate anions. Obtained nanopowders were characterized by X-ray powder diffraction, Fourier transform IR analysis, scanning electron microscopy, and Energy-dispersive X-ray spectroscopy. X-ray powder diffraction confirmed the formation of high purity NiO and ?-Fe2O3 crystal phases. In the case of ?-Fe2O3, about five times larger average crystallite size was obtained. Fourier transform IR spectra of synthesized materials showed characteristic peaks for NiO and ?-Fe2O3 nanostructures. To visualize the morphology and the chemical composition of the final products Scanning electron microscopy and Energy-dispersive X-ray spectroscopy were performed. The thermogravimetric analysis was done for a better understanding of the general thermal behavior of precursor compounds. This easy-to-perform and fast preparation method opens a broad range of obtained materials? usage, particularly due to its economic viability

Movements of the Substrate-Binding Clamp of Cypemycin Decarboxylase CypD

Linaridins are a small but growing class of natural products belonging to the ribosomally synthesized and post-translationally modified peptide (RiPP) superfamily. The class A linaridins, exemplified by cypemycin, possess an unusual S-[( Z)-2-aminovinyl]-d-cysteine (AviCys) residue. Formation of the AviCys in cypemycin requires an oxidative decarboxylation of the precursor peptide C-terminal Cys, and this reaction is catalyzed by a flavin-dependent decarboxylase CypD. In this work, we investigate the molecular recognition processes of CypD by a combination of computational and biochemical analysis. We show that the substrate binding clamp of CypD undergoes dramatic fluctuation, mediating both the substrate entrance into and product release from the catalytic pocket. Extensive molecular dynamic simulations and Fourier transform IR analyses indicated that binding of the substrate induces substantial structural change of the enzyme, converting the substrate-binding clamp from a random loop to a more ordered structure comprising two β sheets and a β turn. The salt bridge between Arg159 guanine and the Cys carboxylate of substrate plays an important role in mediating substrate binding, while hydrophobic interactions are also important in this process. These results provide important mechanistic insights into CypD and other flavin-dependent Cys decarboxylases, and could facilitate future biosynthetic and bioengineering efforts in studying AviCys-containing RiPPs.

Synthesis of multifunctional high strength, highly swellable, stretchable and self‐healable pH‐responsive ionic double network hydrogels

AbstractThe multifunctional double network (DN) soft hydrogels reported here are highly swellable and stretchable pH‐responsive smart hydrogel materials with sufficient strength and self‐healing properties. Such multifunctional hydrogels are achieved using double crosslinking structures with multiple physical and chemical crosslinks. They consist of a copolymer network of acrylamide (AM) and sodium acrylate (Na‐AA) and other reversible network of poly(vinyl alcohol)–borax complex. They were characterized by Fourier transform IR analysis and studied for their hydrogen bonding and ionic interaction. The degree of equilibrium swelling was observed to be as high as 5959% (at pH 7.0) for a hydrogel with AM/Na‐AA = 25/75 wt% in the network (GS‐6 sample). The highest degree of swelling was observed to be 6494% at pH 8.5. The maximum tensile strength was measured to be 1670, 580 and 130 kPa for a DN hydrogel (GS‐2 sample: AM/Na‐AA =75/25 wt% with 20, 40 and 60 wt% water content, respectively). The self‐healing efficiency was estimated to be 69% for such a hydrogel. These multifunctional DN hydrogels with amalgamation of many functional properties are unique in hydrogel materials and such materials may find applications in sensors, actuators, smart windows and biomedical applications. © 2018 Society of Chemical Industry

Structural Insights into the Microemulsion‐Mediated Formation of Fluoroquinolone Nanoantibiotics

AbstractMicroemulsions (μEs) are being exploited as a potential route for yielding an extensive range of nanoparticles of different chemical nature, shapes and sizes. Nanodrugs offer new avenues for structuring better “drug delivery systems”. In this study, an oil‐in‐water (o/w) μE formulation comprising N‐butyl acetate/polysorbate 80/ethanol/water was developed for the preparation of nanoparticles of fluoroquinolone antibiotics (FLQ‐NPs). A pseudoternary phase diagram was mapped at constant surfactant/cosurfactant (1:2), revealing improved and high loading of FLQs in an optimum μE formulation. The as‐formulated μE showed high loading of FLQs as; levofloxacin (4.20 wt.%), ciprofloxacin (3.16 wt.%), moxifloxacin (2.53 wt.%), gatifloxacin (1.36 wt.%), ofloxacin (0.70 wt.%). Fourier transform IR analysis indicated good compatibility of each FLQ drug with μE excipients. However, dynamic light scattering showed an increase in the average particle size of the μE on drug loading, indicating the accumulation of FLQ at interface layer of the micelle. Additionally, lyophilized levofloxacin (a selected antibiotic) showed long‐term stability, amorphous morphology and improved dissolution rate, inspected by scanning transmission electron microscopy, X‐ray diffraction and electronic spectroscopy, respectively. Moreover, fluorescence measurements suggested the interfacial vicinity of levofloxacin within the μE domain, which may support controlled release of drug during systemic circulation.

Study on extraction and purification of apigenin and the physical and chemical properties of its complex with lecithin

Background:The apigenin has important medicinal value. However, the low solubility of apigenin in water significantly reduced its application.Objective:In this study, the apigenin was extracted, and the complex of apigenin and lecithin was obtained by the solvent method and its physical and chemical properties were investigated.Materials and Methods:The apigenin was extracted from the leaves of Adinandra nitida. Afterward, its apigenin was obtained by hydrolysis and recrystallization. The solvent method was used to synthesis the complex of apigenin and lecithin. Tetrahydrofuran was used as the solvent. The physicochemical properties of the complex were investigated by the various methods such as ultraviolet (UV)-visible spectrometry, infrared spectrometry (IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffractometry.Results:No distinct difference was examined between the complex and physical mixture according to the UV analysis. While the result of Fourier transform-IR analysis indicated the characteristic absorption peaks of apigenin was subdued by the absorption peaks of lecithin. SEM showed the irregular form of the complex. In the DSC thermogram of the complex, the characteristic endothermic peak belonging to apigenin disappears, and the apparent amorphous properties are shown in the X-ray X-diffractograms of the complex.Conclusion:The synthetic process does not break the conjugated structure of apigenin. The complex is held together by Hydrogen bonding and van der Waals force and processes new physical and chemical characteristics. The industrial application of apigenin might be enhanced by the increase of the bioavailability.SUMMARY The apigenin was extracted from the leaves of Adinandra nitidaThe complex of apigenin and lecithin was obtained by solvent methodThe physical and chemical properties of the complex were investigatedThe complex is held together by Hydrogen bonding and van der Waals force and processes new physical and chemical characteristics. Abbreviation used: SLA: The synthesis of the complex of soy lecithin and apigenin, PMSLA: The manufacture of a physical mixture of soybean lecithin and apigenin, UV: Ultraviolet, IR; Infrared Radiation, FT-IR: Fourier transform infrared, NMR: Nuclear magnetic resonance, SEM: Scanning electron microscopy, DSC: Differential scanning calorimetry, XRD: X-ray diffractometry.

Compatibilization of poly(lactic acid)/polycarbonate blends by different coupling agents

In this study, PLA/PC blends were prepared in order to investigate the effects of the addition of PC loading level into PLA matrix on the mechanical properties of these blends. After that, PLA/PC (70/30), which has the lowest tensile strength value, was selected as a control sample for the compatibilization study. Commercial styrene-acrylic multi-functional-epoxide oligomeric agent (SAmfE), styrene maleic anhydride copolymer (SMA), tetrasilanol phenyl polyhedral oligomeric silsesquioxane (T-POSS) and glycidyl isooctyl-polyhedral oligomeric silsesquioxane (G-POSS) were used as compatibilizers for PLA/PC blends. The variation of mechanical, thermal, structural and morphological properties were examined by conducting tensile tests, dynamic mechanical analyses, differential scanning calorimetry, Fourier Transform IR and scanning electron microscope analyses. Tensile test results showed that the tensile strength and elongation at break values of the PLA/PC blend compatibilized with SAmfE were higher than those of the other blends. DSC analyses revealed that Tg and Tm values of the blends were not significantly affected by compatibilizer but, degree of crystallinity was found to be sensitive to compatibilizer type. DMA results showed that the best mechanical properties were obtained for the PLA/PC/SAmfE blend. When all of the results evaluated, it was found that the SAmfE is the most effective compatibilizer among the using compatibilizer types for PLA/PC blends.

Towards a new strategy of a chitosan‐based molecularly imprinted membrane for removal of 4‐nitrophenol in real water samples

AbstractThe issue of water contaminants, which affects human and environmental health, is not trivial. It is thus paramount to find new cheap and user friendly ways to detect and remove them from the environment. Here, the synthesis of a green chitosan (CS) based molecularly imprinted membrane for the detection and quantification of 4‐nitrophenol (4‐NO2Ph) in aqueous media is proposed. The concentration of 4‐NO2Ph in a water solution was measured by HPLC analysis. CS as a functional polymer, 4‐NO2Ph as template, 4‐[(4‐hydroxy)phenylazo]benzenesulfonic acid as ligand, and glutaraldehyde as crosslinker in the presence of polyethylene glycol as porogen were used. The membrane was characterized by SEM and Fourier transform IR analyses, which confirmed the CS and polyethylene glycol backbone of the membrane. Kinetic studies of the detection system were performed by using pseudo‐first‐order and pseudo‐second‐order models. Then, the binding efficiency between 195.33 µmol L−1 and 9235.55 µmol L−1 of 4‐NO2Ph was evaluated, finding a maximum adsorption of 723.25 µmol 4‐NO2Ph per gram of membrane consistent with the Qmax calculated from the Langmuir isotherm. The selectivity of the membrane versus three phenolic competitor molecules, sharing very similar molecular structure to 4‐NO2Ph, was demonstrated. Finally, the applicability of the membrane to real‐world samples was evaluated, by using drinking water spiked with 7.19 µmol L−1 of 4‐NO2Ph, obtaining a removal efficiency of 70.6%. © 2017 Society of Chemical Industry

Encapsulation of Antibiotic Levofloxacin in Biocompatible Microemulsion Formulation: Insights from Microstructure Analysis.

Microemulsions (μEs) are unique systems that offer exciting perspectives in biophysical research for mimicing biomembranes at the molecular level. In the present study, biocompatible μE formulation of a new oil-in-water (o/w) system comprising clove oil/Tween 20/2-propanol/water was accomplished for encapsulating an antibiotic, levofloxacin (LVF). The pseudoternary phase diagram was delineated at a constant cosurfactant/surfactant (2:1) ratio to meet the economic feasibility. The gradual changes occurring in the microstructure of the as-formulated four-component μEs were explored via multiple complementary characterization techniques. The results of electrical conductivity (σ), viscosity (η), and optical microscopic measurements suggested the existence of a percolation transition to a bicontinuous structure in the microregions of the as-formulated μE. LVF displayed a high solubility (5.0 wt %) at the pH of 6.9 in an optimum μE formulation comprising 2-propanol (36.4%), Tween 20 (18.2%), clove oil (20.7%), and water (24.7%). The LVF-loaded μE composition showed long-term stability for over 6 months of storage. Fourier transform IR analysis showed that LVF was stable inside the μE formulation, indicating the absence of any possible aggregation of LVF. Dynamic light scattering revealed that the average particle size of drug-free μE (64.5 ± 3.4 nm) increases to 129.7 ± 5.8 nm upon loading of LVF, suggesting the accumulation of LVF in the interfacial layers of the micelles. Moreover, fluorescence measurements indicated that LVF might be localized in the interfacial film of μE system, which may result in a controlled release of drug.

H2PO4-- and Solvent-Induced Polymorphism of an Amide-Functionalized [Pt(N^C^N)Cl] Complex.

A simple [Pt(N^C^N)Cl] complex functionalized with an amide group was prepared, and its absorption and emission properties were examined in different solvents in response to various anions. On the one hand, in the presence of H2PO4-, the solution of the complex shows distinct color changes in CH3CN, together with a ratiometric emission change from a green emission band at 537 nm to a deep red emission band at 680 nm. On the other hand, two-step spectral changes were observed in response to H2PO4- in CH2Cl2, with the green emission being attenuated first followed by the appearance of enhanced and yellow-green emissions at a lower-energy region. These recognition processes are highly selective for H2PO4- against other common anions including F-, Cl-, Br-, I-, OAc-, NO3-, and HSO4-. In addition, the platinum complex displays multistage emission polymorphism in mixed CH3CN/H2O solvent of various ratios. The hydrogen-bonding interaction between H2PO4- and the amide unit was confirmed by NMR analysis. In the solid state, this platinum complex emits red light. However, the composite material of the platinum complex with H2PO4- shows purely monomeric yellow emissions. The solid-state materials were further analyzed by single-crystal X-ray and Fourier-transform IR analysis. These studies suggest that this simple platinum complex is useful for the selective recognition of H2PO4- and as solid-state emitting materials with tunable emission colors.

Preparation of glycopolypeptides bearing mannose moieties and biphenyl pendants and their upper‐critical‐solution‐temperature‐type thermoresponsive properties in alcohol/water solvent mixtures

AbstractA series of glycopolypeptides with constant main‐chain lengths and various compositions of mannose moieties and biphenyl pendants were synthesized by copper‐mediated 1,3‐dipolar cycloadditions. 1H NMR and Fourier transform IR (FTIR) analysis confirmed the molecular structures of the resulting polypeptides. FTIR analysis characterized the molar contents of the mannose pendants and α‐helical conformations in the solid state. Glycopolypeptides conjugated with tetra‐O‐acetyl‐d‐(+)‐mannopyranoside showed a reversible upper‐critical‐solution‐temperature‐type (UCST‐type) phase behavior both in MeOH/H2O and EtOH/H2O binary solvent mixtures depending on the weight percentage of alcohols (fw). Incorporation of a low content of biphenyl pendants (≤0.20) can broaden the range of fw at which polymers showed UCST‐type phase behaviors. The UCST‐type transition temperature (Tpt) was highly related to the incorporation of biphenyl pendants, polymer concentrations, and the nature and weight percentage of alcohols. It decreased as the polymer concentration decreased and increased on incorporation of biphenyl groups. © 2016 Society of Chemical Industry

Bioremediation Potential of Arthrospira platensis (Spirulina) against Chromium(VI)

Phycoremediation is an eco‐friendly, emerging and economically feasible technique for the removal of heavy metals from the environment. In this study, the bioremediation potential of the cyanobacterium Arthrospira platensis was explored by treating it with various concentrations of chromium(VI) (0.01, 0.05 and 0.1 mM) and as well with tannery effluent containing Cr. Arthrospira platensis was grown in Zarrouk's medium (pH 9.5) at room temperature. The effect of Cr(VI) on A. platensis was studied via biochemical parameters (chlorophyll, protein), physicochemical parameters (total solids, total dissolved solids, total suspended solids) and analytical parameters (Fourier transform IR (FTIR), atomic absorption spectroscopy). The results indicated that A. platensis had a maximum adsorption potential of 98.5% and a reduction potential of 73.5% against Cr(VI). The FTIR analysis revealed that there is an interaction of A. platensis with Cr. These findings suggest that A. platensis can be used for phycoremediation of industrial effluents contaminated with Cr(VI).

Structural and microstructural interpretations of Zn-doped biocompatible bone-like carbonated hydroxyapatite synthesized by mechanical alloying

Single-phase nanocrystalline biocompatible Zn-dopedA-type carbonated hydroxyapatite (A-cHAp) powder has been synthesizedviamechanical alloying of a stoichiometric mixture of CaCO3, CaHPO4·2H2O and ZnO powders in open air at room temperature by 10 h of milling. TheA-type carbonation in HAp (A-cHAp) is confirmed by Fourier transform IR analysis. The structural and microstructural parameters of the as-milled powders are revealed by Rietveld powder structure refinement analysis and transmission electron microscopy. Zn substitution along with mechanical alloying causes partial amorphization of crystallineA-cHAp, analogous to native bone mineral. Zn2+cations substitute into the ninefold-coordinated Ca2+sites in theA-cHAp unit cell. An assay test using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] reveals a high percentage of cell viability and hence confirms the biocompatibility of the sample. The overall results indicate that the processedA-cHAp has a chemical composition very close to that of natural biological apatite.

Pyomelanin production in Penicillium chrysogenum is stimulated by L-tyrosine.

From a tomb in Upper Egypt we isolated a strain of Penicillium chrysogenum that was capable of producing brown pigment in vitro when grown in a minimal salts medium containing tyrosine. We present evidence that this pigment is a pyomelanin, a compound that is known to assist in the survival of some micro-organisms in adverse environments. We tested type strains of Pe. chrysogenum, which were also able to produce this pigment under similar conditions. Inhibitors of the DHN and DOPA melanin pathways were unable to inhibit the formation of the pigment. Fourier transform IR analysis indicated that this brown pigment is similar to pyomelanin. Pyrolysis-GC/MS revealed the presence of phenolic compounds. Using LC/MS, homogentisic acid, the monomeric precursor of pyomelanin, was detected in supernatants of Pe. chrysogenum cultures growing in tyrosine medium but not in cultures lacking tyrosine. Partial regions of the genes encoding two enzymes in the homogentisic acid pathway of tyrosine degradation were amplified. Data from reverse-transcription PCR demonstrated that hmgA transcription was increased in cultures grown in tyrosine medium, suggesting that tyrosine induced the transcription.

Immobilization of lipase SMG1 and its application in synthesis of partial glycerides

Production and immobilization of lipase SMG1 and its application in catalyzing the esterification of oleic acid with glycerol were investigated. Resin D380 was screened to immobilize enzyme among five types of macroporous resins, and Fourier transform IR analysis proved the ionic bonds between functional group (NH2) and the amino acid residues in protein molecules. The immobilized lipase SMG1, with lipase/support ratio of 75 mg/g resin and pH 7.0, was used to catalyze the esterification, and high esterification degree of 68.37% was obtained under the conditions of the immobilized lipase at a concentration of 7.5% (w/w, with respect to total reactants), a fatty acid/glycerol molar ratio of 1:7, and 40°C. The immobilized lipase retained 49.7% of its initial activity after being used for six times. Compared with the free lipase SMG1, the immobilized one was discovered to exhibit higher temperature tolerance (40°C for the immobilized lipase SMG1 and 30°C for the free one) in the esterification of fatty acid and glycerol. The new finding on the improved operation temperature of the immobilized lipase SMG1 will push the enzyme's application in the oils and fats industry.Practical applications: The immobilized lipase SMG1‐catalyzed process for production of partial glycerides from glycerol and oleic acid described in this study provides several advantages over conventional methods including the absence of TAG product, the repeatable utilization of catalyst, and a high purity of DAG.Research on the immobilization of lipase SMG1, which is a novel mono‐ and diacylglycerol enzyme, has been firstly investigated. Compared with the free lipase, immobilized lipase SMG1 presented enhanced thermal stability in the esterification of glycerol with fatty acid. The new finding on the improved operation temperature of immobilized lipase SMG1 will push the enzyme's application in the oils and fats industry.

Chemically Stable Multilayered Covalent Organic Nanosheets from Covalent Organic Frameworks via Mechanical Delamination

A series of five thermally and chemically stable functionalized covalent organic frameworks (COFs), namely, TpPa-NO2, TpPa-F4, TpBD-(NO2)2, TpBD-Me2, and TpBD-(OMe)2 were synthesized by employing the solvothermal aldehyde-amine Schiff base condensation reaction. In order to complete the series, previously reported TpPa-1, TpPa-2, and TpBD have also been synthesized, and altogether, eight COFs were fully characterized through powder X-ray diffraction (PXRD), Fourier transform IR (FT-IR) spectroscopy, (13)C solid-state NMR spectroscopy, and thermogravimetric analysis. These COFs are crystalline, permanently porous, and stable in boiling water, acid (9 N HCl), and base (3 N NaOH). The synthesized COFs (all eight) were successfully delaminated using a simple, safe, and environmentally friendly mechanical grinding route to transform into covalent organic nanosheets (CONs) and were well characterized via transmission electron microscopy and atomic force microscopy. Further PXRD and FT-IR analyses confirm that these CONs retain their structural integrity throughout the delamination process and also remain stable in aqueous, acidic, and basic media like the parent COFs. These exfoliated CONs have graphene-like layered morphology (delaminated layers), unlike the COFs from which they were synthesized.

Removal of bacteria by clinoptilolite rich mineral and its surfactant modified forms

Batch experiments were carried out to understand the potential values of clinoptilolite rich mineral and its surfactant modified forms in the removal of Gram-positive and Gram-negative bacteria. Zeta potential and Fourier Transform IR analysis were performed to explain the possible interactions between the bacteria and the zeolite samples. The results revealed that hydrogen bonding was significant mechanism in the removal of bacteria with clinoptilolite rich mineral and anionic surfactant modified clinoptilolite rich mineral whereas both attractive electrostatic forces and hydrogen bonding were dominant mechanism in the removal of bacteria with cationic surfactant modified clinoptilolite rich mineral. Cationic and anionic surfactant modified clinoptilolite rich mineral are promising materials in removal of bacteria studies.