Several Types Of Functional Groups Research Articles

Sequestration and recovery of thorium ions using a recyclable, low-cost, glutathione-based magnetic nanocomposite: Experimental study and statistical modeling

Efficient removal and recovery of thorium from water resources is necessary to resolve the problem of radioactive contamination. To address this issue, magnetically separable Glu@MNPs have been fabricated and efficiently utilized for the removal of Th(IV). 99.40 % removal of Th(IV) by Glu@MNPs could attain an equilibrium state within 10 min at a dosage level of 6 mg for 20 ml of 50 mg/L thorium solution at pH 4 and 25 °C. It obeys Langmuir isotherm with maximum adsorption capacity of 636.94 mg g−1, which is independent of temperature variation. Kinetically, the adsorptive performance of Glu@MNPs fits well in the pseudo-second-order equation. The high removal efficiency is due to the existence of several types of functional groups on the surface of Glu@MNPs, which provide electrostatic attraction, and vander wall forces between adsorbate and adsorbent. The optimum conditions obtained from Box-Behnken composite design model was well matched with batch adsorption studies. Further, the results obtained for removal of Th(IV) by UV–vis spectroscopy matched well with ICP-OES. The removal efficiency still remained high (85.65 %) even after 10 adsorption–desorption cycles. Thus, Glu@MNPs acts as a timesaving adsorbent for sequestration of Th(IV) from an aqueous media with excellent removal performance.

Novel Design of Co-Poly(Hydrazide Imide) and Its Complex with Cu(I) for Membrane Separation of Methanol/Dimethyl Carbonate Mixture

Poly(2,2'-biquinoline-6,6'-dicarbohydrazide)-co-(bistrimelliteimide)methylene-bisanthranylide (PHI) and its metal-polymer complex PHI-Cu(I) containing several types of functional groups (hydrazide, carboxyl, amide, and imide fragments) were synthesized to prepare two types of dense nonporous membranes. The study on morphology using scanning electron microscopy (SEM), measurements of mechanical, thermal, and transport properties of the membrane samples was carried out. The main mechanical properties of both membranes do not differ significantly, but the values of ultimate deformation differ palpably as a result of a non-uniform character of the deformation process for the PHI membrane. The thermal analysis based on the curves of thermogravimetric (TGA) and differential thermal (DTA) analyses of the PHI and PHI-Cu(I) membranes revealed peculiarities of the membrane structure. Transport properties were studied in pervaporation (PV) of methanol (MeOH) and dimethyl carbonate (DMC) mixtures including an azeotropic point. Intrinsic properties of the penetrant-membrane system were also determined. It was found that the total flux is higher through the PHI membrane, but the PHI-Cu(I) membrane exhibits a higher separation factor. Calculation of the pervaporation separation index (PSI) allowed to conclude that the PHI-Cu(I) membrane exhibits better transport properties as compared with the PHI membrane.

Prospects of co‐poly(biquinoline‐hydrazide‐imide)s for separation of benzene‐isopropanol mixture via pervaporation

AbstractPoly(biquinoline dicarbohydrazide)‐co‐(bistrimelliteimide) methylene‐bisanthranylide (PQHI) and its metal‐polymer complex PQHI‐Cu+ containing several types of functional groups (hydrazide, carboxyl, amide, and imide fragments) were synthesized. Dense thin‐film membranes were prepared to study transport properties of these polymers in the separation of a benzene and isopropanol (IPA) mixture via pervaporation. Comprehensive studies of structure, physical and mechanical properties of the novel membranes were carried out. Structure of the polymer films was characterized using scanning electron microscopy. Measurements of physical and mechanical properties showed good performance capabilities of polymers as membrane materials. Transport properties of the synthesized polymers in pervaporation of benzene–IPA mixtures were characterized by determination of total flux, separation factor, as well as permeability and selectivity of the films. It was experimentally found and confirmed by quantum chemical calculations that the novel PQHI‐based membranes are benzene selective due to the presence of functional groups capable of H‐bonding. The benzene/IPA separation factor is equal to 38 for the PQHI membrane in pervaporation of the mixture containing 20 wt% of benzene.

Factors Influencing the Antibacterial Activity of Chitosan and Chitosan Modified by Functionalization

The biomedical and therapeutic importance of chitosan and chitosan derivatives is the subject of interdisciplinary research. In this analysis, we intended to consolidate some of the recent discoveries regarding the potential of chitosan and its derivatives to be used for biomedical and other purposes. Why chitosan? Because chitosan is a natural biopolymer that can be obtained from one of the most abundant polysaccharides in nature, which is chitin. Compared to other biopolymers, chitosan presents some advantages, such as accessibility, biocompatibility, biodegradability, and no toxicity, expressing significant antibacterial potential. In addition, through chemical processes, a high number of chitosan derivatives can be obtained with many possibilities for use. The presence of several types of functional groups in the structure of the polymer and the fact that it has cationic properties are determinant for the increased reactive properties of chitosan. We analyzed the intrinsic properties of chitosan in relation to its source: the molecular mass, the degree of deacetylation, and polymerization. We also studied the most important extrinsic factors responsible for different properties of chitosan, such as the type of bacteria on which chitosan is active. In addition, some chitosan derivatives obtained by functionalization and some complexes formed by chitosan with various metallic ions were studied. The present research can be extended in order to analyze many other factors than those mentioned. Further in this paper were discussed the most important factors that influence the antibacterial effect of chitosan and its derivatives. The aim was to demonstrate that the bactericidal effect of chitosan depends on a number of very complex factors, their knowledge being essential to explain the role of each of them for the bactericidal activity of this biopolymer.

Immunomodulation by Human Milk Oligosaccharides: The Potential Role in Prevention of Allergic Diseases.

The prevalence and incidence of allergic diseases is rising and these diseases have become the most common chronic diseases during childhood in Westernized countries. Early life forms a critical window predisposing for health or disease. Therefore, this can also be a window of opportunity for allergy prevention. Postnatally the gut needs to mature, and the microbiome is built which further drives the training of infant's immune system. Immunomodulatory components in breastmilk protect the infant in this crucial period by; providing nutrients that contain substrates for the microbiome, supporting intestinal barrier function, protecting against pathogenic infections, enhancing immune development and facilitating immune tolerance. The presence of a diverse human milk oligosaccharide (HMOS) mixture, containing several types of functional groups, points to engagement in several mechanisms related to immune and microbiome maturation in the infant's gastrointestinal tract. In recent years, several pathways impacted by HMOS have been elucidated, including their capacity to; fortify the microbiome composition, enhance production of short chain fatty acids, bind directly to pathogens and interact directly with the intestinal epithelium and immune cells. The exact mechanisms underlying the immune protective effects have not been fully elucidated yet. We hypothesize that HMOS may be involved in and can be utilized to provide protection from developing allergic diseases at a young age. In this review, we highlight several pathways involved in the immunomodulatory effects of HMOS and the potential role in prevention of allergic diseases. Recent studies have proposed possible mechanisms through which HMOS may contribute, either directly or indirectly, via microbiome modification, to induce oral tolerance. Future research should focus on the identification of specific pathways by which individual HMOS structures exert protective actions and thereby contribute to the capacity of the authentic HMOS mixture in early life allergy prevention.

Multiplurifunctionalized Phosphorus Dendrimers: Selective Functionalization of P(X)CL2 Terminal Groups

Dendrimers are hyperbranched macromolecules constituted of repetitive branched units. They are synthesized step-by-step, a method which ensures a perfectly defined structure. This mini-review reports examples of rare “multiplurifunctionalized” dendrimers that have several types of functional groups precisely located on each terminal branching point. They are obtained thanks to the specificity of the reactivity of each Cl of P(X)Cl2 (X = generally S, but also O) terminal groups on the surface of poly(phosphorhydrazone) dendrimers.

Assessment of the Role of Micropore Size and N-Doping in CO2 Capture by Porous Carbons

The role of micropore size and N-doping in CO2 capture by microporous carbons has been investigated by analyzing the CO2 adsorption properties of two types of activated carbons with analogous textural properties: (a) N-free carbon microspheres and (b) N-doped carbon microspheres. Both materials exhibit a porosity made up exclusively of micropores ranging in size between <0.6 nm in the case of the pristine materials and up to 1.6 nm for the highly activated carbons (47% burnoff). The N-doped carbons possess ~3 wt % of N heteroatoms that are incorporated into several types of functional groups (i.e., pyrrole/pyridone, pyridine, quaternary, and pyridine-N-oxide). Under conventional operation conditions (i.e., T ~ 0-25 °C and P(CO2) ~ 0-1 bar), CO2 adsorption proceeds via a volume-filling mechanism, the size limit for volume-filling being ~0.7-0.8 nm. Under these circumstances, the adsorption of CO2 by nonfunctionalized porous carbons is mainly determined by the volume of the micropores with a size below 0.8 nm. It was also observed that the CO2 capture capacities of undoped and N-doped carbons are analogous which shows that the nitrogen functionalities present in these N-doped samples do not influence CO2 adsorption. Taking into account the temperature invariance of the characteristic curve postulated by the Dubinin theory, we show that CO2 uptakes can be accurately predicted by using the adsorption data measured at just one temperature.

Click‐ligation of coumarin to polyether polyols for polyurethane foams

AbstractA simple strategy for the synthesis and functionalization of polyurethanes is described. Anionic ring‐opening polymerization was combined with ‘click’ chemistry to synthesize polyols with fluorescent properties. This route allows the incorporation of a wide range of functionalities in the polyols with an easy, clean and highly selective process compatible with several types of functional groups. The proposed strategy opens the way to the production, in a cost‐effective way, of ‘smart’ polyurethanes with non‐conventional properties like fire retardancy, antimite properties, antibacterial properties, etc. Alkynyl groups were introduced into the polyol chains by the controlled addition of glycidyl propargyl ether as co‐monomer during a conventional anionic ring‐opening copolymerization with propylene oxide. Subsequently 4‐azidomethyl‐7‐methoxycoumarin molecules were introduced onto the alkynyl‐polyether polyols by copper‐catalysed cycloaddition reactions to produce end‐functionalized polyols. The chemical structure of the novel polyols was characterized using infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography with triple detection and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectroscopy. These characterization techniques confirmed the presence of a considerable amount of functional groups in the structure of the polyols. Finally, various fluorescent rigid foams, based on the functionalized polyols, were synthesized. Copyright © 2012 Society of Chemical Industry

Synthesis of new hybrid nanomaterials: promising systems for cancer therapy

Polyrotaxanes consisting of cyclodextrin rings, polyethylene glycol axes and quantum dot (QD) stoppers were synthesized and characterized. The molecular self-assembly of polyrotaxanes led to spindlelike nano-objects whose shape, size and position were dominated by QD stoppers. Due to their well-defined molecular self-assemblies, carbohydrate backbone, high functionality and several types of functional groups together with the high luminescence yield, synthesized hybrid nanostructures were recognized as promising candidates for biomedical applications. The potential applications of the molecular self-assemblies as drug-delivery systems was investigated by conjugation of doxorubicin (DOX) to their functional groups and then release the drug inside the cancer cells in mouse tissue connective fibroblast adhesive cell line L929. It was found that the molecular self-assemblies quickly transfer through the cell membrane and slowly release the drug into the intracellular environment. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and cell cycle assays showed that the molecular self-assemblies degrade back into individual molecules that can be broken down by the cell metabolically, confirming that they can be used as new drug-delivery systems with high treatment efficacy and minimum side effects for future cancer therapy, thus forming a firm foundation for further study and improvement. From the Clinical EditorThis study investigates polyrotaxanes consisting of cyclodextrin rings, polyethylene glycol axes and quantum dot (QD) stoppers as promising candidates for biomedical applications, including cancer therapy.

ChemInform Abstract: Chemistry Within Megamolecules: Regiospecific Functionalization After Construction of Phosphorus Dendrimers.

The synthesis of dendrimers including PN−PS linkages specifically placed at some generations within the dendrimeric architecture allows the grafting of several types of functional groups at site- and depth-specific locations in the internal layers. The synthesis is carried out up to the fourth generation starting from a difunctional core, or up to the third generation starting from a hexafunctional core. These dendrimers include 2, 6, or 18 PN−PS groups, depending on the type of core and the generation considered. The functional groups are introduced by several types of reactions. First, the strong polarization of the PN−PS linkage induces a facile reactivity with various alkyl triflates such as methyl, allyl, and propargyl triflates, leading to the formation of functionalized phosphonium salts [PNP−S−R]+. The alkylation induces a weakening of the P−S bond which is cleaved with P(NMe2)3, leading to the formation of internal aminophosphite groups [PN−P:]. These highly reactive tricoordinated phosphorus ato...

Dendritic macromolecules containing several types of functional groups

AbstractDendritic macromolecules containing several types of functional groups were successfully synthesized through divergent method. Poly(ethylene glycol) was functionalized using cyanuric chloride and it was reacted with p‐toluidine at room temperature and a macromolecule containing chloride and methyl functional groups (PEG‐Cl2‐Me2) was obtained. Substitution of chloride functional groups of PEG‐Cl2‐Me2 by hydroxyl functional groups led to a macromolecule containing methyl and hydroxyl functional groups (PEG‐Me2‐OH4). Hydroxyl functional groups of PEG‐Me2‐OH4 were reacted with cyanuric chloride and PEG‐Me2‐Cl8 was obtained. Finally, PEG‐Me2‐Cl8 was reacted with p‐aminophenol at room temperature and a macromolecule containing methyl, hydroxyl, and chloride functional groups (PEG‐Me2‐(PhOH)4‐Cl4) was obtained. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Chemistry within Megamolecules: Regiospecific Functionalization after Construction of Phosphorus Dendrimers

The synthesis of dendrimers including PN−PS linkages specifically placed at some generations within the dendrimeric architecture allows the grafting of several types of functional groups at site- and depth-specific locations in the internal layers. The synthesis is carried out up to the fourth generation starting from a difunctional core, or up to the third generation starting from a hexafunctional core. These dendrimers include 2, 6, or 18 PN−PS groups, depending on the type of core and the generation considered. The functional groups are introduced by several types of reactions. First, the strong polarization of the PN−PS linkage induces a facile reactivity with various alkyl triflates such as methyl, allyl, and propargyl triflates, leading to the formation of functionalized phosphonium salts [PNP−S−R]+. The alkylation induces a weakening of the P−S bond which is cleaved with P(NMe2)3, leading to the formation of internal aminophosphite groups [PN−P:]. These highly reactive tricoordinated phosphorus atoms are alkylated by methyl or allyl iodide, leading to a second series of functionalized dendrimers including phosphonium salts at some precise internal layers. A third series of internally functionalized dendrimers is obtained by the Staudinger reaction of functionalized azides with the aminophosphite internal groups. Isothiocyanate, aldehyde, and primary amine derivatives have been grafted regiospecifically in this way [PN−PN−R]. The reactivity of the aldehyde internal functions leading to the grafting of azides or crown-ethers is also described.

Chemical synthesis and hemisynthesis in the field of glycosaminoglycans.

Glycosaminoglycans are complex polysaccharides having several types of functional groups: acetamido, sulfamido, sulfate ester, carboxylate, primary and secondary hydroxyls. The biological function of these glycosaminoglycans is at least in part related to precise distributions of these functional groups on unique oligosaccharide sequences as illustrated by the binding of heparin to antithrombin III which involves a unique pentasaccharide sequence1.

Separation and characterization of asphaltenes from Saudi Arabian crudes

The separation and characterization of asphaltenes from the four marketable Saudi Arabian crudes have been carried out by various analytical techniques. The asphaltenes were precipitated by addition of excess n-pentane to the heavy ends of each crude; Arab heavy crude gave the greatest yield. Elemental analysis showed the greatest amount of nitrogen, indicating the presence of basic functional groups, in Arab heavy crude and the greatest amount of oxygen, indicating the presence of acidic functional groups, in Arab Berri crude. Arab heavy asphaltenes also showed the highest molecular weight and phenol interaction value. In a spot test the amount of n-pentane or n-heptane required for the precipitation of asphaltenes was greatest for Arab Berri crude. Infrared spectra showed characteristic frequencies indicating the presence of several types of functional groups.