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Binding Groups (binding + groups)
Selected AbstractsEfficient Removal of Anionic Surfactants Using Mesoporous Functionalised Hybrid MaterialsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2009Carmen Coll Abstract A new hybrid system for surfactant removal from water has been developed using mesoporous material (MCM-41) functionalised with suitable binding groups. Solid S1, S2 and S3 were prepared by reaction of the mesoporous material with N -methyl- N, -(propyltrimethoxysilyl)imidazolium chloride, (3-aminopropyl)trimethoxysilane or 4-[(triethoxysilylpropylthio)methyl]pyridine, respectively. The functionalised materials were characterised following standard solid-state techniques. The final prepared solids consist of a siliceous MCM-41-type mesoporous support with the surface decorated by imidazolium, amine and pyridine binding groups suitable for anion coordination. Equilibrium adsorption studies of linear alkylbenzenesulfonate (LAS) using S1, S2 and S3 in water have been carried out. The obtained adsorption data were correlated with a Langmuir isotherm model that gives an acceptable description of the experimental data. The maximum surfactant uptake/binding site (mol,mol,1) and the surfactant adsorption capacity (mmol,g,1) for materials S1, S2 and S3 were calculated. S1 shows a positive-charged functionalised surface that is independent of the pH of the solution, whereas S2 and S3 are functionalised with neutral groups that need to be protonated in order to display electrostatic binding interactions with the anionic surfactants. Therefore, whereas the adsorption capacity of S1 is pH-independent, S2 and S3 display larger LAS adsorption at acidic pH. The adsorption ability at a certain pH follows the order S1 >> S3 > S2. A remarkable maximum surfactant adsorption of 1.5 mmol per gram of material was observed for S1 at neutral pH. S2 and S3 behave as poorer adsorbents and show maximum surfactant adsorption of 0.197 and 0.335 mmol per gram of material, respectively, at pH 2.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Iron(III) Chelation: Tuning of the pH Dependence by Mixed LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2003Anne-Marie Albrecht-Gary Abstract The iron(III) chelating properties of two heteropodands with 8-hydroxyquinoline and catechol binding groups were examined and compared to those of the corresponding homopodal analogues, O-TRENSOX and TRENCAMS. Like the parent homopodands, the two heteropodands are based on the TREN scaffold and the chelating units are connected by amide groups, TRENSOX2CAMS having two 8-hydroxyquinoline and one catechol arms and TRENSOXCAMS2 one 8-hydroxyquinoline and two catechol moieties. The aqueous coordination chemistry of these ligands was examined by potentiometric and spectrophotometric methods in combination with 1H NMR spectroscopy. The respective pFeIII values showed a cooperative effect of the mixed chelating units. Moreover, the pFeIII dependence on pH showed that the mixed ligands exhibit a higher complexing ability than the parent ligands over the pH range 5,9 which is of biological relevance. This result could be of great interest for medical applications. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Co-operative effect of the isoforms of type III antifreeze protein expressed in Notched-fin eelpout, Zoarces elongatus KnerFEBS JOURNAL, Issue 2 2005Yoshiyuki Nishimiya We found that Notched-fin eelpout, which lives off the north east coast of Japan, expresses an antifreeze protein (AFP). The liver of this fish contains DNAs that encode at least 13 type III AFP isoforms (denoted nfeAFPs). The primary sequences of the nfeAFP isoforms were categorized into SP- and QAE-sephadex binding groups, and the latter were further divided into two subgroups, QAE1 and QAE2 groups. Ice crystals observed in HPLC-pure nfeAFP fractions are bipyramidal in shape with different ratios of c and a axes, suggesting that all the isoforms are able to bind ice. We expressed five recombinant isoforms of nfeAFP and analyzed the thermal hysteresis (TH) activity of each as a function of protein concentration. We also examined the change in activity on mixing the isoforms. TH was estimated to be 0.60 °C for the QAE1 isoform, 0.11 °C for QAE2, and almost zero for the SP isoforms when the concentrations of these isoforms was standardized to 1.0 mm. Significantly, the TH activity of the SP isoforms showed concentration dependence in the presence of 0.2 mm QAE1, indicating that the less active SP isoform becomes ,active' when a small amount of QAE1 is added. In contrast, it does not become active on the addition of another SP isoform. These results suggest that the SP and QAE isoforms of type III AFP have different levels of TH activity, and they accomplish the antifreeze function in a co-operative manner. [source] Mesoporous Hybrid Materials Containing Nanoscopic "Binding Pockets" for Colorimetric Anion Signaling in Water by using Displacement AssaysCHEMISTRY - A EUROPEAN JOURNAL, Issue 36 2009Marķa Comes Abstract Mesoporous solids functionalized with anion-binding groups have proved to be suitable anion hosts and have been used in selective colorimetric displacement assays. The material UVM-7, a mesoporous MCM41-type support characterized by the presence of nanometric mesoporous particle conglomerates, was selected as inorganic scaffolding. Reaction of the template-free UVM-7 solid with 3-aminopropyltriethoxysilane (1) yielded solid S1, from which the derivatives S2 and S3 were obtained by reaction with 2-methylthio-2-imidazoline hydroiodide (2) and butyl isocyanate (3), respectively. Solids S4 and S5 were prepared by reaction of the starting mesoporous UVM-7 scaffolding with N -methyl- N,-propyltrimethoxysilyl imidazolium chloride (4) and with 3-(trimethoxysilyl)propyl- N,N,N -trimethylammonium chloride (5), respectively. The solids synthesized contain mesoporous binding pockets that can interact with anions through electrostatic attractive forces (S1, S2, S4, S5) and hydrogen-bonding interactions (S1, S2, S3, S4). These functionalized solids were loaded with a dye (d) capable of interacting coordinatively with the anchored binding sites, in our case 5-carboxyfluorescein, to yield the hybrid materials S1d, S2d, S3d, S4d and S5d. These dye-containing solids are the signaling reporters. Their sensing ability towards a family of carboxylates, namely acetate, citrate, lactate, succinate, oxalate, tartrate, malate, mandelate, glutamate and certain nucleotides, has been studied in pure water at pH,7.5 (Hepes, 0.01,mol,dm,3). In the sensing protocol, a particular analyte may be bonded preferentially by the nanoscopic functionalized pocket, leading to delivery of the dye to the solution and resulting in colorimetric detection of the guest. The response to a given anion depends on the characteristics of the binding pockets and the specific interaction of the anion with the binding groups in the mesopores. We believe that the possibility of using a wide variety of mesoporous supports that can easily be functionalized with anion-binding sites, combined with suitable dyes as indicators, make this approach significant for opening new perspectives in the design of chromogenic assays for anion detection in pure water. [source] | ||||||||||