02972nas a2200253 4500008004100000022001400041245012000055210006900175260011000244300001400354490000600368520200200374100001602376700002202392700001802414700002102432700002202453700002002475700002002495700002102515700003202536700002202568856012802590 2012 eng d a1744-683X00aCompetition between gelation and crystallisation of a peculiar multicomponent liquid system based on ammonium salts0 aCompetition between gelation and crystallisation of a peculiar m aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcFEB a3446-34560 v83 a

An exemplar competition between gelation and crystallisation phenomena was examined with an unusual synergistic multicomponent (organo) gelator solution (MGS), which consists of a well-defined methanolic solution of (1R, 2R)-1,2-diaminocyclohexane L-tartrate containing 2.4 equiv. of concentrated hydrochloric acid. The optimal composition of the MGS was determined through meticulous solubility, gelation and structural studies, which support a transient gelation mechanism based on the kinetic self-assembly of the tartrate salt driven by hydrogen-bonding interactions, involving ammonium nitrogen donors and hydroxyl oxygen acceptors, and electrostatic interactions. The hydrochloric acid is involved in the solubilisation of the salt through an ionic dissociation-exchange process, which ends up with the formation-precipitation of (1R, 2R)-1,2-diaminocyclohexane dihydrochloride. As a consequence, an irreversible destruction of the gel takes place, which indicates the metastable nature of this phase that cannot be accessed from the thermodynamically equilibrated state. Gelation of a variety of oxygenated and nitrogenated solvents with moderate polarity occurred efficiently using extremely low MGS concentrations at low temperatures, and the gel phase was confirmed by dynamic rheological measurements. Several features make the described MGS unique: (1) it is a multicomponent solution where each component and its stoichiometry play a key role in the reproducible formation and stabilization of the gels; (2) it is formed by simple, small, and commercially available chiral building blocks (dissolved in a well-defined solvent system), which are easily amenable for further modifications; (3) the gelation phenomenon takes place efficiently at low temperature upon warming up the isotropic solution, conversely to the typical gel preparation protocol; and (4) the formed organogels are not thermoreversible despite the non-covalent interactions that characterize the 3D-network.

1 aKapoor, Iti1 aSchoen, Eva-Maria1 aBachl, Jurgen1 aKuehbeck, Dennis1 aCativiela, Carlos1 aSaha, Subhadeep1 aBanerjee, Rahul1 aRoelens, Stefano1 aMarrero-Tellado, Jose, Juan1 aDiaz, David, Diaz uhttps://library.ncl.res.in/content/competition-between-gelation-and-crystallisation-peculiar-multicomponent-liquid-system-002454nas a2200205 4500008004100000022001400041245014800055210006900203260011000272300001600382490000700398520159900405100002002004700002202024700001702046700001802063700002202081700002002103856012502123 2012 eng d a0959-942800aFine-tuning the balance between crystallization and gelation and enhancement of CO2 uptake on functionalized calcium based MOFs and metallogels0 aFinetuning the balance between crystallization and gelation and  aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcMAY a14951-149630 v223 a

The synthesis, structure, gas adsorption and catalytic properties of a new 3D porous, crystalline metal-organic framework (Ca-5TIA-MOF) as well as stable viscoelastic metallogels (Ca-5TIA-Gel) are reported. Remarkably, the preparation of both types of materials can be carried out starting from the same organic ligand (i.e. 5-(1,2,4-triazoleyl) isophthalic acid (5TIA)), divalent metal ion (i.e. Ca(II)) and organic solvent (i.e. DMF). In this particular case, the presence of water in the solvent system favors the formation of a crystalline MOF, whereas a pure organic solvent induces gelation. The characterization of the materials was carried out using a series of techniques including XRD, FT-IR, TGA, TEM, SEM, SAXS and dynamic rheology. Experimental PXRD peaks of both Ca-5TIA-xerogel and Ca-5TIA-MOF matched reasonably well with simulated PXRD, suggesting the presence of, at least, some common structural elements in the 3D networks of both xerogel and crystalline phases. Moreover, the nature of the metal counteranion was found to have a critical influence on the gelation phenomenon. To the best of our knowledge, this report describes unprecedented Ca-based LMW-metallogels, as well as the first porous Ca-based MOF, which shows adsorption capacity for CO2 at 1 atm pressure. Interestingly, Ca-5TIA-xerogel presented 20% higher CO2-uptake than the crystalline Ca-5TIA-MOF at 1 atm and 298 K. Both Ca-5TIA-MOF and Ca-5TIA-Gel also displayed a modest catalytic activity towards the hydrosilylation of benzaldehyde, with slightly better performance for the gel phase material.

1 aMallick, Arijit1 aSchoen, Eva-Maria1 aPanda, Tamas1 aSreenivas, K.1 aDiaz, David, Diaz1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/fine-tuning-balance-between-crystallization-and-gelation-and-enhancement-co2-uptake-001838nas a2200265 4500008004100000022001400041245007400055210006900129260008600198300001400284490000600298520092700304653001701231653003301248653001201281653001901293653001201312100002101324700002401345700002201369700002201391700002901413700002201442856010801464 2013 eng d a1860-539700aC-C Bond formation catalyzed by natural gelatin and collagen proteins0 aCC Bond formation catalyzed by natural gelatin and collagen prot aTRAKEHNER STRASSE 7-9, FRANKFURT AM MAIN, 60487, GERMANYbBEILSTEIN-INSTITUTcJUN a1111-11180 v93 a

The activity of gelatin and collagen proteins towards C-C bond formation via Henry (nitroaldol) reaction between aldehydes and nitroalkanes is demonstrated for the first time. Among other variables, protein source, physical state and chemical modification influence product yield and kinetics, affording the nitroaldol products in both aqueous and organic media under mild conditions. Significantly, the scale-up of the process between 4-nitrobenzaldehyde and nitromethane is successfully achieved at 1 g scale and in good yield. A comparative kinetic study with other biocatalysts shows an increase of the first-order rate constant in the order chitosan < gelatin < bovine serum albumin (BSA) < collagen. The results of this study indicate that simple edible gelatin can promote C-C bond forming reactions under physiological conditions, which may have important implications from a metabolic perspective.

10abiocatalysis10acarbon-carbon bond formation10agelatin10aHenry reaction10aprotein1 aKuehbeck, Dennis1 aDhar, Basab, Bijayi1 aSchoen, Eva-Maria1 aCativiela, Carlos1 aGotor-Fernandez, Vicente1 aDiaz, David, Diaz uhttps://library.ncl.res.in/content/c-c-bond-formation-catalyzed-natural-gelatin-and-collagen-proteins-001490nas a2200253 4500008004100000022001400041245012300055210006900178260007700247300001400324490000700338520054500345653001100890653003300901653001600934653002400950653002900974100002001003700002201023700002201045700002201067700002001089856012701109 2013 eng d a0947-653900aProton-conducting supramolecular metallogels from the lowest molecular weight assembler ligand: a quote for simplicity0 aProtonconducting supramolecular metallogels from the lowest mole aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcJUL a9562-95680 v193 a

Oxalic acid has been proven to be the lowest molecular weight organic ligand able to form robust supramolecular metallogel networks in the presence of metal salts. In particular, two novel multifunctional metallogels were readily prepared at room temperature by simple mixing of stock solutions of Cu-II acetate monohydrate or Cu-II perchlorate hexahydrate and oxalic acid dihydrate. Formation of different polymorphs and unprecedented proton conduction under anhydrous conditions were also demonstrated with some of these materials.

10aCopper10alow-molecular-weight ligands10ametallogels10aproton conductivity10asupramolecular chemistry1 aSaha, Subhadeep1 aSchoen, Eva-Maria1 aCativiela, Carlos1 aDiaz, David, Diaz1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/proton-conducting-supramolecular-metallogels-lowest-molecular-weight-assembler-ligand-0