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JournalISSN: 0947-6539

Chemistry: A European Journal 

Wiley
About: Chemistry: A European Journal is an academic journal. The journal publishes majorly in the area(s): Catalysis & Enantioselective synthesis. It has an ISSN identifier of 0947-6539. Over the lifetime, 34889 publications have been published receiving 1232298 citations.


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Journal ArticleDOI
TL;DR: Analysis of the hydration process by solid-state NMR has clearly indicated that the trapped water molecules interact with the carboxylate groups through hydrogen bonds, but do not affect the hydroxyl species bridging the aluminum atoms.
Abstract: Aluminum 1,4-benzenedicarboxylate Al(OH)[O2CC6H4CO2]⋅ [HO2CC6H4CO2H]0.70 or MIL-53 as (Al) has been hydrothermally synthesized by heating a mixture of aluminum nitrate, 1,4-benzenedicarboxylic acid, and water, for three days at 220 °C. Its 3 D framework is built up of infinite trans chains of corner-sharing AlO4(OH)2 octahedra. The chains are interconnected by the 1,4-benzenedicarboxylate groups, creating 1 D rhombic-shaped tunnels. Disordered 1,4-benzenedicarboxylic acid molecules are trapped inside these tunnels. Their evacuation upon heating, between 275 and 420 °C, leads to a nanoporous open-framework (MIL-53 ht (Al) or Al(OH)[O2CC6H4CO2]) with empty pores of diameter 8.5 A. This solid exhibits a Langmuir surface area of 1590(1) m2 g−1 together with a remarkable thermal stability, since it starts to decompose only at 500 °C. At room temperature, the solid reversibly absorbs water in its tunnels, causing a very large breathing effect and shrinkage of the pores. Analysis of the hydration process by solid-state NMR (1H, 13C, 27Al) has clearly indicated that the trapped water molecules interact with the carboxylate groups through hydrogen bonds, but do not affect the hydroxyl species bridging the aluminum atoms. The hydrogen bonds between water and the oxygen atoms of the framework are responsible for the contraction of the rhombic channels. The structures of the three forms have been determined by means of powder X-ray diffraction analysis. Crystal data for MIL-53 as (Al) are as follows: orthorhombic system, Pnma (no. 62), a = 17.129(2), b = 6.628(1), c = 12.182(1) A; for MIL-53 ht (Al), orthorhombic system, Imma (no. 74), a = 6.608(1), b = 16.675(3), c = 12.813(2) A; for MIL-53 lt (Al), monoclinic system, Cc (no. 9), a = 19.513(2), b = 7.612(1), c = 6.576(1) A, β = 104.24(1)°.

1,737 citations

Journal ArticleDOI
TL;DR: A self-consistent system of additive covalent radii, R(AB)=r(A) + r(B), is set up for the entire periodic table, Groups 1-18, Z=1-118, and is close to the methyl-based one of Suresh and Koga and its predecessors.
Abstract: A self-consistent system of additive covalent radii, R(AB)=r(A) + r(B), is set up for the entire periodic table, Groups 1-18, Z=1-118. The primary bond lengths, R, are taken from experimental or theoretical data corresponding to chosen group valencies. All r(E) values are obtained from the same fit. Both E-E, E-H, and E-CH 3 data are incorporated for most elements, E. Many E-E' data inside the same group are included. For the late main groups, the system is close to that of Pauling. For other elements it is close to the methyl-based one of Suresh and Koga [J. Phys. Chem. A 2001, 105, 5940] and its predecessors. For the diatomic alkalis MM' and halides XX', separate fits give a very high accuracy. These primary data are then absorbed with the rest. The most notable exclusion are the transition-metal halides and chalcogenides which are regarded as partial multiple bonds. Other anomalies include H 2 and F 2 . The standard deviation for the 410 included data points is 2.8 pm.

1,585 citations

Journal ArticleDOI
TL;DR: Aromatic substrates with oxygen- and nitrogen-containing substituents undergo oxidative coupling with alkynes and alkenes under rhodium catalysis through regioselective C-H bond cleavage, creating fused-ring systems through these reactions.
Abstract: Aromatic substrates with oxygen- and nitrogen-containing substituents undergo oxidative coupling with alkynes and alkenes under rhodium catalysis through regioselective C-H bond cleavage. Coordination of the substituents to the rhodium center is the key to activate the C-H bonds effectively. Various fused-ring systems can be constructed through these reactions.

1,538 citations

Journal ArticleDOI
TL;DR: Investigating the growth mechanisms for silver nanocubes, nanowires, and nanospheres produced through a polymer-mediated polyol process found that the crystallinity of a seed and the extent of the PVP coverage on the seed were both instrumental in controlling the morphology of final product.
Abstract: The concept of shape-controlled synthesis is discussed by investigating the growth mechanisms for silver nanocubes, nanowires, and nanospheres produced through a polymer-mediated polyol process. Experimental parameters, such as the concentration of AgNO(3) (the precursor to silver), the molar ratio between poly(vinylpyrrolidone) (PVP, the capping agent) and AgNO(3), and the strength of chemical interaction between PVP and various crystallographic planes of silver, were found to determine the crystallinity of seeds (e.g., single crystal versus decahedral multiply twinned particles). In turn, the crystallinity of a seed and the extent of the PVP coverage on the seed were both instrumental in controlling the morphology of final product. The ability to generate silver nanostructures with well-defined morphologies provides a great opportunity to experimentally and systematically study the relationship between their properties and geometric shapes.

1,474 citations

Journal ArticleDOI
TL;DR: Water proved to be essential for the formation of well-ordered Zr-bdc-NH(2) and the first single-crystal structural analysis of a ZR-based metal-organic framework.
Abstract: We present an investigation on the influence of benzoic acid, acetic acid, and water on the syntheses of the Zr-based metal-organic frameworks Zr-bdc (UiO-66), Zr-bdc-NH(2) (UiO-66-NH(2)), Zr-bpdc (UiO-67), and Zr-tpdc-NH(2) (UiO-68-NH(2)) (H(2) bdc: terephthalic acid, H(2) bpdc: biphenyl-4,4'-dicarboxylic acid, H(2) tpdc: terphenyl-4,4''-dicarboxylic acid). By varying the amount of benzoic or acetic acid, the synthesis of Zr-bdc can be modulated. With increasing concentration of the modulator, the products change from intergrown to individual crystals, the size of which can be tuned. Addition of benzoic acid also affects the size and morphology of Zr-bpdc and, additionally, makes the synthesis of Zr-bpdc highly reproducible. The control of crystal and particle size is proven by powder XRD, SEM and dynamic light scattering (DLS) measurements. Thermogravimetric analysis (TGA) and Ar sorption experiments show that the materials from modulated syntheses can be activated and that they exhibit high specific surface areas. Water proved to be essential for the formation of well-ordered Zr-bdc-NH(2) . Zr-tpdc-NH(2), a material with a structure analogous to that of Zr-bdc and Zr-bpdc, but with the longer, functionalized linker 2'-amino-1,1':4',1''-terphenyl-4,4''-dicarboxylic acid, was obtained as single crystals. This allowed the first single-crystal structural analysis of a Zr-based metal-organic framework.

1,249 citations

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Performance
Metrics
No. of papers from the Journal in previous years
YearPapers
20212,088
20202,129
20192,050
20182,516
20172,427
20162,349