Saturday, March 13, 2010

Composition of symmetry led to a surprise.

Usually, you expect the two compounds of similar composition premises, the connectivity of atoms with atoms and also symmetrical so that is chemically identical. But the scientists who investigate the metal organic framework have found a surprising exception to this rule by identifying the two isomers with the same symmetry and bound but different gas storage properties.

A team led by Ma Shengqian at Argonne National Laboratory, Illinois, United States, investigating the molecular tetracarboxylate like a twig (ebdc) which can be attached to a metal atom from one part of any bond on four points, one at each corner of the rectangle. When heated with copper salt at a temperature of 75 ° C, a crystalline phase formed (-phase) and temperature 65 ° C a phase with properties - properties different from that formed (-phase).

So far, it seems normal. But when Ma finished crystal analysis on these two compounds, he found that they have the same composition, the same connectivity and the atom to the same symmetry. 'This type of symmetry that maintains this isomerism has not been studied previously in metal organic framework, "said Ma.

Isomer has the same symmetry but different properties = properties
The key to what has happened lies in the ligand, clearly Ma. In-phase, a ligand bound to the tip end of each unit of copper, which in-phase, they are bound together. This makes the biggest ring in-phase rather than in-phase. Thus, although the same chemical units joined together - each with the same sort of bond and the overall symmetry of the same, the property - the property is still different. In particular, the area available for hydrogen absorption was significantly higher in-isomer: 'This means that it is possible to boost gas storage capacity by finding isomers - the new isomer of unknown structure,' said Ma. Paul Forster, a materials chemist at the University of Nevada, Las Vegas, United States, was fascinated by what he called a form of isomerism is 'highly unusual'. 'Structure - which is identical in structure and konektifitasnya composition, but differ on the hole geometry, provides a unique opportunity to address important questions related to the kinetic and thermodynamics of the synthesis of hybrid materials, "he said.

Usually, you expect the two compounds of similar composition premises, the connectivity of atoms with atoms and also symmetrical so that is chemically identical. But the scientists who investigate the metal organic framework have found a surprising exception to this rule by identifying the two isomers with the same symmetry and bound but different gas storage properties.

A team led by Ma Shengqian at Argonne National Laboratory, Illinois, United States, investigating the molecular tetracarboxylate like a twig (ebdc) which can be attached to a metal atom from one part of any bond on four points, one at each corner of the rectangle. When heated with copper salt at a temperature of 75 ° C, a crystalline phase formed (-phase) and temperature 65 ° C a phase with properties - properties different from that formed (-phase).

So far, it seems normal. But when Ma finished crystal analysis on these two compounds, he found that they have the same composition, the same connectivity and the atom to the same symmetry. 'This type of symmetry that maintains this isomerism has not been studied previously in metal organic framework, "said Ma.

Isomer has the same symmetry but different properties = properties
The key to what has happened lies in the ligand, clearly Ma. In-phase, a ligand bound to the tip end of each unit of copper, which in-phase, they are bound together. This makes the biggest ring in-phase rather than in-phase. Thus, although the same chemical units joined together - each with the same sort of bond and the overall symmetry of the same, the property - the property is still different. In particular, the area available for hydrogen absorption was significantly higher in-isomer: 'This means that it is possible to boost gas storage capacity by finding isomers - the new isomer of unknown structure,' said Ma. Paul Forster, a materials chemist at the University of Nevada, Las Vegas, United States, was fascinated by what he called a form of isomerism is 'highly unusual'. 'Structure - which is identical in structure and konektifitasnya composition, but differ on the hole geometry, provides a unique opportunity to address important questions related to the kinetic and thermodynamics of the synthesis of hybrid materials, "he said.

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