Metal-Ligand Polyhedra: Difference between revisions

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Eric Martz, Alexander Berchansky

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+Metal ions with square planar coordination, when mixed with bent bidentate ligands, can self-assemble into polyhedra of various sizes. Geometrical constraints limit the number of metal ions (vertices) to 6, 12, 24, 30, or 60 for entropically favored regular or semiregular polyhedra<ref>Coxeter, H. S. M., ''Regular Polytopes'', Dover Publications, New York, 3rd ed., 1973.</ref>. In 2010 was reported self-assembly of a "giant" polyhedron with 24 metal ions, and a hollow spherical interior 36 &Aring; in diameter. The self-assembly process demonstrates emergent behavior, and is reminiscent of the self-assembly of large biological structures, such as virus capsids. Such nano-spheres can also be functionalized to create, among other possibilities, synthetic receptors and nanoreactors.
 ==M24L48 Polyhedron (26 Faces)==
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 <applet size='400' frame='true' align='right'
 scene='Metal-Ligand_Polyhedra/Polyhedron_main_chains/4' />
-Metal ions with square planar coordination, when mixed with bent bidentate ligands, can self-assemble into polyhedra of various sizes. Geometrical constraints limit the number of metal ions (vertices) to 6, 12, 24, 30, or 60 for entropically favored regular or semiregular polyhedra<ref>Coxeter, H. S. M., ''Regular Polytopes'', Dover Publications, New York, 3rd ed., 1973.</ref>. Shown at right (<scene name='Metal-Ligand_Polyhedra/Polyhedron_main_chains/4'>restore initial scene</scene>) is the "main chain" of a crystallographic model for the largest such structure reported as of May, 2010<ref name="sun-fujita-2010" >PMID: 20430973</ref>. <scene name='Metal-Ligand_Polyhedra/Polyhedron_main_chains/5'>24 palladium ions</scene> form the vertices of a 26-face polyhedron<ref>M24L48 forms a 26-faced ''rhombicubooctahedron'' with 18 square faces and 8 triangular faces. In this instance, the rectangular faces are very close to squares 13.35 &Aring;ngstroms on a side.</ref>. Three square faces and one triangular face meet at each vertex.
+Shown at right (<scene name='Metal-Ligand_Polyhedra/Polyhedron_main_chains/4'>restore initial scene</scene>) is the "main chain" of a crystallographic model for the largest such structure reported as of May, 2010<ref name="sun-fujita-2010" >PMID: 20430973</ref>. <scene name='Metal-Ligand_Polyhedra/Polyhedron_main_chains/5'>24 palladium ions</scene> form the vertices of a 26-face polyhedron<ref>M24L48 forms a 26-faced ''rhombicubooctahedron'' with 18 square faces and 8 triangular faces. In this instance, the rectangular faces are very close to squares 13.35 &Aring;ngstroms on a side.</ref>. Three square faces and one triangular face meet at each vertex.
 Each palladium ion is coordinated by <scene name='Metal-Ligand_Polyhedra/Polyhedron_main_chains/6'>four nitrogens</scene>. The nitrogens are bridged by a <scene name='Metal-Ligand_Polyhedra/Single_main_chain_ligand/1'>dipyridylthiophene</scene> ("ligand"). There are two ligand molecules (L) per metal ion (M); hence, this structure is called '''M24L48'''.