Metal-Ligand Polyhedra: Difference between revisions
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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 Å in diameter<ref name="sun-fujita-2010" />. 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<ref name="news-and-views" />. | <StructureSection load='' size='450' side='right' scene='40/405708/Polyhedron_main_chains/11' caption=''> | ||
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 Å in diameter<ref name="sun-fujita-2010" />. 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<ref name="news-and-views" />. A 2022 extensive review<ref name="2022rev">McTernan, Charlie T., Jack A. Davies, and Jonathan R. Nitschke, [https://pubs.acs.org/doi/10.1021/acs.chemrev.1c00763 Beyond Platonic: How to Build Metal–Organic Polyhedra Capable of Binding Low-Symmetry, Information-Rich Molecular Cargoes], Chem. Rev. 2022, 122, 10393−10437.</ref> cites potential applications in sensing, catalysis, and drug delivery<ref name="2015apps">PMID: 25319756</ref><ref name="2021biomed">PMID: 32255835</ref>. | |||
==M24L48 Polyhedron (26 Faces)== | ==M24L48 Polyhedron (26 Faces)== | ||
Shown at right (<scene name='40/405708/Polyhedron_main_chains/11'>restore initial scene</scene>) is a crystallographic model for the largest metal-ligand polyhedron reported as of May, 2010<ref name="sun-fujita-2010" >PMID: 20430973</ref>. It has an interior cavity about 32 Å in diameter. <scene name='Metal-Ligand_Polyhedra/Polyhedron_main_chains/10'>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 Ångstroms on a side.</ref>. Three square faces and one triangular face meet at each vertex. | |||
Shown at right (<scene name=' | <span style="font-size:200%;">{{Template:ColorKey_Element_C}}, {{Template:ColorKey_Element_N}}, '''<span style="background-color:black;color:yellow;"> S </span>, {{Font color|#00b000|Pd}}'''</span> | ||
Each palladium ion is coordinated by <scene name='Metal-Ligand_Polyhedra/Polyhedron_main_chains/9'>four nitrogens</scene>. The nitrogens are bridged by a <scene name='Metal-Ligand_Polyhedra/Single_main_chain_ligand/2'>dipyridylthiophene</scene> ("ligand"). There are two ligand molecules (L) per metal ion (M); hence, this structure is called '''M24L48'''. | Each palladium ion is coordinated by <scene name='Metal-Ligand_Polyhedra/Polyhedron_main_chains/9'>four nitrogens</scene>. The nitrogens are bridged by a <scene name='Metal-Ligand_Polyhedra/Single_main_chain_ligand/2'>dipyridylthiophene</scene> ("ligand"). There are two ligand molecules (L) per metal ion (M); hence, this structure is called '''M24L48'''. | ||
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==Ligand Angle vs. Polyhedron Size== | ==Ligand Angle vs. Polyhedron Size== | ||
* '''149<sup>o</sup>: M24L48.''' The dipyridylthiphene ligand described above, in the M24L48 polyhedron, has a bend angle of 149<sup>o</sup><ref name="sun-fujita-2010" />. | |||
* '''149<sup>o</sup>: M24L48.''' The dipyridylthiphene ligand | * '''127<sup>o</sup>: M12L24.''' A ligand with a sharper bend of 127<sup>o</sup> (dipyridylfuran<ref>Dipyridylfuran differs from dipyridylthiophene in that oxygen replaces the sulfur.</ref>) forms a <scene name='Metal-Ligand_Polyhedra/M12l24_single_polyhedron/2'>smaller polyhedron, M12L24</scene><ref name="tominaga-fujita-2004">PMID: 15455450</ref>. | ||
* '''127<sup>o</sup>: M12L24 | |||
Interestingly, mixtures of the two ligands (149 and 127 degrees) form only one size of polygon: a 3:7 mixture respectively (and up to 10:0) forms only M24L48, while a 2:8 mixture (and down to 0:10) forms only M12L24<ref name="sun-fujita-2010" />. | Interestingly, mixtures of the two ligands (149 and 127 degrees) form only one size of polygon: a 3:7 mixture respectively (and up to 10:0) forms only M24L48, while a 2:8 mixture (and down to 0:10) forms only M12L24<ref name="sun-fujita-2010" />. | ||
* '''90<sup>o</sup>: M6L12.''' A ligand with an even sharper bend of 90<sup>o</sup> forms M6L12<ref name="suzuki-fujita-2009">PMID: 19294246</ref>. | * '''90<sup>o</sup>: M6L12.''' A ligand with an even sharper bend of 90<sup>o</sup> forms M6L12<ref name="suzuki-fujita-2009">PMID: 19294246</ref>. | ||
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*M24L48 main chain atoms only: [[Image:M24L48_main_chains.pdb]] | *M24L48 main chain atoms only: [[Image:M24L48_main_chains.pdb]] | ||
**[http://firstglance.jmol.org/fg.htm?mol= | **[http://firstglance.jmol.org/fg.htm?mol=https://proteopedia.org/wiki/images/a/ad/M24L48_main_chains.pdb View in FirstGlance in Jmol] | ||
*M24L48 all atoms: [[Image:M24l48-single-polyhedron.pdb]] (This is actually in the XYZ atomic coordinate file format.) | *M24L48 all atoms: [[Image:M24l48-single-polyhedron.pdb]] (This is actually in the XYZ atomic coordinate file format.) | ||
**[http://firstglance.jmol.org/fg.htm?mol= | **[http://firstglance.jmol.org/fg.htm?mol=https://proteopedia.org/wiki/images/b/ba/M24l48-single-polyhedron.pdb View in FirstGlance in Jmol], then: | ||
** Views tab, Vines/Sticks. | |||
*M12L24 all atoms: [[Image:M12L24-single-polyhedron.pdb]] | *M12L24 all atoms: [[Image:M12L24-single-polyhedron.pdb]] | ||
**[http://firstglance.jmol.org/fg.htm?mol= | **[http://firstglance.jmol.org/fg.htm?mol=https://proteopedia.org/wiki/images/d/d5/M12L24-single-polyhedron.pdb View in FirstGlance in Jmol] | ||
</StructureSection> | |||
==References and Notes== | ==References and Notes== | ||
<references/> | <references/> | ||