Coordination polymers
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2008-06-04T16:42:51Z
Magnetawan
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/* Reviews of coordination polymers */
'''Coordination polymer''' is the term given in ''[[inorganic chemistry]]'' to a metal [[coordination compound]] where a [[ligand]] [[bridge]]s between metal centres, where each metal centre binds to more than one [[ligand]] to create an infinite [[array]] of [[metal]] centres e.g a [[polymer]]. The majority of common halides and oxides are coordination polymers. More conventionally, the term coordination polymer is reserved for compounds where the metals are bridged by polyatomic ligands, such as [[cyanide]], [[carboxylic acid|carboxylate]]s. One of the first coordination compounds ever studied systematically, [[Prussian blue]], is a coordination polymer based on Fe-CN-Fe linkages.
==Carboxylates==
Examples of such materials include many of the metal salts of [[benzene]]-1,3,5-tricarboxylic acid ([[trimesic acid]], '''BTC'''). This tricarboxylic acid has been one of the most popular bridging ligands used in the synthesis of these polymers. The first major paper on the topic of coordination polymers using BTC was by Yaghi et al. <ref>O.M. Yaghi, Hailian Li, and T. L. Groy in ''J. Am. Chem. Soc.'', 1996, '''118'''(38), 9096 - 9101</ref>. The senior author on this paper was O. M. Yaghi who has since published a large amount on coordination polymers.
A series of solid polymers have been made via the reaction of this tri-[[acid]] with salts of [[cobalt]], [[manganese]], [[zinc]], [[cadmium]], [[copper]], [[lead]], [[uranium]] and other metals. Other di- and tricarboxylic acids have been used to form polymers <ref>An example of a research group active in this field can be found at [http://cheminfo.chem.ou.edu/~rph/rph/lab/index.html]</ref>
One rare but important pair of acids are 4,6-dinitro-5-hydroxyisophthalic acid and 2,4-dinitro-3-hydroxybenzoic acid which are formed by the reaction of a mixture of [[lead(II) nitrate]], [[nickel nitrate]], [[pyridine]] and 5-hydroxy[[isophthalic acid]] inside an [[autoclave]]. The resulting acids then form mixed lead/[[nickel]] polymers <ref>See Xiaoju Li, Rong Cao, Zhengang Guo and Jian Lü, ''Chemical Communications'', 2006, 1938 - 1940 (DOI: 10.1039/b600684a).</ref>
It is the case that by using a non bridging [[ligand]] such as 2,2'-[[bipyridine]] on a first row [[transition metal]] (such as [[zinc]], [[manganese]] or [[cobalt]]) a less [[cross-link|cross linked]] polymer can be obtained than that which is formed by the reaction of '''BTC''' and the simple metal salt in the absence of the non bridging ligand. <ref>For example compare the solids in M.J.Plater, M.R.St. J. Foreman, E. Coronado, C.J. Gomez-Garcia, A.M.Z. Slawin ''J.Chem. Soc.,Dalton Trans.'', 1999, 4209 (where 2,2'-bipy is used as an additive for forming solids from '''BTC''' and zinc, manganese and cobalt [[acetates]]) with the solids formed without bipy for examples see D. Cheng, M.A. Khan and R.P. Houser, ''Cryst. Growth Des.'', 2004, '''4''', 599-604.</ref>
A common type of solid formed using '''BTC''' is a layered solid where the benzene rings are [[coplanar]] with the planes. This is a layered solid which is similar to [[graphite]] in the fact that it is colvently bonded layers which are arranged on top of each other <ref>L.A. Borkowski and C.L. Cahill, ''Acta Crystallogr.,Sect. E:Struct. Rep. Online'', 2004, '''60''', m198. This is a [[uranium]] containing polymer which has [[uranyl]] units linked by the '''BTC''' units.</ref>
==Polypyridines==
Another common synthetic method is to react a poly[[pyridine]] whose geometry renders it unable to [[chelate]] a metal atoms with all its [[nitrogen]] atoms. For instance 4,4'-[[bipyridine]] can be used to form polymers with many metals. One of the most developed metals is [[cadmium]], it is the case that cadmium [[nitrate]] reacts with a wide array of polypyridines to form different solids. One of the key developments is the use of exotic polypyridines where the pyridine rings are separated by [[covalent]] spacers such as prop-1,3-diyl groups.<ref>F.A.A. Paz and J. Klinowski, ''Inorganic Chemistry'', 2004, '''43''', 3948 described in the literature a coordination polymer which contains a polypyridine and trimesate groups.</ref>
==Bridging at a single atom==
Yet another method of forming coordination polymers is to use a donor atom which bears more than one [[lone pair]] for instance this type of bridging has been seen in [[uranium]] fluorides and the [[lead]] [[carboxylate]]s.
[[Image:UF5solid.jpg|400px|It is clear that the UF5 solid is a 1D coordination polymer]]
==References==
{{Reflist}}
===Illustrative discoveries===
*Jensen, K. A., "Nickel mercaptides", Z. anorg. Chem., 1944, volume 252, pages 227-33 (pioneering report on thiolato-bridged coordination polymer)
*Schmitz-Dumont, O.; Pilzecker, J. and Piepenbrink, H. F., "The amides of trivalent Cr and Co", Z. anorg. allgem. Chem., 1941, volume 248, pages 175-207 (discovery of NH<sub>2</sub>-bridged polymers).
*Ludi, A., "[[Prussian blue]], an Inorganic Evergreen", Journal of Chemical Education 1981, volume 58, 1013.
===Reviews of coordination polymers===
*Mueller, U., et al., "Metal-organic frameworks-prospective industrial applications", Journal of Materials Chemistry, 2006, volume 16, pages 626-636.
*Uemura, K.; Matsuda, R. and Kitagawa, S., "Flexible microporous coordination polymers", Journal of Solid State Chemistry, 2005, volume 178, pages 2420-2429
*Kitagawa, S.; Kitaura, R. and Noro, S.-i., "Functional porous coordination polymers", Angewandte Chemie, International Edition, 2004, volume 43, pages 2334-2375.
*Kitagawa, S. and Noro, S., "Coordination polymers: infinite systems", Comprehensive Coordination Chemistry II, 2004, volume 7, pages 231-261
*Kesanli, B. and Lin, W., "Chiral porous coordination networks: rational design and applications in enantioselective processes", Coordination Chemistry Reviews, 2003, volume 246, pages 305-326.
*Carlucci, L.; Ciani, G. and Proserpio, D. M., "Polycatenation, polythreading and polyknotting in coordination network chemistry", Coordination Chemistry Reviews, 2003, volume 246, pages 247-289.
*Batten, S. R. and Murray, K. S., "Structure and magnetism of coordination polymers containing dicyanamide and tricyanomethanide", Coordination Chemistry Reviews, 2003, volume 246, pages 103-130.
*[[Richard J. Puddephatt|Puddephatt, R. J.]], "Coordination polymers: polymers, rings and oligomers containing gold(I) centres", Coordination Chemistry Reviews, 2001, volumes 216-217, pages 313-332.
*Zaworotko, M. J., "Superstructural diversity in two dimensions: crystal engineering of laminated solids", Chemical Communications, 2001, pages 1-9.
*Robson, R., "A net-based approach to coordination polymers", Dalton, 2000, pages 3735-3744.
==See also==
* [[Crystal engineering]]
[[Category:Organometallic chemistry]]
[[Category:Coordination chemistry]]
[[Category:Chemical reactions]]
[[Category:Polymer chemistry]]
[[ja:配位高分子]]