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'''Polypyridine complexes''' are compounds[[coordination incomplex]]es whichcontaining apolypyridine polypyridineligands, such as [[2,2'-bipyridine]], 1,10-[[phenanthroline]], or 2,2';6'2"-terpyridine, coordinates to a metal [[Ion (physics)|ionterpyridine]].
Polypyridine compoundsPolypyridines are multidentate [[ligand|ligands]]s whichthat haveconfer characteristic properties, suchto asthe photosensitization. Themetal complexes arethat verythey stableform. to light,Some electricity,complexes andstrongly heatabsorb becauselight thevia bondsa betweenprocess the centralcalled metal-to-ligand ion[[Intervalence andcharge polypyridinetransfer|charge ligands aretransfer]] usually very strong; furthermore(MLCT).<ref>Balzani, polypyridine itself is generally very stableV., The compounds have peculiar opticalJuris, electrochemicalA., "Photochemistry and magneticphotophysics properties.of SomeRu(II)-polypyridine complexes exhibitin athe strongBologna absorptiongroup. bandFrom inearly thestudies visibleto lightrecent regiondevelopments", whichCoord. isChem. calledRev. metal-to-ligand2001, charge211, transfer97. (MLCT) or ligand{{doi|10.1016/S0010-to-metal charge transfer 8545(LMCT00)00274-5}}.</ref> The properties of thethese complexes can be tuned easily by introducingchanges in substituents,. forFor example, electron donation, electron withdrawal, and ππ-conjugating groups, to the polypyridine [[Moiety (chemistry)|moiety]]. The MLCT absorption band can be shifted, the emission wavelength can be changed, and the emission lifetime can be extended.<ref>Hammarstroem, L., Johansson, O., "Expanded bite angles in tridentate ligands. Improving the photophysical properties in bistridentate Ru<sup>II</sup> polypyridine complexes", Coord. Chem. Rev. 2010, 254, 2546. {{doi|10.1016/j.ccr.2010.01.006}}</ref>
[[File:Tris(bipyridine)ruthenium(II) chloride.png|thumb|right|224px|[[Tris(bipyridine)ruthenium(II) chloride|Tris(bipyridine)ruthenium(II)]] is the preeminent example of a polypyridine complex.]]
A well-known example of a polypyridine complex is rutheniumtristhe tris(bipyridine) derivative of ruthenium(II), Ru[Ru(bpy)<sub>3</sub>]<sup>2+</sup>. This complex exhibits intense [[luminescence]] at room temperature in aqueous solution. Another example is a platinum-bipyridine-dithiolate complex, Pt(bpy)(bdt), in which bdt denotes a 1,2-benzenedithiolate [[ion|anion]]. This complex also exhibits [[Fluorescence|photoluminescence]] at room temperature, and its wavelength and lifetime can be tuned by substitution of either bipyridine or dithiolate moieties. StructualStructural control is easier than for [[ruthenium]] complexes due to the square planar structure of the [[platinum]] complex.
Some other areas of investigation involves immobilizing these complexes on electrodes.<ref>Zhong, Y.-W., Yao, C.-J., Nie, H.-J., "Electropolymerized films of vinyl-substituted polypyridine complexes: Synthesis, characterization, and applications", Coord. Chem. Rev. 2013, 257, 1357. {{doi|10.1016/j.ccr.2013.01.001}}</ref> Some polypyridyl complexes intercalate into [[DNA]] and show promise as drugs.<ref>Komor, Alexis C.; Barton, Jacqueline K. "The path for metal complexes to a DNA target" Chemical Communications 2013, vol. 49, 3617-3630. {{doi|10.1039/c3cc00177f}}</ref>
==See also==
* [[Transition metal complexes of 2,2'-bipyridine]]
==References==
<references />
{{DEFAULTSORT:Polypyridine Complex}}
[[Category:Bipyridines]]
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