Polypyridine Complex

Polypyridine complexes are

coordination complex A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''ligands'' or complexing agents. Many ...

es containing polypyridine ligands, such as

2,2'-bipyridine The comma is a punctuation mark that appears in several variants in different languages. It has the same shape as an apostrophe or single closing quotation mark () in many typefaces, but it differs from them in being placed on the baseline o ...

, 1,10-

phenanthroline 1,10-Phenanthroline (phen) is a heterocyclic organic compound. It is a white solid that is soluble in organic solvents. The 1,10 refer to the location of the nitrogen atoms that replace CH's in the hydrocarbon called phenanthrene. Abbreviated " ...

, or 2,2';6'2"-

terpyridine Terpyridine (2,2';6',2"-terpyridine, often abbreviated to Terpy or Tpy) is a heterocyclic compound derived from pyridine. It is a white solid that is soluble in most organic solvents. The compound is mainly used as a ligand in coordination chemist ...

. Polypyridines are multidentate

ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electr ...

s that confer characteristic properties to the metal complexes that they form. Some complexes strongly absorb light via a process called metal-to-ligand charge transfer (MLCT). The properties of these complexes can be tuned by changes in substituents. For example, electron donation, electron withdrawal, and π-conjugating groups, to the polypyridine

moiety Moiety may refer to: Chemistry * Moiety (chemistry), a part or functional group of a molecule ** Moiety conservation, conservation of a subgroup in a chemical species Anthropology * Moiety (kinship), either of two groups into which a society is ...

. The MLCT absorption band can be shifted, the emission wavelength can be changed, and the emission lifetime can be extended. Tris(bipyridine)ruthenium(II) chloride

A well-known example of a polypyridine complex is the tris(bipyridine) derivative of ruthenium(II), u[(bpy)₃sup>2+._This_complex_exhibits_intense_

u[(bpy)₃sup>2+._This_complex_exhibits_intense_luminescence">bpy)₃.html"_;"title="u[(bpy)₃">u[(bpy)₃sup>2+._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_ An_ion_()_is_an_atom_or_molecule_with_a_net_electrical_charge. The_charge_of_an_electron_is_considered_to_be_negative_by_convention_and_this_charge_is_equal_and_opposite_to_the_charge_of_a_proton,_which_is_considered_to_be_positive_by_convent_...

._This_complex_also_exhibits_Fluorescence.html" "title="ion.html" "title="luminescence.html" ;"title="bpy)₃.html" ;"title="u[(bpy)₃">u[(bpy)₃sup>2+. This complex exhibits intense luminescence">bpy)₃.html" ;"title="u[(bpy)₃">u[(bpy)₃sup>2+. 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 An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

. This complex also exhibits Fluorescence">photoluminescence Photoluminescence (abbreviated as PL) is light emission from any form of matter after the absorption of photons (electromagnetic radiation). It is one of many forms of luminescence (light emission) and is initiated by photoexcitation (i.e. photon ...

See also

References