Abstract
Ruthenium bipyridine or terpyridine complexes functionalized carbon-based nanocomposites have special properties in the electromagnetic and photochemical research field. The aims of this chapter include development of functionalized fullerene, carbon nanotubes, and graphene with ruthenium complex and characterization of their nanostructural properties. Such nanocomposites can be accomplished using either covalent or non-covalent functionalization methods.
TopBackground
Since 1987, supramolecular chemistry has become a well-known concept and a major field in today’s research community. This concept has been defined as ‘chemistry beyond the molecule’, bearing on the organized entities of higher complexity that result from the association of two or more chemical species held together by intermolecular forces.” (Lehn, 1995) One of the most important interactions found in supramolecular chemistry is metal-ligand coordination. In this arena, chelate complexes derived from N-heteroaromatic ligands, largely based on 2, 2′-bipyridine and 2,2′:6′,2″-terpyridine (Figure 1), have become an ever-expanding synthetic and structural frontier.
Figure 1. Structures of 2,2′-bipyridine and 2,2′:6′,2″-terpyridine
Bipyridine has been known since 1888, (Paul, Spey, Adams, & Thomas, 2004) ruthenium bipyridine complexes contained [Ru(bipy)3]2+have very interesting photochemical properties making them ideal candidates for solar energy conversion. This is due to the long lifetime of the triplet excited state and in part due to the fact that the structure of the molecule allows for charge separation. Its singlet-triplet transitions are forbidden and therefore often slow. This unusual situation arises because the excited state can be described as a Ru3+ complex containing a bipy- ligand. Thus, the photochemical properties of [Ru(bipy)3]2+ are reminiscent of the photosynthetic assembly, which also involves separation of an electron and a hole (Bard & Fox, 1995). Ruthenium(II) complexes of tris(bipyridine)ruthenium [Ru(bipy)3]2+ have received considerable attention recently. The stability and unique photophysical properties of these systems have been exploited for artificial photosynthesis, in sensors, in photorefractive materials, in studies of electron transfer in proteins and DNA, antitumor ability, and a wide range of other purposes.
Key Terms in this Chapter
Terpridine: A Terpyridine is a tridentate ligand that binds metals at three meridional sites. 2, 2'; 6', 2”-terpyridine, often abbreviated to terpy or tpy) is a heterocyclic compound derived frompyridine. This colourless solid is used as a ligand in coordination chemistry.
Ruthenium Complex: Ruthenium forms a variety of coordination complexes with organic or inorganic ligands. Ruthenium (II) complex chelated organic ligands can be utilized for photoillumination and anti-cancer durgs.
Graphene: A graphene is a 2-dimensional, crystalline allotrope of carbon. In graphene, carbon atoms are densely packed in a regular sp2-bondedatomic-scale chicken wire (hexagonal) pattern. Graphene can be described as a one-atom thick layer of graphite.
Carbon Nanotube: A carbon nanotube is a tube-shaped material, made of carbon and has a diameter measuring on the nanometer scale. The graphite layer appears somewhat like a rolled-up wire with a continuous unbroken hexagonal mesh and carbon molecules at the apexes of the hexagons.
Bipyridine: A bypridine is a family of chemical compounds with the formula (C 5 H 4 N) 2 , which are formed by the coupling of two pyridine rings. Six isomers of bipyridine exist, but two isomers are prominent: 2, 2'-bipyridine is a popular ligand in coordination chemistry. 2, 2'-bipyridine is a chelating ligand that forms complexes with most transition metal ions.
Fullerene: A fullerene is a pure carbon molecule composed of at least 60 atoms of carbon. Because a fullerene takes a shape similar to a soccer ball or a geodesic dome, it is sometimes referred to as a buckyball after the inventor of the geodesic dome, Buckminster Fuller, for whom the fullerene is more formally named.