2,2 -bipyridyl ruthenium derivatives

Li Y, Qi H, Fang F, Zhang C (2007) Ultrasensitive electrogenerated chemiluminescence detection of DNA hybridization using carbon-nanotubes loaded with tris(2,2 -bipyridyl) ruthenium derivative tags. Talanta 72(5) 1704-1709... 

Metzler-Nolte et al. successfully created organometallic PNA hybrids to provide an analytically observable tag for PNA strands, including ferrocene-PNA for electrochemical detection, (benzene)-chromiumtricarbonyl-PNA for IR detection of the carbonyl groups, and a bipyridyl-ruthenium derivative for spectroscopic and electron transfer properties. Hybridization of these strands with ssDNA has been shown to produce duplexes with stabilities only sUghtly lower ( 2°C) than an unmodified PNA-DNA system, which allows these organometallic structures to act as markers for duplex formation.Functionalized PNAs should... 

X.B. Yin, S. Dong and E. Wang, Analytical applications of the electrochemiluminescence of tris(2,2,-bipyridyl) ruthenium and its derivatives, Trends Anal. Chem., 23 (2004) 432-441. 

Polymer bound tris-(2,2 -bipyridyl)-ruthenium-(II)-derivatives were synthesized by reaction of 4-(3-chloroformyl-propyl)-4 -methyl-2,2 -bipyridyl with crosslinked amino-groups containing poly(styrene) gel or crosslinked sucrose-methacrylate gels, and by... 

A sensor for organic chloride-containing compounds was constructed by immobilization of luminol or tris (2,2 bipyridyl) ruthenium (III) between a PMT and a poly (tetrafluoro) ethylene (PTFE) membrane [15], through which a stream of air was sampled by diffusion. A heated Pt filament incorporated in the gas line leading to the CL cell was used to oxidize the analytes prior to diffusion across the PTFE membrane. Detection limits for CC14, CHC13, and CH2C12 were 1.2-4 ppm. A similar device could also be used for the determination of hydrazine and its monomethyl and dimethyl derivatives or NH3 vapor. The detection limit for hydrazine was only 0.42 ppb [16]. 

Aly et al. [16] reported a rapid and sensitive chemiluminescence (CL) method for the determination of three fluoroquinolone derivatives, including ciprofloxacin, in both pharmaceutical dosage forms and in biological fluids. The method is based on the CL reaction of the drugs with tris(2,2 -bipyridyl)ruthenium(II) and cerium(IV) in sulfuric acid medium. The CL intensity was proportional to the concentration of ciprofloxacin in solution over the range 0.05-6 pg/mL, and the limit of detection was reported to be 26 nM. 

More direct ET into the oxidase has been initiated photochemically with an artificial electron donor, tris(2,2 -bipyridyl)ruthenium [17], electrostatically bound to the enzyme, and with Ru-labeled cytochrome c [18]. An objection to these types of experiments is, of course, that they involve unatural electron donors, whose site of interaction with the oxidase may be different from that of cytochrome c itself. This objection does not apply to experiments in which the strongly reducing triplet state of bound Zn-cytochrome c is generated photochemically to inject an electron into the oxidase [19], since this derivative of cytochrome c has the same structure and has been shown to bind to the same site as the native protein [20],... 

This year has seen increased employment for polymer bound reactants. Both sensitiser, usually tris(2,2 -bipyridyl)ruthenium(II), and electron relay, usually a viologen derivative, have been attached to a polymer backbone. 

The chemiluminescence intensity from the reaction of amines with tris(2,2 -bipyridyl)ruthenium(III) is generally in the order tertiary > secondary > primary, but no definitive mechanisms have been elucidated. Derivatives of tris(2,2 -bipyridyl)ruthenium(II) have been introduced as labels for immunoassay or DNA probes (e.g., (13)). The use of chemiluminescent labels is clearly advantageous due to their nonradio-active nature and they can be quantified at sub-pi-comolar levels via oxidation in the presence of tripropylamine. 

The enthalpy is lower than the energy required to produce the lowest excited state, still exceeding the triplet state energy, 3R, which in turn produces IR by subsequent annihilation of 3R (triplet-triplet annihilation, TTA). ECL of ruthenium tris-bipyridyl-type derivatives falls in this category. Additionally, ion annihilation can also follow E-route, ensuing the formation of excimers (excited dimers) and exciplexes (excited complexes). 

Different CL reactions in liquid phase have been applied with analytical purposes. These include luminol, tris(2,2 -bipyridyl)ruthenium(II), lucigenin, lophine, peroxyoxa-late derivatives, acidic potassium permanganate, sulfite, gallic acid, morphine, codeine, pyrogallol acridinium esters, and others. Table 19.2 summarizes some of the commonly used CL reactions in liquid phase and their analytical application in different areas. 

Nucleophilic attack at the carbonyl-carbon of 4,5-diazafluoren-9-one (dzf, 12) coordinated to ruthenium has been demonstrated, and a mechanism outlined, for reaction of [Ru(bpy)2(dzf)]2+ with l,8-diazabicyclo[5,4,0] undec-7-ene (dbu)13, which gives a tris-2,2 -bipyridyl derivative (400). 

Ruthenium complexes with mixed bipyridyl ligands, immobilized inside a Nation film, may also be used as pH-sensitive sensor layers [90]. A completely different approach for a ratiometric imaging of pH sensor foils was developed for diagenetic studies of marine sediments, using the dual fluorescence excitation ratio of the pH-sensitive fluorophore 8-hydroxypyrene-l,3,6-trisulfonic acid (HPTS) [91]. Commonly used dual fluorophors with different absorption and emission maxima in the protonated and basic form for ratiometric measurements are the naphthofluorescein and seminaphthofluorescein derivates (SNARF and SNAFL) [92], It should be noted that ammonia or carbon dioxide can also be detected by some of these pH-sensitive materials [55,93]. 

In analytical chemistry 2,2 -bipyridyl and its derivatives have many applications they form bidentate chelating agents with metal ions, amongst them iron, ruthenium, copper, and platinum. However, a 6-substituent decreases the chelating ability of 2,2 -bipyridyl by a steric interaction, while 6,6 -disubstitution totally inhibits it. 

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