Transition metal complexes sensors

However, because of the mostly very slow electron transfer rate between the redox active protein and the anode, mediators have to be introduced to shuttle the electrons between the enzyme and the electrode effectively (indirect electrochemical procedure). As published in many papers, the direct electron transfer between the protein and an electrode can be accelerated by the application of promoters which are adsorbed at the electrode surface [27], However, this type of electrode modification, which is quite useful for analytical studies of the enzymes or for sensor applications is in most cases not stable and effective enough for long-term synthetic application. Therefore, soluble redox mediators such as ferrocene derivatives, quinoid compounds or other transition metal complexes are more appropriate for this purpose. 

Until relatively recently, most work focused on organic luminophores as sensor-probe materials. However, luminescent transition metal complexes, especially those with platinum metals (Ru(II), Os(II), Re(I), Rh(III), and Ir(III)) have shown considerable promise and are receiving increasing attention. More recently Pt(II) complex have shown promising results.(4) Many of these materials have highly desirable features ... 

E. R. Carraway, J. N. Demas, B. A. DeGraff, and J. R. Bacon, Photophysics and photochemistry of oxygen sensors based on luminescent transition-metal complexes, Ana/. Chem. 63, 337-342(1991). 

Abstract Pressure-sensitive paint (PSP) is applied to the areodynamics measurement. PSP is optical sensor based on the luminescence of dye probe molecules quenching by oxygen gas. Many PSPs are composed of probe dye molecules, such as polycyclic aromatic hydrocarbons (pyrene, pyrene derivative etc.), transition metal complexes (ruthenium(II), osumium(II), iridium(III) etc.), and metalloporphyrins (platinum (II), palladium(II), etc.) immobilized in oxygen permeable polymer (silicone, polystyrene, fluorinated polymer, cellulose derivative, etc.) film. Dye probe molecules adsorbed layer based PSPs such as pyrene derivative and porphyrins directly adsorbed onto anodic oxidised aluminium plat substrate also developed. In this section the properties of various oxygen permeable polymer for matrix and various dye probes for PSP are described. 

Demas and DeGraff reported the design of highly luminescent transition metal complexes for optical oxygen sensor applications [16]. Table 2 shows the photochemical and photophysical properties of sensing probes using luminescent transition metal complexes in immobilizing polymer films. 

This type of chromogenic sensor utilizes the coordination chemistry of transition metal complexes, which have vacant binding sites to bind specific anions or have pendant arms containing anion receptor units. Transition metal complexes already have their own specific colors due to their different electronic structures. Coordinating directly to anions or binding of anions by the pendant arms results in perturbations of their electronic structures and causes color changes. 

Rogers CW, Wolf MO. Luminescent molecular sensors based on analyte coordination to transition-metal complexes. Coord Chem Rev 2002 233-234 341-50. 

One of the most important biomolecules for which fluorescent sensing [94-96] is of great importance is nitric oxide [97-101]. Nitric oxide can react with several organic dyes, switching on their fluorescence as a result of a triazole ring closure reaction [94], There are also useful and selective NO optical sensors based on transition metal complexes (Figures 16.22 and 16.23) [94-96],... 

Crystalline Transition Metal Complexes as Sensor Materials... 

Zhang, Y.C., Kaneko. M., Uchida, K.. Mizusaki, J. and Tagawa, H. (2001) Solid electrolyte CO2 sensors with lithium-ion conductor and Li transition metal complex oxide as solid reference electrode./. Electrochem. Soc., 148 (8). H81-4. 

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