Sensors lanthanide complexes

The d-f heteronuclear or lanthanide-transition metal (abbreviated as Ln-M) complexes attract interest from both academic and industry because of the challenge for their synthesis, the novelty of their structures, and their potential application as advanced materials, such as molecular or nano magnets,bimetallic catalysts, and sensors. The complexes can be assigned to three categories based on the nature of the Ln-M interaction (a) complexes with direct Ln-M bonding, (b) complexes with Ln-M interactions bridged by ligands, and (c) the complexes with ionically associated Ln-coordination units and M-coordination units. Most of the d-f heteronuclear complexes of carboxylic acids reported so far are found with type (b) structure, and very few of them are of structure type (c). The lanthanides and the transition metals in these complexes are far away from each other, and no direct Ln-M interactions have been observed. 

Figure 13.4 Typical design principle of lanthanide complex-based chemosensors based on binding of an analyte (an) (a) directly influencing the Ln(III) luminescence, (b) influencing photophysical properties of the ligand, and (c) addition of a sensitizing analyte onto a poorly luminescent lanthanide-containing sensor [1]. (Reproduced from J.C.G. Bunzli and C. Piguet, Taking advantage of luminescent lanthanide ions, Chemical Society Reviews, 34, 1048-1077, 2005, by permission of The Royal Society of Chemistry.)...

A number of commonly occurring pesticides and herbicides was also examined and found to cause no interference, even at extremely high concentrations. Such sensors, which combine the selectivity of MIPs with the extremely sensitive fluorescence properties of lanthanide complexes, ensure that this will be a very fruitful area of research. 

Following the initial reports of the anteima effect in lanthanide cryptates, many other lanthanide complexes containing additional chromophoric ligands have been investigated and found to be useful as luminescent labels for biological substrates, and in general as sensors based on luminescent properties [21]. 

The photophysics of lanthanide complexes has drawn considerable attention in recent years, in part because of the potential applications of lanthanides (sensors, electroluminescent displays, etc.) and several recent reviews highlighting applications of luminescent lanthanide complexes have appeared. A discussion of infrared f-f luminescence of Yb, Nd, and Er in complexes having macrocyclic ligands such as porphyrins, cyclen derivatives, and calixarenes was published by Korovin and Rusakova. " In addition, DaSilva and co-workers describe the development of highly luminescent lanthanide complexes and their application as light-conversion molecular devices. ... 

An alternative approach to multiparametrism makes use of lanthanide complexes in conjunction with quantum dots as acceptors [157]. Another growing field for applications of lanthanide complexes is the design of luminescent sensors responding to various analytes such as pH, anions (phosphate, carbonates), metal ions, hydrogen peroxide, and ATP. Since many enzymatic reactions are associated with the consumption or formation of small molecules like hydrogen peroxide. 

Although not particularly designed to be a pH-sensitive luminescent probe, Beeby et al. described a phenanthridine-carrying water-soluble Yb complex, in which the photosensitisation mechanism is switched as a functi(m of pH [93], A crown ether-modified neodymium(III) cryptand was proposed for barium ion detection [94], but as with many prototype cation sensors, the probe only works in acetonitrile. Moreover, the complex necessitates ultraviolet excitation, which removes one of the main advantages of using NIR luminescent lanthanide complexes. 

Luminescent Chemical and Physical Sensors Based on Lanthanide Complexes... 

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