Sensitized luminescence

APPLICATION OF EUROPIUM-SENSITIZED LUMINESCENCE FOR POST-COLUMN DETERMINATION OF OXYTETRACYCLINE IN BOVINE MILK... 

Flumequine is a representative of fluoroquinolones which are high-effective antimicrobial medicines used as fodder supplements in cattle-breeding. This causes the necessity in effective testing techniques to detenuine the content of flumequine in meat products. Fluorimetric determination based on sensitized luminescence of fluoroquinolone chelates with lanthanides is a promising one. The literature lacks information of flumequine detemiination with the aid of sensitized fluorescence. 

FLUORIMETRIC DETERMINATION OE KETOROLAC AND KETOPROEEN IN DOSAGE EORMS USING TERBIUM SENSITIZED LUMINESCENCE... 

The original stabilizer (HBC) was modified as the rapid radiationless deactivation of the stabilizer is (at least partly) due to the intramolecular hydrogen bond, the H-atom was substituted by a methyl group (MBC). This "probe molecule" showed fluorescence and phosphorescence and enabled us to demonstrate the energy transfer to the stabilizer, simply by studying its sensitized luminescence. 

DL Dexter, A theory of sensitized luminescence in solids, J. Chem. Phys., 21 836-850, 1953. 

Dexter D. L. (1953) A Theory of Sensitized Luminescence in Solids,/. Chem. Phys. 21, 836-850. 

The positive electrostatic charge of Ru(II) polypyridyl complexes has been combined with hydrogen-bond donating primary carboxamide groups in Beer s 68 to yield anion-sensitive luminescent systems. Structural variations have allowed strong biasing of Cr/HjPO selectivity in either direction. Macrocyclic 69 also raises interesting questions about PET/EET processes (Section 13) across... 

The mechanism for sensitized luminescence using the antenna effect is shown schematically in Fig. 2. 

As has already been discussed, there are three key requirements of ligands for use in the sensitized luminescence of lanthanides ... 

Alkali-Metal Halides. Luminescent alkali-metal halides can be produced easily in high-purity and as large single crystals. They are therefore often used as model substances for the investigation of luminescence processes. Their luminescence processes can be divided into 1) the self-luminescence of the undoped crystals, 2) luminescence by lattice defects, and 3) sensitized luminescence. 

Sensitized Luminescence. Through the incorporation of foreign ions (e.g., Tl+, Ga+, In+) into the crystal lattice, further luminescence centers are formed. The emission spectra are characteristic for the individual foreign ions. The complicated luminescence mechanism is described in [5.408]. 

Europium tetracycline and GOx can be coadsorbed on hydrophilic sensor membranes as described in Sect. 2.4, adding up to ready-for-use glucose-sensitive luminescent foils. These can be implemented in microwell plate formats for a parallel screening of different samples [114]. Figure 18 shows eight adjacent wells of the plate spotted with differently concentrated glucose solutions in MOPS buffer, and the resulting calibration plot of the sensor. 

Further examples of energy transfer processes in assemblies involving Ir(III) polyimine derivatives, from Williams et al., are shown in Fig. 25b and c [133]. These are bimetallic assemblies containing Ir and Ru centers, either an Ir(terpy)23+ connected to a Ru(bpy)32+ via a polyphenyl bridge, Fig. 25b, or a Ru(terpy)22+ connected to an Ir(ppy)2bpy+ moiety, Fig. 25c. Energy transfer occurs in both arrays in the direction Ir->- Ru, but whereas for (b), Fig. 25, the sensitized luminescence of the Ru center upon excitation of the Ir center can be detected also at ambient temperature, in array (c) the sensitized luminescence of the Ru(II)-terpyridine complex can only be revealed at low temperatures (165 K), due to the well-known non-emissive nature of Ru(terpy)22+ at room temperature. 

The EDTA-Tb3+ complex is poorly luminescent, but becomes strongly emissive when it forms a ternary complex with salicylic acid. By using alkaliphosphatase (ALP) as the label of the antibody, a unique immunoassay system specific to Tb3+ was constmcted (fig. 11) by Evangelista et al. (1991) and Christopoulos et al. (1992). The enzyme ALP cleaves the phosphoester bond of the substrate and releases 5-fluorosalicylic acid, which binds to EDTA-Tb3+ and sensitizes luminescence from Tb3+. This method is employed for the determination of semm AFP (cx-fetoprotein) and PSA (prostate-specific antigen). 

Triplet-triplet absorption by benzene has never been detected and evidence for the presence of triplet benzene in fluids has been obtained only recently using energy transfer measurements. Benzene sensitizes both the fluorescence and the phosphorescence of biacetyl. The concentration dependence of this sensitized luminescence has been shown to be consistent with the presence of triplet benzene in the gas phase43 and in cyclohexane solution,80 though another study using hexane as solvent did not yield any evidence for the presence of triplet benzene,27 presumably because of impurities in the hexane. 

This method has found particular use in the preparation of pyridine-substituted dithiolene complexes, which exhibit pH sensitive luminescence properties (263). The a-halocarbonyl starting materials could include related precursors used in the synthesis of unsaturated dithiocarbonates described in Section II.C. 

Keywords Lanthanide Sensor Sensitized luminescence Dipicolinate Macrocycle Ternary complex Bacterial spore Ancillary ligand Gadolinium break Catecholamine Salicylic acid Salicylurate. 

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