Luminescent materials sensors

Metallophosphorus polymers have potential applications as catalysts, luminescent materials, sensors, MRI contrast agents and so on. 

Papkovsky D.B., Ovchinnikov A.N., Ogurtsov V.I., Korpela T., Biosensors on the basis of luminescent oxygen sensor the use of microporous light-scattering support materials. Sens. Actuat.B 1998 51 137-145. 

Even if few systems are proposed for inorganic compounds (with regard to the number of potential pollutants), instruments or sensors for parameters used for treatment process control are available UV systems for residual chlorine in deodorization, electrochemical sensors for dissolved oxygen (with nowadays a luminescent dissolved-oxygen probe utilizing a sensor coated with a luminescent material) and a colorimetric technique for residual ozone. 

A luminescent material in which all excited molecules return to the ground state with the same probability is defined here as a homogeneous sensor. In this case, the number of excited sensor molecules in the excited state, as a function of time is given by a single exponential. 

The fluorescence and phosphorescence of luminescent materials are modulated by the characteristics of the environment to which these materials are exposed. Consequently, luminescent materials can be used as sensors (referred also as transducers or probes) to measure and monitor parameters of importance in medicine, industry and the environment. Temperature, oxygen, carbon dioxide, pH, voltage, and ions are examples of parameters that affect the luminescence of many materials. These transducers need to be excited by light. The manner in which the excited sensor returns to the ground state establishes the transducing characteristics of the luminescent material. It is determined by the concentration or value of the external parameter. A practical and unified approach to characterize the luminescence of all sensors is presented in this chapter. This approach introduces two general mechanisms referred as the radiative and the nonradiative paths. The radiative path, in the general approach, is determined by the molecular nature of the sensor. The nonradiative path is determined by the sensor environment, e.g., value or concentration of the external parameter. The nonradiative decay rate, associated with the nonradiative path, increases... 

In another example, the cyclometalated iridium complex [Ir(ppy)2(4-vinylpyridine)Cl] has been attached via hydrosilation see Hydrosilation) to hydride-terminated poly(dimethylsiloxane) to produce a luminescent material. Evaluation of this material as a luminescent oxygen sensor revealed significantly improved sensitivity over dispersions of the original vinyl pyridine complex in poly(dimethylsiloxane). The luminescent material was blended with polystyrene to give a new sensor that exhibited increased sensitivity and maintained short response times to rapid changes in air pressure. 

An attractive alternative to organic fluorophores in formulated polymeric sensor films for chemical detection is to use inorganic luminescent materials. Semiconductor nanocrystals have a dramatically improved photostability and are attractive as luminescent labels.1415 However, some nanocrystals also exhibit photoluminescence (PL) that is sensitive to the local environment. For example, it was observed that PL of CdSe nanocrystals incorporated into polymer thin films responded reversibly to different gases.16 Because in sensing applications nanomaterials bring previously unavailable capabilities1719 and unexpected results,20 23 we explored the environmental sensitivity of semiconductor nanocrystals upon their incorporation in different rationally selected polymeric matrices.24 26... 

Cation-n Interactions, p. 21A Channel Inclusion Compounds, p. 223 Chiral Guest Recognition, p. 236 Crystal Growth Mechanisms, p. 364 Fluorescent Sensors, p. 572 Hydrogen Bonding, p. 658 Hydrophobic Effect, p. 673 Luminescent Materials, p. S16 Nonlinear Optical Materials, p. 973... 

Biosensors, p. 115 DNA Nanotechnology, p. 475 Fluorescence Sensing of Anions, p. 566 Fluorescent Sensors, p. 572 Imaging and Targeting, p. 687 Luminescent Materials, p. 875 Photochemical Sensors, p. 1053 Supramolecular Photnchernistn, p. 1434... 

Utilizing these functionalized conducting polymers, a solar cell, an electrochromic device, a chemical luminescent material, a sensor, a polymer battery, etc. can be constructed, in which the functionality is attributed to the incorporated functional molecule. 

The luminescence intensity and decay time of EuCls in carboxymethyl cellulose membranes is decreased in presence of heavy metal ions like Cu" or Cu ", but also Cr " and Fe " exert a distinct quenching effect [111]. It is not likely that a sensor with high specificity can be prepared on the basis of LLCs that is free of interferences from other metal ions. However, an adequate choice of the ligand system may help to improve the selectivity of the response. Another approach uses a sol-gel technique to embed a complex of Eu " and silanized 2,6-pyridine-dicarboxylic acid as antenna in a silica network. This luminescent material can sense copper ion concentrations in water down to 50 pg but the sensor was not evaluated with respect to interferences of other metal ions or in environmental samples [112]. 

Essentially, nano-ZnO is an inorganic material of significant interest in nanotechnology, used particularly in gas sensors, solar cells, and luminescent materials. It is a nonvolatile, nonhygroscopic, odorless, and white crystalline solid with versatile properties. It can be easily synthesized in the laboratory by various methods including sol-gel, precipitation, thermal, and pyrolysis techniques and is characterized by... 

The spectroscopic method is based on pressure-induced changes in absorption or/and emission spectra. The idea is to relate the pressme-induced shift of the fluorescence lines of the specific material to the value of the pressure. The material selected for the luminescence pressure sensor should be characterized by strong intensity of the emission line(s), which should be stable at a broad range of pressures and temperatures and the energy of which is possibly related linearly to pressure. It is also important that the emission of the sensor does not overlap the emission of the sample. Considering the above-mentioned requirements, the Raman fluorescence and photoluminescence of transition-metal and rare-earth ions were used. Raman modes of nitrogen [49], which is the pressure-transmitting medium, and Raman frequencies of diamond chips [51] have been used. Recently, a pressure-induced shift of the Raman line 1332 cm of the face of the DAC culet was proposed to estimate pressure < 1,000 kbar [50, 52]. 

Chapter 1 (W. E. Jones et al) is concerned with the emeiging area of n-conjugated polymers that contain transition metal ions. The authors discuss the synthesis and physical characterization of metal-organic n-conjugated polymers. These materials, while fundamentally interesting, are also finding application in the rapidly emerging area of luminescence (optical) sensors. 

Ligands Near-Infrared Materials Lanthanides Magnetic Resonance Imaging Luminescent Bioprobes Sensors for Lanthanides and Actinides. 

Avnir, D Braun, S Lev, 0 Levy, D and Ottolenghi, M. (1994) Organically doped sol-gel porous glasses chemical sensors, enzymatic sensors, electrooptical materials, luminescent materials and photochromic materials, in Sol-Gel Optics Processing and Applications... 

Polymer/sihca composite blends, not only improve the physical properties, snch as the mechanical properties and thermal properties of the materials, but they can also exhibit some unique properties that have attracted strong interest in many industries. Besides common plastics and rubber reinforcanent, many other potential and practical applications of this type of nanocomposites have been reported coatings, flame-retardant materials, optical devices, electronics and optical packaging materials, photo resist materials, photo-luminescent conducting film, per-vaporation membrane, ultra-permeable reverse-selective membranes, proton exchange membranes, grouting materials, sensors and materials for metal uptake, etc. As for the colloidal polymer/sihca nanocomposites with various morphologies, they usually exhibit enhanced, even novel, properties when compared with the traditional nanocomposites and have many potential applications in various areas. 

Lanthanides present another group of luminescent materials suitable for sensors. Dysprosium and samarium pyridinedicarboxylates prepared by hydrothermal synthesis [233] exhibited a set of 3 emission bands assigned to different transitions of Dy and Sm with maxima ranging from 480 to 623 nm for Dy and 560 to 710nm for Sm. The conclusion has been drawn that the energy transfer from the organic ligand to the lanthanide ion is effective. 

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