Sensitization chromophores

The photophysical properties of lanthanide ions are influenced by their local environment, the nature of the quenching pathways available to the excited states of sensitizing chromophores, and the presence of any available quenchers (as we have seen when discussing bioassay). All of these factors can be exploited for the sensing of external species. 

Villegas M.A., Pascual L., Sol-gel coatings doped with a pH sensitive chromophore, Thin Sold Films 1999 351 103-108. 

An analogous system to the cation sensors is the use of optically nonactive anion ionophores together with a pH-sensitive chromophore for the anion sensing. In this system, simultaneous extraction of H+ and anion X- from the aqueous solution into an organic phase results in protonation of the chromophore anion C, e.g. 

Typically the chromophores used are pH sensitive, i.e. acidochromic or ionochromic (see section 1.4), and the medium is one whose pH varies with temperature. A variety of pH sensitive chromophores are known that are readily synthesised and can be modified to provide a wide range of shades. Application of these pH sensitive dyes in pressure and thermally sensitive papers for digital printing, e.g. fax papers, where the whole object is for the process to be irreversible, will be covered under ionochromism. The main area of application for reversible indirect thermochromic materials is as thermochromic organic pigments, as will be described below (section 1.3.4.1). 

Experimental work in the genetics of vision requires a broader understanding of the functional performance of vision. Any inferential relationship between the human genes and the chromophores of vision must accommodate four spectrally distinct narrowband chromophores of vision (including an ultraviolet, UV, sensitive chromophore). If a truly achromatic rhodopsin is also needed, the total number of genes to be located must equal five. 

The above distinctions require a clear separation between the passive substrate material (even though it contains a retinoid) and the photon sensitive chromophores of vision (which contain a different family of retinoids). For the... 

Functionalized organic dyes with polyaminocarboxylate have been widely utilized as feasible sensitizers to afford visible region excitation for sensitization of NIR lanthanide luminescence [36 5]. Verhoeven and coworkers [36, 37] first prepared a series of neodymium(III), erbium(III), and ytterbium(III) complexes with polyaminocarboxylate-functionalized fluorescein (21) and eosin (22) as sensitizing chromophores. These complexes show sensitized NIR... 

Werts, M.H.V, Hofstraat, J.W., Geurts, F.A.J., and Verhoeven, J.W. (1997) Huorescein and eosin as sensitizing chromophores in near-infrared luminescent ytterbium(lll), neodymium(lll) and erbium(lll) chelates. Chemical Physics Letters, 276, 196. 

IMS has been compared with the UV detector after separation with SFC of benzoates and esters, demonstrating the ability of IMS for the detection of compounds that do not have sensitive chromophores for UV detection Often, polymers do not have sufficient UV-visible (Vis) absorbance for detection after LC or SFC, while SFC-IMS can be used for both efficient separation and detection of a variety of polymeric materials. IMS detection of a variety of drugs, such as various steroids, opiates, and benzodiazepines, after SFC separation demonstrated the ease and utility of acquiring ion mobility spectra at ambient pressure. While SFC has only captured a small portion of the separation maiket, the potential of IMS for detecting compounds that cannot be easily seen with a standard UV-Vis approach has led to its use as a stand-alone detector for LC. 

Photochromic molecules, or light-sensitive chromophores, are chemical species having photochromic properties. Examples of photochromic molecules and photochromic processes are summarized in Table 1. 

For a lanthanide complex, the photophysical pathways that can lead to, or disrupt, sensitized luminescence from a lanthanide ion are shown in Fig. 1. Many of these have been discussed in detail in [1], and in arange of review articles [2], but it is worth reprising key points briefly here. For a typical sensitizing chromophore (e.g., an aromatic molecule or a transition metal complex), the first key step is... 

A smart method to introduce pH sensitivity to LLCs is to cmijugate a sensitizer chromophore to a cyclen ligand system which can be protonated. Parker has shown that phenanthridine derivatives 7 are suitable donors [25] (see Sect. 2.1, Table 1). 

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