Charge Transfer Excited States ICT and TICT

As stated, examples of the enabling of the emission by the use of lanthanides have already been given in 3.5.6.9. 

1 Charge Transfer Excited States (ICTand TICT) 

Structurally the fluoroionophores are made up of a fluorophore and a receptor chelate, sometimes linked by a spacer. Three different ways of connecting the fluorophores with the receptors are shown in Eigure 3.17.  

In this book we will categorise these fluoroionophores according to the chemical class of the fluorophore that is attached to the receptor.  

Crowns with Stilbene Fluorophores. Stilbenes undergo cis-trans isomerism on irradiation and this feature is exploited in (3.82). In the case of the frany-isomer, large ionic radius ions such as K+, and Cs, give fluorescent complexes whilst the smaller Lb and Na cause quenching. UV irradiation to the dy-isomer causes a considerable change in the conformation of the crown ether substructure and increases its ability to extract alkali metals, including Lb and Na+, from water into benzene. 

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