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Complexes containing chloride, fluorescence

On a qualitative basis, the fluorescence of the napy complexes containing chloride is weaker than that of the corresponding nitrate compounds. Such variation can be ascribed to the difference in coordinating ability of the anion and/or to the amount of coordinated water. Conductivity studies of the nitiate and chloride complexes in nitromethane yield A values of 13-19, which indicates that the complexes are nonelectrolytes (12, 13, 14). The presence of bands attributable to vM-Cl and vM-OH ) in the IR spectra of the chloride complexes substantiates the conclusion that all species are bound to the rare earth ion (12), Vibrational modes indicative of bidentate nitrate and the lack of bands suggesting monodentate nitrate are reported for the rare earth nitrate complexes of napy and 2,7-dmnapy (13,14),... [Pg.218]

There are a limited number of fluorescent sensors for anion recognition. An outstanding example is the diprotonated form of hexadecyltetramethylsapphyrin (A-7) that contains a pentaaza macrocydic core (Figure 10.31) the selectivity for fluoride ion was indeed found to be very high in methanol (stability constant of the complex 105) with respect to chloride and bromide (stability constants < 102). Such selectivity can be explained by the fact that F (ionic radius 1.19 A) can be accommodated within the sapphyrin cavity to form a 1 1 complex with the anion in the plane of the sapphyrin, whereas Cl and Br are too big (ionic radii 1.67 and 1.82 A, respectively) and form out-of-plane ion-paired complexes. A two-fold enhancement of the fluorescent intensity is observed upon addition of fluoride. Such enhancement can be explained by the fact that the presence of F reduces the quenching due to coupling of the inner protons with the solvent. [Pg.317]

The use of ligand exchange has been examined for the analysis of PTH (phenylthio-hydantoin) amino acids separated on silica gel plates [92]. The method is an extension of the procedure developed for organophosphate pesticides [84]. The chromatoplate is sprayed with a solution of palladium(II) chloride and calcein. Palladium complexes with calcein to form a non-fluorescent chelate. However, in the presence of many sulfur-containing compounds, such as PTH-amino acids, the palladium is displaced from the complex liberating free calcein which gives an intense fluorescence. This method is capable of determining 0.1-nmole amounts of PTH-amino acids. [Pg.159]

An indirect method for the detection of phosphate, which involves the fluorescence quenching of the Al-Morin complex by P04 , has also been described for the detection of phosphorus oxyacids separated by ion chromatography (IC) [103]. More recently, a polyvinyl chloride matrix containing Al-Morin was used to prepare membrane sensor for detection of phosphate by fluorescence quenching. The membrane had a lifespan of 90-120 days and a linear detection range of 6-15 mg (0.19-0.48 mM) making it suitable only for wastewater analysis [104]. [Pg.232]


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Chloride complex

Complexes Containing

Fluorescent complexes

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