Esterification fluorescent detection

Several chiral substituted a-phenyl-alkyl alcohols, which were partially enantio-merically enriched, were successfully purified by this method after esterification with 9-anthroic acid optical purities higher than 95% were obtained.Fluorescence studies of racemic compounds show a characteristic a-type excimer emission, whereas the chiral enantiomer exhibits a typical y-type monomer emission. Figure 7 shows the spectra of l-(2-chlorophenyl)ethyl 9-anthroate for a crystalline sample of enantiomeric (1) and racemic (2) at 77 K. It has been demonstrated that in the absence of configurational disorder chiral impurities in the range of 1 % can be detected by this method. ... 

On the basis of the simple boronic acid-diol reaction at the moleeular level, this chapter focuses on polymer-polymer interaetions triggered by boronic acid-diol esterification. When boronie aeid-diol reaetions oeeur cooperatively along a polymer chain, the structural changes caused by the complexation can easily amplify over hierarchies of nanometer to mierome-ter scale. Even without any signal such as fluorescence emission, the boronic acid-diol reaction based on precise molecular recognition is detectable as phase transition at the micrometer scale. 

Detection may be facilitated by preparation of colored or, more often, fluorescent derivatives prior to spotting and development. Examples include dansylation (reaction with 1-dimethyl aminonaphthalene-5-sulfonyl chloride) of amino acids and formation of 2,5-dinitrophenylhydrazones of amino acids and ketosteroids. Other reactions that have been used include oxidation, reduction, hydrolysis, ha-logenation, enzymatic, nitration, diazotization, esterification, and etherification (Szepesi and Nyiredy, 1996 Kovar and Morlock, 1996). Prechromatographic derivatization sometimes improves separation, stability, and/or quantification of the analytes in addition to providing visualization. 

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