Chiral Sensing of Various Amino Acids Using Induced Circularly Polarized Luminescence from Europium(III) Complexes of Phenanthroline Dicarboxylic Acid Derivatives |
| |
| Authors: | Taka‐aki Uchida Prof Koichi Nozaki Dr Munetaka Iwamura |
| |
| Institution: | Graduated School of Science and Engineering, University of Toyama, Toyama, Japan |
| |
| Abstract: | Circularly polarized luminescence (CPL) was observed from Eu(dppda)2]? (dppda=4,7‐diphenyl‐1,10‐phenanthroline‐2,9‐dicarboxylic acid) and Eu(pzpda)2]? (pzpda=pyrazino2,3‐f]1,10]phenanthroline‐7,10‐dicarboxylic acid) in aqueous solutions containing various amino acids. The selectivity of these complexes towards amino acids enabled them to be used as chiral sensors and their behavior was compared with that of Eu(pda)2]? (pda=1,10‐phenanthroline‐2,9‐dicarboxylic acid). As these EuIII complexes have achiral D2d structures under ordinary conditions, there were no CPL signals in the emission assigned to f–f transitions. However, when the solutions contained particular amino acids they exhibited detectable CPL signals with glum values of about 0.1 (glum=CPL/2 TL; TL=total luminescence). On examining 13 amino acids with these three EuIII complexes, it was found that whether an amino acid induced a detectable CPL depended on the EuIII complex ligands. For example, when ornithine was used as a chiral agent, only Eu(dppda)2]? exhibited intense CPL in aqueous solutions of 10?2 mol dm?3. Steep amino acid concentration dependence suggested that CPL in Eu(dppda)2]? and Eu(pzpda)2]? was induced by the association of four or more amino acid molecules, whereas CPL in Eu(pda)2]? was induced by association of two arginine molecules. |
| |
| Keywords: | amino acids chirality lanthanides luminescence sensors |
|
|
