Potentiometric Studies on Interactions of α-L-glutamic Acid Oligomers with Cu(II) in aqueous Solutions

Four oligomers of α-L -glutamic acid with ends blocked by nonionizable protecting groups were studied in 0.1M NaClO₄ solution using potentiometric measurements. The titrations were analyzed using a pit-mapping method. The results are compared with those obtained with the corresponding polymer. The successive dissociation constants of the carboxylic side chains are obtained for oligomers with degrees of polymerization varying from 1 to 6. Then the successive stability constants corresponding to the association Cu²⁺–oligomer are given, and the M_pH_qL_r distribution is calculated for each oligomer introducing MH_qL complexes.