COPPER(II) COMPLEXES OF POTENTIALLY TERDENTATE N-2-[(R)-2-HYDROXYPROPYL]-(S)-PHENYLALANINAMIDE AND N-2-[(S)-2-HYDROXYPROPYL]-(S)-PHENYLALANINAMIDE FOR CHIRAL RECOGNITION - SYNTHESIS OF THE LIGANDS AND FORMATION-CONSTANTS

Copper(II) complexes of the ligands N-2-[(R)-2-hydroxypropyl]- and N-2 -[(S)-2-hydroxypropyl]-(S)-phenylalaninamide performed chiral separati on of N-dansyl-protected and unmodified amino acids in HPLC (reversed phase). With the aim of investigating which species are potentially in volved in the discrimination mechanism, the two ligands were synthesiz ed and their complexation equilibria with CU2+ studied by potentiometr y and spectrophotometry in aqueous solution up to pH 11.7. The formati on constants of the species observed, [CuL](2+), [CUL(2)](2+), [CuLH(- 1)](+), [CUL(2)H(-1)](+), [CUL(2)H(-2)], and [CUL(2)H(-3)](-), were qu ite similar for both compounds and were compared to those of (S)-pheny lalaninamide. Most probably, in [CUL(2)H(-3)](-) the ligands behave as terdentate, with the deprotonated OH group occupying an apical positi on.