Chromatographic Study of Novel Heteronuclear Complexes with Schiff Base as Main Ligand

The properties of 12 new heterodi- and heterotrinuclear complexes having general formulae Cu₂Ln(L)₂(NO₃)(H₂O)₂](NO₃)₂·3H₂O where Ln = Pr (1), Nd (2), Sm (3) and Eu (4)], and CuLn(L)(NO₃)₂(H₂O)₃MeOH]NO₃·MeOH where Ln = Gd (5), Tb (6), Dy (7), Ho (8), Ef (9), Tm (10), Yb (11) and Lu (12)], and their main ligand L = C₁₉H₁₈N₂O₄Br₂ = N,N’-bis(5-bromo-3-methoxysalicylidene)propylene-1,3-diamine] have been characterized by chromatographic analyses. The parameter of relative lipophilicity (R _M0) of the tested compounds was determined experimentally by reversed-phase high-performance thin layer chromatography method with mixtures of methanol and water as a mobile phase. We also described interactions between chromatographed substances and various surfaces (silica—SiO₂ and modified by hydrocarbon chains—RP-2, RP-8, RP-18 phases). This study also investigates the effect of pH of the mobile phase on the retention on the polar stationary phase. Thin layer chromatography combined with magnetic and electric field has been proposed as a complementary method for the determination of physicochemical properties of the investigated compounds. The chromatograms in the field and outside of it were developed simultaneously in three identical chromatographic chambers. One of them was placed in external magnetic field of 0.4 T inductivity, and the second in external electrical field. In magnetic and electric fields, retention of some complexes changed, which indicated that the presence of these fields influenced physicochemical properties of the compounds and their interactions with the stationary phase.