Studies on synthesis and magnetic resonance of lanthanide complexes with novel Schiff base derived from noncyclic polyether and β-diketone

Nine h( III) complexes with a novel Schiff base derived from diglycolamine and benzoylacetone (BZDA) have been synthesized and characterized. They can be formulated as Ln₂(BZDA)₃(NO₃)₃](NO₃)₃-nH₂O (Ln? La, Pr, Nd, Sm, n = 4; Ln = Gd, Tb, Er, Yb, Y, n = 7). Enamic form mechanism in this β-diketone Schiff base and its Complexes were suggested and proved by IR, UV and NMR methods. The ¹³C spin-lattice relaxation time T₁ and the ratios of r(C_i-In)/ ^r (c_j-in) were measured by a 500 MHz NMR instrument for elucidating the formation of the stable six-membered chelate ring structure in these complexes. The EPR spectrum of the Gd( III) complex exhibits the “U” spectral feature and “zero field effect”. On the basis of them, the crystal field strength and the local symmetry around Gd ³⁺ in the complex have been discussed.