Adjustment of the structures and biological activities by the ratio of NiL to RE for two sets of Schiff Base complexes [(NiL)nRE] (n = 1 or 2; RE = La or Ce)

Two sets of 3d–4f complexes [(NiL)nRE] (n = 1, 2; RE = La and Ce; H2L = N,N′-bis(3-ethoxysalicylidene)ethylenediamine) were obtained by reacting NiL with RE(NO3)3 in the ratios of 1/1 and 2/1, respectively. With the NiL/RE ratio changing from 1/1 to 2/1, not only the crystal structures were changed from discrete dinuclear complexes [(NiL)RE] to sandwich-like trinuclear complexes [(NiL)2RE], but also the biological activities were greatly influenced. The trinuclear complexes [(NiL)2RE] exhibited higher antimicrobial activities than the corresponding dinuclear counterpart [(NiL)RE].