Two Lanthanide(III) Complexes based on the Schiff Base N,N′‐Bis(salicylidene)‐1,5‐diamino‐3‐oxapentane: Synthesis, Characterization, DNA‐binding Properties, and Antioxidation

The Schiff base N,N′‐bis(salicylidene)‐1,5‐diamino‐3‐oxapentane (H2L) and its lanthanide(III) complexes, PrL(NO3)(DMF)(H2O) (1) and Ho2L2(NO3)2·2H2O (2), were synthesized and characterized by physicochemical and spectroscopic methods. Single crystal X‐ray structure analysis revealed that complex 1 is a discrete mononuclear species. The PrIII ion is nine‐coordinate, forming a distorted capped square antiprismatic arrangement. Complex 2 is a centrosymmetric dinuclear neutral entity in which the HoIII ion is eight‐coordinate with distorted square antiprismatic arrangement. The DNA‐binding properties of H2L and its LnIII complexes were investigated by spectrophotometric methods and viscosity measurements. The results suggest that the ligand H2L and its LnIII complexes both connect to DNA in a groove binding mode; the complexes bind more strongly to DNA than the ligand. Moreover, the antioxidant activities of the LnIII complexes were in vitro determined by superoxide and hydroxyl radical scavenging methods, which indicate that complexes 1 and 2 have OH· and O2–· radical scavenging activity.