Synthesis, crystal structures, magnetism and fluorescence of manganese(II) and copper(II) complexes based on 2,5-diketopiperazine-N,N′-diacetic acid ligands

Two novel 2,5-diketopiperazine-N,N′-diacetic acid-based (H₂DPDA) metal complexes [Mn(DPDA)_0.5(phen)₂H₂O]₂Cl₂·2H₂O (1) and {[Cu(DPDA)(phen)H₂O]·4H₂O}_n(2)(H₂DPDA = 2,5-diketopiperazine-N,N′-diacetic acid, phen = phenanthroline) have been hydrothermally synthesized, and the relationship between magnetism, fluorescence and structure was investigated. Crystal structure analysis shows that (1) 1 and 2 belong to the triclinic crystal system, the p-1 space group; (2) 2 shows a 1-dimensional zigzag chain structure. Thermogravimetric analysis shows that the complex 1 has better stability than 2. Magnetic measurements show that 1 exhibits antiferromagnetism but 2 exhibits ferromagnetism. Fluorescence test shows that 1 and 2 have luminescent properties and emits blue fluorescence.