Coordination-Driven Salamo-Salen-Salamo-Type Multinuclear Transition Metal(II) Complexes: Synthesis, Structure, Luminescence, Transformation of Configuration, and Nuclearity Induced by the Acetylacetone Anion.

A flexible polydentate Salamo-Salen-Salamo hybrid ligand H 4 L was designed and synthesized, which has rich pockets (salamo and salen pockets) so that it may have fascinating coordination patterns with transition metal(II) ions. Four multinuclear transition metal(II) complexes, novel butterfly-shaped homotetranuclear [Ni 4 (L)(μ 1 -OAc) 2 (μ 1,3 -OAc) 2 (H 2 O) 0.5 (CH 3 CH 2 OH) 3.5 ]·4CH 3 CH 2 OH ( 1 ), helical homotrinuclear [Zn 3 (L)(μ 1 -OAc) 2 ]·2CH 3 CH 2 OH ( 2 ), double-helical homotrinuclear [Cu 2 (H 2 L) 2 ]·2CH 3 CN ( 3 ), and mononuclear [Ni(H 2 L)]·1.5CH 3 COCH 3 ( 4 ), have been synthesized and characterized by single-crystal X-ray diffraction. The effects of different anions [OAc - and (O 2 C 5 H 7 ) 2- ] on the complexation behavior of H 4 L with transition metal(II) ions were studied by UV-vis spectrophotometry. The fluorescent properties of the four complexes were studied with zebrafish, which are expected to be a potential light-emitting material. Ultimately, interaction region indicator (IRI) valuations, Hirshfeld surface analyses, density functional theory (DFT & TD-DFT), electrostatic potential analyses (ESP), and simulations were carried out to further demonstrate the weak interactions and electronic properties of the free ligand and its four complexes.