An investigation into three-dimensional octahedral multi-nuclear Ni(II)-based complexes supported by a more flexible salamo-type ligand

Abstract

Two new tri- and tetra-nuclear Ni(II)-based complexes, [{NiL(EtOH)(μ-OAc)}2Ni]·4EtOH (1) and [Ni4L2(μ3-OMe)4(MeOH)4] (2), supported by a more flexible salamo-type ligand H2L containing coumarin functional groups have been synthesized. Complex 1 is tri-nuclear, including three Ni(II) atoms with hexa-coordinated octahedral geometries. X-ray single-crystal structure analysis revealed that complex 2 is a novel tetra-nuclear structure previously unreported, and the geometry of four Ni(II) atoms with hexa-coordinate can be regarded as octahedron. Interestingly, due to the improvement of the flexibility of salamo-type ligand H2L, complex 2 is obtained by the form of intramolecular self-assembly. Moreover, the fluorescence properties of H2L and its Ni(II)-based complexes were studied. Subsequently, the supramolecular structure, Hirshfeld surfaces analyses and DFT calculations of the two Ni(II)-based complexes have been performed.