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

• Two multi-nuclear Ni(II)-based complexes have been successfully prepared by the complexation of more flexible salamo-type ligand (H 2 L) with nickel salts of different anions. • The structure of tetra-nuclear complex 2 is particularly unique because the flexibility of the ligand is better, which creates conditions for the intramolecular self-assembly. Two new tri- and tetra-nuclear Ni(II)-based complexes, [{NiL(EtOH)(μ -OAc)} 2 Ni]·4EtOH (1) and [Ni 4 L 2 (μ 3 -OMe) 4 (MeOH) 4 ] (2), supported by a more flexible salamo-type ligand H 2 L 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 H 2 L, complex 2 is obtained by the form of intramolecular self-assembly. Moreover, the fluorescence properties of H 2 L 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. Image, graphical abstract Two new tri- and tetra-nuclear Ni(II)-based complexes, [{NiL(EtOH)(μ -OAc)} 2 Ni]·4EtOH (1) and [Ni 4 L 2 (μ 3 -OMe) 4 (MeOH) 4 ] (2) , supported by a more flexible salamo-type ligand H 2 L containing coumarin functional groups have been synthesized and characterized structurally. Interestingly, complex 2 is a novel tetra-nuclear structure previously unreported. The fluorescence properties, Hirshfeld surfaces analyses and DFT calculations of H 2 L and its Ni(II)-based complexes were studied. [ABSTRACT FROM AUTHOR]