Suitable interplay between various conventional and unconventional non-covalent interactions in forming self-assembled supramolecules of two Ni(II)/Zn(II) Schiff base complexes

Two compartmental Schiff bases, H2L1 [N,N′-bis(3-ethoxysalicylidene)propane-1,3-diamine] and H2L2 [N,N′-bis(3-ethoxysalicylidene)-2,2-dimethylpropane-1,3-diamine], have been utilized to prepare two new hetero-dinuclear nickel(II)/zinc(II) complexes, [(DMSO)2NiL1Zn(NCS)2] (1) and [NiL2Zn(NCS)2] (2) respectively. Both complexes have been characterized by elemental and spectral analysis and single crystal X-ray diffraction. Nickel(II) is located in the inner compartment while zinc(II) is positioned in the outer compartment in both complexes. Supramolecular interactions have been explored for both complexes. Hirshfeld surface analysis has been used for visually analyzing intermolecular C−H⋅⋅⋅O (hydrogen bonding), π-π stacking, conventional C−H⋅⋅⋅π(arene) and unconventional C−H⋅⋅⋅π(SCN) interactions in the crystal structures. Theoretical studies on the formation of C−H⋅⋅⋅O (hydrogen bonding), π-π stacking, conventional C−H⋅⋅⋅π(arene) and unconventional C−H⋅⋅⋅π(SCN) interactions in the solid state X-ray structures of both complexes have been performed using the Gaussian-09 and M06-2X/6-31+G* level of theory