Two novel quinoline-decorated half-salamo-type Co(II) complexes: Synthesis, crystal structure, Hirshfeld surface analysis, DFT calculation and fluorescence properties

Self-assembly through a quinoline-decorated N3O donor half-salamo-type tetradentate ligand HL and coordinative preference of Co(II) ion, two novel Co(II) complexes [Co(L)Cl] (1) and [Co(L)(NCS)] (2) were synthesized and characterized. X-ray crystallography revealed that both complexes 1 and 2 have similar mononuclear structure, in which the five-coordinated Co(II) atoms are not only surrounded by the N3O cavity of the deprotonated ligand (L)(-) unit, but also coordinated with different Cl- and NCS- anions. For the involvement of different anions, the crystal structures of the two complexes exhibit intermolecular C-H center dot center dot center dot Cl and C-H center dot center dot center dot S hydrogen interactions in building supramolecular assemblies, respectively. The two complexes are stabilized by C-H center dot center dot center dot O, C-H center dot center dot center dot N, C-H center dot center dot center dot C, C-H center dot center dot center dot S bonds and C-H center dot center dot center dot Pi, Pi center dot center dot center dot Pi interactions. The spectral properties of the complexes were investigated through UV-Vis and fluorescence spectroscopy. In addition, the detailed analyses of Hirshfeld surfaces and fingerprint plots provide the basis of the intermolecular interactions in building crystal blocks.