Interplay of bifurcated hydrogen bonds in making of inclusion/pseudo-inclusion complexes of Ni(II), Cu(II) and Zn(II) of a salophen type ligand: Crystal structures and spectral aspects

Publication date: 15 April 2017
Source:Journal of Molecular Structure, Volume 1134
Author(s): K.U. Ambili, M. Sithambaresan, M.R. Prathapachandra Kurup
Three novel photoluminescent materials were synthesized by treating Ni(II), Cu(II) and Zn(II) acetate salts with a Schiff base prepared from 3-ethoxysalicylaldehyde and 2-aminobenzylamine. Among the prepared complexes, Ni(II) and Cu(II) complexes are inclusion compounds while Zn(II) complex is a pseudo-inclusion compound. They were characterized by elemental analysis, IR, UV–visible and EPR spectra. Single crystal XRD studies of these complexes suggest that Ni(II) and Cu(II) are in a distorted square planar environment while the spatial arrangement of donor atoms in Zn(II) complex is best described as distorted square based pyramid although significant distortion towards trigonal bipyramid is noticed. Stabilized crystal packing of the complexes is established via supramolecular interactions. The metal chelate rings as the π system for C–H···π interactions found in Cu(II) and Zn(II) complexes explicit the concept of metalloaromaticity. TG-DTG studies reveal that all the complexes are thermally stable. Both ligand and complexes exhibit intense photoluminescence in near UV region. However, Zn(II) complex giving an intense blue-green emission spectrum at maximum wavelength of 518 nm with shoulder peaks, could be used for optoelectronic applications.

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