Induction of chirality through change of substitution in cadmium (II) complexes of 2-benzoylpyridine and 2-acetylpyridine based Schiff bases - Crystal structure, luminescence and thermal properties

Two new cadmium (II) complexes, with the formulae [Cd (L1) I2] (1) and [Cd (L2) Br2] (2) where L1 and L2 are Schiff base ligands 2-(phenyl(pyridine-2-yl)methyleneamino)ethylamino)ethanol and 2-(1-(pyridine-2-yl)ethylideneamino) ethylamino)ethanol respectively, have been synthesized and characterized by single crystal X-ray structural analysis. X-ray crystal structures revealed a change in the substituent from CH3 group in L1 by a phenyl group in L2 led to a completely different supramolecular structure and space group. Complex 1 crystallizes in P21/c space group, where as 2 crystallizes in chiral P212121 space group. Besides the hydrogen bonding interaction, the π-interaction involving the metal-ligand chelate ring is a generic feature of the complexes. The cooperative π···π and hydrogen bonding interaction in 1 led to achiral 1D chains, but in 2 CH···π interaction led to helical chains. At room temperature, luminescence properties of these two complexes in DMF solution were studied. Additionally, we have explored the thermal properties of these two complexes.