Versatile copper(ii) discrete and polymeric coordination compounds with (pyridine-2-yl)methylenenicotinohydrazide and azelaic acid

Abstract

In this contribution, a series of copper(II) discrete and polymeric coordination compounds, namely [Cu₃L₂(aze)₂]_n·nH₂O (1·nH₂O), [CuL₂]·H₂O (2·H₂O) and [CuL(H₂O)(Haze)]·H₂O (3·H₂O) were fabricated from (pyridin-2-yl)methylenenicotinohydrazide (HL) and azelaic acid (H₂aze), using evaporative crystallization, grinding and slurry synthesis methods. The solvent crystallization method produced a crystalline precipitate of complex 1·nH₂O. The filtrate allowed the production of crystals of complex 3·H₂O. The grinding synthetic method gave rise to a mixture of complexes 1·nH₂O, 2·H₂O and an undetermined phase. Results of the slurry synthetic approach highly depend on the stirring time. The obtained coordination compounds have been fully characterized by single crystal X-ray diffraction revealing different structures of complexes, viz. from mononuclear homo- and heteroleptic complexes (2 and 3) to a 1D heteroleptic coordination polymer (1). DFT calculations on non-polymeric complexes were conducted to evaluate the hydrogen-bonding and π-stacking interactions that play a critical role in the solid-state structures of complexes 2 and 3. Additionally, the impact of co-crystallized water molecules, which enhance the π-stacking interactions, was analyzed using energy decomposition analysis.