Coordination Polymer Based on Pentacopper Metallamacrocyclic Units Featured by 3-Hydroxy-4-pyridinone Ligands: Synthesis, Structure and Biological Activity

Abstract

A novel complex {[Cu₅(β-alaha)₄](CuL₂)(H₂O)₁₄}_n (I) was successfully synthesized in the presence of (3-hydroxy-2-methyl-4-oxo-4H-pyridin-1-yl)acetic acid, Cu(Ac)₂·H₂O, and β-alaninehydroxamic acid (H₂β-alaha), with the aim of exploring the potential for binding biologically active ligands of the pyridinone type with the β-alaninehydroximate 12-MC-4 metallacrown fragments. X-ray diffraction and topological studies of the complex I have been carried out. The geometrical characteristics indicate the presence of Cu–O interactions between a metallamacrocyclic cation [Cu₅(β-alaha)₄(H₂O)₄]²⁺ and two adjacent anions [Cu(L)₂]^2–. In the study of the experimental−theoretical electron density topology, it is found that the central and two peripheral copper atoms also increase their coordination number to 6 due to additional contacts with anions. This leads to the formation of a 1D coordination polymer. The energy of all cation-anion interactions in the chain was estimated. It has been demonstrated that 1D chains in the crystal are linked together by hydrogen bonds involving solvate water molecules with formation of 3D networks. Complex I exhibited antimycobacterial activity towards Mycolicibacterium smegmatis (M. smegmatis), as a model for Mycobacterium tuberculosis (M. tuberculosis).