Exploring two helical centrosymmetric homotetranuclear Cu (II) bis (salamo)‐based complexes

Abstract

Abstract Two helical centrosymmetric homotetranuclear Cu (II) complexes, [Cu 4 (L) 2 (EtOH) 2 ](ClO 4 ) 2 ·2EtOH·2CHCl 3 (1) and [{Cu 4 (L) 2 (EtOH) 2 }{Cu 4 (L) 2 (HNO 3 ) 2 }](NO 3 ) 4 ·3EtOH·3MeOH (2) , were synthesized by the reactions of a symmetric bis (salamo)‐based ligand H 3 L with Cu(ClO) 2 ·6H 2 O and Cu(NO) 3 ·3H 2 O, respectively, and certified by elemental analyses, UV–Visible absorption spectra, infrared spectra and single‐crystal X‐ray analysis techniques. X‐ray crystal structure analyses reveal that four Cu (II) atoms of complex 1 are attached to two deprotonated ligand (L) 3− units with the help of two coordinated ethanol molecules, and then forming a helical centrosymmetric complex by H‐bonding and π⋯π interactions. While complex 2 unit cell contains two crystallographically independent but chemically identical homotetranuclear complexes (molecules A and B ), eight Cu (II) atoms are coordinated by four deprotonated ligand (L) 3− units. The coordination mode of four Cu (II) atoms from molecule A is the same as complex 1 ; at the same time, oxygen atoms on nitrates are involved in the coordination of another four Cu (II) atoms from molecule B . The short‐range interactions in complexes 1 and 2 were calculated by Hirshfeld surfaces analyses. The molecular orbital energy levels, molecular stabilities of complexes 1 and 2 were analyzed by DFT calculations. In addition, antibacterial assays were also investigated in detail.