N-HO and N-HCl supported 1D chains of heterobimetallic CuII/NiII-SnIV cocrystals

Abstract

The Schiff base H₂L¹ [N,N'-ethylenebis(3-methoxysalicylaldimine)] or H₂L² [N,N'-ethylenebis(3-ethoxysalicylaldimine)] was reacted with MCl₂·xH₂O and SnCl₄·5H₂O to afford the supramolecular heterobimetallic systems (H₂ED)²⁺·2[ML]·[SnCl₆]^2- [M = Cu, L = L¹ (1), L = L² (2); M = Ni, L = L¹ (3), L = L² (4); ED = 1,2-ethylenediamine], whose structures were established by single crystal X-ray analyses. Each structure includes different entities, viz. a mononuclear [CuL]/[NiL] neutral complex (coformer), a hexachlorostannate dianion [SnCl₆]^2-, a 1,2-ethylenediammonium dication (H₂ED²⁺) and, only in 2 and 4, a methanol molecule. Based on the work of Grothe et al. (Cryst. Growth Des., 2016, 16, 3237-3243), compounds 1 and 3 are cocrystal salts, 2 and 4 are cocrystal salt solvates. The ionic pairs (H₂ED)²⁺·[SnCl₆]^2- in 1-4 are encapsulated by the Cu- or Ni-complexes, and stabilized by N-HO and one N-HCl bond interactions leading to infinite 1D chains. The antimicrobial studies of 1-4 against yeasts (C. albicans and S. cerevisiae) and Gram-positive (S. aureus and E. faecalis) and -negative bacteria (P. aeruginosa and E. coli) indicate that the Ni₂Sn systems (3 and 4) are more active than the analogous Cu₂Sn ones (1 and 2).