Alkaline earth metal-based coordination polymers produced with benzophenone-3,3′,4,4′-tetracarboxylate: synthesis and application

Four alkaline earth metal-based compounds were synthesized under hydrothermal conditions, using BPTC (benzophenone-3,3′,4,4′-tetracarboxylate) as ligand, and are hereinafter referred to as M-BPTC (M = Mg, Ca, Sr, Ba). These compounds exhibit interesting structural diversity, variable chemical and thermal stability, as well as antimicrobial activity and proton conductivity. The Ca-BPTC (C₁₇H₁₃O₁₂Ca) belongs to the triclinic crystal system, P-1 space group (a = 6.9330 Å, b = 9.8359 Å, c = 14.8717 Å, α = 78.351°, β = 81.043°, γ = 71.696°). The Sr-BPTC (C₁₇H₁₀O₁₁Sr₂) crystallized into an orthorhombic crystal system, Pbca space group (a = 6.9945 Å, b = 10.3767 Å, c = 47.882 Å and α = β = γ = 90°) and showed proton conduction up to 55 °C. The compound Ba-BPTC (C₁₇H₈O₁₀Ba₂) belongs to the triclinic crystal system, P-1 space group (a = 4.39030 Å, b = 11.9969 Å, c = 16.0108 Å, α = 71.6830°, β = 86.2360°, γ = 89.790°). The crystal structure of the compound of Mg²⁺ with BPTC was not elucidated. The calcium coordination polymer and magnesium compound showed antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa and antifungal activity against Candida albicans.