In continuation of our studies on zinc (II) coordination chemistry, reactions between the zinc (II) starting material and furosemide were investigated. Furosemide, a well-known pharmaceutical, contains functional groups which could serve as donors in coordination with metal ions. Reactions between zinc oxide or chloride and furosemide in aqueous ammonia solution yielded a mononuclear complex, Zn (NH₃) ₂ (fur) ₂ (1), where fur^− stands for deprotonated furosemide. Unfortunately, some reactions produced mixtures of the desired metal complex 1 and by-product, ammonium salt NH₄fur (2). To further explore the coordination chemistry of furosemide, quinaldinate (an anion of quinoline-2-carboxylic acid, abbreviated as quin^−) was introduced into the reaction system, resulting in the formation of a coordination polymer, Zn₃ (quin) ₄ (fur) ₂ₙ·2nCH₃OH (3). 1 and 3 were evaluated for their antibacterial properties against Gram-positive and Gram-negative bacteria. Notably, compound 3 exhibited moderate antibacterial activity against Staphylococcus epidermidis, representing a promising starting point for the preparation of potential antibacterial zinc (II) complexes.
Rihtaršič et al. (Wed,) studied this question.