Antimicrobial Hexaaquacopper(II) Complexes with Novel Polyiodide Chains.

Zehra Edis,Richie R Bhandare,Guido J Reiss,Radhika Raheja,Hamid Abu Sara,Samir Haj Bloukh

doi:10.3390/polym13071005

Abstract

The non-toxic inorganic antimicrobial agents iodine (I2) and copper (Cu) are interesting alternatives for biocidal applications. Iodine is broad-spectrum antimicrobial agent but its use is overshadowed by compound instability, uncontrolled iodine release and short-term effectiveness. These disadvantages can be reduced by forming complex-stabilized, polymeric polyiodides. In a facile, in-vitro synthesis we prepared the copper-pentaiodide complex [Cu(H2O)6(12-crown-4)5]I6 · 2I2, investigated its structure and antimicrobial properties. The chemical structure of the compound has been verified. We used agar well and disc-diffusion method assays against nine microbial reference strains in comparison to common antibiotics. The stable complex revealed excellent inhibition zones against C. albicans WDCM 00054, and strong antibacterial activities against several pathogens. [Cu(H2O)6(12-crown-4)5]I6 · 2I2 is a strong antimicrobial agent with an interesting crystal structure consisting of complexes located on an inversion center and surrounded by six 12-crown-4 molecules forming a cationic substructure. The six 12-crown-4 molecules form hydrogen bonds with the central Cu(H2O)6. The anionic substructure is a halogen bonded polymer which is formed by formal I5− repetition units. The topology of this chain-type polyiodide is unique. The I5− repetition units can be understood as a triodide anion connected to two iodine molecules.

Highlights

Mankind faces dangerously rising levels of antimicrobial resistance by the so-calledESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp. and Escherichia coli) [1,2]
The morphology and composition of [Cu(H2 O)6 (12-crown-4)5 ]I6 · 2I2 were investigated through SEM and Energy-Dispersive X-ray Spectroscopic (EDS) analysis (Figure 1, Supplement 1)
The sample holder is made of copper, this increased the weight percent of Cu (Supplement 1)

Summary

Introduction

Mankind faces dangerously rising levels of antimicrobial resistance by the so-calledESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp. and Escherichia coli) [1,2]. Pathogens can be acquired in hospital settings through nosocomial infections and lead to delayed recovery, treatment failures, increasing health care costs, morbidity, and mortality [5,6]. In the current COVID-19 pandemic, nosocomial infections originating from emergency rooms and health care settings have negatively impacted the treatment of immunocompromised, severely ill patients with comorbidities [7,8]. Antimicrobial polymeric coatings can reduce the burden of infections through contaminated fomites in all indoor and outdoor settings [8,9,10,11,12,13]. Inclusion of known antimicrobial agents like iodine and copper into polymeric coating materials can mitigate antimicrobial resistance [13,14,15,16]

Methods

Results

Conclusion