Green Preparation of Antimicrobial 1D-Coordination Polymers: [Zn(4,4′-bipy)Cl2]∞ and [Zn(4,4′-bipy)2(OAc)2]∞ by Ultrasonication of Zn(II) Salts and 4,4′-Bipyridine

Abstract

We report on the green preparation of one-dimensional metal coordination polymers by sonochemical approach. The spacer ligand 4,4′-bipyridine was ultrasonicated with chloride or acetate zinc salts to obtain [Zn(4,4′-bipy)Cl2]∞ and [Zn(4,4′-bipy)2(OAc)2]∞, respectively. Benign solvents such as ethanol and water were selected as reaction media, and the synthesis took place in a few minutes—a very short time compared to conventional methods where some days’ synthesis is required. X-ray powder diffraction, Fourier transform infrared spectroscopy, thermal analysis (thermogravimetric and differential scanning calorimetry), and CHN techniques investigated the influence of using different reaction solvents on the chemical, structural, and thermal properties of the final products. The 1D [Zn(4,4′-bipy)Cl2]∞ and [Zn(4,4′-bipy)2(OAc)2]∞ polymers, in agreement with the structures reported in the literature, were obtained in the form of nanocrystals with an average crystal size around 100 nm. As a proof of concept, a set of Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Klebsiella pneumoniae), and three yeast strains (Candida albicans, Candida krusei, Candida glabrata) were tested to evaluate the antimicrobial activity of the coordination polymers, following the Kirby–Bauer procedure and microplate dilution method. Thus, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimal biofilm inhibitory concentration (MBIC) were evaluated. Except for Candida krusei, the compounds showed an appreciable antimicrobial and antibiofilm activity against these strains grown in the liquid medium.

Efficacy of ozonated water as a PS in photodynamic therapy: A tool for dental caries management? An in vitro study

“…If we consider the antibiofilm activity by considering the MBEC “ minimum biofilm eliminating concentration ,” in other words the minimum concentration of an antimicrobial able to interfere with a mature biofilm. 18 , 19 …”

“…If we consider the antibiofilm activity by considering the MBEC "minimum biofilm eliminating concentration," in other words the minimum concentration of an antimicrobial able to interfere with a mature biofilm. 18,19 The results shown in Figure 5 reveal an effective and synergic activity by using the maximum O 3 concentration [0.06 mg/L] plus light in a wavelength range from 450 to 470 nm. This experiment also showed that the photodynamic treatment is ineffective if we use O 3 at a lower concentrations range [0.042 mg/L], in fact, in these conditions, the biofilm inhibition is comparable with only ozone use.…”

Structural and Theoretical Study of Copper(II)-5-fluoro Uracil Acetate Coordination Compounds: Single-Crystal to Single-Crystal Transformation as Possible Humidity Sensor

“…In the isolated mixture, we observed that the yellow solid was composed of very small yellow crystals that partially dissolved if left in the mother liquor (Figure 2b,c). The IR spectrum of compound 1 showed bands at 3062 and 2938 cm −1 corresponding to the ν(C-H) stretching vibrations, as well as bands around 1641 and 806 cm −1 attributed to out-of-plane ν(C-H) stretching vibrations of the pyridine ring [46]. In addition, the vibrational peak for N=O stretching appeared at 1720 cm −1 .…”