This study presents the green synthesis and comprehensive characterization of ZnO–Ag nanocomposites using an eco-friendly approach that incorporates aqueous Tagetes erecta extract via the co-precipitation method. The research systematically evaluates the effect of silver concentration (0.1–0.5%) on material properties and dual applications: solar photocatalytic degradation of methylene blue and antibacterial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Advanced characterization techniques, including UV-Vis, XRD, TEM, FTIR, and TGA, confirmed the successful formation of crystalline nanocomposites with spherical and hemispherical morphologies, consisting of hexagonal wurtzite ZnO and face-centered cubic Ag phases. Results demonstrate that strategic silver incorporation significantly enhances ZnO photocatalytic activity by improving charge separation and reducing recombination rates, with the ZnO–Ag (0.3%) nanocomposite exhibiting optimal performance, achieving complete methylene blue degradation within 25 min under solar irradiation. Antibacterial assays showed efficacy against the bacteria used, with a significantly stronger bactericidal effect against S. aureus than E. coli, especially for ZnO–Ag (0.2%) at a 250 μg/mL concentration. This study highlights the synergistic effect between ZnO, Ag, and bioactive compounds from Tagetes erecta, offering a sustainable approach for developing multifunctional nanomaterials with significant potential in environmental remediation and antibacterial applications.

In this work, we synthesized a series of nine tetraalkylammonium salts derived from N ‐methyl morpholine and assessed their antibacterial efficacy against Methicillin‐Resistant Staphylococcus aureus (MRSA). The investigated morpholinium cations differ by the length of one linear alkyl chain, which ranges from 1 to 18 carbon atoms. We found that compounds with alkyl chains in the n ‐C ₁₂ H ₂₅ ‐( n ‐dodecyl) to C ₁₆ H ₃₃ ‐( n ‐hexadecyl) display the highest bactericidal effects, exhibiting Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values of 3.9 μg/mL – surpassing the effectiveness of the commercial drug Linezolid. Conversely, compounds with shorter chains (<5 carbon atoms) are inactive against MRSA, establishing a clear structure‐activity relationship. Assays on A. salina reveal that short‐alkyl‐chain morpholinium derivatives, inactive against MRSA), are moderately toxic, while the strongest bactericides of our set demonstrate high or extreme toxicity to A. salina . Our findings underscore the potential of morpholine derivatives as a means to control Methicillin‐Resistant Staphylococcus aureus and pinpoint the need to develop safe applications for these compounds given their potential toxicity.

Background/objectives: The increasing prevalence of multidrug-resistant (MDR) bacteria, particularly Klebsiella pneumoniae, calls for the development of new antimicrobial agents. This study investigates a series of fluorinated azolium salts and their rhodium(I) complexes for antibacterial activity against clinical and reference strains of K. pneumoniae. Methods: Eleven fluorinated azolium salts and their corresponding Rh(I) complexes (22 compounds total) were synthesized and tested against several K. pneumoniae strains, including three MDR clinical isolates (U–13685, H–9871, U–13815) and ATCC reference strains. Minimum inhibitory concentrations (MICs) were determined. In silico ADMET analyses were conducted to evaluate intestinal absorption, oral bioavailability, Caco-2 permeability, carcinogenicity, solubility, and synthetic accessibility. Results: Among the Rh(I) complexes, Rh–1, Rh–3, and Rh–11 showed activity against the three MDR isolates (MIC = 62.5–250 µg/mL), while Rh–1, Rh–4, Rh–6, and Rh–11 were active against all ATCC strains (MIC = 3.9–250 µg/mL). The corresponding azolium salts displayed weak or no activity, highlighting the critical role of the metal center. ADMET predictions indicated that most Rh complexes had good intestinal absorption, and all except Rh–3, Rh–4, and Rh–9 were predicted to be orally bioavailable. Compounds Rh–1 to Rh–7 showed Caco-2 permeability, and all were classified as non-carcinogenic. Rh–8 to Rh–11 exhibited lower solubility and synthetic accessibility. Conclusions: The results underscore the potential of fluorinated Rh(I) complexes as antibacterial agents against MDR K. pneumoniae, with Rh–1 and Rh–11 emerging as promising leads based on activity and favorable predicted pharmacokinetics.

In this work, we synthesized a series of nine tetraalkylammonium salts derived from N-methyl morpholine and assessed their antibacterial efficacy against Methicillin-Resistant Staphylococcus aureus (MRSA). The investigated morpholinium cations differ by the length of one linear alkyl chain, which ranges from 1 to 18 carbon atoms. We found that compounds with alkyl chains in the n-C12H25- (n-dodecyl) to C16H33- (n-hexadecyl) display the highest bactericidal effects, exhibiting Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values of 3.9 µg/mL - surpassing the effectiveness of the commercial drug Linezolid. Conversely, compounds with shorter chains (<5 carbon atoms) are inactive against MRSA, establishing a clear structure-activity relationship. Assays on A. salina reveal that short-alkyl-chain morpholinium derivatives, inactive against MRSA), are moderately toxic, while the strongest bactericides of our set demonstrate high or extreme toxicity to A. salina. Our findings underscore the potential of morpholine derivatives as means to control Methicillin-Resistant Staphylococcus aureus and pinpoint the need to develop safe applications for these compounds given their potential toxicity.

This paper presents the synthesis and characterization of Schiff base ligands (L) derived from NH-pyrazole-indole and their ruthenium(II) complexes of the general formula [Ru(p-cymene)(L)Cl₂]. The structural characterization of the ligands and ruthenium complexes was performed using a range of analytical methods, including infrared spectroscopy (IR), Raman spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, elemental analysis, mass spectrometry(ESI-MS), density functional theory (DFT) calculations, and single-crystal X-ray diffraction crystallography for two of the four synthesized compounds. Schiff base ligands (L) derived from NH-pyrazole-indole and their ruthenium(II) complexes were evaluated against antibiotic-resistant bacteria. The effect of substituting the ligand with methoxy groups on biological activity was assessed. The antibacterial activity, Minimal Inhibitory Concentration (MIC), and Minimal Bactericidal Concentration (MBC) of the free ligands and the ruthenium compounds were measured against six bacterial isolates (Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli, Shigella dysenteriae) and two control strains (Enterococcus faecalis ATCC 29212 and Enterobacter cloacae ATCC 13047) from the ESKAPE group of highly antibiotic-resistant pathogens. The free ligands were inactive, whereas all four ruthenium complexes displayed notable antibacterial activity. In particular, compounds Ru3 and Ru4 exhibited higher activity against Staphylococcus aureus than the Trimethoprim control, with MIC values of 15.60 µg/mL, compared with an MIC > 64 µg/mL for Trimethoprim. The activity of those two complexes was similar to that of Gentamicin against this strain. Molecular docking calculations suggested a possible mechanism of action through binding of the complexes to the active site of S. aureus PBP2a.