Antimicrobial Properties of Tris(homoleptic) Ruthenium(II) 2‑Pyridyl-1,2,3-triazole “Click” Complexes against Pathogenic Bacteria, Including Methicillin-Resistant Staphylococcus aureus (MRSA)

A series of tris­(homoleptic) ruthenium­(II) complexes of 2-(1-<b>R</b>-1<i>H</i>-1,2,3-triazol-4-yl)­pyridine “click” ligands (<b>R-pytri</b>) with various aliphatic (R = butyl, hexyl, octyl, dodecyl, and hexdecyl) and aromatic (R = phenyl and benzyl) substituents was synthesized in good yields (52%–66%). The [Ru­(<b>R-pytri</b>)₃]²⁺(X^–)₂ complexes (where X^– = PF₆^– or Cl^–) were characterized by elemental analysis, high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), ¹H and ¹³C nuclear magnetic resonance (NMR) and infrared (IR) spectroscopies, and the molecular structures of six of the compounds confirmed by X-ray crystallography. ¹H NMR analysis showed that the as-synthesized materials were a statistical mixture of the <i>mer</i>- and <i>fac</i>-[Ru­(<b>R-pytri</b>)₃]²⁺ complexes. These diastereomers were separated using column chromatography. The electronic structures of the <i>mer</i>- and <i>fac</i>-[Ru­(<b>R-pytri</b>)₃]²⁺ complexes were examined using ultraviolet–visible (UV-Vis) spectroscopy and cyclic and differential pulse voltammetry. The family of <b>R-pytri</b> ligands and the corresponding <i>mer</i>- and <i>fac</i>-[Ru­(<b>R-pytri</b>)₃]²⁺ complexes were tested for antimicrobial activity <i>in vitro</i> against both Staphylococcus aureus and Escherichia coli bacteria. Agar-based disk diffusion assays indicated that two of the [Ru­(<b>R-pytri</b>)₃]­(X)₂ complexes (where X = PF₆^– and R = hexyl or octyl) displayed good antimicrobial activity against Gram-positive S. aureus and no activity against Gram-negative E. coli at the concentrations tested. The most active [Ru­(<b>R-pytri</b>)₃]²⁺ complexes ([Ru­(<b>hexpytri</b>)₃]²⁺ and Ru­(<b>octpytri</b>)₃]²⁺) were converted to the water-soluble chloride salts and screened for their activity against a wider range of pathogenic bacteria. As with the preliminary screen, the complexes showed good activity against a variety of Gram-positive strains (minimum inhibitory concentration (MIC) = 1–8 μg/mL) but were less effective against Gram-negative bacteria (MIC = 16–128 μg/mL). Most interestingly, in some cases, the ruthenium­(II) “click” complexes proved more active (MIC = 4–8 μg/mL) than the gentamicin control (MIC = 16 μg/mL) against two strains of methicillin-resistant S. aureus (MRSA) (MR 4393 and MR 4549). Transmission electron microscopy (TEM) experiments and propidium iodide assays suggested that the main mode of action for the ruthenium­(II) <b>R-pytri</b> complexes was cell wall/cytoplasmic membrane disruption. Cytotoxicity experiments on human dermal keratinocyte and Vero (African green monkey kidney epithelial) cell lines suggested that the complexes were only modestly cytotoxic at concentrations well above the MIC values

The Reflective Sport and Exercise Science Practitioner

The development of reflective practitioners within the sport and exercise sciences and allied disciplines has started to gain prominence in discussions surrounding education, training, and practice in these fields. However, while the principles associated with doing reflective practice are becoming more widely discussed in the sport and exercise literature, debate concerning what it means to be a reflective practitioner remains limited. This has perhaps resulted in ongoing conceptual and applied considerations relating to the nature and importance of reflective practice, often leading to the promotion of, and engagement in, reflection that is overly technical, restricted, and compliant. Drawing on the perspectives of those who have contributed to this text, in this chapter we (editorial team) present a series of vignettes that offer accounts of what it means to be a reflective practitioner. In doing so, our aim is to allow the reader to immerse themselves within the contributors’ own experiences, perspectives and developmental journeys. Finally, we offer our own analytical summary of the contributors’ vignettes to draw together some of the common ideas and themes concerning the attitudes, skills, perspectives, and philosophy required by the reflective practitioner