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The ligand H3 L (6-[3-oxo-3-(2-hydroxyphenyl)propionyl]pyridine-2-carboxylic acid), which exhibits two different coordination pockets, has been exploited to engender and study energy transfer (ET) in two dinuclear [LnIII LnIII '] analogues of interest, [EuYb] and [NdYb]. Their structural and physical properties have been compared with newly synthesised analogues featuring no possible ET ([EuLu], [NdLu], and [GdYb]) and with the corresponding homometallic [EuEu] and [NdNd] analogues, which have been previously reported. Photophysical data suggest that ET between EuIII and YbIII does not occur to a significant extent, whereas emission from YbIII originates from sensitisation of the ligand. In contrast, energy migration seems to be occurring between the two NdIII centres in [NdNd], as well as in [NdYb], in which YbIII luminescence is thus, in part, sensitised by ET from Nd. This study shows the versatility of this molecular platform to further the investigation of lanthanide-to-lanthanide ET phenomena in defined molecular systems.

There is a dire need for new antimicrobial compounds to combat the growing threat of widespread antibiotic resistance. With a currently very scarce drug pipeline, consisting mostly of derivatives of known antibiotics, new classes of antibiotics are urgently required. Metal complexes are currently in clinical development for the treatment of cancer, malaria and neurodegenerative diseases. However, only little attention has been paid to their application as potential antimicrobial compounds. We report the evaluation of 906 metal-containing compounds that have been screened by the Community for Open Antimicrobial Drug Discovery (CO-ADD) for antimicrobial activity. Metal-bearing compounds display a significantly higher hit-rate (9.9%) when compared to the purely organic molecules (0.87%) in the CO-ADD database. Out of 906 compounds, 88 show activity against at least one of the tested strains, including fungi, while not displaying any cytotoxicity against mammalian cell lines or haemolytic properties. Herein, we highlight the structures of the 30 compounds with activity against Gram-positive and/or Gram-negative bacteria containing Mn, Co, Zn, Ru, Ag, Eu, Ir and Pt, with activities down to the nanomolar range against methicillin resistant S. aureus (MRSA). 23 of these complexes have not been reported for their antimicrobial properties before. This work reveals the vast diversity that metal-containing compounds can bring to antimicrobial research. It is important to raise awareness of these types of compounds for the design of truly novel antibiotics with potential for combatting antimicrobial resistance.

Neurobiological research relies heavily on imaging techniques, such as fluorescence microscopy, to understand neurological function and disease processes. However, the number and variety of fluorescent probes available for ex vivo tissue section imaging limits the advance of research in the field. In this review, we outline the current range of fluorescent probes that are available to researchers for ex vivo brain section imaging, including their physical and chemical characteristics, staining targets, and examples of discoveries for which they have been used. This review is organised into sections based on the biological target of the probe, including subcellular organelles, chemical species (e.g., labile metal ions), and pathological phenomenon (e.g., degenerating cells, aggregated proteins). We hope to inspire further development in this field, given the considerable benefits to be gained by the greater availability of suitably sensitive probes that have specificity for important brain tissue targets. [ABSTRACT FROM AUTHOR]

The reaction of Re(CO)5Br with deprotonated 1H‐(5‐(2,2′:6′,2′′‐terpyridine)pyrid‐2‐yl)tetrazole yields a triangular assembly formed by tricarbonyl Re(I) vertices. Photophysical measurements reveal blue‐green emission with a maximum at 520 nm, 32 % quantum yield, and 2430 ns long‐lived excited state decay lifetime in deaerated dichloromethane solution. Coordination of lanthanoid ions to the terpyridine units red‐shifts the emission to 570 nm and also reveals efficient (90 %) and fast sensitisation of both Eu(III) and Yb(III) at room temperature, with a similar rate constant kET on the order of 107 s−1. Efficient sensitisation of Eu(III) from Re(I) is unprecedented, especially when considering the close proximity in energy between the donor and acceptor excited states. On the other hand, comparative measurements at 77 K reveal that energy transfer to Yb(III) is two orders of magnitude slower than that to Eu(III). A two‐step mechanism of sensitisation is therefore proposed, whereby the rate‐determining step is a thermally activated energy transfer step between the Re(I) centre and the terpyridine functionality, followed by rapid energy transfer to the respective Ln(III) excited states. At 77 K, the direct Re(I) to Eu(III) energy transfer seems to proceed via a ligand‐mediated superexchange Dexter‐type mechanism. [ABSTRACT FROM AUTHOR]

Imaging with multiple modalities can maximise the information gained from the analysis of a single sample. probes for optical fluorescence and X-ray fluorescence microscopy based on brominated 4-amino-1,8-naphthalimide and BODIPY scaffolds have been successfully designed and synthesised. Herein we show that these prototype probes, based on each of these scaffolds, can be imaged in two different cancer cell lines, and that the respective optical fluorescence and X-ray fluorescence signals are well correlated in these images. [ABSTRACT FROM AUTHOR]

Twelve Re(I) tricarbonyl diimine (2,2′-bipyridine and 1,10-phenanthroline) complexes with thiotetrazolato ligands have been synthesised and fully characterised. Structural characterisation revealed the capacity of the tetrazolato ligand to bind to the Re(I) centre through either the S atom or the N atom with crystallography revealing most complexes being bound to the N atom. However, an example where the Re(I) centre is linked via the S atom has been identified. In solution, the complexes exist as an equilibrating mixture of linkage isomers, as suggested by comparison of their NMR spectra at room temperature and 373 K, as well as 2D exchange spectroscopy. The complexes are photoluminescent in fluid solution at room temperature, with emission either at 625 or 640 nm from the metal-to-ligand charge transfer excited states of triplet multiplicity, which seems to be exclusively dependent on the nature of the diimine ligand. The oxygen-sensitive excited state lifetime decay ranges between 12.5 and 27.5 ns for the complexes bound to 2,2′-bipyrdine, or between 130.6 and 155.2 ns for those bound to 1.10-phenanthroline. Quantum yields were measured within 0.4 and 1.5%. The complexes were incubated with human lung (A549), brain (T98g), and breast (MDA-MB-231) cancer cells, as well as with normal human skin fibroblasts (HFF-1), revealing low to moderate cytotoxicity, which for some compounds exceeded that of a standard anti-cancer drug, cisplatin. Low cytotoxicity combined with significant cellular uptake and photoluminescence properties provides potential for their use as cellular imaging agents. Furthermore, the complexes were assessed in disc diffusion and broth microdilution assays against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), Escherichia coli (E. coli), and Pseudomonas aeruginosa (P. aeruginosa) bacterial strains, which revealed negligible antibacterial activity in the dark or after irradiation. [ABSTRACT FROM AUTHOR]