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Antimicrobial resistant (AMR) bacteria are emerging and spreading globally, threatening our ability to treat common infectious diseases. The development of new classes of antibiotics able to kill or inhibit the growth of such AMR bacteria through novel mechanisms of action is therefore urgently needed. Here, a new family of indole-containing arene ruthenium organometallic compounds are screened against several bacterial species and drug resistant strains. The most active complex [(p-cym)Ru(O-cyclohexyl-1H-indole-2-carbothioate)Cl] (3) shows growth inhibition and bactericidal activity against different organisms (Acinetobacter baumannii, Mycobacterium abscessus, Mycobacterium tuberculosis, Staphylococcus aureus, Salmonella enterica serovar typhi and Escherichia coli), demonstrating broad-spectrum inhibitory activity. Importantly, this compound series exhibits low toxicity against human cells. Owing to the novelty of the antibiotic family, their moderate cytotoxicity, and their inhibitory activity against Gram positive, Gram negative and acid-fast, antibiotic resistant microorganisms, this series shows significant promise for further development.

Water-soluble metalla-cages were used to deliver hydrophobic porphin molecules to cancer cells. After internalization, the photosensitizer was photoactivated, significantly increasing the cytotoxicity in cells. During the transport, the photosensitizer remains nonreactive to light, offering a new strategy to tackle overall photosensitization, a limitation often encountered in photodynamic therapy.

Cationic arene ruthenium metallaprisms of the general formula [Ru6(p-cymene)6(tpt)2(OO∩OO)3]6+ {tpt = 2,4,6-tris(4-pyridyl)-1,3,5-triazine; OO∩OO = 9,10-dioxo-9,10-dihydroanthracene-1,4-diolato [1]6+, 6,11-dioxo-6,11-dihydronaphthacene-5,12-diolato [2]6+} have been obtained from the corresponding dinuclear arene ruthenium complexes [Ru2(p-cymene)2(OO∩OO)Cl2] by reaction with tpt and silver trifluoromethanesulfonate. Aromatic molecules (phenanthrene, pyrene, triphenylene, coronene) present during the synthesis of these metallaprisms are permanently encapsulated to give carceplex systems. All empty cages ([1]6+ and [2]6+) and carceplex systems ([guest⊂1]6+ and [guest⊂2]6+) were isolated in good yield as trifluoromethanesulfonate salts and characterized by NMR, UV, and IR spectroscopy. The host–guest properties of [1]6+ and [2]6+ were studied in solution in the presence of small aromatic molecules (phenanthrene andpyrene). The stability constant of association (Ka) wasestimated by NMR spectroscopy for the following host–guest systems: [phenanthrene⊂1]6+, [pyrene⊂1]6+ and [phenanthrene⊂2]6+, [pyrene⊂2]6+. All Ka values were found to be larger than 2.0 × 104M–1 for these host–guest systems ([D3]acetonitrile, 21 °C).

A series of large cationic hexanuclear metalla-prisms, [Ru6(p-iPrC6H4Me)6(tpt)2(donq)3]6+, [Ru6(p-iPrC6H4Me)6(tpt)2(doaq)3]6+ and [Ru6(p-iPrC6H4Me)6(tpt)2(dotq)3]6+, composed of p-cymene–ruthenium building blocks bridged by OO∩OO ligands (donq=5,8-dioxido-1,4-naphthoquinonato; doaq=5,8-dioxido-1,4-anthraquinonato, dotq=6,11-dioxido-5,12-naphthacenedionato) and connected by two 2,4,6-tripyridin-4-yl-1,3,5-triazine (tpt) panels, which encapsulate the guest molecules 1-(4,6-dichloro-1,3,5-triazin-2-yl)pyrene and Pd(acac)2, have been prepared. The host–guest properties of these water-soluble delivery systems were studied in solution by NMR and fluorescence spectroscopy, providing the stability constants (K) for these host–guest systems. Moreover, the ability of the hosts to deliver the guests into cancer cells was evaluated and the uptake mechanism studied; the rate of release of the guest molecule was found to depend on the portal size of the host.

The interactions of four octacationic ruthenium coordination cubes with duplex and quadruplex (telomeric and c-myc) DNA have been studied by FID and SPR, showing these cubes to bind strongly to tetrastranded DNA structures.

A large cationic triangular metalla-prism, [Ru6(p-cymene)6(tpt)2(dhnq)3]6+ ([1]6+), incorporating (p-cymene)ruthenium building blocks, bridged by 5,8-dihydroxy-1,4-naphthoquinonato (dhnq) ligands, and connected by two 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine (tpt) subunits, allows encapsulation of various guest molecules. This cationic cage, isolated as its triflate salt, possesses a portal size smaller than its cavity, thus allowing both, permanent and temporary encapsulation of guest molecules. The host-guest properties of [1]6+ have been studied in solution in the presence of planar molecules [phenanthrene, pyrene, (pyren-1-ylmethyl)amine, Pt(acac)2, triphenylene]. The stability constant of association (Ka) was estimated by NMR spectroscopy for the following host-guest systems: [pyrene1]6+, [phenanthrene1]6+ and [(pyren-1-ylmethyl)amine1]6+. All Ka values were found to be larger than 2.4 × 104 M-1 for these host-guest systems ([D3]acetonitrile, 21 °C). The other two synthesised complexes, [Pt(acac)21]6+ and [triphenylene1]6+, were shown to act as carceplexes only.A large cationic triangular metalla-prism, [Ru6(p-cymene)6(tpt)2(dhnq)3]6+ ([1]6+), incorporating (p-cymene)ruthenium building blocks, bridged by 5,8-dihydroxy-1,4-naphthoquinonato (dhnq) ligands, and connected by two 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine (tpt) subunits, allows encapsulation of various guest molecules. This cationic cage, isolated as its triflate salt, possesses a portal size smaller than its cavity, thus allowing both, permanent and temporary encapsulation of guest molecules. The host-guest properties of [1]6+

Detection of the molecular chirality of a series of octanuclear metalla-boxes can be readily achieved using the NMR chiral solvating agent Λ-BINPHAT in CD3CN: only 0.05 to 0.10 equiv being necessary for a complete baseline separation of some of the proton signals.

Cationic (arene)ruthenium-based tetranuclear complexes of the general formula [Ru4(η6-p-cymene)4(μ-N∩N)2(μ-OO∩OO)2]4+ were obtained from the dinuclear (arene)ruthenium complexes [Ru2 (η6-p-cymene)2(μ-OO∩OO)2Cl2] (p-cymene=1-methyl-4-(1-methylethyl)benzene, OO∩OO=5,8-dihydroxy-1,4-naphthoquinonato(2−), 9,10-dihydroxy-1,4-anthraquinonato(2−), or 6,11-dihydroxynaphthacene-5,12-dionato(2−)) by reaction with pyrazine or bipyridine linkers (N∩N=pyrazine, 4,4′-bipyridine, 4,4′-[(1E)-ethene-1,2-diyl]bis[pyridine]) in the presence of silver trifluoromethanesulfonate (CF3SO3Ag) (Scheme). All complexes 4–12 were isolated in good yield as CF3SO3- salts, and characterized by NMR and IR spectroscopy. The host–guest properties of the metallarectangles incorporating 4,4′-bipyridine and (4,4′-[(1E)-ethene-1,2-diyl]bis[pyridine] linkers were studied in solution by means of multiple NMR experiments (1D, ROESY, and DOSY). The largest metallarectangles 10–12 incorporating (4,4′-[(1E)-ethene-1,2-diyl]bis[pyridine] linkers are able to host an anthracene, pyrene, perylene, or coronene molecule in their cavity, while the medium-size metallarectangles 7–9 incorporating 4,4′-bipyridine linkers are only able to encapsulate anthracene. However, out-of-cavity interactions are observed between these 4,4′-bipyridine-containing rectangles and pyrene, perylene, or coronene. In contrast, the small pyrazine-containing metallarectangles 4–6 show no interaction in solution with this series of planar aromatic molecules.

A series of cationic metalla-rectangles of the general formula [(p-cymene)4Os4(OO∩OO)2(N∩N)2]4+ have been obtained in methanol from the dinuclear arene osmium precursors [(p-cymene)2Os2 (OO∩OO)2Cl2] (OO∩OO = 2,5-dioxydo-1,4-benzoquinonato (dhbq), 2,5-dichloro-1,4-benzoquinonato (dcbq)) by reaction with bipyridine linkers (N∩N = 4,4′-bipyridine, 1,2-bis(4-pyridyl)ethylene) in the presence of AgCF3SO3. All complexes were isolated as triflate salts and characterised by NMR, IR and UV-visible spectroscopy. The cytotoxicities of the dinuclear and tetranuclear osmium complexes were established using ovarian A2780 cancer cell lines. The most active metalla-rectangle, [(p-cymene)4Os4(dhbq)2(4,4′-bipyridine)2]4+, shows an IC50 value of 5.7 μM (comparable to cisplatin) against A2780 cancer cells and 7.5 μM against the cisplatin resistant A2780cisR cells.

A series of cationic metalla-cycles of the general formulae [(η6-p-cym)4Ru4(OO∩OO)2(N∩N)2]4+ and [(η6-p-cym)4Ru4(NO∩NO)2(N∩N)2]4+ has been prepared from the dinuclear arene ruthenium precursors [(η6-p-cym)2Ru2(OO∩OO)2Cl2] (OO∩OO = oxalato, 1,4-benzoquinonato-2,5-diolato, 1,4-naphtoquinonato-5,8-diolato, 9,10-anthraquinonato-1,4-diolato, 5,12-tetraquinonato-6,11-diolato) and [(η6-p-cym)2Ru2(NO∩NO)2Cl2] (NO∩NO = oxamido, oxonico) by reaction with two different bidentate linkers (N∩N = 1,2-bis(4-pyridyl)ethylene, 1,2-bis(4-pyridyl)ethane) in the presence of silver triflate. All complexes were isolated as triflate salts and characterised by NMR, infrared, UV-visible, mass spectrometry and by elemental analysis. The cytotoxicities of the tetranuclear ruthenium complexes have been established using ovarian A2780 and A2780cisR cancer cell lines. All complexes exhibit moderate to excellent activity on both the cisplatin resistant and cisplatin sensitive cells, thus suggesting a mode of action different from cisplatin.

Self-assembly of 4,4′-bipyridylethylene (bpe) bidentate connector with the dinuclear arene ruthenium clip [Ru2(η6-p-cymene)2(μ-oxalato)Cl2] in the presence of silver triflate affords the cationic organometallic rectangle [Ru4(η6-p-cymene)4(μ-oxalato)2(μ-bpe)2]4+ ([1][CF3SO3]4). Upon UV irradiation of a methanol solution of [1]4+, dimerisation of the olefinic double bonds of the two parallel bpe ligands occurs, thus giving rise to the [2+2] cycloaddition derivative [Ru4(η6-p-cymene)4(μ-oxalato)2(μ-tpcb)]4+ ([2][CF3SO3]4) (tpcb = tetrakis(4-pyridyl)cyclobutane). The [2+2] photodimerisation reaction was followed by 1H NMR spectroscopy. Moreover, the molecular structure of these two systems was deduced by one-dimensional and two-dimensional NMR experiments (1H, 13C, ROESY, COSY, HSQC). These data suggest the formation of only the rctt-tetrakis(4-pyridyl)cyclobutane isomer.

Self-assembly of 5,10,15,20-tetra(4-pyridyl)porphyrin (tpp-H2) tetradentate panels with dinuclear arene ruthenium clips [Ru2 (η6-arene)2 (dhbq)Cl2] (arene = C6H5Me, p-PriC6H4Me, C6Me6; dhbq = 2,5-dihydroxy-1,4-benzoquinonato) affords the cationic organometallic boxes [Ru8 (η6-C6H5Me)8 (tpp-H2)2 (dhbq)4]8+ ([1]8+), [Ru8 (η6-p-PriC6H4Me)8 (tpp-H2)2(dhbq)4]8+ ([2]8+) and [Ru8 (η6-C6Me6)8 (tpp-H2)2 (dhbq)4]8+ ([3]8+). These octanuclear cations have been isolated as their triflate salts and characterised by mass spectrometry, NMR and IR spectroscopy. The molecular structure of these systems was deduced by one-dimensional and two-dimensional NMR experiments (ROESY, COSY, HSQC).

A series of large cationic hexanuclear metalla-prisms, [Ru6(p-iPrC6H4Me)6(tpt)2(donq)3]6+, [Ru6(p-iPrC6H4Me)6(tpt)2(doaq)3]6+ and [Ru6(p-iPrC6H4Me)6(tpt)2(dotq)3]6+, composed of p-cymene–ruthenium building blocks bridged by OO∩OO ligands (donq=5,8-dioxido-1,4-naphthoquinonato; doaq=5,8-dioxido-1,4-anthraquinonato, dotq=6,11-dioxido-5,12-naphthacenedionato) and connected by two 2,4,6-tripyridin-4-yl-1,3,5-triazine (tpt) panels, which encapsulate the guest molecules 1-(4,6-dichloro-1,3,5-triazin-2-yl)pyrene and Pd(acac)2, have been prepared. The host–guest properties of these water-soluble delivery systems were studied in solution by NMR and fluorescence spectroscopy, providing the stability constants (K) for these host–guest systems. Moreover, the ability of the hosts to deliver the guests into cancer cells was evaluated and the uptake mechanism studied; the rate of release of the guest molecule was found to depend on the portal size of the host.

The thermal reaction of Ru3(CO)12 with various carboxylic acids (benzoic, 4-hydroxyphenylacetic, ferrocenic, stearic, oleic, 4-(octadecyloxy)benzoic) in refluxing tetrahydrofuran, followed by addition of 5-(4-pyridyl)-10,15,20-triphenylporphyrin (L), gives the dinuclear complexes Ru2(CO)4(OOCR)2L2 (1: R = –C6H5, 2: R = –CH2-p-C6H4OH, 3: R = –C5H4FeC5H5, 4: R = –(CH2)16CH3, 5: R = –(CH2)7CHdouble bond; length as m-dashCH(CH2)7CH3, 6: R = –p-C6H4O(CH2)17CH3). Complexes 1–6 were characterised by IR, NMR, and ESI-MS as well as by elemental analysis. The UV–Vis spectra show the Soret band centred at 417 nm and the Q bands at 515, 550, 590 and 645 nm, respectively.

Cationic arene ruthenium metallaprisms of the general formula [Ru6(p-cymene)6(tpt)2(OO∩OO)3]6+ {tpt = 2,4,6-tris(4-pyridyl)-1,3,5-triazine; OO∩OO = 9,10-dioxo-9,10-dihydroanthracene-1,4-diolato [1]6+, 6,11-dioxo-6,11-dihydronaphthacene-5,12-diolato [2]6+} have been obtained from the corresponding dinuclear arene ruthenium complexes [Ru2(p-cymene)2(OO∩OO)Cl2] by reaction with tpt and silver trifluoromethanesulfonate. Aromatic molecules (phenanthrene, pyrene, triphenylene, coronene) present during the synthesis of these metallaprisms are permanently encapsulated to give carceplex systems. All empty cages ([1]6+ and [2]6+) and carceplex systems ([guest⊂1]6+ and [guest⊂2]6+) were isolated in good yield as trifluoromethanesulfonate salts and characterized by NMR, UV, and IR spectroscopy. The host–guest properties of [1]6+ and [2]6+ were studied in solution in the presence of small aromatic molecules (phenanthrene andpyrene). The stability constant of association (Ka) wasestimated by NMR spectroscopy for the following host–guest systems: [phenanthrene⊂1]6+, [pyrene⊂1]6+ and [phenanthrene⊂2]6+, [pyrene⊂2]6+. All Ka values were found to be larger than 2.0 × 104M–1 for these host–guest systems ([D3]acetonitrile, 21 °C).

The interactions of four octacationic ruthenium coordination cubes with duplex and quadruplex (telomeric and c-myc) DNA have been studied by FID and SPR, showing these cubes to bind strongly to tetrastranded DNA structures.

A large cationic triangular metalla-prism, [Ru6(p-cymene)6(tpt)2(dhnq)3]6+ ([1]6+), incorporating (p-cymene)ruthenium building blocks, bridged by 5,8-dihydroxy-1,4-naphthoquinonato (dhnq) ligands, and connected by two 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine (tpt) subunits, allows encapsulation of various guest molecules. This cationic cage, isolated as its triflate salt, possesses a portal size smaller than its cavity, thus allowing both, permanent and temporary encapsulation of guest molecules. The host-guest properties of [1]6+ have been studied in solution in the presence of planar molecules [phenanthrene, pyrene, (pyren-1-ylmethyl)amine, Pt(acac)2, triphenylene]. The stability constant of association (Ka) was estimated by NMR spectroscopy for the following host-guest systems: [pyrene1]6+, [phenanthrene1]6+ and [(pyren-1-ylmethyl)amine1]6+. All Ka values were found to be larger than 2.4 × 104 M-1 for these host-guest systems ([D3]acetonitrile, 21 °C). The other two synthesised complexes, [Pt(acac)21]6+ and [triphenylene1]6+, were shown to act as carceplexes only.A large cationic triangular metalla-prism, [Ru6(p-cymene)6(tpt)2(dhnq)3]6+ ([1]6+), incorporating (p-cymene)ruthenium building blocks, bridged by 5,8-dihydroxy-1,4-naphthoquinonato (dhnq) ligands, and connected by two 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine (tpt) subunits, allows encapsulation of various guest molecules. This cationic cage, isolated as its triflate salt, possesses a portal size smaller than its cavity, thus allowing both, permanent and temporary encapsulation of guest molecules. The host-guest properties of [1]6+

Water-soluble metalla-cages were used to deliver hydrophobic porphin molecules to cancer cells. After internalization, the photosensitizer was photoactivated, significantly increasing the cytotoxicity in cells. During the transport, the photosensitizer remains nonreactive to light, offering a new strategy to tackle overall photosensitization, a limitation often encountered in photodynamic therapy.