The success of platinum-based anticancer agents has motivated the exploration of novel metal-based drugs for several decades, whereas problems such as drug-resistance and systemic toxicity hampered ...their clinical applications and efficacy. Stimuli-responsiveness of some metal complexes offers a good opportunity for designing site-specific prodrugs to maximize the therapeutic efficacy and minimize the side effect of metallodrugs. This review presents a comprehensive and up-to-date overview on the therapeutic stimuli-responsive metallodrugs that have appeared in the past two decades, where stimuli such as redox, pH, enzyme, light, temperature, and so forth were involved. The compounds are classified into three major categories based on the nature of stimuli, that is, endo-stimuli-responsive metallodrugs, exo-stimuli-responsive metallodrugs, and dual-stimuli-responsive metallodrugs. Representative examples of each type are discussed in terms of structure, response mechanism, and potential medical applications. In the end, future opportunities and challenges in this field are tentatively proposed. With diverse metal complexes being introduced, the foci of this review are pointed to platinum and ruthenium complexes.
The histone deacetylase (HDAC) enzymes have emerged as an important class of molecular targets in cancer therapy, with five inhibitors in clinical use. Recently, it has been shown that a lack of ...selectivity between the 11 Zn-dependent HDAC isoforms may lead to unwanted side-effects. In this paper, we show that piano stool Ru complexes can act as HDAC inhibitors, and variation in the capping arene leads to differences in HDAC isoform selectivity.
In the last few decades, the transition metal‐catalyzed activation of inert C−H bonds has led to a fundamental change in the field of synthetic chemistry. Most of these C−H activation reactions deal ...with simple functionalizations or additions. However, recent years have witnessed an increase of the transition metal‐catalyzed activation of C−H bond and annulation reactions. These annulation reactions are appealing to the organic chemist as they afford highly valuable cyclic compounds in a rapid and sustainable manner from readily available compounds. This review article attempts to highlight the recent advances in the ruthenium metal‐catalyzed C−H bond activation and alkyne annulation reactions.
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•This review deals with the structure and applications of trinuclear ruthenium clusters.•Structural features of several Ru3O(CH3COO)6L3n based compounds are depicted.•Ru3O(CH3COO)6L3n ...analogs act as catalysts.•Ru3O(CH3COO)6L3n analogs engage in photo-processes and as devices.•Ru3O(CH3COO)6L3n analogs act as anticancer, trypanocidal, and vasorelaxant agents.
Polynuclear μ-oxo complexes are commonly observed for second and third row transition metals. This review is particularly interested in the μ3-oxo-bridged ruthenium trinuclear clusters of general formula Ru3O(CH3COO)6(L)3n, where typically L are coordinating solvents, N-heterocyclic ligands, phosphines or small species such as CO, NO, and CN–; and n = 0 or + 1. These molecules are very versatile coordination compounds, characterized by an absorption profile with high coverage of the ultraviolet and visible regions, depending on their formal charges, and rich multi-electron redox behavior, yielding, for example, electrochromic devices and sensors. More recently, innovative approaches allowed the community to explore previously unfathomable applications for this type of system, such as trypanocidal or anticancer agents. Besides their intrinsic characteristics, they have also been used as building blocks for extended structures, opening up a whole new range of options. This text invites the readers to a description, from a structural point of view, of monomeric and extended compounds obtained from the primary unit Ru3O(RCOO)6n, reported on the last 20 years. In addition, we present an overview of the compounds' applications, focusing on their use as catalysts, in the construction of devices, or as final acceptors of excitation energy and electrons in photoinduced processes. Finally, we address the newest application reported in the literature: their biological activities as an anticancer, trypanocidal, or vasorelaxant agent and their interactions with target biomolecules such as DNA and HSA.
A stable Zr-based metal-organic framework (MOF), MOF-808, was used as a promising support to immobilize metallic Ru for the first time. The skeleton structure of MOF-808 can be well preserved during ...the immobilization process. Ru nanoparticles existed both inside and outside of the MOF cavities with good dispersion. The developed Ru/MOF-808 composite was found to be an efficient catalyst for the hydrogenation of biomass-derived levulinic acid (LA) to gamma-valerolactone (GVL). Under mild reaction conditions, full conversion of LA (100%) with high selectivity to GVL (> 99%) was achieved. The catalyst recycling and hot filtration experiments indicate that Ru/MOF-808 possesses a good catalytic stability for the LA hydrogenation reaction, although some catalyst structure changes were observed. The good immobilization effect of MOF-808 for Ru may be related to the high binding affinity between the Zr.sub.6 nodes and Ru particles. Graphic
The viability of building artificial metabolic pathways within a cell will depend on our ability to design biocompatible and orthogonal catalysts capable of achieving non-natural transformations. In ...this context, transition metal complexes offer unique possibilities to develop catalytic reactions that do not occur in nature. However, translating the potential of metal catalysts to living cells poses numerous challenges associated to their biocompatibility, and their stability and reactivity in crowded aqueous environments. Here we report a gold-mediated C-C bond formation that occurs in complex aqueous habitats, and demonstrate that the reaction can be translated to living mammalian cells. Key to the success of the process is the use of designed, water-activatable gold chloride complexes. Moreover, we demonstrate the viability of achieving the gold-promoted process in parallel with a ruthenium-mediated reaction, inside living cells, and in a bioorthogonal and mutually orthogonal manner.
Platinum (Pt)-based anticancer drugs such as cisplatin have been used to treat various cancers. However, they have some limitations including poor selectivity and toxicity towards normal cells and ...increasing chemoresistance. Therefore, there is a need for novel metallo-anticancers, which has not been met for decades. Since the initial introduction of ruthenium (Ru) polypyridyl complex, a number of attempts at structural evolution have been conducted to improve efficacy. Among them, half-sandwich Ru-arene complexes have been the most prominent as an anticancer platform. Such complexes have clearly shown superior anticancer profiles such as increased selectivity toward cancer cells and ameliorating toxicity against normal cells compared to existing Pt-based anticancers. Currently, several Ru complexes are under human clinical trials. For improvement in selectivity and toxicity associated with chemotherapy, Ru complexes as photodynamic therapy (PDT), and photoactivated chemotherapy (PACT), which can selectively activate prodrug moieties in a specific region, have also been investigated. With all these studies on these interesting entities, new metallo-anticancer drugs to at least partially replace existing Pt-based anticancers are anticipated. This review covers a brief description of Ru-based anticancer complexes and perspectives.
Glycosyl anomeric radical addition reactions have been well‐explored and proved efficient for the C‐alkyl glycosides synthesis, but multicomponent Domino transformations for the rapid and ...controllable construction of structurally diversified C‐alkyl glycosides in a single step are still rare. In contrast, we, herein, report a ruthenium(II)‐catalyzed Domino meta‐C−H ethyl glycosylation, enabling the construction of challenging meta‐C‐alkyl glycosides. Our ruthenium(II) catalysis was reflected by the mild reaction condition, exclusive meta‐site selectivity and high levels of anomeric selectivity. In addition, the ruthenium(II)‐catalyzed Domino meta‐C−H glycosylation allowed for the synthesis of versatile 1,2‐trans‐C‐alkyl glycosides with commercially available vinyl arenes, acrylates and easily accessible glycosyl bromides.
A ruthenium(II)/phosphine catalytic system enabled efficient domino meta‐C−H ethyl glycosylations. Thus 1,2‐trans‐C‐alkyl glycosides were obtained via the selective assembly of easily accessible glycosyl bromide and alkenes under mild reaction conditions.
Heteroleptic ruthenium (II) complexes featuring donor functionalized phenyl‐terpyridine (ph‐tpy) and a monocarboxylic‐(ph‐tpy)/(tpy) are synthesized and characterized. Reactions of ruthenium (II) ...precursors at 80 °C favored heteroleptic complexes formation over the homoleptic side products. Visible light excitation of these complexes resulted in the metal‐to‐ligand charge transfer (MLCT) transitions. The inter‐planar torsional angle between the atoms of donor functionalized phenyl ring and the central pyridine (py) of the tpy core strongly influences visible light absorption and photovoltaic properties. The lower inter‐ring py‐ph torsion in the acceptor end of the MLCT structures and its increase in the oxidized doublets could prevent the back electron transfer. The ruthenium atom and the acceptor functionalized tpy host the triplet‐MLCT spin density. Ambient temperature excited‐state decay followed the energy gap law and occurred in the order of a few nanoseconds. Herein, we evaluate the photosensitizing ability of these complexes via a combined experimental and computational approach.
Milder reaction conditions give ruthenium (II) complexes bearing donor and acceptor functionalized terpyridine ligands. The nature of electronic states is studied by spectroscopic methods, electrochemistry and supported by dispersion‐corrected density functional theory calculations. We herein evaluate the solar energy conversion of these thiocyanate‐free complexes in dye‐sensitized solar cells.
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