A general and highly regioselective synthesis approach to multi-functionalized organoimido derivatives of Polyoxometalates

A polyoxomolybdate-based hybrid nano capsule as an antineoplastic agent

Polyoxometalates (POMs) are versatile anionic clusters which have attracted a lot of attention in biomedical investigations. To counteract the increasing resistance effect of cancer cells and the high toxicity of chemotherapeutic treatments, POM-based metallodrugs can be strategically synthesized by adjusting the stereochemical and physicochemical features of POMs. In the present report a polyoxomolybdate (POMo) based organic-inorganic hybrid solid (C6H16N)(C6H15N)2[Mo8O26]·3H2O, solid 1, has been synthesized and its antitumoral activities have been investigated against three cancer cell lines namely, A549 (Lung cancer), HepG2 (Liver cancer), and MCF-7 (Breast cancer) with IC50 values 56.2 μmol L-1, 57.3 μmol L-1, and 55.2 μmol L-1 respectively. The structural characterization revealed that solid 1 consists of an octa molybdate-type cluster connected by three triethylamine molecules via hydrogen bonding interactions. The electron microscopy analysis suggests the nanocapsule-like morphology of solid 1 in the size range of 50-70 nm. The UV-vis absorption spectra were used to assess the binding ability of synthesized POM-based solid 1 to calf thymus DNA (ctDNA), which further explained the binding interaction between POMo and ctDNA and the binding constant was calculated to be 2.246 × 103 giving evidence of groove binding.

Recent Advances of Anderson-Type Polyoxometalates as Catalysts Largely for Oxidative Transformations of Organic Molecules

Anderson-type ([XM₆O₂₄]ⁿ⁻) polyoxometalates (POMs) are a class of polymetallic-oxygen cluster inorganic compounds with special structures and properties. They have been paid extensive attention by researchers now, due to their chemical modification and designability, which have been widely applied in the fields of materials, catalysis and medicine. In contemporary years, the application of Anderson-type POMs in catalytic organic oxidation reaction has gradually shown great significance for the research of green catalytic process. In this paper, we investigate the application of Anderson-type POMs in organic synthesis reaction, and these works are summarized according to the different structure of POMs. This will provide a new strategy for further investigation of the catalytic application of Anderson-type POMs and the study of green catalysis.

Trifunctionalization of alkenes and alkynes

In this review, the development of trifunctionalization methods for alkenes and alkynes, including arynes and allenes, over the last decade is disclosed.

Assembly, disassembly and reassembly: a "top-down" synthetic strategy towards hybrid, mixed-metal {Mo10Co6} POM clusters

Polyoxometalates (POMs) are commonly prepared using a "bottom-up" synthetic procedure. The alternative "top-down" approach of disassembling a pre-formed POM unit to generate new synthetic intermediates is promising, but relatively comparatively underused. In this paper, a rationale for the top-down method is provided, demonstrating that this approach can generate compounds that are fundamentally inaccessible from simple bottom-up assembly. We demonstrate this principle through the synthesis of a series of 10, new, mixed-metal, hybrid compounds with the general formula [TBA]2[MoVI10CoII6O30(RpPO3)6(RcCOO)2(L)x(H2O)6] (TBA = tetrabutylammonium, Rp = phosphonate moiety, Rc = carboxylate moiety, L = pyridyl ligand, and x = 2-4), including a one-dimensional polyoxometalate-based coordination polymer. We propose that these structures are generated from {MoxO3x-1} fragments that cannot be accessed from bottom-up assembly alone. The POM clusters are stabilised by three distinct classes of organic ligand - organophosphonate, carboxylate and pyridyl ligands - which can each be substituted independantly, thus providing a controlled route to ligand functionalisation.

Substitution Effect on the Charge Transfer Processes in Organo-Imido Lindqvist-Polyoxomolybdate

Two new aromatic organo-imido polyoxometalates with an electron donor triazole group ([n-Bu₄N]₂[Mo₆O18NC₆H₄N₃C₂H₂]) (1) and a highly conjugated fluorene ([n-Bu₄N]₂[Mo₆O18NC13H₉]) (2) have been obtained. The electrochemical and spectroscopic properties of several organo-imido systems were studied. These properties were analysed by the theoretical study of the redox potentials and by means of the excitation analysis, in order to understand the effect on the substitution of the organo-imido fragment and the effect of the interaction to a metal centre. Our results show a bathochromic shift related to the charge transfer processes induced by the increase of the conjugated character of the organic fragment. The cathodic shift obtained from the electrochemical studies reflects that the electronic communication and conjugation between the organic and inorganic fragments is the main reason of this phenomenon.

Gas-Phase Chemistry of Arylimido-Functionalized Hexamolybdates [Mo6O19]2

The gas-phase fragmentations of a series of arylimido derivatives of hexamolybdate [Mo₆O₁₈(NC₆H_5-nR _n )]^2- (2-10, where R = CH₃, i-C₃H₇, OCH₃, NO₂; n = 1 or 2) versus the parent species [Mo₆O₁₉]^2- (1) were systematically studied using electrospray tandem mass spectrometry (ESI). Fragmentation of 1 generates two molybdate fragments only, [Mo₃O₁₀]^2- and [Mo₄O₁₃]^2-, whereas decomposition of 2-10 went through two dissociation pathways in which path A generates a variety of molybdate fragments via breaking the Mo-N bond followed by the cleavages of the multiple Mo-O bonds, whereas path B produces a range of molybdate fragments with arylimido group via breaking the multiple Mo-O bonds on POM framework. Moreover, the presences of mixed-oxidation-state molybdate fragments are characteristic for the fragmentation. The gas-phase stability order obtained by energy-variable collision-induced dissociation (CID) experiment reveals that 2-10 are generally less stable than 1 and substitution on the benzene ring exerts a considerable effect on the stabilization of the hybrid clusters. Graphical abstract ᅟ.

The first ReI organometallic complex with an organoimido-polyoxometalate ligand

An electrochemical, spectroscopic and theoretical study of the first Re^I complex with a hybrid organoimido-polyoxometalate ligand is presented.

[V4Mo3O14(NAr)3(μ2-NAr)3]2−: the first polyarylimido-stabilized molybdovanadate cluster

This work presents the first polyarylimido-stabilized molybdovanadate cluster, which will enrich polyoxometalate chemistry and lead to more potential POM-based materials.

β-{Cr[RC(CH2O)3]2Mo6O18}3−: the first organically-functionalized β isomer of Anderson-type polyoxometalates

The first organically-functionalized butterfly-shaped β isomer of Anderson-type polyoxometalates was discovered, which will enrich polyoxometalates chemistry.