K6[P2Mo18O62] as DNase-Mimetic Artificial Nucleases to Promote Extracellular Deoxyribonucleic Acid Degradation in Bacterial Biofilms

In the current study, the DNase-like activity of the Dawson-type polyoxometalate K6[P2Mo18O62] was explored. The obtained findings demonstrated that K6[P2Mo18O62] could effectively cleave phosphoester bonds in the DNA model substrate (4-nitrophenyl phosphate) and result in the degradation of plasmid DNA. Moreover, the application potential of this Dawson-type polyoxometalate as a DNase-mimetic artificial enzyme to degrade extracellular DNA (eDNA) in Escherichia coli (E. coli) bacterial biofilm was explored. The results demonstrated that K6[P2Mo18O62] exhibited high cleavage ability toward eDNA secreted by E. coli and thus eradicated the bacterial biofilm. In conclusion, Dawson-type polyoxometalate K6[P2Mo18O62] possessed desirable DNase-like activity, which could serve as a bacterial biofilm eradication agent by cleaving and degrading eDNA molecules.

Polyoxometalate K6[P2Mo18O62] Inactivates Escherichia coli O157:H7 by Inducing recA Expression and Apoptosis-like Bacterial Death

Polyoxometalates have emerged as promising bactericidal agents. In the current study, the bactericidal activity of polyoxometalate K₆[P₂Mo₁₈O₆₂] against Escherichia coli (E. coli) O157:H7 and its possible underlying mechanisms were explored. The obtained results demonstrated that K₆[P₂Mo₁₈O₆₂] could effectively kill E. coli O157:H7 at millimolar levels. Moreover, K₆[P₂Mo₁₈O₆₂] treatment also induced significant increases in recA protein expression and further triggered characteristic apoptosis-like bacterial death events such as DNA fragmentation and phosphatidylserine exposure. In conclusion, polyoxometalate K₆[P₂Mo₁₈O₆₂] possesses a desirable antibacterial activity, and induction of bacterial apoptosis-like death might be involved in its underlying bactericidal mechanisms.

Extended Mo3IV-Polyoxometalates: 1D-[Mo6IVMo4VIGe2ZnO31py9 (H2O)]4- and 2D-[Mo3IVMo9VIZn6P7O56py8]+ (py = Pyridine)

The first examples of extended Mo₃^IV-polyoxometalates (Mo₃^IV-POMs), 1D-H₂ [Ge₂Mo₆^IVMo₄^VIO₃₁Zn(H₂O)py₉]·2Hpy·HOCH₂CH₂ OH^•4H₂O(H₂[1]·2Hpy^•glycol·H₂O) and 2D-[P@Mo₃^IVMo₉^VIZn₆(PO₄)₆O₃₂py₈]Cl·2py·7H₂O ([2]·Cl^•2py·7H₂O), were prepared through the solvothermal partial oxidation of [Mo₃^IVO₂(O₂CCH₃)₆(H₂O)₃]ZnCl₄ in py/H₂O containing glycol (for 1) or H₃PO₄ (for 2). They were characterized by X-ray crystallography and elemental analyses. Their electronic structure and bonding were discussed on the basis of density functional theory (DFT) theoretical calculations. X-ray photoelectron spectroscopy, IR/UV-vis spectra, powder X-ray diffraction, thermal gravimetric analysis, and mass spectrometry were also performed and discussed for 2D-2.

Unveiling the Chemical Diversity of the Deep-Sea Sponge Characella pachastrelloides

Sponges are at the forefront of marine natural product research. In the deep sea, extreme conditions have driven secondary metabolite pathway evolution such that we might expect deep-sea sponges to yield a broad range of unique natural products. Here, we investigate the chemodiversity of a deep-sea tetractinellid sponge, Characella pachastrelloides, collected from ~800 m depth in Irish waters. First, we analyzed the MS/MS data obtained from fractions of this sponge on the GNPS public online platform to guide our exploration of its chemodiversity. Novel glycolipopeptides named characellides were previously isolated from the sponge and herein cyanocobalamin, a manufactured form of vitamin B₁₂, not previously found in nature, was isolated in a large amount. We also identified several poecillastrins from the molecular network, a class of polyketide known to exhibit cytotoxicity. Light sensitivity prevented the isolation and characterization of these polyketides, but their presence was confirmed by characteristic NMR and MS signals. Finally, we isolated the new betaine 6-methylhercynine, which contains a unique methylation at C-2 of the imidazole ring. This compound showed potent cytotoxicity towards against HeLa (cervical cancer) cells.

Photochromic and photothermal hydrogels derived from natural amino acids and heteropoly acids

A new class of supramolecular hydrogels have been designed and synthesized via the co-assembly of basic amino acids (AAs) and heteropoly acids (HPAs) under acidic conditions. The formation of gel-like samples is identified using an inverted tube method, rheology, and scanning and transmission electron microscopy. Fourier transform infrared spectroscopy reveals that the structural integrity of the HPAs is maintained during the gelation process. X-ray photoelectron spectroscopy (XPS) and proton nuclear magnetic resonance spectroscopy demonstrate that the anionic HPAs interact with both the protonated α-NH₂ and the protonated side groups of the basic amino acids, initiating the preferential growth of one-dimensional nanofibers. These nanofibers bundle and entangle with each other to form extended three-dimensional network structures. The resulting AA/HPA supramolecular hydrogels show clear stereoselectivity of the basic amino acids. With the decreasing enantiomeric excess of the basic amino acids, the gelation propensity of the AA/HPA complexes is found to be depressed. The co-assembled hydrogels show the UV-responsive photochromic behaviour because of the presence of HPAs. The corresponding XPS data confirm that the photochromism of the hydrogels is attributed to the intervalence charge-transfer transition resulting from the reduction of HPAs. Interestingly, the reduced HPAs within the hydrogel matrix can absorb the near-infrared (NIR) light and exhibit photo-thermal conversion properties, which elevates the bulk temperature of the AA/HPA hydrogels and induces the gel-to-sol transition. This study unveils that HPAs have unique capacity to promote the gelation of basic amino acids for the construction of supramolecular soft materials with functional features.

Constructing chiral polyoxometalate assemblies via supramolecular approaches

Polyoxometalates (POMs), as a typical class of discrete metal oxide clusters that are known in inorganic and structural chemistry since long, have displayed more and more interesting applications over recent years. However, in comparison to the chemical synthesis, the photochemical, electrochemical, and magnetic properties, the structural asymmetry, and relative characteristic investigations arising therefrom are far behind even if they are very important for functional materials, especially in solution systems. One of the main reasons is that it is hard to control and maintain a stable chiral state of POMs to carry out further corresponding performances. Aiming to overcome these disadvantages, the main concerns of this review are to discuss the generation of the chirality for discrete metal oxide clusters, chirality transfer via a supramolecular approach, chirality amplification in self-assemblies, and the related functional properties such as photochromism, catalysis, and bioactivities in solutions. Considering that some previous reviews dealt with chiral structures and packing architectures in the crystalline solids of POMs, this article only concentrates on the induced chirality and material properties in solution systems, which have been more active recently but no review article has been involved in this interesting area.

Systematic centricity control using a chiral template: novel noncentrosymmetric polar niobium oxyfluorides and tantalum fluorides directed by chiral histidinium cations, [(l-hisH2)NbOF5], [(d-hisH2)NbOF5], [(l-hisH2)TaF7], and [(d-hisH2)TaF7]

Novel noncentrosymmetric polar niobium and tantalum (oxy)fluorides have been systematically synthesized by using a chiral histidinium template.

Histidinium-Driven Chirality Control of Self-Assembled Hybrid Molybdenum Oxyfluorides

Exploring macroscopic chiral materials with extended structures has become an important and fundamental topic in chemistry. To systematically control the chirality of novel organic-inorganic frameworks, histidinium-based cationic structure-directing agents containing specific chiral information are introduced. In this way, two chiral compounds, [(l-hisH₂ )MoO₂ F₄ ]₃ ⋅H₂ O (L) and [(d-hisH₂ )MoO₂ F₄ ]₃ ⋅H₂ O (D), and an achiral oxyfluoride, (l/d-hisH₂ )MoO₂ F₄ (LD) (his=histidine, C₆ H₉ N₃ O₂ ) have been successfully self-assembled by a slow evaporation method. The structures of these compounds are composed of histidinium cations and distorted [MoO₂ F₄ ]^2- octahedra. Surprisingly, the histidinium cations not only control macroscopic chirality, but also induce O/F ordering in MoO₂ F₄ octahedra through hydrogen-bonding interactions. Compounds L and D crystallize in the extremely rare polar space group P1, and exhibit positive second harmonic generation (SHG) signals attributable to a net moment originating from the MoO₂ F₄ groups. Solid-state circular dichroism (CD) spectra indicate that the MoO₂ F₄ units templated by histidinium cations are chirally aligned through ionic interactions. Crystallization processes influenced by the chirality of the reported materials are also discussed herein.

Reversible self-powered fluorescent electrochromic windows driven by perovskite solar cells

Self-powered electrofluorochromic devices (EFCDs) have attracted particular attention for smart windows of green buildings.

Theoretical studies on the chiral polyoxoanions [P2Mo18O62]6− and [PMo9O31(OH2)3]3− with histidine: chiral inversion and chiral induction

Theoretical studies on the chiral polyoxoanions [P₂Mo₁₈O₆₂]⁶⁻ and [PMo₉O₃₁(OH₂)₃]³⁻ with histidine: Chiral inversion and chiral induction.

Comparison of hydroxycarboxylato imidazole molybdenum(iv) complexes and nitrogenase protein structures: indirect evidence for the protonation of homocitrato FeMo-cofactors

Glycolato and lactato imidazole molybdenum(iv) complexes are used for structural comparison with FeMo-cofactors of MoFe-protein structures.

Controlled chiral electrochromism of polyoxometalates incorporated in supramolecular complexes

Switchable induced chiral electrochromism of achiral polyoxometalates in a ternary supramolecular system, integrated by host–guest recognition and electrostatic interaction, is realized by controlling the electrochemical redox process in aqueous solution.

Synthesis, spectral, and structural characterizations of imidazole oxalato molybdenum(IV/V/VI) complexes

Substitutions of trans-Na(Him)[Mo(2)O(4)(ox)(2)(H(2)O)(2)]·H(2)O (1) and trans-(Him)(2)[Mo(2)O(4)(ox)(2)(H(2)O)(2)] (2) with imidazole result in the formation of the mixed-ligand molybdenum complexes cis-Na(2)[Mo(2)O(4)(ox)(2)(im)(2)]·4.5H(2)O (3), cis-K(2)[Mo(2)O(4)(ox)(2)(im)(2)]·3H(2)O (4), respectively (H(2)ox = oxalic acid; im = imidazole). Further reduction of cis-K(2)[Mo(2)O(4)(ox)(2)(im)(2)]·3H(2)O (4) gives a trinuclear molybdenum(IV) complex K(Him)[Mo(3)O(4)(ox)(3)(im)(3)]·3H(2)O (5), which contains an incomplete cubane cluster [Mo(IV)(3)O(4)](4+). Two novel trinuclear mixed-valence imidazole compounds [Mo(3)O(8)(im)(4)](im)·H(2)O (6) and [Mo(3)O(8)(im)(4)]·H(2)O (7) were obtained by the reduction of (Him)(4)[Mo(8)O(26)(im)(2)] (8). Both 6 and 7 contain a novel Mo(VI)O(4)(Mo(V)(2)O(4)) center, where the [Mo(V)(2)O(4)](2+) unit is linked by [Mo(VI)O(4)](2-) anion. The Mo-Mo bond distances in 1-7 decrease with the decrease of oxidation state of molybdenum. Solid and solution NMR spectra show that imidazole molybdenum compounds 6-8 fully dissociate in solution, where solvated imidazole and imidazolium groups in 6 and 8 could be served as internal references in their solid (13)C NMR spectra. Furthermore, mixed-ligand molybdenum species 3 and 4 are stable in water. Stabilities of 3 and 4 in solution may be attributed to the strong coordination of bidentate oxalate and the formation of hydrogen bond. Dimers 2 and 4 display quasi-reversible redox process, while trimer 6 is irreversible. Bond valence calculations for 1-8 are consistent with their oxidation states of molybdenum atoms. Calculation of the oxidation state in recent structure of iron molybdenum cofactor [MoFe(7)S(9)C(R-homocit)] (FeMo-co) is 3.318.

A new organic-inorganic hybrid layered molybdenum(V) cobalt phosphate constructed from [H24(Mo16O32)Co16(PO4)24(OH)4(C5H4N)2(H2O)6](4-) wheels and 4,4'-bipyridine linkers

A new layered molybdenum cobalt phosphate, Na(2)[Co(H(2)O)(6)][(Mo(16)O(32))Co(16)(PO(4))(4) (HPO(4))(16)(H(2)PO(4))(4)(OH)(4)(C(10)H(8)N(2))(4)(C(5)H(4)N)(2)(H(2)O)(6)]·4H(2)O (1), has been hydrothermally synthesized and structurally characterized. 1 crystallizes in the monoclinic space group P2(1)/n with a = 15.6825(18) Å, b = 39.503(4) Å, c = 17.2763(17) Å, β = 93.791(2)°, V = 10679.4(18) Å(3), and Z = 2. A polyoxoanion of 1 exhibits an unusual organic-inorganic hybrid wheel-type cluster, in which two pyridine ligands link to the surface Co(II) atoms of a [H(24)(Mo(16)O(32))Co(16)(PO(4))(24)(OH)(4)(H(2)O)(6)] (namely, {Mo(16)Co(16)P(24)}) wheel via the Co-N bonds. Furthermore, each {Mo(16)Co(16)P(24)} wheel is connected to four adjacent wheels by four pairs of 4,4'-bipyridine linkers, forming a 2D layered network. The susceptibility measurement shows the existence of dominant antiferromagnetic interactions in 1.