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The 2D {[Cu2(OAc)4]2(W12O40)}n network with unique Cu-POM synergistic cooperation to lead alkyne C–H activation is a super efficient catalyst with high conversion in homo-coupling of terminal alkynes.

Molecular metal chalcogenides have attracted great attention as electrocatalysts for the hydrogen evolution reaction (HER). However, efficient utilisation of the active sites and catalytic performance modulation has been challenging. Here we explore the design of immobilized molecular molybdenum polyselenides [Mo2O2S2(Se2)(Sex)]2– that exhibit efficient hydrogen evolution at low overpotential and stability over 1000 cycles. Density functional calculations provide evidence of a unimolecular mechanism in the HER process via the exploration of viable reaction pathways. The discussed findings are of a broad interest in the development of efficient molecular electrocatalytic materials.

The cation/proton exchange illustration during the reduction/reoxidation process of {P5W30}.

Metal organic polyhedra (MOPs) such as coordination cages and clusters are increasingly utilized across many fields, but their geometrically selective assembly during synthesis is nontrivial. When ligand coordination along these polyhedral edges is arranged in an unsymmetrical mode or the bridging ligand itself is nonsymmetric, a vast combinatorial space of potential isomers exists complicating formation and isolation. Here we describe two generalizable combinatorial methodologies to explore the geometrical space and enumerate the configurational isomers of MOPs with discrimination of the chiral and achiral structures. The methodology has been applied to the case of the octahedron {Bi6Fe13L12} which has unsymmetrical coordination of a carboxylate ligand (L) along its edges. For these polyhedra, the enumeration methodology revealed 186 distinct isomers, including 74 chiral pairs and 38 achiral. To explore the programming of these, we then used a range of ligands to synthesize several configurational isomers. Our analysis demonstrates that ligand halo-substituents influence isomer symmetry and suggests that more symmetric halo-substituted ligands counterintuitively yield lower symmetry isomers. We performed mass spectrometry studies of these {Bi6Fe13L12} clusters to evaluate their stability and aggregation behavior in solution and the gas phase showing that various isomers have different levels of aggregation in solution., We describe combinatorial methodologies to explore the geometrical space and enumerate the configurational isomers of metal organic polyhedra with discrimination of the chiral and achiral structures. The methodology was applied to the octahedral {Bi6Fe13L12} which has an unsymmetrical coordination of a carboxylate ligands (L) along its edges. For these polyhedra, the enumeration methodology revealed 186 distinct isomers, including 74 chiral pairs and 38 achiral. We used a range of ligands to synthesize several configurational isomers.

Determining the relative configuration or enantiomeric excess of a substance may be achieved using NMR spectroscopy by employing chiral shift reagents (CSRs). Such reagents interact noncovalently with the chiral solute, resulting in each chiral form experiencing different magnetic anisotropy; this is then reflected in their NMR spectra. The Keplerate polyoxometalate (POM) is a molybdenum‐based, water‐soluble, discrete inorganic structure with a pore‐accessible inner cavity, decorated by differentiable ligands. Through ligand exchange from the self‐assembled nanostructure, a set of chiral Keplerate host molecules has been synthesised. By exploiting the interactions of analyte molecules at the surface pores, the relative configuration of chiral amino alcohol guests (phenylalaninol and 2‐amino‐1‐phenylethanol) in aqueous solvent was establish and their enantiomeric excess was determined by 1H NMR using shifts of ΔΔδ=0.06 ppm. The use of POMs as chiral shift reagents represents an application of a class that is yet to be well established and opens avenues into aqueous host‐guest chemistry with self‐assembled recognition agents., Chiral resolution of racemic amino alcohol guests (phenylalaninol and 2‐amino‐1‐phenylethanol) has been achieved by using a chirally coordinated enantiopure polyoxometalate host, {Mo132(lactate)30}. NMR spectroscopic methods, including DOSY measurements, were applied to determine the enantiomeric excesses of guest mixtures in addition to the association constants of the host‐guest system binding process.

The assembly of nanoscale polyoxometalate (POM) clusters has been dominated by the highly reduced icosahedral {Mo

Polyoxometalate Molybdenum blue (MBs) complexes typically exist as discrete multianionic clusters and are composed of repeating Mo building units. MB Wheels, such as {Mo176} and {Mo154} are made fr...

We present a chemical discovery robot for the efficient and reliable discovery of supramolecular architectures through the exploration of a huge reaction space exceeding ten billion combinations. The system was designed to search for areas of reactivity found through autonomous selection of the reagent types, amounts, and reaction conditions aiming for combinations that are reactive. The process consists of two parts where reagents are mixed together, choosing from one type of aldehyde, one amine and one azide (from a possible family of two amines, two aldehydes and four azides) with different volumes, ratios, reaction times, and temperatures, whereby the reagents are passed through a copper coil reactor. Next, either cobalt or iron is added, again from a large number of possible quantities. The reactivity was determined by evaluating differences in pH, UV‐Vis, and mass spectra before and after the search was started. The algorithm was focused on the exploration of interesting regions, as defined by the outputs from the sensors, and this led to the discovery of a range of 1‐benzyl‐(1,2,3‐triazol‐4‐yl)‐N‐alkyl‐(2‐pyridinemethanimine) ligands and new complexes: [Fe(L1)2](ClO4)2 (1); [Fe(L2)2](ClO4)2 (2); [Co2(L3)2](ClO4)4 (3); [Fe2(L3)2](ClO4)4 (4), which were crystallised and their structure confirmed by single‐crystal X‐ray diffraction determination, as well as a range of new supramolecular clusters discovered in solution using high‐resolution mass spectrometry., A chemical robot was designed, assembled and utilised for the discovery of supramolecular architectures through the exploration of a chemical space exceeding 109 possible reactions. By searching for reactivity differences, a range of new 1‐benzyl‐(1,2,3‐triazol‐4‐yl)‐N‐alkyl‐(2‐pyridinemethanimine) ligands were found and four new complexes of Fe and Co were discovered, autonomously discovering the rules of self‐assembly for these systems.

Eight alkene-functionalized molybdenum-based spherical Keplerate-type (inorganic fullerene) structures have been obtained via both direct and multistep synthetic approaches. Driven by the opportunity to design unique host–guest interactions within hydrophobic, π-electron rich confined environments, we have synthesised {(NH4)42[Mo132O372(L)30(H2O)72]}, where L = (1) acrylic acid, (2) crotonic acid, (3) methacrylic acid, (4) tiglic acid, (5) 3-butenoic acid, (6) 4-pentenoic acid, (7) 5-hexenoic acid, and (8) sorbic acid. The compounds, which are obtained in good yield (10–40%), contain 30 carboxylate-coordinated alkene ligands which create a central cavity with hydrophobic character. Extensive Nuclear Magnetic Resonance (NMR) spectroscopy studies contribute significantly to the complete characterisation of the structures obtained, including both 1D and 2D measurements. In addition, single-crystal X-ray crystallography and subsequently-generated electron density maps are employed to highlight the distribution in ligand tail positions. These alkene-containing structures are shown to effectively encapsulate small alkyl thiols (1-propanethiol (A), 2-propanethiol (B), 1-butanethiol (C), 2-butanethiol (D) and 2-methyl-1-propanethiol (E)) as guests within the central cavity in aqueous solution. The hydrophobically driven clustering of up to 6 equivalents of volatile thiol guests within the central cavity of the Keplerate-type structure results in effective thermal protection, preventing evaporation at elevated temperatures (ΔT ≈ 25 K).

Giant polyoxomolybdates are traditionally synthesized by chemical reduction of molybdate in aqueous solutions, generating complex nanostructures such as the highly symmetrical spherical {Mo102} and {Mo132}, ring-shaped {Mo154} and {Mo176}, and the gigantic protein sized {Mo368}, which combines both positive and negative curvature. These complex polyoxometalates are known to be highly sensitive to reaction conditions and are often difficult to reproduce, especially {Mo368}, which is often produced in yields far below 1%, meaning further investigation has always been limited. While the electrochemical properties of these materials have been studied, their electrochemical synthesis has not been explored. Herein, we demonstrate an alternative reliable synthetic method by means of electrochemistry. By using electrochemical synthesis, we have shown the synthesis of various reported polyoxomolybdates, along with some unreported structures with unique features that have yet to be reported by traditional synthetic methods. The six different giant polyoxomolybdates that were obtained via electrochemical synthesis range from the spherical {Mo102-xFex} and {Mo132} to the ring-shaped {Mo148} and {Mo154-x}, as well as the largest known polyoxometalate {Mo368}, with improved yield (up to 26.1% for {Mo368}), increased reproducibility, and shorter crystallization time compared to chemical reduction methods.

Eight alkene-functionalized molybdenum-based spherical Keplerate-type (inorganic fullerene) structures have been obtained via both direct and multistep synthetic approaches. Driven by the opportunity to design unique host–guest interactions within hydrophobic, π-electron rich confined environments, we have synthesised {(NH4)42[Mo132O372(L)30(H2O)72]}, where L = (1) acrylic acid, (2) crotonic acid, (3) methacrylic acid, (4) tiglic acid, (5) 3-butenoic acid, (6) 4-pentenoic acid, (7) 5-hexenoic acid, and (8) sorbic acid. The compounds, which are obtained in good yield (10–40%), contain 30 carboxylate-coordinated alkene ligands which create a central cavity with hydrophobic character. Extensive Nuclear Magnetic Resonance (NMR) spectroscopy studies contribute significantly to the complete characterisation of the structures obtained, including both 1D and 2D measurements. In addition, single-crystal X-ray crystallography and subsequently-generated electron density maps are employed to highlight the distribution in ligand tail positions. These alkene-containing structures are shown to effectively encapsulate small alkyl thiols (1-propanethiol (A), 2-propanethiol (B), 1-butanethiol (C), 2-butanethiol (D) and 2-methyl-1-propanethiol (E)) as guests within the central cavity in aqueous solution. The hydrophobically driven clustering of up to 6 equivalents of volatile thiol guests within the central cavity of the Keplerate-type structure results in effective thermal protection, preventing evaporation at elevated temperatures (ΔT ≈ 25 K)., Eight alkene-functionalized molybdenum-based spherical Keplerate-type (inorganic fullerene) structures have been obtained and shown to sequester and thermally insulate volatile organics.

The construction of pure-inorganic framework materials with well-defined design rules and building blocks is challenging. In this work, we show how a polyoxometalate cluster with an integrated pore, based on [P8 W48 O184 ]40- (abbreviated as {P8 W48 }), can be self-assembled into inorganic frameworks using silver ions, which both enable reactions on the cluster as well as link them together. The {P8 W48 } was found to be highly reactive with silver ions resulting in the in situ generation of fragments, forming {P9 W63 O235 } and {P10 W66 O251 } in compound (1) where these two clusters co-crystallize and are connected into a POMZite framework with 11 Ag+ ions as linkers located inside clusters and 10 Ag+ linking ions situated between clusters. Decreasing both the concentration of Ag+ ions, and the reaction temperature compared to the synthesis of compound (1), leads to {P8 W51 O196 } in compound 2 where the {P8 W48 } clusters are linked to form a new POMZite framework with 9 Ag+ ions per formula unit. Further tuning of the reaction conditions yields a cubic porous network compound (3) where {P8 W48 } clusters as cubic sides are joined by 4 Ag+ ions to give a cubic array and no Ag+ ions were found inside the clusters.

By using sugars as the reducing agents, we demonstrate that it is possible to control the self-assembly of polyoxomolybdates through selective preparation of a single heteropolyanion isomer. d-(-)-Fructose has been proved to be an effective reducing sugar compared to the chemically similar carbohydrate d-(+)-glucose. The gentle reduction results in favourable formation of the Wells-Dawson type gamma isomer in 6-fold reduced form at room temperature.

Since 1996 when Muller et al. determined the first giant Molybdenum Blue (MB) wheel {Mo154} and revealed the 200-year-old mystery, many hundreds of compounds of this type and analogous giant polyoxomolybdates have been discovered. These multifunctional and highly complex molecular nano-objects of reduced molybdenum oxide, reaching to the size of proteins, have potential applications in materials science, catalysis, electronic devices and even as biosensors. This family of molecules displays exquisite structures, and even opens the way for adaptive and autocatalytic chemistry. Muller and a few other groups published a number of exceptional reviews on the topic of giant polyoxomolybdates. This chapter presents a detailed summary of recent advances including new synthetic methods, characterization, supramolecular chemistry and applications, focusing on recent work on lanthanide-substituted and amino-acid/peptide functionalized MB wheels, confined reaction in the Keplerate {Mo132} ball and the new discovery of Molybdenum Reds.

The exploration of complex multicomponent chemical reactions leading to new clusters, where discovery requires both molecular self-assembly and crystallization, is a major challenge. This is because the systematic approach required for an experimental search is limited when the number of parameters in a chemical space becomes too large, restricting both exploration and reproducibility. Herein, we present a synthetic strategy to systematically search a very large set of potential reactions, using an inexpensive, high-throughput platform that is modular in terms of both hardware and software and is capable of running multiple reactions with in-line analysis, for the automation of inorganic and materials chemistry. The platform has been used to explore several inorganic chemical spaces to discover new and reproduce known tungsten-based, mixed transition-metal polyoxometalate clusters, giving a digital code that allows the easy repeat synthesis of the clusters. Among the many species identified in this work, the most significant is the discovery of a novel, purely inorganic W24FeIII–superoxide cluster formed under ambient conditions. The modular wheel platform was employed to undertake two chemical space explorations, producing compounds 1–4: (C2H8N)10Na2[H6Fe(O2)W24O82] (1, {W24Fe}), (C2H8N)72Na16[H16Co8W200O660(H2O)40] (2, {W200Co8}), (C2H8N)72Na16[H16Ni8W200O660(H2O)40] (3, {W200Ni8}), and (C2H8N)14[H26W34V4O130] (4, {W34V4}), along with many other known species, such as simple Keggin clusters and 1D {W11M2+} chains., A low-cost, automated modular wheel platform (MWP) is described and used to explore a chemical space. Using a digital synthetic code, the MWP can reproduce known polyoxometalate syntheses and discover novel clusters.

The synthesis of chiral polyoxometalates (POMs) is a challenge because of the difficulty to induce the formation of intrinsically chiral metal-oxo frameworks. Herein we report the stereoselective synthesis of a series of gigantic chiral Mo Blue (MB) POM clusters 1–5 that are formed by exploiting the synergy between coordinating lanthanides ions as symmetry breakers to produce MBs with chiral frameworks decorated with amino acids ligands; these promote the selective formation of enantiopure MBs. All the compounds share the same framework archetype, based on {Mo124Ce4}, which forms an intrinsically chiral Δ or Λ configurations, controlled by the configurations of functionalized chiral amino acids. The chirality and stability of 1–5 in solution are confirmed by circular dichroism, 1H NMR, and electrospray ion mobility–mass spectrometry studies. In addition, the framework of the {Mo124Ce4} MB not only behaves as a host able to trap a chiral {Mo8} cluster that is not accessible by traditional synthesis but also promotes the transformation of tryptophan to kynurenine in situ. This work demonstrates the potential and applicability of our synthetic strategy to produce gigantic chiral POM clusters capable of host–guest chemistry and selective synthetic transformations.

Hydrothermal‐synthesis‐based reactions are normally single step owing to the difficulty of manipulating reaction mixtures at high temperatures and pressures. Herein we demonstrate a simple, cheap, and modular approach to the design reactors consisting of partitioned chambers, to achieve multi‐step synthesis under hydrothermal conditions, in digitally defined reactionware produced by 3D printing. This approach increases the number of steps that can be performed sequentially and allows an increase in the options available for the control of hydrothermal reactions. The synthetic outcomes of the multi‐stage reactions can be explored by varying reaction compositions, number of reagents, reaction steps, and reaction times, and these can be tagged to the digital blueprint. To demonstrate the potential of this approach a series of polyoxometalate (POM)‐containing metal–organic frameworks (MOFs) unavailable by “one‐pot” methods were prepared as well as a set of new MOFs.

Water oxidation is a key reaction for the conversion of solar energy into chemical fuels, but effective water-oxidation catalysts are often based on rare and costly precious metals such as Pt, Ir or Ru. Developing strategies based on earth-abundant metals is important to explore critical aspects of this reaction, and to see whether different and more efficient applications are possible for energy systems. Herein, we present an approach to tuning a redox-active electrocatalyst based on the doping of molybdenum into the tungsten framework of [Co4(H2O)2(PW9O34)2]10−, known as the Weakley sandwich. The Mo-doped framework was confirmed by X-ray crystallography, electrospray ionization mass spectrometry and inductively coupled plasma optical emission spectrometry studies. The doping of molybdenum into the robust Weakley sandwich framework leads to the oxidation of water at a low onset potential, and with no catalyst degradation, whereby the overpotential of the oxygen evolution reaction is lowered by 188 mV compared with the pure tungsten framework.

Utilization of [Mo2S2O2(H2O)6]2+ and a tellurite anion led to the formation of three new clusters, 1–3, with unique structural features. The tellurite anion not only templated the formation of [(Mo2O2S2)4(TeO3)(OH)9]3−1 and [(Mo2O2S2)12(TeO3)4(TeO4)2 (OH)18]10−3, but also the in situ generation of two different types of dimeric {Te2O6} based moieties induced the spontaneous assembly of the chiral [(Mo2O2S2)10(TeO3)(Te2O6)2(OH)18]8− anionic cluster, 2.

Understanding the process of the self-assembly of gigantic polyoxometalates and their subsequent molecular growth, by the addition of capping moieties onto the oxo-frameworks, is critical for the development of the designed assembly of complex high nuclearity cluster species, yet such processes remain far from being understood. Here we describe that the molecular growth from {Mo150} and {Mo120Ce6} to afford two half-closed gigantic molybdenum blue clusters {Mo180} (1) and {Mo130Ce6} (2), respectively. 1 features a hat-shaped structure with the parent wheel-shaped {Mo150} being capped by a {Mo30} unit on one side. Similarly, 2 exhibits an elliptical lanthanide-doped wheel {Mo120Ce6} that is sealed by a {Mo10} unit on one side. Moreover, the observation of the parent uncapped {Mo150} and {Mo120Ce6} clusters as minor products during the synthesis of 1 and 2 strongly suggests that the molecular growth process can be initialized from {Mo150} and {Mo120Ce6} in solution, respectively.

The design of highly flexible framework materials requires organic linkers, whereas inorganic materials are more robust but inflexible. Here, by using linkable inorganic rings made up of tungsten oxide (P8W48O184) building blocks, we synthesized an inorganic single crystal material that can undergo at least eight different crystal-to-crystal transformations, with gigantic crystal volume contraction and expansion changes ranging from −2,170 to +1,720 Å3 with no reduction in crystallinity. Not only does this material undergo the largest single crystal-to-single crystal volume transformation thus far reported (to the best of our knowledge), the system also shows conformational flexibility while maintaining robustness over several cycles in the reversible uptake and release of guest molecules switching the crystal between different metamorphic states. This material combines the robustness of inorganic materials with the flexibility of organic frameworks, thereby challenging the notion that flexible materials with robustness are mutually exclusive., We gratefully acknowledge financial support from the EPSRC for funding (grants EP/L023652/1, EP/K023004/1, EP/H024107/1, EP/I033459/1 and EP/J015156/1) and the Royal-Society Wolfson Foundation for a Merit Award.

A highly functionalized intermediate in the synthesis of Taxol has been synthesized, which features the tricyclic core and the required oxygen substituents at C1, C2, C7, C10, and C13. The key step, a ring-closing dienyne metathesis (RCDEYM) reaction, has been thoroughly optimized to favor the tricyclic product over the undesired bicyclic product resulting from diene metathesis.

Significance Self-replication is an important property of life, yet no one knows how it arose, and the machinery found in modern cells is far too complex to have formed by chance. One suggestion is that simple networks may become able to cooperate and hence replicate together forming autocatalytic sets, but no simple systems have been found. Here we present an inorganic autocatalytic, based on molybdenum blue, that is formed spontaneously when a simple inorganic salt of sodium molybdate is reduced under acidic conditions. This study demonstrates how autocatalytic sets, based on simple inorganic salts, can lead to the spontaneous emergence of self-replicating systems and solves the mystery of how gigantic molecular nanostructures of molybdenum blue can form in the first place., Here we show how a simple inorganic salt can spontaneously form autocatalytic sets of replicating inorganic molecules that work via molecular recognition based on the {PMo12} ≡ [PMo12O40]3– Keggin ion, and {Mo36} ≡ [H3Mo57M6(NO)6O183(H2O)18]22– cluster. These small clusters are able to catalyze their own formation via an autocatalytic network, which subsequently template the assembly of gigantic molybdenum-blue wheel {Mo154} ≡ [Mo154O462H14(H2O)70]14–, {Mo132} ≡ [MoVI72MoV60O372(CH3COO)30(H2O)72]42– ball-shaped species containing 154 and 132 molybdenum atoms, and a {PMo12}⊂{Mo124Ce4} ≡ [H16MoVI100MoV24Ce4O376(H2O)56 (PMoVI10MoV2O40)(C6H12N2O4S2)4]5– nanostructure. Kinetic investigations revealed key traits of autocatalytic systems including molecular recognition and kinetic saturation. A stochastic model confirms the presence of an autocatalytic network involving molecular recognition and assembly processes, where the larger clusters are the only products stabilized by the cycle, isolated due to a critical transition in the network.

The synthesis of anisotropic redox-active polyoxometalates (POMs) that can switch between multiple states is critical for understanding the mechanism of assembly of structures with a high aspect ratio, as well as for their application in electronic devices. However, a synthetic methodology for the controlled growth of such clusters is lacking. Here we describe a strategy, using the heteroanion-directed assembly, to produce a family of 10 multi-layered, anisotropic POM cages templated by redox-active pyramidal heteroanions with the composition [W16Mo2O54(XO3)]n−, [W21Mo3O75/76(XO3)2]m−, and [W26Mo4O93(XO3)3]o− for the double, triple, and quadruple layered clusters, respectively. It was found that the introduction of reduced molybdate is essential for self-assembly and results in mixed-metal (W/Mo) and mixed-valence (WVI/MoV) POM cages, as confirmed by an array of analytical techniques. To probe the archetype in detail, a tetrabutyl ammonium (TBA) salt derivative of a fully oxidized two-layered cage is produced as a model structure to confirm that all the cages are a statistical mixture of isostructures with variable ratios of W/Mo. Finally, it was found that multilayered POM cages exhibit dipolar relaxations due to the presence of the mixed valence WVI/MoV metal centers, demonstrating their potential use for electronic materials.

Investigations of chiral host guest chemistry are important to explore recognition in confined environments. Here, by synthesizing water-soluble chiral porous nanocapsule based on the inorganic metal-oxo Keplerate-type cluster, {Mo132} with chiral lactate ligands with the composition [Mo132O372(H2O)72(x-Lactate)30]42- (x = D or L), it was possible to study the interaction with a chiral guest, L/D-carnitine and (R/S)-2-butanol in aqueous solution. The enantioselective recognition was studied by quantitative 1H NMR and 1H DOSY NMR which highlighted that the chiral recognition is regulated by two distinct sites. Differences in the association constants (K) of L- and D-carnitine, which, due to their charge, are generally restricted from entering the interior of the host, are observed, indicating that their recognition predominantly occurs at the surface pores of the structure. Conversely, a larger difference in association constants (KS/KR = 3) is observed for recognition within the capsule interior of (R)- and (S)-2-butanol.

Correction for ‘Synthesis of polyoxometalate clusters using carbohydrates as reducing agents leads to isomer-selection’ by Eric Janusson et al., Chem. Commun., 2019, DOI: 10.1039/c9cc02361e.

Template‐mediated synthesis is a powerful approach to build a variety of functional materials and complex supramolecular systems. However, the systematic study of how templates structurally evolve from basic building blocks, and then affect the templated self‐assembly, is critical to understanding and utilizing the underlying mechanism, to work towards designed assembly. Here we describe the templated self‐assembly of a series of gigantic Mo Blue (MB) clusters 1–4 using l‐ornithine as a structure‐directing ligand. We show that by using l‐ornithine as a structure director, we can form new template⊂host assemblies. Based on the structural relationship between encapsulated templates of {Mo8} (1), {Mo17} (2) and {Mo36} (4), a pathway of the structural evolution of templates is proposed. This provides insight into how gigantic Mo Blue cluster rings form and could lead to full control over the designed assembly of gigantic Mo‐blue rings.

Template synthesis is a powerful and useful approach to build a variety of functional materials and complicated supramolecular systems. Systematic study on how templates structurally evolve from basic building blocks and then affect the templated self-assembly is critical to understand the underlying mechanism and gain more guidance for designed assembly but remains challenging. Here we describe the templated self-assembly of a series of gigantic Mo Blue (MB) clusters 1-4 using L-ornithine as structure-directing agent. L-ornithine is essential for the formation of such kind of template⊂host assemblies by providing directional forces of hydrogen bonding and electrostatic interactions. Based on the structural relationship between encapsulated templates of {Mo8} (1), {Mo17} (2) and {Mo36} (4), a plausible pathway of the structural evolution of templates is proposed, thus giving more insight on the templated self-assembly of Mo Blue clusters.

The fabrication of redox-active polyoxometalates (POMs) that can switch between multiple states is critical for their application in electronic devices, yet, a sophisticated synthetic methodology is not well developed for such cluster types. Here we describe the heteroanion-directed and reduction-driven assembly of a series of multi-layered POM cages 1-10 templated by 1-3 redox-active pyramidal heteroanions. The heteroanions greatly affect the selfassembly of the resultant POM cages, leading to the generation of unprecedented three-layered peanut-shaped - 4, 7 and 8 - or bulletshaped - 5 and 6 - structures. The introduction of reduced molybdate is essential for the self-assembly of the compounds and results in mixed-metal (W/Mo), and mixed-valence (WVI/MoV) 1-10, as confirmed by redox titration, UV-Vis-NIR, NMR spectroscopy and mass spectrometry. 11, the tetrabutyl ammonium (TBA) salt derivative of the fully oxidized 3, is produced as a model structure for measurements to confirm that 1-10 are a statistical mixture of isostructural clusters with different ratios of W/Mo. Finally, multilayered POM cages exhibit dipole relaxations due to the presence of mixed valence WVI/MoV metal centers, demonstrating their potential uses for electronic materials.

Wir berichten hier uber ein hybrides organisch-anorganisches Polyoxometallat, Na2[(HGMP)2Mo5O15]⋅7 H2O (1) (mit GMP=Guanosinmonophosphat), das sich spontan zu einer Struktur zusammenfugt, deren Dimensionen jenen der naturlich vorkommenden linkshandigen Z-Form der DNA verbluffend ahnlich sind. Die Helixparameter in der Kristallstruktur dieser neuen Verbindung, wie Anstieg pro Windung und helikale Verdrillung pro Dimer, sind nahezu identisch zur DNA, was einen eingehenden Vergleich von beiden Strukturen erlaubt. Zirkulardichroismus (CD) in Losung zeigt, dass Verbindung 1 auch in Losung ausgedehnte Sekundarstrukturen aufweist. Gelelektrophorese-Untersuchungen weisen die Bildung nichtkovalenter Addukte mit naturlichen Plasmiden nach. Damit konnen wir einen Weg aufzeigen, auf dem einfache, hybride organisch-anorganische Monomere, wie in Verbindung 1, sich spontan zu einer Doppelhelix zusammenlagern konnen, ohne dass dazu eine kovalent gebundene lineare Sequenz von Nuklein-Saure-Base-Paaren notig ware.

Herein, we report a hybrid polyoxometalate organic–inorganic compound, Na2[(HGMP)2Mo5O15]⋅7 H2O (1; where GMP=guanosine monophosphate), which spontaneously assembles into a structure with dimensions that are strikingly similar to those of the naturally occurring left-handed Z-form of DNA. The helical parameters in the crystal structure of the new compound, such as rise per turn and helical twist per dimer, are nearly identical to this DNA conformation, allowing a close comparison of the two structures. Solution circular dichroism studies show that compound 1 also forms extended secondary structures in solution. Gel electrophoresis studies demonstrate the formation of non-covalent adducts with natural plasmids. Thus we show a route by which simple hybrid inorganic–organic monomers, such as compound 1, can spontaneously assemble into a double helix without the need for a covalently connected linear sequence of nucleic acid base pairs.

Engineering self-templating inorganic architectures is critical for the development of bottom-up approaches to nanoscience, but systems with a hierarchy of templates are elusive. Herein we describe that the cluster-anion-templated (CAT) assembly of a {CAT}⊂{Mo24 Fe12 } macrocycle forms a giant ca. 220 nm(3) unit cell containing 16 macrocycles clustered into eight face-shared tetrahedral cluster-of-clusters assemblies. We show that {CAT}⊂{Mo24 Fe12 } with different CATs gives the compounds 1-4 for CAT=Anderson {FeMo6 } (1), Keggin {PMo12 } (2), Dawson {P2 W18 } (3), and {Mo12 O36 (HPO3 )2 } (4) polyoxometalates. "Template-free" assembly can be achieved, whereby the macrocycle components can also form a template in situ allowing template to macrocycle to superstructure formation and the ability to exchange the templates. Furthermore, the transformation of template clusters within the inorganic macrocycle {Mo24 Fe12 } allows the self-generation of an uncapped {Mo12 O36 (HPO3 )2 } in compound 4.

Chemical redox reactions have been exploited to transform unreactive vinylferrocene into a powerful dienophile for the Diels–Alder reaction and reactive substrate for thiol addition reactions upon conversion to its ferrocenium state. We have further investigated the ability of these reactions to facilitate redox-auxiliary-like reactivity by further hydrogenolyisis of the Diels–Alder adduct to the corresponding cyclopentane derivative.

Herein, we show the controlled generation of multi-component libraries based on the [MoV2S2O2]2+/MoVIO42−/SeIVO32−/C4O42− system leading to the formation of a whole new family of nanosized molecular chalcoxides, {Se8Mo36} 1, {Se8Mo40} 2, {Se8Mo56} 3, {Se20Mo56} 4 and {Se26Mo68} 5, of the general formula {(MoV2O2S2)a(OH)b(SeIVO3)c(C4O4)d(MoVI2O7)e}n−, where a, b, c, d, e, n = [16, 20, 8, 6, 2, 20] for 1, [18, 24, 8, 6, 2, 20] for 2, [24, 32, 8, 8, 4, 24] for 3, [28, 32, 20, 8, 0, 32] for 4 and [34, 36, 26, 8, 0, 36] for 5. The coordination modulation effect offered by the SeIVO32− and the C4O42− anions lead to the generation of new building blocks, [(MoV2O2S2)3(OH)6(C4O4) (MoVI2O7)]4−, and the discovery of a new family of clusters of increasing nuclearity and complexity.

Utilization of tellurite anion as template, led to the formation of unprecedented oxothiometalate based building blocks and the spontaneous manifestation of chirality., Utilization of [Mo2S2O2(H2O)6]2+ and a tellurite anion led to the formation of three new clusters, 1–3, with unique structural features. The tellurite anion not only templated the formation of [(Mo2O2S2)4(TeO3)(OH)9]3–1 and [(Mo2O2S2)12(TeO3)4(TeO4)2 (OH)18]10–3, but also the in situ generation of two different types of dimeric {Te2O6} based moieties induced the spontaneous assembly of the chiral [(Mo2O2S2)10(TeO3)(Te2O6)2(OH)18]8– anionic cluster, 2.

Mixed valence/metal polyoxometalate (POM) clusters are one of the most interesting host species because they show the ability to incorporate a wide range of heteroatoms of various charges and geometries. We report herein the incorporation of pyramidal EO32- heteroanions (E=PH, S, Se, Te) that are responsible not only for directing the templated assembly of a family of mixed-metal POMs but also for the symmetry-breaking of the traditional Dawson architecture and modulation of the electronic characteristics of the cluster's shell. The isolated family of POMs consists of four members: (Me2 NH2 )5 Na2 [Mo11 V7 O52 (HPO3 )]⋅MeOH⋅5 H2 O (1), (NH4 )7 [Mo11 V7 O52 (SO3 )]⋅12 H2 O (2), K7 [Mo11 V7 O52 (SeO3 )] ⋅31 H2 O (3), and (Me2 NH2 )6 Na[Mo11 V7 O52 (TeO3 )]⋅15 H2 O (4), and were characterized by X-ray structural analysis, electrospray ionization mass spectrometry (ESI-MS), thermogravimetric analysis (TGA), UV/Vis, FTIR, elemental analysis, flame atomic absorption spectroscopy (FAAS), and inductively coupled plasma optical emission spectroscopy (ICP-OES). Cyclic voltammetry (CV) and electron paramagnetic resonance (EPR) spectroscopic studies in concert with density functional theoretical (DFT) calculations have been used to elucidate the effect of the heteroatom on the electronic properties of the cluster.

Heteroanion (HA) moieties have a key role in templating of heteropolyoxometalate (HPA) architectures, but clusters templated by two different templates are rarely reported. Herein, we show how a cross-shaped HPA-based architecture can self-sort the HA templates by pairing two different guests into a divacant {XYW15O54} building block, with four of these building block units being linked together to complete the cross-shaped architecture. We exploited this observation to incorporate HA templates into well-defined positions within the clusters, leading to the isolation of a collection of mixed-HA templated cross-shaped polyanions [(XYW15O54)4(WO2)4]32–/36– (X = H–P, Y = Se, Te, As). The template positions have been unambiguously determined by single crystal X-ray diffraction, NMR spectroscopy, and high-resolution electrospray ionization mass spectrometry; these studies demonstrated that the mixed template containing HPA clusters are the preferred products which crystallize from the solution. Theoretical studies using DFT calculations suggest that the selective self-sorting originates from the coordination of the template in solution. The cross-shaped polyoxometalate clusters are redox-active, and the ability of molecules to accept electrons is slightly modulated by the HA incorporated as shown by differential pulse voltammetry experiments. These results indicate that the cross-shaped HPAs can be used to select templates from solution, and themselves have interesting geometries, which will be useful in developing functional molecular architectures based upon HPAs with well-defined structures and electronic properties.