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Five new compounds are reported herein starting from 2-hydroxy-6-methylnicotinic acid (H2h6mnic) and first-row transition metal ions, although H2h6mnic shows a prototropy in solution to lead to the 6-methyl-2-oxonicotinate (6m2onic) ligand that is the molecule eventually present in the compounds. The structural and chemical characterization reveals the following chemical formulae: {[MnNa(μ

Two new crystal structures of phosphotetradecavanadates are reported and theoretical calculations, including DFT analysis, disclose their intermolecular binding interactions.

The synergistic combination of a zirconium metal–organic cluster and a Keggin type polyoxotungstate led to a chemically stable and photoactive porous material.

Clustering chemistry is a key point in the design and synthesis of the secondary building units that comprise metal-organic frameworks (MOFs) based on group IV metals. In this work, the first stages of the zirconium-carboxylate clustering process in alcohol/water mixtures are studied in detail using the monocarboxylic benzoic and hydroxybenzoic acids to avoid the polymerization. Mass spectroscopy measurements performed on the reactions revealed the presence of hexa- and pentanuclear species even at low pH values and also evidenced the acid-base nature and pH dependence of the transformation between both species. The control on the chemistry governing the equilibria between these species has allowed us to isolate six new compounds in the solid state. The single-crystal X-ray diffraction analysis revealed that they are closely related to the well-known [Zr

This work was funded by Eusko Jaurlaritza/Gobierno Vasco (EJ/GV, grants IT1291-19 and KK-2020/00008) and Ministerio de Ciencia e Innovación (MCIN, grant MAT2017–89553-P). E.R.B. is indebted to EJ/GV for her predoctoral fellowship (PRE_2018_1_0143). E.C. thanks MCIN/AEI/10.13039/501100011033/ “FEDER Una manera de hacer Europa” (project PGC2018 102052-B-C21) and the I+D+i FEDER program 2018 of Junta de Andalucı́a (Project A-FQM-172-UGR18) for financial support., The reaction of mid to late lanthanide ions with the N,N′-dimethyl-N,N′-bis(2-hydroxy-3-formyl-5-bromobenzyl)ethylene-diamine organic ligand and monolacunary Keggin type [α-SiW11O39]8- anion affords a series of isostructural compounds, namely, K5[LnIII(α-SiW11O39)(C20H22Br2N2O4)]·14H2O (1-Ln, Ln = Sm to Lu). The molecular structure of these sandwich-type complexes is formed by the LnIII ion in a biaugmented trigonal prismatic geometry, which occupies the external O4 site of the organic ligand and the vacant site of the lacunary polyoxometalate (POM) unit. The empty N2O2 coordination site of the organic ligand allows its unprecedented folding, which displays a relative perpendicular arrangement of aromatic groups. Weak Br···Br and ?-πinteractions established between adjacent molecular units govern the crystal packing, which results in the formation of assemblies containing six hybrid species assembled in a chairlike conformation. 1-Gd and 1-Yb display slow relaxation of the magnetization after the application of an external magnetic field with maxima in the out-of-phase magnetic susceptibility plots below ?5-6 K, which is ascribed to the presence of various relaxation mechanisms. Moreover, photoluminescent emission is sensitized for 1-Sm and 1-Eu in the visible region and 1-Er and 1-Yb in the NIR. In contrast, the quenching of metal-centered luminescence in the 1-Tb derivative has been attributed to the out-of-pocket coordination mode of the lanthanide center within the POM fragment. It is demonstrated that the 1-Yb dual magneto-luminescent material represents the first lanthanide-containing POM reported to date with simultaneous slow magnetic relaxation and NIR emission. Solution stability of the hybrid molecular species in water is also confirmed by ESI-mass spectrometry experiments carried out for 1-Tb and 1-Tm., Eusko Jaurlaritza/Gobierno Vasco IT1291-19, KK-2020/00008, I+D+i FEDER A-FQM-172-UGR18, Ministerio de Ciencia e Innovación MAT2017–89553-P, PGC2018 102052-B-C21

The unprecedented heptavanadate cluster has been isolated from reactions between trisalkoxide ligands and vanadate in water at pH = 2 as a series of alkylammonium [HxV7O18(H2O)((OCH2)3CR)](4-x)- salts (1-3, R = CH2OH; 4, R = CH3). Their structures have been determined and the partial stability of 4 in water assessed by a combination of multinuclear NMR spectroscopy and ESI-MS. The heptavanadate unit reported herein could represent an intermediate species in the formation of decavanadate that is blocked by attachment of tripodal ligands.

Capture and sensing of emerging pollutants is one of the increasing environmental concerns due to the adverse ecological and human health effects. Here, we report the synthesis of a supramolecular metal-organic framework (SMOF) [CrCu6(m-H2O)6(m3-OH)6(m-adeninato-kN33:kN9)6](SO4)1.5 which is able to capture anionic drugs and exhibits magnetic properties useful for sensing purposes. The features of the nucleobase decorated CrCu6 building block allow the incorporation of up to 9 drug molecules (i.e., ibuprofen and naproxen in this work) per heptameric entity. In addition, we provide a simple way to quantify the incorporated number of drug molecules through a magnetic sustentation experiment in which the field required to keep the particles attached to the electromagnet pole is linearly related to the total mass of the anionic counterion. In this way, it also provides an easy way to determine the amount of entrapped drug molecules, making this SMOF a promising candidate for environmental remediation technologies. This work has been funded by the Universidad del País Vasco/Euskal Herriko Unibertsitatea (GIU17/50), the Gobierno Vasco/Eusko Jaurlaritza (PIBA18/14; IT1291-19), the Ministerio de Economía y Competitividad (MAT2016-75883-C2-1-P), the Ministerio de Ciencia e Innovación (PID2019-108028GB-C21), and FEDER funds. Technical and human support provided by SGIker (UPV/EHU, MICINN, GV/EJ, and ESF) is also acknowledged.

The hybrid compound [Cu(cyclam)(H2O)2]0.5[{Cu(cyclam)}1.5{B-H2As2Mo6O26(H2O)}]·9H2O (1) (cyclam = 1,4,8,11-tetraazacyclotetradecane) was synthesized in aqueous solution by reacting the {Cu(cyclam)}2+ complex with a mixture of heptamolybdate and an arsenate(V) source. Crystal packing of 1 exhibits a supramolecular open-framework built of discrete covalent molybdoarsenate/metalorganic units and additional [Cu(cyclam)(H2O)2]2+ cations, the stacking of which generates squarelike channels parallel to the z axis with an approximate cross section of 10 × 11 Å2 where all the hydration water molecules are hosted. Thermal evacuation of solvent molecules yields a new anhydrous crystalline phase, but compound 1 does not preserve its single-crystalline nature upon heating. However, when crystals are dehydrated under vacuum, they undergo a structural transformation that proceeds via a single-crystal-to-single-crystal pathway, leading to the anhydrous phase [{Cu(cyclam)}2(A-H2As2Mo6O26)] (2). Total dehydration results in important modifications within the inorganic cluster skeleton which reveals an unprecedented solid-state B to A isomerization of the polyoxoanion. This transition also involves changes in the CuII bonding scheme that lead to covalent cluster/metalorganic layers by retaining the open-framework nature of 1. Compound 2 adsorbs ambient moisture upon air exposure, but it does not revert back to 1, and the hydrated phase [{Cu(cyclam)}2(A-H2As2Mo6O26)]·6H2O (2h) is obtained instead. Structural variations between 1 and 2 are reflected in electron paramagnetic resonance spectroscopy measurements, and the permanent microporosity of 2 provides interesting functionalities to the system such as the selective adsorption of gaseous CO2 over N2., A supramolecular open framework built of copper(II)-complexes of a macrocyclic tetraaza ligand and arsenomolybdate anions undergoes a single-crystal-to-single-crystal transformation upon dehydration that implies an unprecedented solid state cluster isomerization. The permanent porosity of the system allows the selective adsorption of CO2 over N2.

Coumarin derivatives are a class of compounds with a pronounced wide range of applications, especially in biological activities, in the medicine, pharmacology, cosmetics, coatings and food industry. Their potential applications are highly dependent on the nature of the substituents attached to their nucleus. These substituents modulate their photochemical and photophysical properties, as well as their interactions in their crystalline form, which largely determines the final field of application. Therefore, in this work a series of mono and dihydroxylated coumarin derivatives with different chemical substituents were synthesized and characterized by UV-Visible spectroscopy, thermal analysis (differential scanning calorimetry (DSC) and TGA), 1H NMR and X-Ray Diffraction to identify limitations and possibilities as a function of the molecular structure for expanding their applications in polymer science., This research was funded by the Basque Government within the framework ELKARTEK through the research project KK-2018/00108 and KK-2019/00077. This work was also funded by the Ministry of Economy and Competitiveness—Spain (MINECO) through the research Projects RTC-2016-4887-4 and RTI2018-096636-J-100 within the framework of the National Programme for Research Aimed at the Challenges of Society

S. Reinoso, B. Artetxe and J. M. Gutierrez-Zorrilla. Single-crystal-to-single-crystal transformations triggered by dehydration in polyoxometalate-based compounds. En: Acta Crystallographica Section C 2018;74(11):1222-1242. https://doi.org/10.1107/S2053229618011269 Single-crystal-to-single-crystal transformations are solid-state phase transitions between different crystalline states in which the crystal integrity and the long-range structural order are retained through the whole transformation process. Such a phenomenon constitutes the structural response that some compounds afford when being exposed to a given external stimulus (temperature, pressure, light, etc.) and, therefore, its study has become a relevant focus of interest within crystal engineering because it allows for monitoring how certain properties (colour, magnetism, luminescence, porosity) of the stimuli-responsive material are modified as the structure evolves into the activated form. A range of organic, inorganic and hybrid systems have been found to undergo such phase transitions, but these examples only include a small number of compounds that incorporate polyoxometalate anions, among which the removal of guest solvent molecules (dehydration) stands out as the most common external stimulus able to induce the occurrence of a single-crystal-to-single-crystal transformation. This feature article compiles the examples of dehydration-triggered single-crystal-to-single-crystal transformation studies that have been reported to date for polyoxometalate-based compounds and reviews some of their most relevant structural aspects. © International Union of Crystallography, 2018 The following institutions are acknowledged for support: Universidad Pública de Navarra, Obra Social la Caixa and Fundación Caja Navarra (contract to SR in the framework of the program ‘Captación del Talento’); Universidad del País Vasco UPV/EHU (grants PPG17/37 and GIU17/050); Ministerio de Economía, Industria y Competitividad (grant MAT2017-89553P).

The hybrid compound [{Cu(cyclam)}3(W7O24)]·15.5H2O (1) (cyclam= 1,4,8,11-tetraaza-cyclotetradecane) was synthesized by reacting the {Cu(cyclam)}2+ complex with a tungstate source in water at pH = 8. Compound 1 exhibits an unprecedented three-dimensional covalent structure built of heptatungstate clusters linked through metalorganic complexes in a POMOF-like framework that displays water-filled channels. This dynamic architecture undergoes two sequential single-crystal-to-single-crystal transformations upon thermal evacuation of water molecules to result in the partially dehydrated [{Cu(cyclam)}3(W7O24)]·12H2O (2) and anhydrous [Cu(cyclam)]0.5[{Cu(cyclam)}2.5(W7O24)] (3) crystalline phases. These transitions are associated with cluster rotations and modifications in the CuII coordination geometries, which reduce the dimensionality of the original lattice to layered systems but preserving the porous nature. Phase 3 reverts to 2 upon exposure to ambient moisture, whereas the transition between 1 and 2 proved to be irreversible. The permanent microporosity of 3 was confirmed by gas sorption measurements (N2, CO2), which reveal a system of parallel channels made of wide cavities connected through narrow necks that limit the adsorption process, in good agreement with Grand Canonical Monte Carlo simulations.

Two new organic–inorganic hybrid compounds based on Keggin-type polyoxometalates and melaminium cations, namely (C3N6H7)3[PW12O40]·6H2O (1) and (C3N6H7)4[SiW12O40]·6H2O (2) have been synthesized at room temperature by a solvent diffusion method and characterized by IR spectroscopy, CHN analyses and single-crystal X-ray diffraction. Hybrid 1 consists of three melamonium cations per [PW12O40]3− unit with the hydration water molecules connected to each other via hydrogen bonding forming a 1D zigzag chain. In compound 2, [SiW12O40]4− polyanions and water molecules act as inorganic layers that are alternating with layers of monoprotonated organic melaminium cations.

A hydrothermal reaction between the monolacunary polyoxometalate [SiW11O39]8–, a copper(II) salt, and 1,4,8,11-tetraazacyclotetradecane (cyclam) affords the first example of a hybrid compound combining metal complexes of such an N4-tetradentate macrocyclic ligand and Keggin-type clusters, namely, [Cu(cyclam)(H2O)][{Cu(cyclam)}2SiW11O39Cu(H2O)]·5H2O (1). This compound has been characterized by infrared spectroscopy and thermal and elemental analyses. Single-crystal X-ray diffraction (scXRD) reveals a layered crystal packing made of corrugated two-dimensional covalent grids in which four octahedral {Cu(cyclam)}2+ bridging moieties connect copper(II)-monosubstituted {SiW11O39Cu(H2O)}6– polyanions to four adjacent clusters, and additional [Cu(cyclam)(H2O)]2+ square-pyramidal counterions are embedded into square-like grid voids. Thermostructural analyses confirm the presence in the 130–250 °C temperature range of a stable and crystalline anhydrous phase, which displays a diffraction pattern different from that of 1. This thermally triggered phase transition proceeds through a single-crystal to single-crystal transformation pathway, which according to scXRD, involves not only the release of water molecules, but also the cleavage and formation of Cu–O bonds induced by the rotation of Keggin-type anions. These modifications fully dismantle the parent two-dimensional covalent assembly to result in the neutral, discrete [{Cu(cyclam)}3SiW11O39Cu] hybrid species (2), in which the cluster exhibits three square-pyramidal {Cu(cyclam)}2+ decorating moieties grafted at its surface. This species must display a five-coordinated copper(II) center in the Keggin skeleton, and therefore, it constitutes one of the scarce examples of such type of coordinatively unsaturated substituted cluster observed in the solid state. The irreversibility of the phase transition has been confirmed by combined thermal and diffractometric analyses, which evidenced also the great flexibility of the supramolecular framework of 2, as this anhydrous phase is able to adsorb up to six water molecules per cluster to lead to the hydrated derivative [{Cu(cyclam)}3SiW11O39Cu(H2O)]·5H2O (2h) without any significant alteration in its cell parameters, nor in its crystalline structure., This work was funded by Eusko Jaurlaritza/Gobierno Vasco (EJ/GV, Grants IT1291-19 and PIBA2018-59) and Ministerio de Ciencia, Innovacion y Universidades (Grant MAT2017- 89553-P). L.F.N. and E.R.B. are indebted to EJ/GV for their predoctoral fellowships (PRE_2019_1_0106 and PRE_2018_1_0143).

The first decavanadate-based microporous hybrid, namely, [Cu(cyclam)][{Cu(cyclam)}2(V10O28)]·10H2O (1, cyclam = 1,4,8,11-tetraazacyclotetradecane) was prepared by reaction of (VO3)− anions and {Cu(cyclam)}2+ complexes in NaCl (aq) at pH 4.6–4.7 and characterized by elemental analyses, thermogravimetry, and X-ray diffraction (powder, single-crystal) techniques. Compound 1 exhibits a POMOF-like supramolecular open-framework built of covalent decavanadate/metalorganic layers with square-like voids, the stacking of which is aided by interlamellar cementing complexes and generates water-filled channels with approximate cross sections of 10.4 × 8.8 Å2. The framework is robust enough to remain virtually unaltered upon thermal evacuation of all water molecules of hydration, as demonstrated through single-crystal X-ray diffraction studies on the anhydrous phase 1a. This permanent microporosity renders interesting functionality to 1, such as selective adsorption of CO2 over N2 and remarkable activity as heterogeneous catalyst toward the H2O2-based oxidation of the highly-stable, tricyclic alkane adamantane. This work was funded by Eusko Jaurlaritza/Gobierno Vasco (Grant No. IT477-10), MINECO (Grant No. MAT2013-48366-C2-2-P), and UPV/EHU (Grant No. UFI11/53). J.A.-M. thanks Generalitat Valenciana and FEDER (Grant No. PROMETEO2/2014/010), as well as MICINN and Plan E (Grant No. CTQ2012-31762) for financial support.

Two new Melamine-Keggin hybrid nanorods, MELH-PMo12 and MELH-PW12, for the first time are successfully synthesized by two chemical methods, one-step solid-state chemical reaction method and experimental solvent diffusion method at room temperature. One-step solid-state reactions involve grounded nanorod materials along with grinding of row material and with solvent diffusion method these nanorods synthesized in single crystals form. These compounds crystallized in trigonal space groups P-3. Elemental analysis, infrared spectroscopy, UV spectroscopy and XRD analysis results prove that the samples still possess Keggin type structure. Transmittance electron microscopy and single-crystal X-ray have shown that the samples have nanorod structures.

In agriculture, the applied nitrogen (N) can be lost in the environment in different forms because of microbial transformations. It is of special concern the nitrate (NO3-) leaching and the nitrous oxide (N2O) emissions, due to their negative environmental impacts. Nitrification inhibitors (NIs) based on dimethylpyrazole (DMP) are applied worldwide in order to reduce N losses. These compounds delay ammonium (NH4+) oxidation by inhibiting ammonia-oxidizing bacteria (AOB) growth. However, their mechanism of action has not been demonstrated, which represent an important lack of knowledge to use them correctly. In this work, through chemical and biological analysis, we unveil the mechanism of action of the commonly applied 3,4-dimethyl-1H-pyrazole dihydrogen phosphate (DMPP) and the new DMP-based NI, 2-(3,4-dimethyl-1H-pyrazol-1-yl)-succinic acid (DMPSA). Our results show that DMP and DMPSA form complexes with copper (Cu2+) cations, an indispensable cofactor in the nitrification pathway. Three coordination compounds namely [Cu(DMP)4Cl2] (CuDMP1), [Cu(DMP)4SO4]n (CuDMP2) and [Cu(DMPSA)2]·H2O (CuDMPSA) have been synthesized and chemical and structurally characterized. The CuDMPSA complex is more stable than those containing DMP ligands; however, both NIs show the same nitrification inhibition efficiency in soils with different Cu contents, suggesting that the active specie in both cases is DMP. Our soil experiment reveals that the usual application dose is enough to inhibit nitrification within the range of Cu and Zn contents present in agricultural soils, although their effects vary depending on the content of these elements. As a result of AOB inhibition by these NIs, N2O-reducing bacteria seem to be beneficed in Cu-limited soils due to a reduction in the competence. This opens up the possibility to induce N2O reduction to N2 through Cu fertilization. On the other hand, when fertilizing with micronutrients such as Cu and Zn, the use of NIs could be beneficial to counteract the increase of nitrification derived from their application.

Additive manufacturing in comparison to traditional fabrication methods dis-plays numerous advantages such as freedom of design, mass customization, the ability to manufacture complex structures or the rapid creation of prototypes. Although there are many materials used in the 3d printing technologies, polymers are the most prominent due to their versatility, low cost and suitable physico-chemical properties. Thus, this article gives an overview of 3d printing technologies applied to polymeric materials, the main pol-ymers used, as well as their applications in fields like biomedicine, electronics and aero-space engineering.; Fabrikazio gehigarriak, metodo tradizionalekin alderatuta, abantaila ugari ditu, hala nola diseinu askatasuna, pertsonalizazioa, egitura konplexuak fabrikatzeko gai-tasuna edota prototipoen sorrera azkarra. 3D inprimaketa teknologietan material ezberdin ugari erabiltzen badira ere, polimeroak dira gailentzen direnak, haien aldakortasuna, kostu baxua eta propietate fisiko-kimikoak direla eta. Horrela, artikulu honek polimeroetan oina-rritutako fabrikazio gehigarrirako metodoak eta horietan erabiltzen diren polimero nagusiak laburbiltzen ditu, baita zenbait arlotan dituzten erabilera-esparruak ere: biomedikuntzan, elektronikan eta ingeniaritza aeroespazialean.

Kanpo-estimuluen bitartez aktibatutako fase-trantsizioak, eta haien artean kristal bakun izaera mantentzen duten kasuak, hots monokristal-monokristal (MKMK) eraldaketak, interes handikoak dira; izan ere, gai dira i) ezaugarri berriak dituzten produktuak emateko eta ii) materialaren propietateetan gertatzen diren aldaketak, egitura kristalinoak jasaten dituenekin erlazionatzeko. Polioxometalatoen (POMen) kasuan bezala, egiturei zurruntasuna ematen dieten oinarrizko unitateak erabiltzea bide egokia da prozesuan zehar gerta litekeen kristalinitatearen galera saihesteko. Gaur egun POMetan oinarritutako sistemetan aurki daitezkeen MKMK eraldaketa urrien artean, aipatzekoak dira termikoki aktibatutako adibideak. Lan honetan azken hauek laburbilduko dira eta bereziki gure ikerketa taldean prestatutako konposatuak eta haien erabilerak (katalisia eta gasen xurgapen selektiboa) goraipatuko ditugu. Phase transitions induced by external stimuli in which crystallinity is retained, so-called single-crystal-to-single-crystal transformations (SCSC), are being widely studied because they allow for i) obtaining products with novel characteristics and ii) correlating structural changes with how a given property of the material is modified. The use of building blocks that provide robustness to the system such as polyoxometalates (POM) are a suitable option to avoid the loss of crystallinity throughout the process. Among the scarce SCSC transformations reported to date for POM-based systems, it is worth highlighting the temperature-triggered examples. This work reviews the later cases with strong focus on the compounds obtained in our research group and their applications (catalysis and selective gas sorption). Artikulu hau Eusko Jaurlaritzak Estibaliz Ruiz-Bilbaori eskainitako doktorego-aurreko diru-laguntzari esker (PRE_2018_1_0143) burutu da. Egileek UPV/EHU (PPG17/37, GIU17/050), Eusko Jaurlaritzaren (PIBA2018-59, KK-2018/00054) eta Ekonomia, Industria eta Lehiakortasun Ministerioaren (MAT2017-89553-P) finantziazioa eskertu nahi dute. Santiago Reinosok Obra Social la Caixa, Fundación Caja Navarra eta Nafarroako Unibertsitate Publikoaren «Captación de Talento» programaren bidez jasotako diru-laguntza eskertzen du.

In this work the immobilization of hybrid polyoxometalates (POMs) onto functional polymeric surfaces is exposed and discussed. Thus, various hybrid polymer‒inorganic films were prepared by anchoring selected hybrid POMs onto tailored polymeric surfaces that consisted of breath figures (BFs) made of polystyrene-b-poly(acrylic acid)/polystyrene (PS-b-PAA/PS) blends. Functionalization of the BF films was performed by selective arrangement of acrylic acid groups of the amphiphilic block copolymer on the surface pores because of their affinition for the water condensed during breath figure formation. These carboxylic acid functional groups contained within the PAA blocks were then employed to anchor [Cu(cyclam)][{Cu(cyclam)}2(V10O28)]&middot, 10H2O (1-CuV10) and [{Cu(cyclam)}(VO3)2]&middot, 5H2O (1-CuV1), hybrid POMs by immersing the films into aqueous solutions of the in situ formed hybrid clusters, resulting in the hybrid films BF1 and BF2, respectively. Superficial analysis of these hybrid polymeric films was carried out by the sophisticated ion beam-based technique time-of-flight secondary ion mass spectrometry (ToF-SIMS) that was revealed to be an excellent method for the superficial compositional mapping of patterned surfaces.

A series of 14 isostructural [Cu(cyclam)](2)[{Cu(cyclam)}4{(a-GeW11O39)Ln(H2O)-(OAc)(12)].18H(2)O (1-Ln, where Ln = La Lu; cyclam = 1,4,8,11-tetraazacyclotetradecane) polyoxometalate-based hybrids reported herein represent (i) the first example of a twodimensional covalent hybrid lattice involving the [{(aXWI 1039)Ln(H2O)(OAc)}2in- archetype and (ii) the first structural characterization of such a dimeric polyoxotungste for Ln = La and Pr as well as for the combination of X = Ge and Ln = Ce, Nd, Sm, or Lu. Compounds 1-Ln have been characterized by elemental analyses, infrared spectroscopy, and thermogravimetric analysis, and their thermostructural behavior has been monitored by powder and single-crystal Xray diffraction. The title compounds undergo two single-crystal-to-single-crystal transformations triggered dehydration leading to the [{Cu(cydam)}6{(alpha-GeW11O39)Ln(H2O)(OAc)}2]-4H(2)O intermediate (2-Ln, where Ln = Eu or Er) and [Cu(cyclam)]0.5[{Cu(cyclam)}55{(alpha-GeW11O39)Ln(0Ac)}2] (3-Ln, where Ln = Ce or Eu) final anhydrous phases, the latter evidencing a coordinatively unsaturated derivative of the dimeric archetype for the first time. These transitions involve formation and disruption of Cu Opom bonds that result in different {Cu(cydam)}(2+) moieties grafting onto and being released from Keggin surfaces, which reduces the dimensionality of 1-Ln to one-dimensional covalent assemblies for 2-Ln and 3-Ln. While all 3-Ln phases rehydrate fully upon exposure to air for 24 h, the kinetics governing the crystal transitions back toward 1Ln through 2-Ln depend on the nature of Ln. Under ambient moisture, the anhydrous structures fully revert back to the parent framework for Ln = La Sm, while the samples containing Eu to Lu afford mixtures of 1-Ln and 2-Ln and require immersion in water for the structural reversion to reach completion. Single-crystal X-ray diffraction analyses of the rehydrated 1R-Ln samples (Ln = Ce, Eu, and Er) support these observations. This work was funded by Eusko Jaurlaritza/Gobierno Vasco (Grant PIBA2018-59 and ELKARTEK bG18 10(2018/00054), MINECO (Grant MAT2017-89553-P), and UPV/EHU (Grants PPG17/37 and GIU17/050). S.R. thanks Obra Social la Caixa, Fundacion Caja Navarra, and UPNA for a research contract in the framework of the program "Captación del Talento". Technical and human support provided by SGIker (UPV/EHU) is gratefully acknowledged.

The structures are reported of six racemic tris­(bipyrid­yl)iron salts with a range of 2-substituted-1,1,3,3-tetra­cyano­propenide anions, mostly also containing either perchlorate or tetra­fluorido­borate as co-anions. In three of the compounds the polynitrile anions are fully ordered, and in three others they are disordered, while the co-anion is also ordered in three compounds, but disordered in two others. Supra­molecular assemblies range from no continuous aggregation up to a three-dimensional hydrogen-bonded framework structure., Structures are reported for six closely related salts of tris­(bipyrid­yl)iron(II) cations, namely tris­(2,2′-bi­pyridine)­iron(II) bis­(1,1,3,3-tetra­cyano-2-meth­oxy­propenide) 0.776-hydrate, [Fe(C10H8N2)3](C8H3N4O)2.0.776H2O, (I), tris­(2,2′-bi­pyridine)­iron(II) 1,1,3,3-tetra­cyano-2-(propyl­sulfan­yl)propenide perchlor­ate, [Fe(C10H8N2)3](C10H7N4S)(ClO4), (II), tris­(5,5′-dimethyl-2,2′-bi­pyridine)­iron(II) 1,1,3,3-tetra­cyano-2-meth­oxy­propenide tetra­fluorido­borate ethanol 0.926-solvate, [Fe(C12H12N2)3](C8H3N4O)(BF4).0.926C2H2O, (III), tris­(5,5′-dimethyl-2,2′-bi­pyridine)­iron(II) 1,1,3,3-tetra­cyano-2-eth­oxy­propenide tetra­fluorido­borate, [Fe(C12H12N2)3](C9H5N4O)(BF4), (IV), tris­(5,5′-dimethyl-2,2′-bi­pyridine)­iron(II) 1,1,3,3-tetra­cyano-2-(ethyl­sufanyl)propenide tetra­fluorido­borate, [Fe(C12H12N2)3](C9H5N4S)(BF4), (V), and tris­(5,5′-dimethyl-2,2′-bi­pyri­dine)­iron(II) 1,1,3,3-tetra­cyano-2-prop­oxypropenide tetra­fluorido­borate, [Fe(C12H12N2)3](C10H7N4O)(BF4), (VI). In compound (I), one of the anions is disordered over two sets of atomic sites with equal occupancies while, in the second anion, just one of the C(CN)2 units is disordered, again over two sets of atomic sites with equal occupancies: the anionic components are linked by multiple C—H⋯N hydrogen bonds to form a three-dimensional framework. In compound (II), the polynitrile anion is disordered over two sets of atomic sites with occupancies in the approximate ratio 3:1, while the perchlorate anion is disordered over three sets of atomic sites: there are C—N⋯π inter­actions between the cations and the polynitrile anion. The polynitrile anion in compound (III) is fully ordered, but the tetra­fluorido­borate anion is disordered over two sets of atomic sites with occupancies 0.671 (4) and 0.329 (4): the cations and the tetra­fluorido­borate anions are linked by C—H⋯F inter­actions to form an inter­rupted chain. Compounds (IV) and (V) are isostructural and all of the ionic components are fully ordered in both of them: the cations and tetra­fluorido­borate anions are linked into C 2 2(12) chains. The polynitrile anion in compound (VI) is disordered over two sets of atomic sites with approximately equal occupancies, and here the chains formed by the cations and the tetra­fluorido­borate anions are of the C 2 2(13) type.

Polyoxometalates (POMs) have been revealed as interesting antitumor agents inhibiting the action of Sox2 transcription factor, which reduces the risk of metastasis during hormonal therapies. However, they have shown serious concerns to be incorporated into the cells due to their cytotoxicity. Taking this into consideration, this study aims to develop polyoxometalate-based nanocarriers to be potentially applied as new forms of anticancer therapies. Thus, the Wells-Dawson type [P2Mo18O62]6− phosphomolybdate was physically loaded into covalently crosslinked chitosan nanogels that can act as nanocarriers for local delivery. The obtained nanocomposites were extensively characterized by 31P-NMR, TEM microscopy, DLS and zeta potential measurements. This work revealed that selected chitosan nanocarriers would present great potential for POM delivery into tumoral cells due to their pH-triggered deliverability that inhibits cytotoxic drug release at physiological pH. Furthermore, the high uptakes values reported herein make prepared nanocomposites interesting candidates for future breast antitumoral treatments.

Reaction of early lanthanides, GeO2 , and Na2 WO4 in a NaOAc buffer results in large crown-shaped polyoxometalates based on [Ln2 GeW10 O38 ](6-) subunits. By using Ni(2+) as a crystallizing agent, [Na⊂Ln12 Ge6 W60 O228 (H2 O)24 ](35-) (Na⊂Ln12 ) hexamers formed by alternating β(1,5)/β(1,8) subunits were obtained for Ln=Pr, Nd. The addition of K(+) led to a similar anion for Ln=Sm, namely, [K⊂Sm12 Ge6 W60 O228 (H2 O)22 ](35-) (K⊂Sm12 ) and [K⊂K7 Ln24 Ge12 W120 O444 (OH)12 (H2 O)64 ](52-) (K⊂Ln24 ) dodecamers that consist of a central core identical to K⊂Sm12 decorated with six external γ(3,4) subunits for Ln=Pr, Nd. These anions dissociate in water into hexameric cores and monomeric entities, as shown by ESI mass spectrometry. The former self-assemble into spherical, hollow, and single-layered blackberry-type structures with radii of approximately 75 nm, as monitored by laser light scattering (LLS) and TEM techniques. Analogous studies performed for K⊂Nd24 in water/acetone mixtures show that the dodecamers remain stable and form in turn their own type of blackberries with sizes that increase from approximately 20 to 50 nm with increasing acetone content. This control over both the composition and size of the vesicle-like assemblies is achieved for the first time by modifying the architecture of the species that undergoes supramolecular association through the solvent polarity.

A new hybrid inorganic-organometallic salt has been obtained from the reaction of the Keggin-type silicotungstate anion with ferrocene in a water/methanol mixture as a result of the partial oxidation of ferrocene molecules to ferrocenium cations. Single-crystal X-ray diffraction analysis reveals the presence of four ferrocenium (FeIII) cations and one ferrocene (FeII) molecule per plenary Keggin anion in the crystal structure of [FeIII (Cp)2]4[SiW12O40]&middot, [FeII(Cp)2]&middot, 2CH3OH (1). Compound 1 thus constitutes the first example in the literature in which ferrocenium and ferrocene species coexist in the structure of a polyoxometalate-based salt. The two crystallographically independent ferrocenium species in the asymmetric unit of 1 exhibit different configurations: One displays an eclipsed conformation with ideal D5h symmetry, whereas the conformation in the other one is staggered D5d. The crystal packing of 1 can be best described as an organometallic sub-lattice of ferrocenium and ferrocene species linked by a network of &pi, &pi, interactions that generates rectangular cavities of about 14 &times, 10 &Aring, in which strings of Keggin anions and methanol molecules are hosted, further connected to each other via weak OPOM&middot, &middot, CMeOH-OMeOH&middot, OPOM type hydrogen bonds. The charge-transfer nature of the salt has been studied by solid-state diffuse reflectance UV-Vis spectroscopy and the presence of magnetically isolated FeIII/FeII centres has been confirmed by M&ouml, ssbauer spectroscopy. A topological study carried out on all of the pristine ferrocenyl species deposited in the Cambridge Structural Database (CSD) has allowed two main conclusions to be drawn: (1) these species tend to adopt extreme conformations (either eclipsed or staggered) with less than a 15% of examples showing intermediate states and (2) the oxidation state of the iron centres can be unequivocally assigned on the basis of a close inspection of the Fe&middot, Cp distances, which allows ferrocene neutral molecules and ferrocenium cations to be easily distinguished.

A new organic-inorganic compound based on octamolybdate building blocks and copper(II) complexes of tetradentate N-donor ligands has been hydrothermally synthesized, namely [Cu(cyclam)](2)[Mo8O26]center dot 1.5H(2)O (1), (cyclam: 1,4,8,11-tetraazacyclotetradecane). Compound 1 has been chemically (elemental and thermal analyses), spectroscopically (infrared spectroscopy), and structurally (single crystal and powder X-ray diffraction) characterized. The crystal packing of 1 shows a covalent framework structure formed by [Mo8O26](n)(4n-) chains running along the 100 direction which are linked to each other through the coordination spheres of {Cu(cyclam)}(2+) complexes leading to a three-dimensional open network. This structural assembly generates voids that can be described as a succession of cavities communicated through narrow bottlenecks with approximate cross section of 4 x 7 angstrom(2) where the hydration water molecules are hosted. The robust open structure of 1 remains virtually unaltered upon thermal evacuation of guest solvent molecules at 130 degrees C, resulting in the anhydrous phase [Cu(cyclam)](2)[Mo8O26] (1a) with potentially accessible micropores as demonstrated by single-crystal X-ray diffraction measurements. Electron paramagnetic resonance spectroscopy analysis of 1 has also been assessed. This work was funded by UPV/EHU (Grant PPG17/37 and GIU17/050) and University of Tunis El Manar (predoctoral fellowship to N.D., including a three-month stay at Universidad del Pais Vasco, UPV/EHU). B.A. thanks UPV/EHU for a postdoctoral fellowship within the program "Convocatorias de Ayudas para la Especializacion de Personal Investigador". Technical and human support provided by SGIker (UPV/EHU) is gratefully acknowledged.

TheE porous hybrid metavanadate [{Cu(cyclam)}(VO3)2]·5H2O (1) (cyclam = 1,4,8,11-tetraazacyclotetradecane) undergoes thermally-triggered sequential single-crystal-to-single-crystal (SCSC) transformations upon gradual dehydration to produce three new porous crystalline phases, namely [{Cu(cyclam)}(VO3)2]·3H2O (2), [{Cu(cyclam)}(VO3)2]·1.3H2O (3) and [{Cu(cyclam)}(VO3)2] (4). Compound 1 has a three-dimensional structure formed by metavanadate chains linked by {Cu(cyclam)} moieties in a hybrid open framework with two different types of hexagonal channels where water molecules of hydration are hosted. The SCSC transformations cause a rearrangement o/f the metavanadate chains in such a way that they contract when going from 1 to 2 and stretch back when 2 transforms into 3. The size of the channels is also modified as the hybrid dehydrates. The transition from 2 to 3 leads to the cleavage of a Cu–O bond and consequent coordination of a {Cu(cyclam)} moiety to a different {VO4} unit, which drastically decreases the size of the channel in the process. In contrast, total dehydration of 3 enlarges the channel in the anhydrous phase 4 due to the migration of another Cu atom. The reversibility of such transformations has been monitored by a combination of thermogravimetric and powder X-ray diffraction analyses. While 1 and 3 are stable in open-air conditions, 2 transforms back into 1 upon exposure to air for three weeks. The anhydrous phase 4 rapidly rehydrates into 3 when in contact with ambient moisture. Furthermore, 3 can also be transformed into the parent hybrid 1 when soaked in water for seven days. Therefore, all crystal transitions described herein are fully reversible by applying the appropriate conditions.