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The main challenge for the preparation of protein single-chain nanoparticles (SCNPs) is the natural complexity of these macromolecules. Herein, we report the suitable conditions to produce “neat” bovine serum albumin (BSA) single-chain nanoparticles (SCNPs) from partially denatured BSA, which involves denaturation in urea and intramolecular cross-linking below the overlap concentration. We use two disuccinimide ester linkers containing three and six methylene spacer groups: disuccinimidyl glutarate (DSG) and disuccinimidyl suberate (DSS), respectively. Remarkably, the degree of internal cross-linking can be followed simply and efficiently via 1H NMR spectroscopy. The associated structural changes─as probed by small-angle neutron scattering (SANS)─reveal that the denatured protein has a random-like coil conformation, which progressively shrinks with the addition of DSG or DSS, thus allowing for size control of the BSA-SCNPs with radii of gyration down to 5.4 nm. The longer cross-linker exhibits slightly more efficiency in chain compaction with a somewhat stronger size reduction but similar reactivity at a given cross-linker concentration. This reliable method is applicable to a wide range of compact proteins since most proteins have appropriate reactive amino acids and denature in urea. Critically, this work paves the way to the synthesis of “neat”, biodegradable protein SCNPs for a range of applications including nanomedicine., The authors acknowledge the financial support received from the IKUR Strategy under the collaboration agreement between the Ikerbasque Foundation and the Materials Physics Center on behalf of the Department of Education of the Basque Government. Financial support by MCIN/AEI/10.13039/ 501100011033 and “ERDF−A way of making Europe” (grant PID2021-123438NB-I00), Eusko Jaurlaritza−Basque Government (grantIT-1566-22) and the Gipuzkoako Foru Aldundia, Programa Red Gipuzkoana de Ciencia, Tecnología e Innovación (2021-CIEN-000010-01) is gratefully acknowledged. A.I. thanks MICINN for a Personal Técnico de Apoyo contract (PTA2017-14359-I).

We present results concerning the fabrication of a new magnetorheological fluid with FeCo magnetic nanoparticles (NPs) as magnetic fillers. These NPs have been fabricated by using the chemical reduction technique and show a pure crystalline phase with size ranging among 30–50 nm and high magnetization, 212 ± 2 A m2 kg−1. They agglomerate due to the strong magnetic dipolar interaction among them. These FeCo nanoparticles were used to synthesize a magnetorheological fluid by using oleic acid as surfactant, mineral oil as carrier liquid and Aerosil 300 as additive to control the viscosity of the fluid. The synthesized fluid showed a strong magnetorheological response with increasing shear stress values as the magnetic field intensity increases. Thus, we have measured a superior performance up to 616.7 kA m−1, with a yield stress value of 2729 Pa, and good reversibility after demagnetization process. This value competes with the best ones reported in the most recent literature. We have compared the obtained results with our previous reported ones by using high magnetization Fe NPs fabricated by the electrical explosion of wire method (Fe-EEW)., J. Berasategi, A. Gómez and M. M. Bou-Ali would like to thank the financial support provided by the Basque Government under research project PI-2017-1-0055 and MMMfavIN (KK-2020/00099, Elkartek program). V. Vadillo, J. Gutiérrez, J.M. Barandiarán, M. Insausti and I. Gil de Muro would like to thank the financial support provided also by the Basque Government under PI-2017-1-0043, the MMMfavIN (KK-2020/00099, Elkartek program) and Research Groups (IT1245-19 and IT1226-19) research projects. A. A. and A. I. gratefully acknowledge the financial support of the Basque Government (Research Groups IT-1175-19) and the Ministerio de Economía y Competitividad (PGC2018-094548-B-I00, MCIU/AEI/FEDER, UE).

Organic solar cells incorporating non-fullerene acceptors (NFAs) have reached remarkable power conversion efficiencies of over 18%. Unlike fullerene derivatives, NFAs tend to crystallize from solutions, resulting in bulk heterojunctions that include a crystalline acceptor phase. This must be considered in any morphology-function models. Here, it is confirmed that high-performing solution-processed indacenodithienothiophene-based NFAs, i.e., ITIC and its derivatives ITIC-M, ITIC-2F, and ITIC-Th, exhibit at least two crystalline forms. In addition to highly ordered polymorphs that form at high temperatures, NFAs arrange into a low-temperature metastable phase that is readily promoted via solution processing and leads to the highest device efficiencies. Intriguingly, the low-temperature forms seem to feature a continuous network that favors charge transport despite of a poorly order along the π–π stacking direction. As the optical absorption of the structurally more disordered low-temperature phase can surpass that of the more ordered polymorphs while displaying comparable—or even higher—charge transport properties, it is argued that such a packing structure is an important feature for reaching highest device efficiencies, thus, providing guidelines for future materials design and crystal engineering activities., This work is supported by the Ministerio de Ciencia e Innovacion/FEDER (under Ref. PGC2018-094620-A-I00 and PGC2018-095411-B-I00, CEX2019-000917-S and PGC2018- 095411-B-100) and the Basque Country Government (Ref. PIBA19-0051). S.M. is grateful to POLYMAT for the doctoral scholarship. The authors thank A. Arbe, A. Alonso-Mateo, L. Hueso for their support and access to characterization tools. The authors also thank the technical and human support provided by SGIker of UPV/EHU and European funding (ERDF and ESF). GIWAXS experiments were performed at BL11 NCD-SWEET beamline at ALBA Synchrotron (Spain) with the collaboration of ALBA staff. J.M and E.F.-G. acknowledge support through the European Union's Horizon 2020 research and innovation program, H2020-FETOPEN 01- 2018-2020 (FET-Open Challenging Current Thinking), ‘LION-HEARTED', grant agreement n. 828984. J.M and N.S. would like to thank the financial support provided by the IONBIKE RISE project, which has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 823989. N.S. and A.K. and A.B. furthermore are grateful to the U.S. National Science Foundation (NSF) for support via project # 1905901 within NSF’s Division of Materials Research. A. S. and M. C. acknowledge financial support by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program “HEROIC,” grant agreement 638059. This work was partially carried out at Polifab, the micro- and nanotechnology center of the Politecnico di Milano. .C.M. thanks the Knut and Alice Wallenberg Foundation for funding through the project “Mastering Morphology for Solution-borne Electronics”.

We have investigated how variations in primary structure (distribution of monomeric units, chain length) and degree of branching affect the crystallization behavior of polysulfides. In particular, we have used copolymers of crystallizable (ethylene sulfide, ES) and non-crystallizable (propylene sulfide, PS) units, prepared via anionic ring-opening mechanism. PS units interrupt the crystallization of ES sequences; therefore, strong differences in thermal properties are expected between copolymers with a gradient (single addition of ES/PS mixtures) or a semirandom structure (sequential additions, which yield a more constant composition along the chain). Additionally, we prepared different chain topologies: linear, 4- and 8-armed stars, and combs with 10, 15, and 20 arms, in a comparison where each arm had a gradient primary structure and degree of polymerization (DP) of 10, 20, and 30. The influence of these variables (topology, number of arms, and DP) on the thermal properties was studied by polarized light optical microscopy (PLOM), standard and advanced DSC techniques (i.e., self-nucleation and successive self-nucleation and annealing (SSA)), and small and wide angle X-ray scattering (WAXS and SAXS). First, we have confirmed the much higher order obtained in gradient polymers, in comparison to the semirandom ones. Second, we have seen that the type of crowding of polymer chains affected the level of order achievable. In star polymers, an increasing number of arms increased topological restrictions, which in turn decreased crystallization and melting temperatures, crystallinity, and lamellar thickness. For combs, which are characterized by a more parallel than convergent crowding of the chains, the increase in arms number did not produce a significant decrease in crystalline order; on the contrary, the higher density of chains caused moderate increases in crystallization and melting temperatures, crystallinity, and lamellar thickness., The POLYMAT/UPV/EHU team would like to acknowledge funding from the following projects: UPV/EHU Infrastructure: INF 14/38; Mineco/FEDER: SINF 130I001726XV1/Ref: UNPV13-4E-1726; and Mineco MAT2017-83014-C2-1-P*. R.A.P.-C. gratefully acknowledges the award of a Ph.D. fellowship by POLYMAT Basque Center for Macromolecular Design and Engineering. A.A. and A.I. acknowledge financial support from IT-654-13 and MAT2015-63704-P (MINECO/ FEDER, UE). We gratefully acknowledge the ALBA synchrotron facility (Proposal Number: 2018022683) for the funding and help to perform experiments at BL11-NCDSWEET beamline with the collaboration of ALBA staff.

Herein, we elucidate the impact of tubular confinement on the structure and relaxation behavior of poly(vinylidene difluoride) (PVDF) and how these affect the para-/ferroelectric behavior of this polymer. We use PVDF nanotubes that were solidified in anodic aluminum oxide (AAO) templates. Dielectric spectroscopy measurements evidence a bimodal relaxation process for PVDF nanotubes: besides the bulk-like α-relaxation, we detect a notably slower relaxation that is associated with the PVDF regions of restricted dynamics at the interface with the AAO pore. Strikingly, both the bulk-like and the interfacial relaxation tend to become temperature independent as the temperature increases, a behavior that has been observed before in inorganic relaxor ferroelectrics. In line with this, we observe that the real part of the dielectric permittivity of the PVDF nanotubes exhibits a broad maximum when plotted against the temperature, which is, again, a typical feature of relaxor ferroelectrics. As such, we propose that, in nanotubular PVDF, ferroelectric-like nanodomains are formed in the amorphous phase regions adjacent to the AAO interface. These ferroelectric nanodomains may result from an anisotropic chain conformation and a preferred orientation of local dipoles due to selective H-bond formation between the PVDF macromolecues and the AAO walls. Such relaxor-ferroelectric-like behavior has not been observed for nonirradiated PVDF homopolymer; our findings thus may enable in the future alternative applications for this bulk commodity plastic, e.g., for the production of electrocaloric devices for solid-state refrigeration which benefit from a relaxor-ferroelectric-like response., J.M. acknowledges support from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant, agreement No. 654682. A.A. and A.I. acknowledge financial support from the Spanish Ministry Ministerio de Economia y Competitividad (MINECO) (code: MAT2015-63704-P (MINECO/FEDER, UE)) and the Eusko Jaurlaritza (Basque Government) (code: IT-654-13). A.C. would like to acknowledge the financial support of the EPSRC (EP/M014142/1). A.N., T.A.E., and C.M. acknowledge financial support from MINECO (codes: MAT2014-59187-R, MAT2015-66443-C02-1-R, and MAT2014-53437-C2-1P, respectively). N.S. is in addition grateful for support from a European Research Council ERC Starting Independent Research Fellowship under the grant agreement No. 279587.

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).

Cyclic polymers behave different than linear polymers due to the lack of end groups and smaller coil dimensions. Herein, we demonstrate that cyclic polyethylene glycol (PEG) can be used as an alternative of classical linear PEG ligands for gold nanoparticle (AuNP) stabilization. We observed that the brush height of cyclic PEG on AuNPs of diameter 4.4 and 13.2 nm increases identically as that of linear brushes with (Nσ1/2)0.7 (N, number of monomers in a chain and σ, grafting density) and that cyclic brushes are more stretched than their linear analogues when compared to their unperturbed dimensions. Such structural effect and the reduced footprint diameter in cyclic brushes with the entire chain in a concentrated polymer brush regime explains the distinct response of NPs to ionic strength and temperature, respectively, compared to linear analogues. These experiments are an important step in understanding the effect of polymer brush topology on colloidal properties., We gratefully acknowledge support from the Spanish Ministry “Ministerio de Ciencia, Innovación y Universidades” (PGC2018-094548-B-I00, MICIU/AEI/FEDER, UE), Basque Government (IT-1175-19 and PIBA 2018-34) and Diputación Foral de Guipúzcoa (RED 2018).

By means of intramolecular folding/collapse of individual polymer chains (precursors), ultra-small soft nano-objects called single-chain nano-particles (SCNPs) can be synthesized. Here we present a combination of scattering techniques [small angle X-Ray and neutron scattering (SAXS and SANS), neutron spin echo (NSE) and dynamic light scattering (DLS)] to investigate the structure and dynamics of SCNPs in solution and their linear precursors as reference. Coarse-grained molecular dynamics (MD) simulations have also been carried out to complement this study. The application of SANS and SAXS has proved the compaction of the macromolecules upon creation of internal cross-links. However, the SCNPs obtained by different routes exhibit a far from globular topology in good solvent. Regarding the dynamics, we report on the first experimental investigation of the dynamic structure factor of SCNPs in solution. It reveals a clear impact of internal cross-links through (i) a reduction of the translational diffusion coefficient and (ii) an important slowing down of the internal modes. The data have been analyzed in terms of theoretical approximations based on the Zimm model. Both, structurally and dynamically, SCNPs show striking resemblances with intrinsically disordered proteins: similar scaling properties reflecting sparse morphologies and an extremely high internal friction.

The synthesis of symmetric cyclo poly(ε-caprolactone)–block–poly(l(d)-lactide) (c(PCL–b–PL(D)LA)) by combining ring-opening polymerization of ε-caprolactone and lactides and subsequent click chemistry reaction of the linear precursors containing antagonist functionalities is presented. The two blocks can sequentially crystallize and self-assemble into double crystalline spherulitic superstructures. The cyclic chain topology significantly affects both the nucleation and the crystallization of each constituent, as gathered from a comparison of the behavior of linear precursors and cyclic block copolymers. The stereochemistry of the PLA block does not have a significant effect on the nonisothermal crystallization of both linear and cyclo PCL-b-PDLA and PCL-b-PLLA copolymers., The authors acknowledge funding by the following projects: MAT2014-53437-C2-P and MAT2015-63704-P (Spanish MINECO); IT-654-13 (Basque Government), the Science Policy Office of the Belgian Federal Government (PAI 7/5), and the Belgian FRFC-FNRS (No. 2.4508.12). O.C. is Research Associate of the F.R.S.-FNRS. N.Z. acknowledges the fellowship from the UPV/EHU.

The structure and thermal properties of linear low-density polyethylene (LLDPE)/medium soft paraffin wax blends, prepared by melt mixing, were investigated by differential scanning calorimetry (DSC) and small- and wide-angle X-ray scattering (SAXS and WAXS). The blends form a single phase in the melt as determined by SAXS. Upon cooling from the melt, two crystalline phases develop for blends with more than 10 wt % wax characterized by widely different melting points. The wax acts as an effective plasticizer for LLDPE, decreasing both its crystallization and melting temperature. The higher melting point crystalline phase is formed by less branched LLDPE fractions. On the other hand, the lower melting point crystalline phase is a wax-rich phase constituted by cocrystals of extended chain wax and short linear sequences of highly branched LLDPE chains. The presence of cocrystals was evidenced by standard DSC results, successive self-nucleation and annealing (SSA) thermal fractionation and by the detection of a new SAXS signal attributed to the lamellar long period of the cocrystals., The POLYMAT/UPV/EHU team would like to acknowledge funding from the following projects: “UPV/EHU Infrastructure: INF 14/38”; “Mineco/FEDER: SINF 130I001726XV1/Ref: UNPV13–4E–1726”; and “Mineco MAT2014-53437-C2-P”. Financial support from the Projects MAT2012-31088 (Spanish-MINECO and EU) and IT-654-13 (Basque Government) is acknowledged by CFM team. The National Research Foundation South Africa is also acknowledged for financial support of the project. R.A.P.-C gratefully acknowledges the award of a PhD fellowship by POLYMAT Basque Center for Macromolecular Design and Engineering (BERC BOVP N°134).

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.

et al., The sequential crystallization of poly(ethylene oxide)-b-poly(ε-caprolactone)-b-poly(l-lactide) (PEO-b-PCL-b-PLLA) triblock terpolymers, in which the three blocks are able to crystallize separately and sequentially from the melt, is presented. Two terpolymers with identical PEO and PCL block lengths and two different PLLA block lengths were prepared, thus the effect of increasing PLLA content on the crystallization behavior and morphology was evaluated. Wide angle X-ray scattering (WAXS) experiments performed on cooling from the melt confirmed the triple crystalline nature of these terpolymers and revealed that they crystallize in sequence: the PLLA block crystallizes first, then the PCL block, and finally the PEO block. Differential scanning calorimetry (DSC) analysis further demonstrated that the three blocks can crystallize from the melt when a low cooling rate is employed. The crystallization process takes place from a homogenous melt as indicated by small angle X-ray scattering (SAXS) experiments. The crystallization and melting enthalpies and temperatures of both PEO and PCL blocks decrease as PLLA content in the terpolymer increases. Polarized light optical microscopy (PLOM) demonstrated that the PLLA block templates the morphology of the terpolymer, as it forms spherulites upon cooling from the melt. The subsequent crystallization of PCL and PEO blocks occurs inside the interlamellar regions of the previously formed PLLA block spherulites. In this way, unique triple crystalline mixed spherulitic superstructures have been observed for the first time. As the PLLA content in the terpolymer is reduced the superstructural morphology changes from spherulites to a more axialitic-like structure., We gratefully acknowledge funds received through the following projects: “MAT2014-53437-C2-P, MAT2012-31088 (Spanish-MINECO and EU)”, UPV/EHU (UFI 11/56) and GIC IT-586-13, IT-654-13 (Basque Government).

Ring closure click chemistry methods have been used to produce cyclic c-PLLA and c-PDLA of a number-average molecular weight close to 10 kg/mol. The effects of stereochemistry of the polymer chains and their topology on their structure, nucleation, and crystallization were studied in detail employing wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), polarized light optical microscopy (PLOM), and standard and advanced differential scanning calorimetry (DSC). The crystal structures of linear and cyclic PLAs are identical to each other, and no differences in superstructural morphology could be detected. Cyclic PLA chains are able to nucleate much faster and to produce a higher number of nuclei in comparison to linear analogues, either upon cooling from the melt or upon heating from the glassy state. In the samples prepared in this work, a small fraction of linear or higher molecular weight cycles were detected (according to SEC analyses). The presence of such “impurities” retards spherulitic growth rates of c-PLAs, making them nearly the same as those of l-PLAs. On the other hand, the overall crystallization rate determined by DSC was much larger for c-PLAs, as a consequence of the enhanced nucleation that occurs in cyclic chains. The equilibrium melting temperatures of cyclic chains were determined and found to be 5 °C higher in comparison with values for l-PLAs. This result is a consequence of the lower entropy of cyclic chains in the melt. Self-nucleation studies demonstrated that c-PLAs have a shorter crystalline memory than linear analogues, as a result of their lower entanglement density. Successive self-nucleation and annealing (SSA) experiments reveal the remarkable ability of cyclic molecules to thicken, even to the point of crystallization with extended collapsed ring conformations. In general terms, stereochemistry had less influence on the results obtained in comparison with the dominating effect of chain topology., The UPV/EHU team acknowledges funding from the following projects: “UPV/EHU Infrastructure: INF 14/38”; “Mineco/FEDER: SINF 130I001726XV1/Ref: UNPV13-4E-1726” and “Mineco MAT2014-53437−C2-P”, ’Ministerio de Economia y Competitividad (MINECO), code: MAT2015-63704-P (MINECO/FEDER, UE) and by the Eusko Jaurlaritza (Basque Government), code: IT-654-13. O.C. acknowledges financial support from the European Commission and Region Wallonne FEDER program (Materia Nova) and OPTI2 MAT program of excellence, by the Interuniversity Attraction Pole Program (P7/ 05) initiated by the Belgian Science Policy office and by the FNRS-FRFC. O.C. is a Research Associate of the F.R.S.-FNRS. The Organic Synthesis and Mass Spectrometry Laboratory thanks F.R.S.-FNRS for the financial support for the acquisition of the Waters QToF Premier and Synapt-G2Si mass spectrometers and for continuing support. Finally, all authors acknowledge Research and Innovation Staff Exchange (RISE) H2020-MSCA-RISE-2017-778092, project BIODEST, for promoting cooperation between the Mons team and the UPV/EHU team.

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.

In this paper, the preparation of PBS-ran-PCL copolyesters by enzymatic ring opening polymerization is presented for the first time. The copolyesters were produced in a wide composition range and free of metallic contaminants, so they may be regarded as potential biomaterials. The copolymers have been characterized by proton and carbon nuclear magnetic resonance (H and C NMR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), polarized light optical microscopy (PLOM) and wide angle X-ray scattering (WAXS). The PBS-ran-PCL copolyesters were able to crystallize in the entire composition range and displayed a pseudo-eutectic region. Most copolymers away from the pseudo-eutectic region exhibited a single crystalline phase (PBS-rich or PCL-rich crystalline phase), while within the pseudo-eutectic region the copolymers were double crystalline. Observations by PLOM, during isothermal crystallization showed that both nucleation density and spherulitic growth rate of the copolyesters are determined by the component that constitutes the majority phase. WAXS studies revealed that d spacings of selected crystallographic planes depend on composition. Therefore, both DSC and WAXS results suggest that the copolymers are probably isodimorphic, as the PBS-rich crystalline phase may contain small inclusions of PCL co-units, while the PCL-rich crystalline domains may also contain a minor quantity of PBS co-units inside., This work received financial support from Ministerio de Economia y Competitividad (MINECO) of Spain with Grant MAT2012-38044-C03-03 and MAT2016-77345-C3-1-P and from Agència de Gestió d'Ajuts Universitaris i de Recerca (AGAUR) (Catalonia, Spain) with grant 2009SGR1469. The POLYMAT/UPV/EHU team would like to acknowledge funding from the following projects: “UPV/EHU Infrastructure: INF 14/38”; “MINECO/FEDER: SINF 130I001726XV1/Ref.: UNPV13-4E-1726” and “MINECO MAT2014-53437-C2-P”. A.A. and A.I. acknowledge financial support from the Spanish Ministry (MINECO), Ref: MAT2015-63704-P (MINECO/FEDER, UE) and by the Eusko Jaurlaritza (Basque Government), Ref: IT-654-13. C.C. wishes to acknowledge CNPq (National Research Council) Brazil for the financial support. M.S. gratefully acknowledges the award of a PhD fellowship by POLYMAT Basque Center for Macromolecular Design and Engineering. JC M-H thanks to Consejo Nacional de Ciencia y Tecnología (CONACYT) (Mexico) for the awarded PhD grant.

Hydrothermal reaction of the Keggin-type [α-GeW11O39]8– anion with copper(II) complexes of the tetradentate N-donor ligands N,N′-dimethyl-N,N′-bis-(pyridine-2-ylmethyl)-1,2-diaminoethane (bpmen) or N,N′-dimethyl-N,N′-bis-(pyridine-2-ylmethyl)-1,3-diaminopropane (bpmpn) results in three new hybrid compounds [Cu(bpmen)(H2O)][GeW12O40{Cu(bpmen)}]·3.5H2O (1), [GeW12O40{Cu(bpmpn)(H2O)}2]·3H2O (2), and [Cu(bpmpn)(H2O)][GeW12O40{Cu(bpmpn)}]·8H2O (3). All compounds have been characterized by elemental analyses and infrared spectroscopy, and their structures have been established by single-crystal X-ray diffraction. Both 1 and 3 contain monodecorated polyanions and additional complex cations, but their layered structures show noticeable differences. For 1, the polyanions are arranged in rows whose stacking generates intralamellar cavities where complex cations and lattice water molecules are hosted, whereas double-layers of hybrid anions pillared by the cations occupying the interlamellar space are observed for 3....

Two-scale multicomposite (meth)acrylate latexes containing nano-sized liquid crystalline domains were synthesized in a two step (mini)emulsion polymerization using a series of methacrylate side chain liquid crystalline monomers and mixture of short chain (meth)acrylates. Detailed characterization of the composite films obtained from the latexes using a combination of DSC, TEM, polarized light microscopy, SAXS and WAXS showed that the liquid crystalline polymers had a layered structure with a 2D-organization that was not perturbed by the amorphous polymer, which on the other hand was partially intercalated between layers. This leads to a two-scale composite with enhanced mechanical properties and higher number of degrees of freedom to fine tune the mechanical properties. The effect of liquid crystalline domains on barrier properties as well as on the water resistance of the films formed from these latexes was also investigated. The persistence of crystalline order of the liquid crystalline polymer phase up to very high temperatures leads to materials with a very broad temperature range of application, improving significantly the performance with respect to other routes based on incorporation of crystalline domains via copolymerization with comb-like monomers., Financial support of the Industrial Liaison Program on Polymerization in Dispersed Media (Akzo Nobel, Allnex, Arkema, BASF, Foresa, Nuplex Resin, Solvay, Stahl, Synthomer, Vinavil, Wacker) is gratefully acknowledged. A. A. and A. I. acknowledge financial support by the Spanish Ministry 'Ministerio de Economia y Competitividad', code: MAT2015-63704-P (MINECO/FEDER, UE) and by the Eusko Jaurlaritza, code: IT-654-13. J. R. L. acknowledges financial support from the Spanish Ministry ’Ministerio de Economia y Competitividad’, code: CTQ2014-59016-R (MINECO).

The synthesis of a series of methacrylate side-chain liquid crystal polymers (SCLCPs) bearing biphenyl mesogen with different spacer lengths and a fixed tail, poly[ethyl 4′-((n-(methacryloyloxy)alkyl)oxy)-[1,1′-biphenyl]-4-carboxylate]s (n-PMLCM, n = 3, 4, 5, 6), in aqueous media by free radical miniemulsion polymerization is described. This method offers the advantage of producing high molar masses (>105 Da) and full monomer conversion, not possible to achieve with conventional routes (solution polymerization). The resulting n-PMLCMs proved to have high thermal stability. The phase behaviors of the polymers were investigated by a combination of techniques including differential scanning calorimetry, polarized light microscopy, and small and wide angle X-ray scattering. The results show mesomorphic liquid crystalline behavior with a monolayer structure where the side-groups on both sides of the backbone would be interpenetrated. The liquid crystal phase transition of n-PMLCM follows the sequence smectic E (smectic E or smectic C for 4-PMLCM) ↔ smectic A ↔ isotropic liquid. The transition temperatures and the associated entropy changes exhibit a distinct odd–even effect as the length and parity of the spacer are varied, with the odd members exhibiting the higher values. The high molar masses achievable using miniemulsion polymerization translate into a more perfect and stable ordering, characterized by larger lamellar domains and higher transition temperatures, than in low molar mass SCLCPs. Compared to polymeric liquid crystals with similar mesogens but shorter tails, we found that longer tails facilitate the ordering of the mesogens and allow more efficient packing around the backbones, imparting a high stability to the smectic phases formed., The financial support from the Industrial Liaison Program on Polymerization in Dispersed Media (Akzo Nobel, Allnex, Arkema, BASF, Foresa, Nuplex Resin, Solvay, Stahl, Synthomer, Vinavil, Wacker) is gratefully acknowledged. A. A. and A. I. acknowledge financial support from the projects MAT2015-63704-P (Spanish-MINECO) and IT-654-13 (Basque Government). J. R. L. acknowledges financial support from the project CTQ2014-59016-R (MINECO).

Poly(butylene succinate-ran-butylene azelate) random copolyesters were thermally fractionated by successive self-nucleation and annealing (SSA). The samples before and after SSA were analyzed by differential scanning calorimetry (DSC) and X-ray diffraction (WAXS and SAXS). WAXS results indicate that a small degree of comonomer inclusion is present in the crystalline phases that are formed in the copolymers depending on composition: a PBS-like unit cell or/and a PBAz-like unit cell, thus confirming the isodimorphic behavior of the samples. SSA on the other hand demonstrated that the degree of comonomer exclusion during crystallization is far larger than comonomer inclusion, as judged by the increase in fractionation degree with compositions leading to the pseudo-eutectic point. Furthermore, WAXS, SAXS, and SSA results show that the isodimorphic behavior is not highly dependent on kinetic factors, as the degree of comonomer inclusion or exclusion in the samples was not significantly altered by SSA thermal fractionation, a thermal treatment that promotes annealing and molecular segregation of defects to the amorphous regions of the material., I. A. acknowledges the fellowship from the University of the Basque Country UPV/EHU. Financial support is acknowledged from UPV/EHU (UFI11/56), “UPV/EHU Infrastructure: INF 14/38”; “Mineco/FEDER: SINF 130I001726XV1/Ref: UNPV13–4E–1726” and “Mineco MAT2014-53437-C2-P”. G.M.L acknowledges the support from the Youth Innovation Promotion Association of CAS (2015026). A.A. and A.I. acknowledge financial support from the Projects MAT2012-31088 and MAT2015-63704-P (Spanish-MINECO and EU) and IT-654-13 (Basque Government).

Reaction of in situ generated copper(II)-monosubstituted Keggin polyoxometalates and copper(II)-phenanthroline-oxalato complexes in ammonium or rubidium acetate buffers led to the formation of the hybrid inorganic-metalorganic compounds E4[Cu(phen)(H2O)4]2[Cu4(phen)4(H2O)4(ox)3]0.6[Cu2(phen)2(H2O)4(ox)]0.4[Cu(phen)(ox)]0.8[{SiW11O39Cu(H2O)}2{Cu2(phen)2(ox)}].20H2O [E: Rb (1), NH4 (2)]. The two compounds have been characterized by means of elemental analysis, thermogravimetry, infrared and electron paramagnetic resonance spectroscopies, and magnetic susceptibility measurements, and their structures have been established by single-crystal X-ray diffraction. Both compounds are isostructural, and they contain a discrete bimolecular hybrid polyanion and several types of copper-phenanthroline complexes of variable nuclearity. The main structural features of these compounds are the presence of the new hybrid POM [{SiW11O39Cu(H2O)}2{Cu2(phen)2(mu-ox)}]10-, where the dinuclear copper-oxalato complex is sandwiched by two copper-monosubstituted POMs, and the coexistence of five different copper-phenanthroline species with nuclearities ranging from one to four.

Three new hybrid inorganic-metalorganic compounds containing Keggin-type polyoxometalates, neutral copper(II)-picolinate complexes and guanidinium cations have been synthesized in bench conditions and characterized by elemental analysis, infrared spectroscopy and single-crystal X-ray diffraction: the isostructural [C(NH2)(3)](4)[{XW12O40}{Cu-2(pic)(4)}] . [Cu-2(pic)(4)(H2O)](2) .6H(2)O [X = Si (1), Ge (3)] and [C(NH2)(3)]8[{SiW12O40}(2){Cu(pic)(2)}3{Cu-2(pic)4(H2O)}(2)] .8H(2)O (2). The three compounds show a pronounced two-dimensional character owing to the structure-directing role of guanidinium. In 1 and 3, layers of [{XW12O40}{Cu-2(pic)(4)}] n(4n-) hybrid POM chains and layers of [Cu-2(pic)(4)(H2O)] complexes and [C(NH2)(3)](+) cations pack alternately along the z axis. The hydrogen-bonding network established by guanidinium leads to a trihexagonal tiling arrangement of all copper(II)-picolinate species. In contrast, layers of [C(NH2)(3)](+)-linked [{SiW12O40}(2){Cu(pic)(2)}(3)] n(8n-) double chains where each Keggin cluster displays a {Cu-2(pic)(4)(H2O)} moiety pointing at the intralamellar space are observed in 2. The thermal stability of 1-3 has been studied by thermogravimetric analyses and variable temperature powder X-ray diffraction. Compounds 1 and 3 undergo single-crystal to single-crystal transformations promoted by reversible dehydration processes and the structures of the corresponding anhydrous phases 1a and 3a have been established. Despite the fact that the [Cu-2(pic)(4)(H2O)] dimeric complexes split into [Cu( pic)(2)] monomers upon dehydration, the packing remains almost unaltered thanks to the preservation of the hydrogen-bonding network established by guanidinium and its associated Kagome-type lattice. Splitting of the dimeric complexes has been correlated with the electron paramagnetic resonance spectra. This work was funded by Eusko Jaurlaritza/Gobierno Vasco (grant IT477- 10 and predoctoral fellowship to A. P.), Ministerio de Economia y Competitividad (grant MAT2013-48366-C2-2P) and Universidad del Pais Vasco UPV/EHU (grant UFI11/53). Technical and human support provided by SGIker (UPV/EHU) is gratefully acknowledged.

In the title compound, [Cu(C5H3N2O2)2(H2O)2], the CuIIion, located on an inversion center, exhibits an octahedral coordination geometry. The equatorial plane is defined by twotrans-relatedN,O-bidentate pyridazine-3-carboxylate ligands and the axial positions are occupied by two water molecules. In the crystal, molecules are connected by O—H...O hydrogen bonds between the water molecules and the noncoordinating carboxylate O atoms, forming layers parallel to thebcplane. The layers are stacked along theaaxis by further O—H...O hydrogen bonds between the water molecules and the coordinating carboxylate O atoms. Weak C—H...O hydrogen bonds are also observed between the pyridazine rings and the water molecules and between the pyridazine rings and the non-coordinating carboxylate O atoms.

Two new hybrid compounds constructed from Keggin type polyoxometalates and copper(II) complexes of tetradentate ligands containing amine and pyridyl groups, namely [Cu(bpmen)(H2O)][SiW12O40{Cu(bpmen)}] (1) and [SiW12O40{Cu(bpmpn)(H2O)}2]·3H2O (2) (bpmen, N,N'-dimethyl-N,N'-bis-(pyridin-2-ylmethyl)-1,2-diaminoethane; bpmpn, N,N'-dimethyl-N,N'-bis(pyridin-2-ylmethyl)-1,3-diaminopropane), have been synthesized under hydrothermal conditions and characterized by elemental analyses and infrared and Raman spectroscopy. Thermal stability of 1 and 2 has been studied by means of thermogravimetric analyses and variable temperature powder X-ray diffraction. Both compounds undergo single-crystal to single-crystal transformations promoted by reversible dehydration processes that have been followed by single-crystal X-ray diffraction. Structures of 1 and 2, and also of their corresponding anhydrous phases 1a and 2a, have been established. The layered structure of 1 shows rows of monodecorated polyanions with complex cations occupying intralamellar spaces, whereas trans-didecorated species in 2 lead to stacked honeycomb-like metal-organic layers forming channels where Keggin clusters are accommodated. Structural differences relate to changes in the complex geometry and ligand conformation when going from bpmen to bpmpn. Dehydration of 1 promotes coordination of the complex countercation and consequent formation of a cis-didecorated species in 1a, whereas changes in the structure of 2a are more subtle. Structural variations upon dehydration are reflected in the electron paramagnetic resonance spectra.