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The interplay of spin-orbit coupling with other relevant parameters gives rise to the rich phase competition in complex ruthenates featuring octahedrally coordinated Ru 4+ . While locally, spin-orbit coupling stabilizes a nonmagnetic J eff = 0 state, intersite interactions resolve one of two distinct phases at low temperatures: an excitonic magnet stabilized by the magnetic exchange of upper-lying J eff = 1 states or Ru 2 molecular orbital dimers driven by direct orbital overlap. Pyrochlore ruthenates A 2 Ru 2 O 7 ( A = rare earth, Y) are candidate excitonic magnets with geometrical frustration. We synthesized In 2 Ru 2 O 7 with covalent In─O bonds. This pyrochlore ruthenate hosts a local J eff = 0 state at high temperatures; however, at low temperatures, it forms a unique nonmagnetic ground state with nearly linear Ru─O─Ru molecules, in stark contrast to other A 2 Ru 2 O 7 compounds. The disproportionation of covalent In─O bonds drives Ru 2 O molecule formation, quenching not only the local spin-orbit singlet but also geometrical frustration.

Controlled synthesis of phase-pure metal-organic frameworks (MOFs) is essential for their application in technological areas such as catalysis or gas sorption. Yet, knowledge of their phase formation and growth remain rather limited, particularly with respect to species such as water whose vital role in MOF synthesis is often neglected. As a consequence, synthetic protocols often lack reproducibility when multiple MOFs can form from the same metal source and linker, and phase mixtures are obtained with little or no control over their composition. In this work, the role of water in the formation of the Zr-porphyrin MOF disordered PCN-224 (dPCN-224) is investigated. Through X-ray total scattering and scanning electron microscopy, it is observed that dPCN-224 forms via a metal-organic intermediate that consists of Zr 6 O 4 (OH) 4  clusters linked by tetrakis(4-carboxy-phenyl)porphyrin molecules. Importantly, water is not only essential to the formation of Zr 6 O 4 (OH) 4  clusters, but it also plays a primary role in dictating the formation kinetics of dPCN-224. This multidisciplinary approach to studying the speciation of dPCN-224 provides a blueprint for how Zr-MOF synthesis protocols can be assessed and their reproducibility increased, and highlights the importance of understanding the role of water as a decisive component in Zr-MOF formation., (© 2023 The Authors. Advanced Materials published by Wiley‐VCH GmbH.)

Plants and animals that thrive in arid regions utilize the diurnal changes in environmental temperature and humidity to optimize their water budget by combining water-harvesting mechanisms and morphophysiological traits. The Athel tamarisk ( Tamarix aphylla ) is a halophytic desert shrub that survives in arid, hypersaline conditions by excreting concentrated solutions of ions as droplets on its surface that crystallize into salt crystals and fall off the branches. Here, we describe the crystallization on the surface of the plant and explore the effects of external conditions such as diurnal changes in humidity and temperature. The salt mixtures contain at least ten common minerals, with NaCl and CaSO 4 ·2H 2 O being the major products, SiO 2 and CaCO 3 main sand contaminants, and Li 2 SO 4 , CaSO 4 , KCl, K 2 Ca(SO 4 ) 2 ·H 2 O, CaMg(CO 3 ) 2 and AlNaSi 3 O 8 present in smaller amounts. In natural conditions, the hanging or sitting droplets remain firmly attached to the surface, with an average adhesion force of 275 ± 3.5 µN measured for pure water. Rather than using morphological features of the surface, the droplets adhere by chemical interactions, predominantly by hydrogen bonding. Increasing ion concentration slightly increases the contact angle on the hydrophobic cuticle, thereby lowering surface wettability. Small amounts of lithium sulfate and possibly other hygroscopic salts result in strong hygroscopicity and propensity for deliquescence of the salt mixture overnight. Within a broader context, this natural mechanism for humidity harvesting that uses environmentally benign salts as moisture adsorbents could provide a bioinspired approach that complements the currently available water collection or cloud-seeding technologies.

In pursuit of accessible and interpretable methods for direct and real-time observation of mechanochemical reactions, we demonstrate a tandem spectroscopic method for monitoring of ball-milling transformations combining fluorescence emission and Raman spectroscopy, accompanied by high-level molecular and periodic density-functional theory (DFT) calculations, including periodic time-dependent (TD-DFT) modelling of solid-state fluorescence spectra. This proof-of-principle report presents this readily accessible dual-spectroscopy technique as capable of observing changes to the supramolecular structure of the model pharmaceutical system indometacin during mechanochemical polymorph transformation and cocrystallisation. The observed time-resolved in situ spectroscopic and kinetic data are supported by ex situ X-ray diffraction and solid-state nuclear magnetic resonance spectroscopy measurements. The application of first principles ( ab initio ) calculations enabled the elucidation of how changes in crystalline environment, that result from mechanochemical reactions, affect vibrational and electronic excited states of molecules. The herein explored interpretation of both real-time and ex situ spectroscopic data through ab initio calculations provides an entry into developing a detailed mechanistic understanding of mechanochemical milling processes and highlights the challenges of using real-time spectroscopy., Competing Interests: The authors declare no competing interests., (This journal is © The Royal Society of Chemistry.)

The structure of the first lithium-containing bismuth ortho ( o )-thiophosphate was determined using a combination of powder X-ray, neutron, and electron diffraction. Li 60-3 x Bi 16+ x (PS 4 ) 36 with x in the range of 4.1-6.5 possesses a complex monoclinic structure [space group C 2/ c (No. 15)] and a large unit cell with the lattice parameters a = 15.4866 Å, b = 10.3232 Å, c = 33.8046 Å, and β = 85.395° for Li 44.4 Bi 21.2 (PS 4 ) 36 , in agreement with the structure as observed by X-ray and neutron pair distribution function analysis. The disordered distribution of lithium ions within the interstices of the dense host structure and the Li ion dynamics and diffusion pathways have been investigated by solid-state nuclear magnetic resonance (NMR) spectroscopy, pulsed field gradient NMR diffusion measurements, and bond valence sum calculations. The total lithium ion conductivities range from 2.6 × 10 -7 to 2.8 × 10 -6  S cm -1 at 20 °C with activation energies between 0.29 and 0.32 eV, depending on the bismuth content. Despite the highly disordered nature of lithium ions in Li 60-3 x Bi 16+ x (PS 4 ) 36 , the underlying dense host framework appears to limit the dimensionality of the lithium diffusion pathways and emphasizes once more the necessity of a close inspection of the structure-property relationships in solid electrolytes.

The outstanding diversity of Zr-based frameworks is inherently linked to the variable coordination geometry of Zr-oxo clusters and the conformational flexibility of the linker, both of which allow for different framework topologies based on the same linker-cluster combination. In addition, intrinsic structural disorder provides a largely unexplored handle to further expand the accessibility of novel metal-organic framework (MOF) structures that can be formed. In this work, we report the concomitant synthesis of three topologically different MOFs based on the same M 6 O 4 (OH) 4 clusters (M = Zr or Hf) and methane-tetrakis( p -biphenyl-carboxylate) (MTBC) linkers. Two novel structural models are presented based on single-crystal diffraction analysis, namely, cubic c-(4,12)MTBC-M 6 and trigonal tr-(4,12)MTBC-M 6 , which comprise 12-coordinated clusters and 4-coordinated tetrahedral linkers. Notably, the cubic phase features a new architecture based on orientational cluster disorder, which is essential for its formation and has been analyzed by a combination of average structure refinements and diffuse scattering analysis from both powder and single-crystal X-ray diffraction data. The trigonal phase also features structure disorder, although involving both linkers and secondary building units. In both phases, remarkable geometrical distortion of the MTBC linkers illustrates how linker flexibility is also essential for their formation and expands the range of achievable topologies in Zr-based MOFs and its analogues.

Crystal engineering has exclusively focused on the development of advanced materials based on small organic molecules. We now demonstrate how the cocrystallization of a polymer yields a material with significantly enhanced thermal stability but equivalent mechanical flexibility. Isomorphous replacement of one of the cocrystal components enables the formation of solid solutions with melting points that can be readily fine-tuned over a usefully wide temperature range. The results of this study credibly extend the scope of crystal engineering and cocrystallization from small molecules to polymers., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

This work reports on the ion transport properties and defect chemistry in anhydrous lithium thiocyanate Li(SCN), which is a pseudo -halide Li + cation conductor. An extensive doping study was conducted, employing magnesium, zinc and cobalt thiocyanate as donor dopants to systematically vary the conductivity and derive a defect model. The investigations are based on impedance measurements and supported by other analytical techniques such as X-ray powder diffraction (XRPD), infrared (IR) spectroscopy, and density functional theory (DFT) calculations. The material was identified as Schottky disordered with lithium vacancies being the majority mobile charge carriers. In the case of Mg 2+ as dopant, defect association with lithium vacancies was observed at low temperatures. Despite a comparably low Schottky defect formation enthalpy of (0.6 ± 0.3) eV, the unexpectedly high lithium vacancy migration enthalpy of (0.89 ± 0.08) eV distinguishes Li(SCN) from the chemically related lithium halides. A detailed defect model of Li(SCN) is presented and respective thermodynamic and kinetic data are given. The thiocyanate anion (SCN) - has a significant impact on ion mobility due to its anisotropic structure and bifunctionality in forming both Li-N and Li-S bonds. More details about the impact on ion dynamics at local and global scale, and on the defect chemical analysis of the premelting regime at high temperatures are given in separate publications (Part II and Part III).

In lithium thiocyanate Li(SCN), the temperature regime below the melting point (274 °C) is characterized by excess conductivities over the usual Arrhenius behavior (premelting regime). Here, the Schottky defect pair concentration is high, and the point defect chemistry can no longer be considered as dilute. Coulomb interactions of Schottky pairs are expected to occur lowering the formation energy of new carriers and hence leading avalanche-like to a transition into a fully defective superionic state. The respective non-linear behavior is investigated using the cube-root law approach characterized by a defect interaction parameter J , which is a measure of the effective defect-lattice energy. In the case of Li(SCN), the rather pronounced volume expansion is to be included in the model. A literature comparison with other materials emphasizes to what degree defect formation as well as defect interactions depend not only on the dominant mobile defect, but also on the respective sublattice. Overall, a quantitative description of the defect chemistry of Li(SCN) in the premelting regime is derived.

Specific aspects of the Li + cation conductivity of anhydrous Li(SCN) are investigated, in particular the high migration enthalpy of lithium vacancies. Close inspection of impedance spectra and conductivity data reveals two bulk relaxation processes, with comparatively fast ion transport at high frequencies and slow ion migration at low frequencies. The impedance results are supported by solid state nuclear magnetic resonance (ssNMR), and pair distribution function (PDF) analysis. This behavior reflects a frequency dependent conductivity, which is related to the extremely slow thiocyanate (SCN) - anion lattice relaxation that occurs when a Li + cation jumps to the next available site. Two possible migration models are proposed: the first model considers an asymmetric energy landscape for Li + cation hopping, while the second model is connected to the jump relaxation model and allows for 180° rotational disorder of the (SCN) - anion. A complete kinetic analysis for the hopping of Li + cations is presented, which reveals new fundamental insights into the ion transport mechanism of materials with complex anions.

Sodium thiophosphates are promising materials for large-scale energy storage applications benefiting from high ionic conductivities and the geopolitical abundance of the elements. A representative of this class is Na 4 P 2 S 6 , which currently shows two known polymorphs-α and β. This work describes a third polymorph of Na 4 P 2 S 6 , γ, that forms above 580 °C, exhibits fast-ion conduction with low activation energy, and is mechanically soft. Based on high-temperature diffraction, pair distribution function analysis, thermal analysis, impedance spectroscopy, and ab initio molecular dynamics calculations, the γ-Na 4 P 2 S 6 phase is identified to be a plastic crystal characterized by dynamic orientational disorder of the P 2 S 6 4- anions translationally fixed on a body-centered cubic lattice. The prospect of stabilizing plastic crystals at operating temperatures of solid-state batteries, with benefits from their high ionic conductivities and mechanical properties, could have a strong impact in the field of solid-state battery research., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Covalent organic frameworks (COFs) with a pore size beyond 5 nm are still rarely seen in this emerging field. Besides obvious complications such as the elaborated synthesis of large linkers with sufficient solubility, more subtle challenges regarding large-pore COF synthesis, including pore occlusion and collapse, prevail. Here we present two isoreticular series of large-pore imine COFs with pore sizes up to 5.8 nm and correlate the interlayer interactions with the structure and thermal behavior of the COFs. By adjusting interlayer interactions through the incorporation of methoxy groups acting as pore-directing "anchors", different stacking modes can be accessed, resulting in modified stacking polytypes and, hence, effective pore sizes. A strong correlation between stacking energy toward highly ordered, nearly eclipsed structures, higher structural integrity during thermal stress, and a novel, thermally induced phase transition of stacking modes in COFs was found, which sheds light on viable design strategies for increased structural control and stability in large-pore COFs.

Li[SCN]·THF and Li[SCN]·2THF can be obtained from solutions of anhydrous Li[SCN] in tetrahydrofuran (C 4 H 8 O, THF). Both compounds are very hygroscopic and slowly decompose even at room temperature. At ambient conditions Li[SCN]·THF crystallizes in the monoclinic space group P 2 1 / c with the lattice parameters a = 574.41(2), b = 1643.11(6), c = 830.15(3) pm and β = 99.009(1)° for Z = 4 as determined by laboratory X-ray powder diffraction. Its crystal structure contains Li + cations surrounded by one THF molecule and three thiocyanate anions [SCN] - forming {Li[NCS] 2 [SCN](OC 4 H 8 )} 2- tetrahedra, which join together as pairs via shared N⋯N edges. CHNS combustion analysis and vibrational spectroscopy confirmed its composition, whereas differential scanning calorimetry and thermogravimetric analysis coupled with a mass spectrometer were applied to record its thermal behaviour. Li[SCN]·2THF crystallises in a primitive monoclinic lattice as well, but in the space group P 2 1 / n with the lattice parameters a = 1132.73(3), b = 1637.98(3), c = 1264.88(2) pm and β = 94.393(2)° for Z = 8 as determined from single-crystal X-ray diffraction data at 100 K. Its structure contains two crystallographically independent Li + -centred tetrahedra {Li[NCS] 2 (OC 4 H 8 ) 2 } - , which form dimers {(C 4 H 8 O) 2 Li[μ 2 -NCS] 2 Li(OC 4 H 8 ) 2 } via shared N⋯N edges. They are merely stabilised by weak agostic H⋯S interactions between some CH 2 -groups of the C 4 H 8 O molecules and the [NCS] - ligands.

The Jahn-Teller (JT) theorem constitutes one of the most fundamental concepts in chemistry. In transition-element chemistry, the 3d 4 and 3d 9 configurations in octahedral complexes are particularly illustrative, where a distortion in local geometry is associated with a reduction of the electronic energy. However, there has been a lasting debate about the fact that the octahedra are found to exclusively elongate. In contrast, for Na 9 Bi 5 Os 3 O 24 , the octahedron around Os 6+ (5d 2 ) is heavily compressed, lifting the degeneracy of the t 2g set of 5d orbitals such that in the sense of a JT compression a diamagnetic ground state results. This effect is not forced by structural constraints, the structure offers sufficient space for osmium to shift the apical oxygen atoms to a standard distance. The relevance of these findings is far reaching, since they provide new insights in the hierarchy of perturbations defining ground states of open shell electronic systems., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Mg(SCN)2·4H2O can be converted into previously unknown compounds Mg(SCN)2·(4 - x) H2O·xTHF with x = 0, 2 and 4 by multiple recrystallization in tetrahydrofuran (THF). The phases were characterized by infrared spectroscopy (IR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and their crystal structures were solved from X-ray powder diffraction (XRPD) data. In the crystal structures isolated Mg(NCS)2(H2O)4-x(THF)x units form layered motifs. The thermal behavior of Mg(SCN)2·4H2O and Mg(SCN)2·4THF was investigated by temperature dependent in situ XRPD, where Mg(SCN)2·4THF was found to acquire a room temperature (α-form) and high temperature modification (β-form). The phase transformation is associated with an order-disorder transition of the THF molecules and with a reversion of the stacking order of the layered motifs. Further heating eventually leads to the formation of Mg(SCN)2·2THF. There thiocyanate related sulfur atoms fill the voids in the coordination sphere of magnesium, which leads to the formation of one dimensional electroneutral ∞[Mg(NCS)2/2(SCN)2/2(THF)2] chains. All investigated Mg(SCN)2·(4 - x) H2O·xTHF phases exhibit a remarkable anisotropic thermal expansion, and Mg(SCN)2·4H2O and Mg(SCN)2·2THF were found to show both positive and negative thermal expansion coefficients.

Porphyrin-based metal-organic frameworks (MOFs), exemplified by MOF-525, PCN-221, and PCN-224, are promising systems for catalysis, optoelectronics, and solar energy conversion. However, subtle differences between synthetic protocols for these three MOFs give rise to vast discrepancies in purported product outcomes and description of framework topologies. Here, based on a comprehensive synthetic and structural analysis spanning local and long-range length scales, we show that PCN-221 consists of Zr 6 O 4 (OH) 4 clusters in four distinct orientations within the unit cell, rather than Zr 8 O 6 clusters as originally published, and linker vacancies at levels of around 50%, which may form in a locally correlated manner. We propose disordered PCN-224 (dPCN-224) as a unified model to understand PCN-221, MOF-525, and PCN-224 by varying the degree of orientational cluster disorder, linker conformation and vacancies, and cluster-linker binding. Our work thus introduces a new perspective on network topology and disorder in Zr-MOFs and pinpoints the structural variables that direct their functional properties.

Covalent organic frameworks have emerged as a powerful synthetic platform for installing and interconverting dedicated molecular functions on a crystalline polymeric backbone with atomic precision. Here, we present a novel strategy to directly access amine-linked covalent organic frameworks, which serve as a scaffold enabling pore-wall modification and linkage-interconversion by new synthetic methods based on Leuckart-Wallach reduction with formic acid and ammonium formate. Frameworks connected entirely by secondary amine linkages, mixed amine/imine bonds, and partially formylated amine linkages are obtained in a single step from imine-linked frameworks or directly from corresponding linkers in a one-pot crystallization-reduction approach. The new, 2D amine-linked covalent organic frameworks, rPI-3-COF, rTTI-COF, and rPy1P-COF, are obtained with high crystallinity and large surface areas. Secondary amines, installed as reactive sites on the pore wall, enable further postsynthetic functionalization to access tailored covalent organic frameworks, with increased hydrolytic stability, as potential heterogeneous catalysts.

Tb-diluted and Tb-rich apatite-type silicates with compositions Y 7.75 Tb 0.25 Ca 2 (SiO 4 ) 6 O 2 and Tb 8 Ca 2 (SiO 4 ) 6 O 2 , respectively, exhibit field induced multiple slow relaxation of magnetization. The former reveals two slow relaxation paths, the latter only one with a longer relaxation time of several seconds. The relaxation features of the Tb-diluted one are comparable with those of analogue compounds, where Tb is replaced by Dy, as well as with those of a Tb-doped calcium phosphate apatite. The relaxation parameters of the Tb-rich compound virtually match those of the Dy-based analogue Dy 8 Ca 2 (SiO 4 ) 6 O 2 . The latter represents the first instance of independence of magnetization relaxation on the nature of a paramagnetic rare-earth metal ion in single ion magnet like materials., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Thermally responsive crystals hold great potential for their use as actuating materials by acting as energy transducers to convert heat energy to mechanical work. Control over defined phase transition temperature with rapid reconfiguration is of great advantage for actuation. The thermosalient (TS) effect is a rarely observed phenomenon in coordination polymers (CPs), let alone the reversibility of thermosalience in CPs. Herein, we report the reversible TS effect in a one-dimensional CP due to the martensitic phase transition during both heating and cooling cycles. The TS effect was preceded by anisotropic thermal expansion showing high expansion coefficients. In addition, the nonmolecular crystals show reversible contraction and recovery during multiple heating-cooling cycles due to the self-restorative shape memory effect. The reversible actuation of the CP could be repeated for 20 heating-cooling cycles in differential scanning calorimetry experiments, suggesting its great potential as a multicyclic actuator. Such thermal responsive behavior is unique in metal-organic materials.

Gas capture and sequestration are valuable properties of metal-organic frameworks (MOFs) driving tremendous interest in their use as filtration materials for chemical warfare agents. Recently, the Zr-based MOF UiO-67 was shown to effectively adsorb and decompose the nerve-agent simulant, dimethyl methylphosphonate (DMMP). Understanding mechanisms of MOF-agent interaction is challenging due to the need to distinguish between the roles of the MOF framework and its particular sites for the activation and sequestration process. Here, we demonstrate the quantitative tracking of both framework and binding component structures using in situ X-ray total scattering measurements of UiO-67 under DMMP exposure, pair distribution function analysis, and theoretical calculations. The sorption and desorption of DMMP within the pores, association with linker-deficient Zr6 cores, and decomposition to irreversibly bound methyl methylphosphonate were directly observed and analyzed with atomic resolution., (© 2021. The Author(s).)

Cyclic peptoids are macrocyclic N-substituted oligoglycines, with remarkable structural, chemical and physical properties. The gas adsorption properties of a permanently porous hexameric cyclopeptoid decorated with four propargyl and two methoxyethyl side chains were monitored by in situ X-ray powder diffraction (XRPD). High-resolution XRPD data together with Rietveld and density functional based tight binding (DFTB) method allowed us to locate propyne guest molecules inside the host channels, even though the powder sample contains more than one phase. We were able to characterize the host-guest interactions, providing useful information on the host recognition sites and discuss host adaptiveness and host-guest chemical affinity in comparison with analogous compounds., (© 2020 Wiley-VCH GmbH.)

Structural and morphological interplay between hard and soft phases determine the bulk properties of thermoplastic polyurethanes. Commonly employed techniques rely on different physical or chemical phenomena for characterizing the organization of domains, but detailed structural information can be difficult to derive. Here, total scattering pair distribution function (PDF) analysis is used to determine atomic-scale insights into the connectivity and molecular ordering and compared to the domain size and morphological characteristics measured by AFM, TEM, SAXS, WAXS, and solid-state NMR 1 H- 1 H spin-diffusion. In particular, density distribution functions are highlighted as a means to bridging the gap from the domain morphology to intradomain structural ordering. High real-space resolution PDFs are shown to provide a sensitive fingerprint for indexing aromatic, aliphatic, and polymerization-induced bonding characteristics, as well as the hard phase structure, and indicate that hard phases coexist in both ordered and disordered states., Competing Interests: The authors declare no competing financial interest., (© 2020 American Chemical Society.)

Dy-Mg silicate Dy 8 Mg 2 (SiO 4 ) 6 O 2 has been prepared by high-temperature solid state reaction. It has an apatite type structure ( P 6 3 / m ) with the Dy atoms fully occupying the 6h site and being in random distribution with the Mg atoms at the 4f site. The compound reveals dual magnetization relaxation with widely varying contributions from fast (FR) and slow (SR) relaxation paths controlled by field and temperature. The SR path is stabilized by a strong magnetic field, exhibits a weak dependence of relaxation time τ on field and temperature, and sustains large τ of a few seconds up to a temperature of 40 K and under a field of 50 kOe. The analysis of the electronic structure and comparison with the known Dy-doped phosphate apatites suggests that the Orbach and Raman processes are suppressed., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Mechanochemistry provides an efficient, but still poorly understood route to synthesize and screen for polymorphs of organic solids. We present a hitherto unexplored effect of the milling assembly on the polymorphic outcome of mechanochemical cocrystallisation, tentatively related to the efficiency of mechanical energy transfer to the milled sample. Previous work on mechanochemical cocrystallisation has established that introducing liquid or polymer additives to milling systems can be used to direct polymorphic behavior, leading to extensive studies how the amount and nature of grinding additive affect reaction outcome and polymorphism. Here, focusing on a model pharmaceutical cocrystal of nicotinamide and adipic acid, we demonstrate that changes to the choice of milling media ( i.e. number and material of milling balls) and/or the choice of milling assembly ( i.e. jar material) can be used to direct polymorphism of mechanochemical cocrystallisation, enabling the selective synthesis, and even reversible and repeatable interconversion of cocrystal polymorphs. While real-time mechanistic studies of mechanochemical transformations of metal-organic materials have previously suggested that reactions follow a path described by Ostwald's rule of stages, i.e . from metastable to increasingly more stable product structures, the herein presented systematic study presents an exception to that rule, revealing that modification of energy input in the mechanochemical system, combined with a small energy difference between polymorphs, permits the selective synthesis of either the more stable room temperature form, or the new metastable high-temperature form, of the target cocrystal., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Time-resolved mechanochemical cocrystallisation studies have so-far focused solely on neat and liquid-assisted grinding. Here, we report the investigation of polymer-assisted grinding reactions using in situ X-ray powder diffraction, revealing that reaction rate is almost double compared to neat grinding and independent of the molecular weight and amount of the polymer additive used.

Interactions between extended π-systems are often invoked as the main driving force for stacking and crystallization of 2D organic polymers. In covalent organic frameworks (COFs), the stacking strongly influences properties such as the accessibility of functional sites, pore geometry, and surface states, but the exact nature of the interlayer interactions is mostly elusive. The stacking mode is often identified as eclipsed based on observed high symmetry diffraction patterns. However, as pointed out by various studies, the energetics of eclipsed stacking are not favorable and offset stacking is preferred. This work presents lower and higher apparent symmetry modifications of the imine-linked TTI-COF prepared through high- and low-temperature reactions. Through local structure investigation by pair distribution function analysis and simulations of stacking disorder, we observe random local layer offsets in the low temperature modification. We show that while stacking disorder can be easily overlooked due to the apparent crystallographic symmetry of these materials, total scattering methods can help clarify this information and suggest that defective local structures could be much more prevalent in COFs than previously thought. A detailed analysis of the local structure helps to improve the search for and design of highly porous tailor-made materials., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Helical motifs are common in nature, for example, the DNA double or the collagen triple helix. In the latter proteins, the helical motif originates from glycine, the smallest amino acid, whose molecular confirmation is closely related to acetic acid. The combination of acetic acid with calcium and water, which are also omnipresent in nature, materializing as calcium acetate hemihydrate, was now revealed to exhibit a collagen-like triple helix structure. This calcium salt is observed as efflorescence phase on calcareous heritage objects, like historic Mollusca shells, pottery or marble reliefs. In a model experiment pure calcium acetate hemihydrate was crystallized on the surface of a terracotta vessel. Calcium acetate hemihydrate crystallizes in a surprisingly large unit cell with a volume of 11,794.5(3) Å 3 at ambient conditions. Acetate ions bridge neighboring calcium cations forming spiral chains, which are arranged in a triple helix motif., (© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Using the mechanosynthesis of the calcium urea phosphate fertilizer cocrystal as a model, we provide a quantitative investigation of chemical autocatalysis in a mechanochemical reaction. The application of in situ Raman spectroscopy and synchrotron X-ray powder diffraction to monitor the reaction of urea phosphate and either calcium hydroxide or carbonate enabled the first quantitative and in situ study of a mechanochemical system in which one of the products of a chemical reaction (water) mediates the rate of transformation and underpins positive feedback kinetics. The herein observed autocatalysis by water generated in the reaction enables reaction acceleration at amounts that are up to 3 orders of magnitude smaller than in a typical liquid-assisted mechanochemical reaction., Competing Interests: T. F. is a co-founder of the company Form-Tech Scientific, Inc. that manufactures some of the equipment used in this study., (This journal is © The Royal Society of Chemistry.)

Apatite-type silicates Y7.75Dy0.25Ca2(SiO4)6O2 and Dy8Ca2(SiO4)6O2 were prepared by high-temperature solid state synthesis. In the crystal lattice, Dy3+ partially substitutes Ca2+, preferably at the 6h Ca2-site, and forms a short bond of 2.2 Å with the intra-channel O2-. The imposed strong ligand field anisotropy provides large magnetic anisotropy, which manifests itself as slow relaxation of magnetization at low temperatures. The magnetic dynamics is characterized by three or two characteristic values of relaxation time, respectively, which may be attributed to a single Dy3+ center. A phenomenological model is proposed which explains this response in terms of single paramagnetic center multiple relaxation.

The microstructures of six stacking-faulted industrially produced cobalt- and aluminium-bearing nickel layered double hydroxide (LDH) samples that are used as precursors for Li(Ni 1- x -y Co x Al y )O 2 battery materials were investigated. Shifts from the brucite-type (AγB)□(AγB)□ stacking pattern to the CdCl 2 -type (AγB)□(CβA)□(BαC)□ and the CrOOH-type (BγA)□(AβC)□(CαB)□ stacking order, as well as random intercalation of water molecules and carbonate ions, were found to be the main features of the microstructures. A recursive routine for generating and averaging supercells of stacking-faulted layered substances implemented in the TOPAS software was used to calculate diffraction patterns of the LDH phases as a function of the degree of faulting and to refine them against the measured diffraction data. The microstructures of the precursor materials were described by a model containing three parameters: transition probabilities for generating CdCl 2 -type and CrOOH-type faults and a transition probability for the random intercalation of water/carbonate layers. Automated series of simulations and refinements were performed, in which the transition probabilities were modified incrementally and thus the microstructures optimized by a grid search. All samples were found to exhibit the same fraction of CdCl 2 -type and CrOOH-type stacking faults, which indicates that they have identical Ni, Co and Al contents. Different degrees of interstratification faulting were determined, which could be correlated to different heights of intercalation-water-related mass-loss steps in the thermal analyses., (© Sebastian Bette et al. 2020.)

Interpenetration in metal-organic frameworks (MOFs) is an intriguing phenomenon with significant impacts on their properties, and functional applications. Herein, we show that a 7-fold interpenetrated MOF (1) is transformed into an 8-fold interpenetrated MOF by the loss of DMF in a single-crystal-to-single-crystal manner. This is accompanied by a giant enhancement of the second harmonic generation (SHG ca. 125 times) and two-photon photoluminescence (ca. 14 times). The strengthened π-π interaction between the individual diamondoid networks and intensified oscillator strength of the molecules aid the augment of dipole moments and boost the nonlinear optical conversion efficiency. Large positive and negative thermal expansions of 1 occur at 30-150 °C before the loss of DMF. These results offer an avenue to manipulate the NLO properties of MOFs using interpenetration and provide access to tunable single-crystal NLO devices., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Although a plethora of metal complexes have been characterized, those having multifunctional properties are very rare. This article reports three isotypical complexes, namely [Cu(benzoate) L 2 ], where L = 4-styryl-pyridine (4spy) ( 1 ), 2'-fluoro-4-styryl-pyridine (2F-4spy) ( 2 ) and 3'-fluoro-4-styryl-pyridine (3F-4spy) ( 3 ), which show photosalient behavior (photoinduced crystal mobility) while they undergo [2+2] cyclo-addition. These crystals also exhibit anisotropic thermal expansion when heated from room temperature to 200°C. The overall thermal expansion of the crystals is impressive, with the largest volumetric thermal expansion coefficients for 1 , 2 and 3 of 241.8, 233.1 and 285.7 × 10 -6  K -1 , respectively, values that are comparable to only a handful of other reported materials known to undergo colossal thermal expansion. As a result of the expansion, their single crystals occasionally move by rolling. Altogether, these materials exhibit unusual and hitherto untapped solid-state properties., (© Yadava et al. 2020.)

Tetratopic porphyrin-based metal-organic frameworks (MOFs) represent a particularly interesting subclass of zirconium MOFs due to the occurrence of several divergent topologies. Control over the target topology is a demanding task, and reports often show products containing phase contamination. We demonstrate how mechanochemistry can be exploited for controlling the polymorphism in 12-coordinated porphyrinic zirconium MOFs, obtaining pure hexagonal PCN-223 and cubic MOF-525 phases in 20-60 min of milling. The reactions are mainly governed by the milling additives and the zirconium precursor. In situ monitoring by synchrotron powder X-ray diffraction revealed that specific reaction conditions resulted in the formation of MOF-525 as an intermediate, which rapidly converted to PCN-223 upon milling. Electron spin resonance measurements revealed significant differences between the spectra of paramagnetic centers in two polymorphs, showing a potential of polymorphic Zr-MOFs as tunable supports in spintronics applications.

During the systematic investigation of the ternary system Ca(CH 3 COO) 2 -Ca(HCOO) 2 -H 2 O at room temperature, the congruent crystallisation of two solid calcium acetate formates was observed: the hitherto unknown Ca 3 (CH 3 COO) 4 (HCOO) 2 ·4H 2 O and the poorly characterised Ca(CH 3 COO)(HCOO)·H 2 O. The latter is a frequently observed efflorescence phase found on calcareous objects and it could be also identified as a corrosion phase in a natural history collection of birds' eggs. Elemental and thermal analyses were employed to determine the phase compositions and by Raman and IR spectroscopy the presence of acetate and formate anions in both solids was confirmed. Laboratory X-ray powder diffraction data were used to solve the crystal structures. Ca 3 (CH 3 COO) 4 (HCOO) 2 ·4H 2 O crystallises in a primitive tetragonal unit cell with space group P4 1 2 1 2 and lattice parameters of a = 6.8655(1) Å and c = 45.5454(6) Å, while Ca(CH 3 COO)(HCOO)·H 2 O crystallises in a primitive monoclinic unit cell with space group P2 1 /c and lattice parameters of a = 9.2729(1) Å, b = 6.8002(1) Å, c = 11.2219(2) Å and β = 121.232(1)°. Calcium carboxylate zig-zag chains [Ca(μ 2 -RCOO) + ] n (R = CH 3 or H) are the main motif of both crystal structures. In Ca 3 (CH 3 COO) 4 (HCOO) 2 ·4H 2 O these chains are exclusively composed of acetate anions, whereas in Ca(CH 3 COO)(HCOO)·H 2 O only formate anions are situated in the chains. The remaining places in the 7-8 fold coordination sphere of the calcium cations are filled by water molecules and additional carboxylate anions that interconnect neighbouring chains, which eventually leads to layered motifs in both structures.

Solving the structure of carbon nitrides has been a long-standing challenge due to the low crystallinity and complex structures observed within this class of earth-abundant photocatalysts. Herein, we report on two-dimensional layered potassium poly(heptazine imide) (K-PHI) and its proton-exchanged counterpart (H-PHI), obtained by ionothermal synthesis using a molecular precursor route. We present a comprehensive analysis of the in-plane and three-dimensional structure of PHI. Transmission electron microscopy and solid-state NMR spectroscopy, supported by quantum-chemical calculations, suggest a planar, imide-bridged heptazine backbone with trigonal symmetry in both K-PHI and H-PHI, whereas pair distribution function analyses and X-ray powder diffraction using recursive-like simulations of planar defects point to a structure-directing function of the pore content. While the out-of-plane structure of K-PHI exhibits a unidirectional layer offset, mediated by hydrated potassium ions, H-PHI is characterized by a high degree of stacking faults due to the weaker structure directing influence of pore water. Structure-property relationships in PHI reveal that a loss of in-plane coherence, materializing in smaller lateral platelet dimensions and increased terminal cyanamide groups, correlates with improved photocatalytic performance. Size-optimized H-PHI is highly active toward photocatalytic hydrogen evolution, with a rate of 3363 μmol/gh H 2 placing it on par with the most active carbon nitrides. K- and H-PHI adopt a uniquely long-lived photoreduced polaronic state in which light-induced electrons are stored for more than 6 h in the dark and released upon addition of a Pt cocatalyst. This work highlights the importance of structure-property relationships in carbon nitrides for the rational design of highly active hydrogen evolution photocatalysts., Competing Interests: The authors declare no competing financial interest., (Copyright © 2019 American Chemical Society.)

Powder samples of Ag3LiIr2O6 and Ag3LiRu2O6 were synthesized from α-Li2IrO3 and Li2RuO3 respectively by ion exchange in an AgNO3 melt. The crystal structures of the title compounds were solved from high resolution laboratory X-ray powder diffraction (XRPD) patterns and from pair distribution function (PDF) analysis using synchrotron X-ray powder diffraction data. In both crystal structures edge sharing LiO6/3- and (Ir/Ru)O6/3-octahedra form honeycomb like layers that are stacked in a staggered fashion. Silver cations, situated in-between the layers mediate the interlayer interactions by linear O-Ag-O bonds. Anisotropic peak broadening in the XRPD patterns and diffuse scattering occurring as streaks in the precession electron diffraction (PED) patterns indicate the presence of stacking faults, which could be also visualized by high resolution transmission electron microscopy (HRTEM). Possible alternative stacking sequences were derived from the ideal crystal and incorporated into a microstructure model. By applying a supercell approach that randomly generates and averages stacking sequences based on transition probabilities and combining it with a grid search algorithm, the microstructures, i.e. the degrees of faulting in the structures of the title compounds were refined to the measured XRPD data. In result the crystal structures of Ag3LiIr2O6 and Ag3LiRu2O6 were found to be vastly faulted with almost no coherence of the stacked layers.

Iridium(IV) oxides have gained increased attention in recent years owing to the presence of competing spin-orbit coupling and Coulomb interactions, which facilitate the emergence of novel quantum phenomena. In contrast, the electronic structure and magnetic properties of Ir IV -based molecular materials remain largely unexplored. In this paper, we take a fresh look at an old but puzzling compound, Na 2 IrCl 6 , which can be hydrated to form two stable phases with formulas Na 2 IrCl 6 ·2H 2 O and Na 2 IrCl 6 ·6H 2 O. Their crystal structures are well illustrated based on X-ray powder diffraction data. Magnetic studies reveal that Na 2 IrCl 6 and Na 2 IrCl 6 ·2H 2 O are canted antiferromagnets with ordering temperatures of 7.4 and 2.7 K, respectively, whereas Na 2 IrCl 6 ·6H 2 O is paramagnetic down to 1.8 K. First-principle calculations on Na 2 IrCl 6 reveal a J eff = 1/2 ground state, and the band structures show that Na 2 IrCl 6 is a spin-orbital-induced semiconductor with an indirect gap of about 0.18 eV.

Long-term crystallisation from aqueous copper(ii)-acetate solution after the addition of ammonia at 25 °C led to the formation of a hitherto poorly characterised phase in the verdigris pigment system Cu(CH3COO)2-Cu(OH)2-H2O. Laboratory X-ray powder diffraction (XRPD) was successfully employed to solve the crystal structure. The structure solution reveals a phase composition of the Cu3(CH3COO)4(OH)2·5H2O ≡ 2-1-5 phase, which was also confirmed by thermal analysis. The 2-1-5 phase crystallises in space group P21/c (14) with lattice parameters of a = 12.4835(2) Å, b = 14.4246(2) Å, c = 10.7333(1) Å and β = 102.871(1)°. The crystal structure consists of Cu2(CH3COO)2(CH3COO)1/2(OH)4/3H2O1/6+ dimers that are interconnected by Cu(CH3COO)(CH3COO)1/2(OH)2/31/6- squares forming chains running in the c-direction. Non-coordinating hydrate water molecules are intercalated inbetween the chains and mediate the inter-chain interaction. IR and Raman spectroscopy techniques were also employed to confirm selected aspects of the determined crystal structure. The magnetic properties of the 2-1-5 phase decompose into two independent subsystems: a strongly antiferromagnetically spin exchange coupled magnetic Cu-Cu dimer and a significantly weaker coupled Cu monomer. The light blue colour of the sample originates from a reflectance maximum at 488 nm and significantly differs from the known verdigris phases. An investigation of several historic verdigris pigment samples revealed that this phase occurs both as a minor and a major component. Hence, our reference data for the title compound will help to improve the understanding of the multiphase mixtures occurring in historic verdigris samples.

The use of a dodecanuclear zirconium acetate cluster as a precursor enables the rapid, clean mechanochemical synthesis of high-microporosity metal-organic frameworks NU-901 and UiO-67, with surface areas up to 2250 m2 g-1. Real-time X-ray diffraction monitoring reveals that mechanochemical reactions involving the conventional hexanuclear zirconium methacrylate precursor are hindered by the formation of an inert intermediate, which does not appear when using the dodecanuclear acetate cluster as a reactant.

The demand to outperform current technologies pushes scientists to develop novel strategies, which enable the fabrication of materials with exceptional properties. Along this line, lightweight structural materials are of great interest due to their versatile applicability as sensors, catalysts, battery electrodes, and acoustic or mechanical dampers. Here, we report a strategy to design ultralight (ρ = 3 mg/cm 3 ) and hierarchically structured ceramic scaffolds of macroscopic size. Such scaffolds exhibit mechanical reversibility comparable to that of microscopic metamaterials, leading to a macroscopically remarkable dynamic mechanical performance. Upon mechanical loading, these scaffolds show a deformation mechanism similar to polyurethane foams, and this resilience yields ultrahigh damping capacities, tan δ, of up to 0.47.

Reaction of Ni(NCS) 2 with 4-aminopyridine in different solvents leads to the formation of compounds with the compositions Ni(NCS) 2 (4-aminopyridine) 4 (1), Ni(NCS) 2 (4-aminopyridine) 2 (H 2 O) 2 (2), [Ni(NCS) 2 (4-aminopyridine) 3 (MeCN)]·MeCN (3), and [Ni(NCS) 2 (4-aminopyridine) 2 ] n (5-LT). Compounds 1, 2, and 3 form discrete complexes, with octahedral metal coordination. In 5-LT the Ni cations are linked by single thiocyanate anions into chains, which are further connected into layers by half of the 4-aminopyridine coligands. Upon heating, 1 transforms into an isomer of 5-LT with a 1D structure (5-HT), that on further heating forms a more condensed chain compound [Ni(NCS) 2 (4-aminopyridine)] n (6) that shows a very unusual chain topology. If 3 is heated, a further compound with the composition Ni(NCS) 2 (4-aminopyridine) 3 (4) is formed, which presumably is a dimer and which on further heating transforms into 6 via 5-HT as intermediate. Further investigations reveal that 5-LT and 5-HT are related by enantiotropism, with 5-LT being the thermodynamic stable form at room-temperature. Magnetic and specific heat measurements reveal ferromagnetic exchange through thiocyanate bridges and magnetic ordering due to antiferromagnetic interchain interactions at 5.30(5) K and 8.2(2) K for 5-LT and 6, respectively. Consecutive metamagnetic transitions in the spin ladder compound 6 are due to dipolar interchain interactions. A convenient formula for susceptibility of the ferromagnetic Heisenberg chain of isotropic spins S = 1 is proposed, based on numerical DMRG calculations, and used to determine exchange constants.

We demonstrate that the simultaneous substitution of calcium and aluminum for strontium and iron in strontium hexaferrite results in a significant increase of coercivity up to a record high of 21.3 kOe. We propose that the effect is originated from a crystal structure distortion causing an increase of the magnetocrystalline anisotropy.

A powder sample of pure H 3 LiIr 2 O 6 was synthesized from α-Li 2 IrO 3 powder by a soft chemical replacement of Li + with H + . The crystal structure of H 3 LiIr 2 O 6 consists of sheets of edge sharing LiO 6 - and IrO 6 -octahedra forming a honeycomb network with layers stacked in a monoclinic distorted HCrO 2 type pattern. Heavy stacking faulting of the sheets is indicated by anisotropic peak broadening in the X-ray powder diffraction (XRPD) pattern. The ideal, faultless crystal structure was obtained by a Rietveld refinement of the laboratory XRPD pattern while using the LiIr 2 O 6 3- -layers of α-Li 2 IrO 3 as a starting model. The low radial distances of the PDF function, derived from synchrotron XRPD data, as constraints to stabilize the structural refinement. DIFFaX-simulations, structural considerations, high radial distances of the PDF function and a Rietveld compatible global optimization of a supercell were employed to derive a suitable faulting model and to refine the microstructure using the experimental data. We assumed that the overall stacking pattern of the layers in the structure of H 3 LiIr 2 O 6 is governed by interlayer O-HO contacts. From the constitution of the layers, different stacking patterns with similar amounts of strong O-HO contacts are considered. Random transitions among these stacking patterns can occur as faults in the crystal structure of H 3 LiIr 2 O 6 , which quantitatively describe the observed XRPD.

Known synthesis approaches for basic copper(ii) acetates, the main components of historic verdrigis pigments were reinvestigated and revealed to be partially irreproducible. A modification of the reaction conditions led to the successful and reproducible synthesis of the 1-2-0 phase (Cu 3 (CH 3 COO) 2 (OH) 4 = 1Cu(CH 3 COO) 2 ·2Cu(OH) 2 ·0H 2 O). The phase composition was derived from elemental and thermal analysis and confirmed by the crystal structure solution using synchrotron X-ray powder diffraction (XRPD) data. The 1-2-0 phase crystallises in space group Pbca with lattice parameters of a = 20.9742(1) Å, b = 7.2076(1) Å, and c = 13.1220(1) Å. The crystal structure consists of Cu 2 (CH 3 -COO) 2 (OH) 4/3 (OH) 2/2 1/3- dimers, which are interconnected by corner sharing Cu(OH) 2/3 (OH) 2/2 1/3+ squares forming layers perpendicular to the a-axis. The deep blue color of the solid originates from a reflectance maximum at 472 nm and from an absorbance maximum at 676 nm that is comparable with other historic blue pigments like azurite or Egyptian blue. IR- and Raman-spectroscopic properties of the solid were investigated as well, which demonstrated that the obtained product is identical with a previously synthesised verdigris phase that was obtained by applying historical procedures. Therefore, our reference data for the title compound will help to improve the understanding of the multiphase mixtures occurring in historic verdigris samples. The magnetic properties of the 1-2-0 phase were also investigated. At low temperatures the magnetic susceptibility is well described by a spin-1/2 Heisenberg chain with uniform antiferromagnetic nearest-neighbour spin exchange coupling of only one of three Cu magnetic moments. Due to the very strong antiferromagnetic coupling of the Cu 2 (CH 3 -COO) 2 (OH) 4/3 (OH) 2/2 1/3- dimers their contribution to magnetism becomes relevant above ∼140 K, which results in the presence of two distinct temperature regions where Curie-Weiss behaviour of the magnetic susceptibility with different Curie constants and Weiss temperatures is found.

In salient effects, still crystals of solids that switch between phases acquire a momentum and are autonomously propelled because of rapid release of elastic energy accrued during a latent structural transition induced by heat, light, or mechanical stimulation. When mechanical reconfiguration is induced by change of temperature in thermosalient crystals, bursts of detectable acoustic waves are generated prior to self-actuation. These observations provide compelling evidence that the thermosalient transitions in organic and organic-containing crystals are molecular analogues of the martensitic transitions in some metals, and metal alloys such as steel and shape-memory alloys. Within a broader context, these results reveal that, akin to metallic bonding, the intermolecular interactions in molecular solids are capable of gradual accrual and sudden release of a substantial amount of strain during anisotropic thermal expansion, followed by a rapid transformation of the crystal packing in a diffusionless, non-displacive transition., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We prepared trirutile-type polycrystalline samples of CuTa 2 O 6 by low-temperature decomposition of a Cu-Ta-oxalate precursor. Diffraction studies at room temperature identified a slight monoclinic distortion of the hitherto surmised tetragonal trirutile crystal structure. Detailed high-temperature X-ray and neutron powder diffraction investigations as well as Raman scattering spectroscopy revealed a structural phase transition at 503(3) K from the monoclinic structure to the tetragonal trirutile structure. GGA+U density functional calculations of the spin-exchange parameters as well as magnetic susceptibility and isothermal magnetization measurements reveal that CuTa 2 O 6 is a new 1D Heisenberg magnet with predominant anti-ferromagnetic nearest-neighbor intrachain spin-exchange interaction of ∼50 K. Interchain exchange is a factor of ∼5 smaller. Heat capacity and low-temperature high-intensity neutron powder diffraction studies could not detect long-range order down to 0.45 K.

The investigation of the corrosion of a lid made from a tin-lead alloy of a 200 years old beer jug induced by the degradation of the potash based glass revealed SnO, Cerussite (PbCO 3 ) and K(OH)·2PbCO 3 as main corrosion product. A model experiment, simulating the corrosion of lead at room temperature confirmed the formation of K(OH)·2PbCO 3 as a corrosion product in alkaline, potassium containing medium. For detailed characterization K(OH)·2PbCO 3 was prepared by hydrothermal synthesis, as well. K(OH)·2PbCO 3 crystallizes in space group P6 3 /mmc with lattice parameters of a = 5.3389(1) Å and c = 13.9295(5) Å. The structure consists of Pb(OH) 1/2 (CO 3 ) 6/9 [CO 3 ] 3/9 1/2- layers and intercalated K + and exhibits a close relationship to the crystal structure of hydrocerussite (Pb(OH) 2 ·2PbCO 3 ), also known as "lead white". A novel structure family, M n+ (OH) n ·2PbCO 3 (with n = 1,2), was identified by structure solution of K(OH)·2PbCO 3 , which can be assigned to a 2H-type subspecies and detailed comparison to Pb(OH) 2 ·2PbCO 3 , which represents a 3R-type subspecies.

In recent years, continuous process technologies have attracted increasing attention, as a means of overcoming limitations in the repeatability and reproducibility of metal-organic framework (MOF) synthesis. Research in this area, however, has neglected to provide insight into the phenomenon leading to the formation of MOFs. In this work, we report the adaption of high-energy synchrotron powder X-ray diffraction analysis to a continuous ZIF-8 production process for online monitoring of the reaction behavior and crystallite formation during the first seconds of the MOF synthesis. It was confirmed that a diffusion-controlled growth mechanism was accelerated by additional radial diffusion processes in the flow reactor. Kinetic analysis revealed a rapid crystallite formation of ZIF-8, which was completed after 8 s of reaction time and which offers the potential for future process optimization.

An apatite-type barium phosphate with a high content of cobalt ions in the trigonal channels features slow relaxation of magnetization with an energy barrier U eff of up to 387 cm -1 , which is well above the values for all so far known d-metal based single-molecule magnets (SMMs).

The synthesis of ceramic materials combining high porosity and permeability with good mechanical stability is challenging, as optimising the latter requires compromises regarding the first two properties. Nonetheless, significant progress can be made in this direction by taking advantage of the structural design principles evolved by nature. Natural cellular solids achieve good mechanical stability via a defined hierarchical organisation of the building blocks they are composed of. Here, we report the first synthetic, ceramic-based scaffold whose architecture closely mimics that of cuttlebone -a structural biomaterial whose porosity exceeds that of most other natural cellular solids, whilst preserving an excellent mechanical strength. The nanostructured, single-component scaffold, obtained by ice-templated assembly of V 2 O 5 nanofibres, features a highly sophisticated and elaborate architecture of equally spaced lamellas, which are regularly connected by pillars as lamella support. It displays an unprecedented porosity of 99.8 %, complemented by an enhanced mechanical stability. This novel bioinspired, functional material not only displays mechanical characteristics similar to natural cuttlebone, but the multifunctionality of the V 2 O 5 nanofibres also renders possible applications, including catalysts, sensors and electrodes for energy storage.