Search

This study demonstrates the potential of copper nanotechnology for the topical treatment of burn injuries and opens new horizons in oncological dermatology.

Wodegongjieite occurs in the Cr-11 chromitite orebody of the Luobusa ophiolite in the Kangjinla district, Tibet, China. It is found in two inclusions in corundum: (1) as a partial overgrowth (holotype) up to 1.5 μm thick around a spheroid 20 μm across of wenjiite (Ti10(Si,P,□)7), kangjinlaite (Ti11(Si,P)10), zhiqinite (TiSi2) and badengzhuite (TiP), and (2) as pools up to 0.25 μm wide filling interstices between wenjiite, jingsuiite (TiB2), osbornite–khamrabaevite (Ti[N,C]) and corundum. Energy dispersive analyses gave Al2O3 34.09, SiO2 49.11, K2O 2.56, CaO 11.71, SrO 2.53, total 100.0 wt.%, corresponding to K0.58Sr0.26Ca2.25Al7.20Si8.80O31.20, ideally KCa3(Al7Si9)O32, for Si + Al = 16 cations.Single-crystal studies were carried out with three-dimensional electron diffraction providing data for an ab initio structure solution in the hexagonal space group P6/mcc (#192) with a = 10.2(2) Å, c = 14.9(3) Å, V = 1340(50) Å3 and Z = 2. Density (calc.) = 2.694 g⋅cm–3. The refinement, which assumes complete Si–Al disorder, gives average T1–O and T2–O bond lengths both as 1.65 Å. It was not practical to use unconstrained refinement for the occupancies of the large cation sites 6f and 2a. The ab initio model shows clearly that the two cation sites have different sizes and coordination. Consequently, we imposed the condition (1) that all the K occupies the 2a site as the average K–O bond length of 3.07 Å is close to the average K–O bond lengths reported in kokchetavite and (2) that all the Ca occupies the 6f site as the average Ca–O bond length of 2.60 Å (2.36 Å and 2.84 Å for Ca–O1 and Ca–O3, respectively) is reasonable for Ca–O. Assuming that all K and all Ca are located at the 2a site and 6f site, respectively, Sr occupancies of these sites could be refined. Thermal parameters are positive and in a reasonable range. The structure is a sheet silicate isostructural with the K-feldspar polymorph kokchetavite, with two crystallographically distinct sites for K, but not with the topologically identical anorthite polymorph dmisteinbergite (CaAl2Si2O8) with only a single site for Ca. Substitution of K by Ca at the 6f site is associated with marked rotation of the Si,Al tetrahedra and a collapse of the structure to accommodate the smaller Ca ion.The spheroid of intermetallic phases is believed to have formed from the interaction of mantle-derived CH4 + H2 fluids with basaltic magmas at depths of ~30–100 km, resulting in precipitation of corundum that entrapped intermetallic melts. Associated immiscible silicate melt of granodioritic composition crystallised metastably to wodegongjieite instead of a mixture of anorthite and K-feldspar.

The Mineo pallasite is a relatively poorly known meteorite, which shows interesting features that are not fully understood, such as the occurrence of iron oxide regions bordering both the olivine grain boundaries and the (Fe,Ni) metal. In this study, the Fe oxides have been characterised by Raman spectroscopy, electron microprobe analysis, field emission scanning electron microscopy, transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and 3D electron diffraction (3D ED). The combination of TEM–EDS and 3D ED yields a reliable identification of the chemical and crystallographic features of the cryptocrystalline portion of the sample investigated, enabling the Fe-oxide regions to be positively identified as goethite, FeO(OH).The occurrence of goethite was unambiguously associated with terrestrial alteration, also confirmed by the presence of calcite, detected by TEM-EDS and 3D ED. Goethite contains minor elements such as Na, Si and Ca, probably coming from alumino-silicates in the terrestrial environment, and Ni associated with the (Fe,Ni) metal. The observation of goethite along olivine grain boundaries, as an alteration product of the (Fe,Ni) metal diagenesis, is also very intriguing as it might be related to the (Fe,Ni) metal intruded into the sub-micrometric olivine fragments during pallasite formation. Further work is needed to extensively analyse the texture and composition of olivine/metal boundaries.

The new minerals wenjiite, Ti10(Si,P,☐)7 (IMA2019-107c) and kangjinlaite, Ti11(Si,P)10 (IMA2019-112b) occur with badengzhuite, zhiqinite, and a K-bearing dmisteinbergite-like mineral in a spheroid 20 μm across enclosed in corundum from the Cr-11 podiform chromitite orebody near the Kangjinla, Luobusa ophiolite, Tibet, China. In addition, wenjiite occurs with deltalumite, jingsuiite, osbornitekhambaraevite, and the K-bearing dmisteinbergite-like mineral in a lamellar intergrowth 100 μm long, also enclosed in corundum from the same locality. The new minerals were characterized by energy-dispersive spectroscopy and three-dimensional electron diffraction, which enabled us to obtain an ab initio structure solution and dynamical refinement from grains a few micrometers across hosted in a FIB lamella. Four analyses of wenjiite from the spheroid gave in wt% Si 21.67, P 6.24, Ti 66.39, V 1.37, Cr 2.20, Mn 0.97, and Fe 1.17 (normalized to 100), which corresponds to (Ti0.93Cr0.03Mn0.01Fe0.01V0.02)10 (Si0.79P0.21)6.51 on the basis of 10 cations excluding Si and P. The simplified formula is Ti10(Si,P)6.5, or more generally Ti10SixPy, where x > y and 6 ≤ (x + y) ≤ 7, i.e., Ti10(Si,P,☐)7. Wenjiite has hexagonal symmetry, space group: P63/mcm (no. 193), with a = 7.30(10) Å, c = 5.09(10) Å, V = 235(6) Å3, Z = 1, and is isostructural with xifengite, mavlyanovite, synthetic Ti5Si3, and synthetic Ti5P3.15. Four analyses of kangjinlaite gave in wt% Si 25.56, P 9.68, Ti 62.35, V 0.21, Cr 0.83, Mn 0.42, and Fe 0.95 (normalized to 100), which corresponds to (Ti10.65V0.03Cr0.13Mn0.06Fe0.14)Σ11.01(Si7.43P2.55)Σ9.99. The simplified formula is Ti11(Si,P)10. Kangjinlaite is tetragonal, with space group: I4/mmm (no. 139), a = 9.4(2) Å, c = 13.5(3) Å, V = 1210(50) Å3, Z = 4, and is isostructural with synthetic compounds of the Ho11Ge10 type, being the most compact of these phases. Despite there now being over 70 compounds containing 38 elements isostructural with Ho11Ge10, synthesis of an analog of kangjinlaite has not been previously reported in either the Ti-P or Ti-Si binary systems or in a multicomponent system. The previously deduced crystallization sequence with decreasing temperature of the four minerals in the spheroid is wenjiite → kangjinlaite → zhiqinite + badengzhuite. This sequence is consistent with relationships reported in 9 binary systems containing intermetallic compounds of Ge and Sn isostructural with Mn5Si3 and Ho11Ge10. In eight of these systems the Mn5Si3 analog melts congruently, whereas the Ho11Ge10 analog never does. Instead, the Ho11Ge10 analog melts peritectically, generally to an Mn5Si3 analog and less commonly to compounds with 5:4 stoichiometry. Final crystallization of the spheroid to zhiqinite + badengzhuite is expected to be well below the temperature of 1500 °C for the congruent melting of zhiqinite in the Ti-Si system, i.e., in the range of ~1100–1300 °C.

The true molecular conformation and the crystal structure of benzo[e]dinaphtho[2,3-a;1′,2′,3′,4′-ghi]fluoranthene, 7,14-diphenylnaphtho[1,2,3,4-cde]bisanthene and 7,16-diphenylnaphtho[1,2,3,4-cde]helianthrene were determined ab initio by 3D electron diffraction. All three molecules are remarkable polycyclic aromatic hydrocarbons. The molecular conformation of two of these compounds could not be determined via classical spectroscopic methods due to the large size of the molecule and the occurrence of multiple and reciprocally connected aromatic rings. The molecular structure of the third molecule was previously considered provisional. These compounds were isolated as by-products in the synthesis of similar products and were at the same time nanocrystalline and available only in very limited amounts. 3D electron diffraction data, taken from submicrometric single crystals, allowed for direct ab initio structure solution and the unbiased determination of the internal molecular conformation. Detailed synthetic routes and spectroscopic analyses are also discussed. Based on many-body perturbation theory simulations, benzo[e]dinaphtho[2,3-a;1′,2′,3′,4′-ghi]fluoranthene may be a promising candidate for triplet–triplet annihilation and 7,14-diphenylnaphtho[1,2,3,4-cde]bisanthene may be a promising candidate for intermolecular singlet fission in the solid state.

The crystal structure of linagliptin hemihydrate hemiethanolate was solved by direct methods and refined by least-squares on the basis of 3D electron diffraction data. Linagliptin is one of the lar...

The elusive structure of the mineral kaliophilite has been determined by 3D electron diffraction and refined using single-crystal X-ray data. Despite its simple formula, ideally KAlSiO4, the structure of this mineral remained a mystery for over a century as a result of pseudo-symmetry and twinning, which reduce the coherent crystalline domain size to a few hundreds of nanometres., Kaliophilite is a feldspathoid mineral found in two Italian magmatic provinces and represents one of the 12 known phases with composition close to KAlSiO4. Despite its apparently simple formula, the structure of this mineral revealed extremely complex and resisted structure solution for more than a century. Samples from the Vesuvius–Monte Somma and Alban Hills volcanic areas were analyzed through a multi-technique approach, and finally the crystal structure of kaliophilite was solved using 3D electron diffraction and refined against X-ray diffraction data of a twinned crystal. Results were also ascertained by the Rietveld method using synchrotron powder intensities. It was found that kaliophilite crystallizes in space group P3 with unit-cell parameters a = 27.0597 (16), c = 8.5587 (6) Å, V = 5427.3 (7) Å3 and Z = 54. The kaliophilite framework is a variant of the tridymite topology, with alternating SiO4 and AlO4 tetrahedra forming sheets of six-membered rings (63 nets), which are connected along [001] by sharing the apical oxygen atoms. Considering the up (U) and down (D) orientations of the linking vertex, kaliophilite is the first framework that contains three different ring topologies: nine (1-3-5) (UDUDUD) rings, six (1-2-3) (UUUDDD) rings and twelve (1-2-4) (UUDUDD) rings. This results in a relatively open (19.9 tetrahedra nm−3) channel system with multiple connections between the double six-ring cavities. Such a framework requires a surprisingly large unit cell, 27 times larger than the cell of kalsilite, the simplest phase with the same composition. The occurrence of some Na for K substitution (3–10%) may be related to the characteristic structural features of kaliophilite. Micro-twinning, pseudo-symmetries and anisotropic hkl-dependent peak broadening were also detected, and they may account for the elusive character of the kaliophilite crystal structure.

Cowlesite, ideally Ca6Al12Si18O60·36H2O, is to date the only natural zeolite whose structure could not be determined by X-ray methods. In this paper, we present the ab initio structure determination of this mineral obtained by three-dimensional (3D) electron diffraction data collected from single-crystal domains of a few hundreds of nanometers. The structure of cowlesite consists of an alternation of rigid zeolitic layers and low-density interlayers supported by water and cations. This makes cowlesite the only two-dimensional (2D) zeolite known in nature. When cowlesite gets in contact with a transmission electron microscope vacuum, a phase transition to a conventional 3D zeolite framework occurs in few seconds. The original cowlesite structure could be preserved only by adopting a cryo-plunging sample preparation protocol usually employed for macromolecular samples. Such a protocol allows the investigation by 3D electron diffraction of very hydrated and very beam-sensitive inorganic materials, which were previously considered intractable by transmission electron microscopy crystallographic methods., The mineral cowlesite, solved by cryo-plunging three-dimensional electron diffraction, shows a unique structure with weakly bonded two-dimensional zeolitic layers. It transforms into a fully connected framework upon dehydration at about 120 °C.

The formation conditions and stability fields of Fe-serpentines are still poorly understood in both terrestrial (natural or anthropic) and extraterrestrial environments. Knowledge of the effects of physical-chemical parameters on compositional and structural features of Fe-serpentines is lacking, and only a few thermodynamic parameters of these minerals are available in the literature. To fill these gaps, the synthesis of these minerals, while controlling all the physicochemical experimental parameters, was undertaken. Two hydrothermal syntheses were carried out at 90°C to investigate the effect of two different starting mineralogical mixtures on the nature of Fe-serpentines. The run products were identified by several analytical techniques (powder X-ray diffraction, transmission, and scanning electron microscopy). Berthierine crystals were synthesized from a starting mixture of kaolinite and metal iron. The berthierines synthesized show different morphologies and iron contents (~3–38 at.%). From a starting mineralogical mixture composed of quartz and metal iron, cronstedtite crystallizes. Most of the crystals are 1M polytypes. Magnetite is always associated with both berthierine and cronstedtite. Lepidocrocite was observed only in the experiment with kaolinite. These experimental results demonstrated that Fe enrichment in serpentines depends on the silicate precursor (kaolinite or quartz) of the starting mixture. The results are also in agreement with the geochemical equilibrium predicted by thermodynamic modeling, i.e. the formation of berthierine and cronstedtite in association with magnetite at the expense of metal iron and silicates.

An effort to synthesize the Cu(I) variant of a lead-free double perovskite isostructural with Cs2AgInCl6resulted in the formation of Cs3Cu4In2Cl13nanocrystals with an unusual structure, as revealed by single-nanocrystal three-dimensional electron diffraction. These nanocrystals adopt a A2BX6structure (K2PtCl6type, termed vacancy ordered perovskite) with tetrahedrally coordinated Cu(I) ions. In the structure, 25% of the A sites are occupied by [Cu4Cl]3+clusters (75% by Cs+), and the B sites are occupied by In3+. Such a Cs3Cu4In2Cl13compound prepared at the nanoscale is not known in the bulk and is an example of a multinary metal halide with inorganic cluster cations residing in A sites. The stability of the compound was supported by density functional theory calculations that also revealed that its bandgap is direct but parity forbidden. The existence of the Cs3Cu4In2Cl13structure demonstrates that small inorganic cluster cations can occupy A sites in multinary metal halides.

We report the rst co-crystals of TCNQ and TCNB based on orthocetamol, a regioisomer of paracetamol. Through a simple solution growth process, co-crystals were produced containing orthocetamol as electron donors, with co-formers of either 7,7,8,8-tetracyanoquinodimethane (TCNQ) or 1,2,4,5-tetracyanobenzene (TCNB), as electron acceptors. Due to sub-micron crystalline domains, 3D electron di raction was employed for structure solution in both systems. This revealed that both systems crystallise in a 1:1 stoichiometry, in which orthocetamol forms a backbone allowing for linking of acceptor molecules in a mixed-stack con guration. Orthocetamol-TCNQ adopts an non-centrosymmetric Pc symmetry, and orthocetamol-TCNB a centrosymmetric P-1 symmetry. UV-Vis and FT-IR were employed to probe the ability of these co-crystals to create CT systems, revealing a low degree of charge transfer. Still, the possibility to use orthocetamol backbone as structural sca old paves the way for an entirely new class of CT materials.

The new mineral jingsuiite (TiB2, IMA-2018-117b), together with osbornite-khamrabaevite solid solution (TiN-TiC), deltalumite, and a potential new mineral, hexagonal Ti10(Si,P,☐)7, constitute four inclusions up to 50 μm across in corundum recovered from the Cr-11 podiform chromitite orebody near Kangjinla, Luobusa ophiolite, Tibet, China. EELS, EDS, and 3D electron diffraction were applied to study the phases. In one inclusion, jingsuiite forms a rounded grain 40 μm across. Associated osbornite-khamrabaevite solid solution forms an irregular mass up to 10 μm across having the composition Ti(N0.5C0.5) and the Ti10(Si,P,☐)7 phase forms an incomplete overgrowth up to 20 μm thick around the grain of jingsuiite. In a second inclusion, jingsuiite, osbornite-khamrabaevite solid solution, Ti10(Si,P,☐)7 and deltalumite form a lamellar intergrowth 100 μm long composed of tablets of the four phases up to 50 μm long × 4 μm in thickness. Jingsuiite has a primitive hexagonal cell with a = 3.04(6), b = 3.04(6), c = 3.22(6) Å, α = 90°, β = 90°, γ = 120°, V = 25.8 (9) Å3, space group P6/mmm, Z = 1. Its structure was determined ab initio and dynamically refined on the basis of three-dimensional electron diffraction data; it is equivalent to that of synthetic TiB2. Results of EELS analyses of jingsuiite in foil no. 5357 (N = 20) gave B 61.87(1.22), C 1.53 (1.26), Ti 36.62 (1.45) at% from which an empirical formula of Ti1.10(B1.86C0.05)Σ1.91 was calculated on the basis of 3 atoms. The ideal formula is TiB2. Our preferred scenario is that corundum with entrapped Ti-Si-P-Fe intermetallic melts was precipitated from basaltic magmas during exhumation following deep subduction. Enrichment of B in the melt pockets is attributed to the highly reducing conditions that led to the segregation of siderophile elements into intermetallic melts and to the siderophile behavior of B, thereby concentrating it in the intermetallic melts in preference to silicate melt. Experimental work on the Ti-Fe-Si system indicates that minerals enclosed in corundum grains such as Ti, FeTiSi2, and TiSi2 could have crystallized from alloy melts at the lowest T accessible on the liquidus, i.e.

Herein we demonstrate the prowess of the 3D electron diffraction approach by unveiling the structure of terrylene, the third member in the series of peri‐condensed naphthalene analogues, which has eluded structure determination for 65 years. The structure was determined by direct methods using electron diffraction data and corroborated by dispersion‐inclusive density functional theory optimizations. Terrylene crystalizes in the monoclinic space group P21/a, arranging in a sandwich‐herringbone packing motif, similar to analogous compounds. Having solved the crystal structure, we use many‐body perturbation theory to evaluate the excited‐state properties of terrylene in the solid‐state. We find that terrylene is a promising candidate for intermolecular singlet fission, comparable to tetracene and rubrene., Terylene for singlet fission? 3D electron diffraction (ED) is used to overcome a gap in the crystallographic knowledge, by reporting the first structural solution of terylene. Cutting‐edge computational analysis show that terylene has the potential to act as an effective singlet fission chromophore. This represents a substantial milestone in evolution of 3D ED, by demonstrating that hitherto unobtainable structures can be used in the prediction of physical properties of functional materials.

The incommensurately modulated crystal structure of the mineral daliranite has been determined using 3D electron diffraction data obtained on nanocrystalline domains. Daliranite is orthorhombic witha= 21,b= 4.3,c= 9.5 Å and shows modulation satellites alongc. The solution of the average structure in thePnmaspace group together with energy-dispersive X-ray spectroscopy data obtained on the same domains indicate a chemical formula of PbHgAs2S5, which has one S fewer than previously reported. The crystal structure of daliranite is built from columns of face-sharing PbS8bicapped trigonal prisms laterally connected by[2+4]Hg polyhedra and (As3+2S5)4−groups. The excellent quality of the electron diffraction data allows a structural model to be built for the modulated structure in superspace, which shows that the modulation is due to an alternated occupancy of a split As site.

Orthocetamol is a regioisomer of the well-known pain medication paracetamol and a promising analgesic and an anti-arthritic medicament itself. However, orthocetamol cannot be grown as single crystals suitable for X-ray diffraction, so its crystal structure has remained a mystery for more than a century. We report here the ab-initio structure determination of orthocetamol obtained by 3D electron diffraction, combining a low dose acquisition method and a dedicated single electron detector for recording the diffracted intensities. The structure is monoclinic, with a pseudo-tetragonal cell that favors multiple twinning on a scale of a few tens of nanometers. The successful application of 3D electron diffraction to orthocetamol introduces a new gold standard of total structure solution in all cases where X-ray diffraction and electron microscope imaging methods fail.

Stepwise nanobeam precession-assisted electron diffraction allows the structure determination of macromolecular nanocrystals, while limiting radiation damage. A new monoclinic polymorph of lysozyme was revealed and analyzed., Recent advances in 3D electron diffraction have allowed the structure determination of several model proteins from submicrometric crystals, the unit-cell parameters and structures of which could be immediately validated by known models previously obtained by X-ray crystallography. Here, the first new protein structure determined by 3D electron diffraction data is presented: a previously unobserved polymorph of hen egg-white lysozyme. This form, with unit-cell parameters a = 31.9, b = 54.4, c = 71.8 Å, β = 98.8°, grows as needle-shaped submicrometric crystals simply by vapor diffusion starting from previously reported crystallization conditions. Remarkably, the data were collected using a low-dose stepwise experimental setup consisting of a precession-assisted nanobeam of ∼150 nm, which has never previously been applied for solving protein structures. The crystal structure was additionally validated using X-ray synchrotron-radiation sources by both powder diffraction and single-crystal micro-diffraction. 3D electron diffraction can be used for the structural characterization of submicrometric macromolecular crystals and is able to identify novel protein polymorphs that are hardly visible in conventional X-ray diffraction experiments. Additionally, the analysis, which was performed on both nanocrystals and microcrystals from the same crystallization drop, suggests that an integrated view from 3D electron diffraction and X-ray microfocus diffraction can be applied to obtain insights into the molecular dynamics during protein crystal growth.

Coesite in impact rocks is traditionally considered a retrograde product formed during pressure release by the crystallisation of an amorphous phase (either silica melt or diaplectic glass). Recently, the detailed microscopic and crystallographic study of impact ejecta from Kamil crater and the Australasian tektite strewn field pointed in turn to a different coesite formation pathway, through subsolidus quartz-to-coesite transformation. We report here further evidence documenting the formation of coesite directly from quartz. In Kamil ejecta we found sub-micrometric single-coesite-crystals that represent the first crystallization seeds of coesite. Coesite in Australasian samples show instead well-developed subeuhedral crystals, growing at the expenses of hosting quartz and postdating PDF deformation. Coesite (010) plane is most often parallel to quartz {10–11} plane family, supporting the formation of coesite through a topotactic transformation. Such reaction is facilitated by the presence of pre-existing and shock-induced discontinuities in the target. Shock wave reverberations can provide pressure and time conditions for coesite nucleation and growth. Because discontinuities occur in both porous and non-porous rocks and the coesite formation mechanism appears similar for small and large impacts, we infer that the proposed subsolidus transformation model is valid for all types of quartz-bearing target rocks.

We report the effect of pressure on a membrane made of dense electrospun NASICON-like Li1.3Al0.3Ti1.7(PO4)3 (LATP). The properties and performance of the pressed LATP nanofibers were investigated and compared with those of pristine LATP nanofibers. While the applied pressure affects the purity and homogeneity of LATP, it is beneficial for ionic transport across the solid electrolyte. The presence of impurity phases as well as the decrease of porosity results in a two order of magnitude higher ionic conductivity at room temperature (3 × 10−5 S cm−1) which is promising to replace bulk NASICON materials in energy storage devices.

We analysed the heterogenous fine-grained (sub-μm) matrix of a small (58 × 93 μm), unmelted and minimally heated (

In the past few years, many exciting papers reported results based on crystal structure determination by electron diffraction. The aim of this review is to provide general and practical information to structural chemists interested in stepping into this emerging field. We discuss technical characteristics of electron microscopes for research units that would like to acquire their own instrumentation, as well as those practical aspects that appear different between X-ray and electron crystallography. We also include a discussion about applications where electron crystallography provides information that is different, and possibly complementary, with respect to what is available from X-ray crystallography.

Gold nanomaterials have been recognized as considerably active and effective catalysts toward several industrial and environmentally relevant reactions, among which are hydrocarbon selective oxidation, CO oxidation and propylene epoxidation. Engineered nanomaterials may be able to suppress some of the more severe issues that block their industrial applicability, such as recyclability, catalytic activity reduction during time due to sintering effects or leakage of the active material. In this regard, the composition of hybrid nanomaterials comprising encapsulated ultrasmall gold nanoparticles, also called ultrasmall-in-nano, will broaden and enhance their potential catalytic applications by including synergic features. Here, we report a systematic investigation on the design and production of optimized titania-decorated gold nano-architectures together with their efficiency evaluation on both formic acid (thermo/photo-induced) decomposition and cyclic carbonates formation by carbon dioxide fixation for carbon capture and storage technology. This work paves the way for the next development of ultrasmall-in-nano catalysts bearing an early–late transition metal combination for sustainable processes.

The pharmaceutical metaxalone (MTX) was obtained as a conglomerate Form A-R/S, via a newly reported crystallization method exploiting volatile deep eutectic solvents. Homochiral crystals of Form A-S, could previously be obtained only by crystallization from enantiopure MTX, synthesized from enantiopure starting materials, and never from a racemic solution of MTX. Homochiral crystals of Form A-R were obtained here concomitantly for the first time. Powder X-ray diffraction and chiral high performance liquid chromatography were used to infer that the structure of the crystals obtained were a conglomerate relating to the known Form A-S. However, this pathway results in exclusively micron-sized needles, below typical structural solution size, and so 3D electron diffraction, combining low-dose continuous acquisition and a dedicated single-electron detector was used for ab-initio structural solution of Form A-R/S. Crystallization via volatile deep eutectic solvents allowed the structural landscape of metaxalone to be further explored, adding a point to its phase diagram. This example highlights the possibility for symbiotic relationships between structural solution via electron diffraction and crystallisation pathways which do not result in crystals of a suitable size and quality for single-crystal X-ray diffraction.

Titanium minerals enclosed in corundum separated from the Cr-11 orebody include native Ti, zamboite (FeTiSi 2 ), osbornite (TiN)-khamrabaevite (TiC) solid solutions, and jingsuiite (TiB 2 ), as well as the new minerals badengzhuite (TiP) and zhiqinite (TiSi 2 ) and two potentially new minerals, Ti 11 (Si,P )10 and Ti 10 (Si,P, □)7 , where □ indicates a vacancy. These minerals together constitute a spheroid 20 µ m across inferred to have crystallized from a droplet of Ti–Si–P intermetallic melt. Energy-dispersive spectroscopy and three-dimensional electron diffraction were applied to characterize the two new minerals. Badengzhuite has a primitive hexagonal cell with a=3.49(7) A, c=11.70(23) A, V=124(4) A 3 , and crystallizes in space group P 6 3∕mmc ( Z=4 ). It is isostructural with synthetic TiP. Two EDX (energy dispersive X-ray spectroscopy) analyses of badengzhuite gave 60.56 wt %Ti and 39.44 wt % P and 62.74 wt % Ti and 37.26 wt % P from which an empirical formula of Ti 1.020 P 0.980 was calculated on the basis of two atoms (ideally TiP). Zhiqinite has a primitive orthorhombic cell with a=8.18(16) A, b=4.85(10) A, c=8.42(17) A, V=334(12) A 3 , and crystallizes in space group Fddd ( Z=8 ). It is isostructural with synthetic TiSi 2 (C54 type). Four EDX analyses of zhiqinite gave 39.58–44.79 wt % Ti and 55.21–60.42 wt % Si, from which an empirical formula of Ti 0.905 Si 2.095 was calculated on the basis of three atoms (ideally TiSi 2 ). We suggest that interaction of mantle-derived CH 4 + H 2 fluids with basaltic magmas in the shallow lithosphere (depths of ∼ 30–100 km) under conditions more reducing than 6 log units below the oxygen fugacities corresponding to the iron–wustite buffer resulted in precipitation of corundum that entrapped intermetallic melts, some of which crystallized to ultra-reduced Ti–P–Si phases. Experimental work on the Ti–Si and Ti–P systems indicates that the minerals enclosed in corundum could have crystallized from the alloy melt at the lowest temperature accessible on the liquidus. It has been alleged that these ultra-reduced phases are anthropogenic contaminants inadvertently introduced with fused alumina abrasive during preparation of mineral separates. Nonetheless, we conclude that the differences between the ultra-reduced minerals in the separates and the ultra-reduced phases in fused alumina are more convincing evidence for these minerals having a natural origin than the similarities between them are evidence for an anthropogenic origin.

The crystal structure of the mineral decrespignyite-(Y) from the Paratoo copper mine (South Australia) has been obtained by applying δ recycling direct methods to 3D electron diffraction (ED) data followed by Rietveld refinements of synchrotron data. The unit cell is a= 8.5462(2), c= 22.731(2) Å and V= 1437.8(2) Å3, and the chemical formula for Z=1 is (Y10.35REE1.43Ca0.52Cu5.31)Σ17.61(CO3)14Cl2.21(OH)16.79⋅18.35H2O (REE: rare earth elements). The ED data are compatible with the trigonal P3¯m1 space group (no. 164) used for the structure solution (due to the disorder affecting part of the structure, the possibility of a monoclinic unit cell cannot completely be ruled out). The structure shows metal layers perpendicular to [001], with six independent positions for Y, REE and Cu (sites M1 to M4 are full, and sites M5 and M6 are partially vacant), and two other sites, Cu1 and Cu2, partially occupied by Cu. One characteristic of decrespignyite is the existence of hexanuclear (octahedral) oxo-hydroxo yttrium clusters [Y6(μ6-O)(μ3-OH)8O24] (site M1) with the 24 bridging O atoms belonging to two sets of symmetry-independent (CO3)2− ions, with the first set (2×) along a ternary axis giving rise to a layer of hexanuclear clusters and the second set (6×) tilted and connecting the hexanuclear clusters with hetero-tetranuclear ones hosting Cu, Y and REE (M2 and M3 sites). The rest of the crystal structure consists of two consecutive M3 + M4 layers containing the partially occupied M5, M6, and Cu2 sites and additional carbonate anions in between. The resulting structure model is compatible with the chemical analysis of the type material which is poorer in Cu and richer in (REE, Y) than the above-described material., This research received financial support from the Spanish MINECO (project RTI2018-098537-B-C21), from FEDER and from the European Union Fund for Regional Development POCTEFA (grant no. EFA 194/16 TNSI). We acknowledge support for the publication fee from the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).

Metastable polymorphs typically display higher solubility than their thermodynamically stable counterparts, whilst having dissimilar mechanical and biopharmaceutical properties. It is unsurprising then, that generic and innovator companies alike pursue isolation and characterisation of these materials. Here we report the determination of the crystal structure of the metastable form II of loratadine using a combination of low-resolution 3D electron diffraction data and density functional theory. Importantly, electron diffraction was able to establish that the crystallites were phase pure i.e. no other polymorphic forms were identified throughout the sample. 3D data collected at room temperature circumvented potential phase changes, conveniently preserving the metastable polymorph during structural elucidation. The limited resolution of the electron diffraction data (>1 A), combined with the complexity of configurational disorder and possible beam-induced amorphization, meant that the structure could not be obtained by ab initio direct methods. This is a recurrent situation for nanocrystalline pharmaceutical crystals. Instead, two possible starting models arose from simulated annealing based on diffraction data alone. Density functional theory energy minimisation followed, determining the correct model, with an independent validation of the experimental structural solution, comparing favourably to single-crystal X-ray diffraction studies. Our results reveal a promising protocol enabling the exploitation of electron diffraction data with limited resolution obtained from beam sensitive organic materials. The method is widely extendable to a number of pharmaceutical compounds that are not amenable for the growth of large single crystals required by X-ray diffraction, and for which efficient structure determination is required.

The carbon arc in liquid benzene produces carbon dust in addition to phenylacetyene and a number of other molecular products. The carbon dust was analyzed by Transmission Electron Microscopy (TEM), electron diffraction and Raman spectroscopy, revealing that it consists of a highly structured carbon black with high surface area. The carbon dust from benzene arc was also analyzed with FT-IR spectroscopy suggesting stricking spectral analogy with a mature coal infrared spectrum. During benzene arcing, phenylacetyene undergoes a free radicals induced polymerization to a low molecular weight poly(phenylacetylene).

The crystal structures of two important marketed pharmaceuticals, namely, ramelteon (RAM) and tolvaptan (TOL), were determined for the first time using 3D precession electron diffraction tomography (PEDT) on 500 nm-sized crystals. The results were compared with the same structures determined by single-crystal X-ray diffraction on subsequently grown 50–200 μm single crystals, indicating a good match of molecular conformation, crystal packing, and unit cell parameters. The X-ray crystal structures were used to validate the developed workflow of data acquisition and structure solution with electron diffraction. This study highlights that 3D PEDT alone is able to provide accurate crystal structures from pharmaceutical nanocrystals that will suffice for most practical applications when no larger crystals can be grown.

This article analyzes the use of supercritical CO2 green technology in the reactive crystallization processes involved in the formation of a bioMOF that contains curcumin and ZnII metal centers. A new phase with a [Zn(curcumin)]n composition, termed sc-CCMOF-1, is presented. The developed scCO2 protocol allows high yields of the small-sized crystalline material, which was characterized by the use of the recently developed electron diffraction tomography method applied to the resolution of submicrometric crystals. A remarkable 3D macrostructure with a complex morphology was obtained. To analyze the crystallization mechanism, multiple identical runs were performed under similar experimental conditions to study in each time period the crystal growth progress ex situ by X-ray diffraction and scanning electron microscopy. These experiments indicated that the process to achieve the sc-CCMOF-1 in a crystalline form involves the formation of amorphous or semicrystalline metastable phases that derived into hierarc...

The structure solution of the δ-polymorph of indomethacin was obtained using three-dimensional electron diffraction. This form shows a significantly enhanced dissolution rate compared with the more common and better studied α- and γ-polymorphs, indicating an increased bioavailability for medicinal applications. The structure was solved in non-centrosymmetric space group P21 and comprises two molecules in the asymmetric unit. Packing and molecule conformation closely resemble indomethacin methyl ester and indomethacin methanol solvate. Knowledge of the structure allowed the rational interpretation of spectroscopic IR and Raman data for δ-polymorph and a tentative interpretation for still unsolved indomethacin polymorphs. Finally, we observed a solid-solid transition from δ-polymorph to α-polymorph that can be driven by similarities in molecular conformation.

An effort to synthesize the Cu(I) variant of a lead-free double perovskite isostructural with Cs2AgInCl6 resulted in the formation of Cs3Cu4In2Cl13 nanocrystals with an unusual structure, as revealed by single-nanocrystal three-dimensional electron diffraction. These nanocrystals adopt a A2BX6 structure (K2PtCl6 type, termed vacancy ordered perovskite) with tetrahedrally coordinated Cu(I) ions. In the structure, 25% of the A sites are occupied by [Cu4Cl]3+ clusters (75% by Cs+), and the B sites are occupied by In3+. Such a Cs3Cu4In2Cl13 compound prepared at the nanoscale is not known in the bulk and is an example of a multinary metal halide with inorganic cluster cations residing in A sites. The stability of the compound was supported by density functional theory calculations that also revealed that its bandgap is direct but parity forbidden. The existence of the Cs3Cu4In2Cl13 structure demonstrates that small inorganic cluster cations can occupy A sites in multinary metal halides., We report the synthesis of Cs3Cu4In2Cl13 nanocrystals with a vacancy ordered A2BX6 perovskite structure, in which Cu(I) ions are tetrahedrally coordinated. In this new structure (determined by single-nanocrystal three-dimensional electron diffraction), 25% of the A sites are occupied by [Cu4Cl]3+ clusters (75% by Cs+), while the B sites are occupied by In3+. Such a compound, not known in the bulk, is the first case of a perovskite-related structure with inorganic cluster cations residing in A sites.