Crystallization Conditions Research Articles

Experimental Modeling of the Mantle–Slab Interaction in the Metal–Carbonate System, Conditions of Crystallization and Indicator Characteristics of Diamond

Abstract —Experimental studies aimed at determining the conditions for the formation of diamond and graphite as a result of the redox interaction of reduced mantle rocks and oxidized rocks of the slab in a wide temperature range, including the conditions of both “cold” and “hot” subduction, were carried out on a “split-sphere” multianvil high-pressure apparatus (BARS) in the (Fe,Ni)–(Mg,Ca)CO3 system, at 6.3 GPa and 800–1550 °C for 35–105 h, using the “sandwich” assembly. We have established that the interaction of Fe,Ni metal and carbonate is due to the creation and propagation of a redox front, at rates from 1.3 (800 °C) to 118 μm/h (1550 °C). At T < 1200 °С, this interaction leads to the formation of alternating reaction zones (from the reduced center to the oxidized periphery): metal → metal + wüstite/magnesiowüstite → magnesiowüstite + graphite ± Mg,Fe,Ca carbonates → magnesite + aragonite. In this case, in the reduced part of the samples, the formation of a Ni,Fe metal phase strongly enriched in Ni (up to 65–70 wt.% vs. the initial 10 wt.%) was recorded. At higher temperatures, the formation of Fe,Ni metal–carbon (≥1200 °C) and carbonate (≥1330 °C) melts was observed. We have found that the presence of nickel precludes the formation of carbides in the reduced part of the sample and ensures stable diamond crystallization at 1400–1550 °C both in metal–carbon and carbonate melts. Our experiments demonstrate that diamonds from the metal–carbon melt are characterized by inclusions of taenite and magnesiowüstite. The morphology of these diamonds is determined by the {111} layer-by-layer grown faces, and their indicator characteristics are nitrogen–vacancy and nickel-related (884 nm) centers at 1400 °C or nickel–nitrogen centers (S3, 598 nm, 727 nm, 746 nm, etc.) at 1550 °C. For diamonds formed in the carbonate melt, the morphology is determined by the {100} and {111} (vicinal-growth) faces; carbonates are identified as inclusions; and nitrogen–vacancy centers H3, NV0, and NV– are fixed in the photoluminescence spectra. Experiments show that the indicator of the metal–carbonate interaction temperature is the degree of structural perfection of graphite, which increases in the range of 800–1550 °C.

Ultrafast Infrared Laser Crystallization of Amorphous Si/Ge Multilayer Structures.

Silicon-germanium multilayer structures consisting of alternating Si and Ge amorphous nanolayers were annealed by ultrashort laser pulses at near-infrared (1030 nm) and mid-infrared (1500 nm) wavelengths. In this paper, we investigate the effects of the type of substrate (Si or glass), and the number of laser pulses (single-shot and multi-shot regimes) on the crystallization of the layers. Based on structural Raman spectroscopy analysis, several annealing regimes were revealed depending on laser fluence, including partial or complete crystallization of the components and formation of solid Si-Ge alloys. Conditions for selective crystallization of germanium when Si remains amorphous and there is no intermixing between the Si and Ge layers were found. Femtosecond mid-IR laser annealing appeared to be particularly favorable for such selective crystallization. Similar crystallization regimes were observed for both single-shot and multi-shot conditions, although at lower fluences and with a lower selectivity in the latter case. A theoretical analysis was carried out based on the laser energy absorption mechanisms, thermal stresses, and non-thermal effects.

Partial crystallization in a Zr-based bulk metallic glass in selective laser melting

Metals and alloys in amorphous state are promising for the use as structural and functional materials due to their superior properties related to the absence of such defects as grain boundaries and dislocations. Obtaining the amorphous state requires quenching from liquid state with a high cooling rate. In conventional technologies, this is the reason for a considerable size limitation hindering application of amorphous alloys. Additive manufacturing (AM) is free of the size limitation. The so-called bulk metallic glass (BMG) alloys have extremely low critical cooling rates and can be used in AM. Recent studies on AM from Zr-based BMGs by selective laser melting (SLM) has proved the possibility of attaining the amorphous state and revealed partial crystallization to be the principal drawback of this process. The present work aims to analyze the conditions for partial crystallization and attempts to control it by optimizing the process parameters. A comprehensive parametric analysis is accomplished in single-track SLM experiments with Zr-based BMG alloy Vit 106. The observed microstructures are related to the temperature fields and thermal cycles estimated by an analytic heat-transfer model in the laser-impact zone. In the cross section of a laser track, a central bright domain is identified as the remelted zone. An annular darker crystallization zone encircles the remelted zone. The model fits the experimentally obtained dependencies of the remelted zone size versus laser power and scanning speed and indicates that 43 ± 2% of the incident laser energy is transferred into the substrate thermal energy. The principal energy losses are reflection of the incident laser radiation and material evaporation. Primary crystalline inclusions existing in the substrate before laser processing dissolve at the laser melting. The mean cooling rate in the remelted zone is up to 4 orders of magnitude greater than the critical cooling rate. Therefore, homogeneous nucleation is not expected. Nevertheless, the theoretically estimated crystallization times are sufficient for a considerable crystal growth in the heat-affected zone where primary crystalline inclusions and nuclei are not completely dissolved.

The origin of olivine basalts from Medvezhya Mount (Avachinsky group of volcanoes, Kamchatka): The evidence of assimilation of sulfide-bearing cumulates

The role and conditions of liquid immiscibility and crystallization of sulfide phase during evolution of subduction related magmas remains to be a debated topic, which bears relevance to mechanisms of porphyry copper deposit formation and evolution of the continental crust. We studied rare volcanic rocks with inclusions of magmatic sulfides in olivine – the basalts of Medvezhya Mount in the Avachinsky group of volcanoes. The rocks belong to primitive (Mg# = 66 mol. %) middle-K island arc olivine basalts. Olivine with normal zoning predominate (~98%) among phenocrysts. The olivine compositions are typical for Kamchatka basalts, except for an unusual trend of increase of MnO content from 0.20 to 0.55 wt. % and decrease of Fe/Mn from 60 to 35 with change of olivine composition from Fo87.8 to Fo78.2. Olivines of this group contain numerous inclusions of minerals of the spinel group varying in composition from chromium spinel to magnesian magnetite. Olivine phenocrysts with sulfide inclusions are characterized by the absence or weak reverse zoning and reduced contents of Ca, Ni, Mn, Cr, and Al. The estimated crystallization temperatures for olivines of the prevailing type are 1036–1241°C, for sulfide-bearing olivines – 1010–1062°C. The data suggest that crystallization of the main olivine population occurred under relatively shallow conditions and was accompanied by strong oxidation of the magmas. On the contrary, the zoning and composition features of sulfide-bearing olivine suggest its xenogenic origin and probable crystallization at conditions of deep crust from low temperature water-rich and/or low-Ca magmas. The results obtained confirm the possibility of saturation of oxidized island-arc magmas with sulfide phase at lower crustal conditions, but show that this process is rare and not typical for low-pressure crystallization stage.

Cage versus sheet: Probing the Determinants of Protein – Cucurbit[7]uril Crystalline Architectures

The donut-shaped cucurbit[n]urils (Qn) are a class of rigid macrocyclic receptor with protein recognition capabilities. Qn encapsulation of amino acid side chains can enable protein assembly. Recently, cucurbit[7]uril (Q7) has been applied as a molecular glue for organizing protein building blocks into crystalline architectures. Q7 co-crystallization with dimethylated Ralstonia solanacearum lectin (RSL*) has yielded novel crystalline architectures. Co-crystallization of RSL* and Q7 yields either cage- or sheet-like architectures which may be modulated via protein engineering. However, questions remain as to the factors dictating the formation of one architecture over another (cage versus sheet). Here, we make use of an engineered RSL*-Q7 system which co-crystallizes as the cage or sheet assembly with easily-distinguished crystal morphologies. Using this model system, we probe how the crystallization conditions dictate which crystalline architecture is adopted. Protein-ligand ratios and the sodium concentration were identified as key determinants for the growth of the cage versus sheet assemblies.

Engineering CsPbX3 (X = Cl, Br, I) Quantum Dot-Embedded Borosilicate Glass through Self-Crystallization Facilitated by NaF as a Phosphor for Full-Color Illumination and Laser-Driven Projection Displays.

All inorganic perovskite (CsPbX3, X = Cl, Br, I) quantum dot (QD) glass samples are considered the next generation of lighting materials for their excellent luminescence properties and stability, but crystallization conditions are difficult to control, which often leads to the inhomogeneous crystallinity of QDs. Here, we provided evidence that the presence of sodium fluoride induced self-crystallization of CsPbBr3 QDs during routine glass formation without the need for additional heat treatment. We showed that NaF simultaneously affected the network structure of glass and promoted the formation of CsPbBr3 QDs, that is, Na+ ions entered the glass network skeleton, partially interrupting the network structure, while the strong electronegativity of F- ions attracted Cs+ and Pb2+ ions into the gaps formed in the glass networks that had been loosened up by Na+ ions, which reduced the activation energy of crystallization processes. Our results showed that NaF-induced CsPbBr3 QDs glass had excellent thermal stability, high photoluminescence quantum efficiency (49%), and luminescent stability under high-power laser irradiation. Finally, this work also demonstrated the general applicability of this method in the making of a series of CsPbX3 (X = Cl, Br, I) QD glass samples by NaF-induced self-crystallization, which drastically expanded the color gamut to a range of full spectrum for luminescence and laser-driven projection displays. We believe that the work presented here represents a new direction for the research and development of full-color gamut inorganic perovskite quantum dot glass samples, which could have a significant impact on the future applications of laser-driven projection displays as well.

Insights into the self-assembly of fampridine hydrochloride: how the choice of the solvent affects the crystallization of a simple salt

Abstract Crystalline materials and crystallization processes play an important role in several fields of science, such as pharmaceuticals, material science, pigments, optoelectronics, catalysis and energy storage. Understanding and defining the right conditions of crystallization is therefore crucial. Among the several factors influencing the crystallization of a given compound, the choice of the solvent system is perhaps one of the most important. The nature of solvent–solute interactions can indeed have a role in promoting specific molecular assemblies, therefore affecting crystallisation rates of a crystal and often resulting in the nucleation of different polymorphs and solvates. Here we investigated the role of a binary mixture of solvent (water/acetone) in the crystallisation of a simple salt of 4-aminopyridinium chloride. Previous results on this compound showed that when crystallised from water it forms a simple hydrate structure, while in the presence of acetone, it undergoes a liquid-liquid phase separation, followed by the crystallisation of a complex structure belonging to the Frank–Kasper (FK) phases, a particular family of topologically close-packed structures never observed in small and rigid molecules. To broaden the understanding of how such a simple molecule may crystallise as an FK phase, we carried out the crystallization of the complex phase by antisolvent diffusion (in a mixture of water/acetone) and that of the monohydrate phase in water, monitoring the liquid precursors by liquid-state NMR. In particular, we applied 1H, 13C, 14N, 17O, and 35/37Cl NMR as a function of the concentration of 4APH+Cl− until the moment when precipitation of the crystalline phases occurred. Variations of chemical shifts, T1 relaxation times of 13C signals, and full-width at half-maximum of the signals of quadrupolar nuclei were also measured. The spatial proximity between the different species in the solution was investigated by NOE experiments. In order to support these results, we also performed Molecular Dynamics simulations, investigating the potential solute/solvents interactions. The results strongly suggest that acetone, instead of behaving as an anti-solvent, interacts directly with the solute, preventing the formation of the simple monohydrate structure and, at the same time, promoting specific molecular aggregations.

Polymorphic triphenylamine derivative showing aggregation-induced emission and high-contrast mechanical force-induced blue shift

Mechanical force-induced, high-contrast blue-shift luminescent mechanochromic (MC) molecules have rarely been reported. Herein, we designed and synthesized an AIE luminogens (AIEgens) triphenylamine derivative N, N-diphenyl-4-(6-phenyl-[2,2′-bipyridin]-4-yl)aniline (DPTPA). Three different emission wavelengths from blue crystals (B-DPTPA), sky-blue crystals (S-DPTPA), and green crystals (G-DPTPA) were obtained by culturing the crystals under different crystallization conditions. All three crystal polymorphs showed high solid luminescent efficiency, each of which was sensitive to external pressure and was accompanied by significant fluorescence blue shift. Under a mechanical force, B-DPTPA shows a 12 nm blue shift, S-DPTPA fluorescence color changed from sky-blue to blue with an increase emission and G-DPTPA changed its color from green (510 nm) to sky-blue (428 nm) with an 82 nm blue shift. Such obvious color change and large blue shift were rarely been reported. Characterization of the photophysical properties, theoretical calculations, hydrostatic pressure, powder X-ray diffraction and X-ray single crystal structures showed that three crystal polymorphs of DPTPA originated from single molecules, space interactions, molecular pairs (dimers), and the blue shift of B-DPTPA, S-DPTPA, G-DPTPA were ascribed to the solid-state morphology transition from crystal to amorphous due to the destruction of space interactions and dimers. This study provides the relationship between the molecular packings and the blue shift emission of AIEgens materials under mechanical forces is understood in the molecular level.

Preparation of ultra-pure ammonium metavanadate via heterogeneous self-assembly crystallization

Although the demand for ultra-pure V2O5 in industry is significant, the current technologies used to obtain the principal precursor, ammonium metavanadate, in high purity are costly and low-yielding. In this study, a cost-efficient and high-yielding heterogeneous self-assembly crystallization (HSC) process is proposed for obtaining large, high-purity NH4VO3 crystals. The method entails establishing a wide crystallization window, controlling the NH3 mass transfer rate and buffering the pH of the mother liquor with CO2 released during the pyrolysis of the ammonia source, (NH4)2CO3 to achieve the separation of chromium impurities, the most difficult-to-remove impurities in vanadium products, from the chromium-containing NaVO3 solution, and purification of NH4VO3 via reactive crystallization. Under the optimized crystallization conditions, namely an N/V mass ratio of 3.9, temperature of 60 °C, and pH of 12.5, the yield and purity of the obtained NH4VO3 in 20 g·L−1 V(V) simulated solution containing 0.05 g·L−1 Cr(VI) reached 93.09% and 99.99%, respectively, and the obtained NH4VO3 crystals were as large as 1.8 mm in size. In the case of a real leaching solution, the NH4VO3 yield and purity were higher than 80% and 99.99%, respectively, and the purity of final V2O5 reached 99.99%. The curbed pyrolysis rate of (NH4)2CO3 ensures heterogeneous nucleation and slow growth of NH4VO3 crystals to acquire large and pure crystals, and the excessive adsorption of Cr(VI) onto the crystal surface during self-assembly is avoided at the appropriate pH, thus guaranteeing efficient precipitation, crystallization, and purification. This study provides a reference strategy for the low-cost preparation to obtain high-purity V2O5.

Water stabilizes an alternate turn conformation in horse heart myoglobin

Comparison of myoglobin structures reveals that protein isolated from horse heart consistently adopts an alternate turn conformation in comparison to its homologues. Analysis of hundreds of high-resolution structures discounts crystallization conditions or the surrounding amino acid protein environment as explaining this difference, that is also not captured by the AlphaFold prediction. Rather, a water molecule is identified as stabilizing the conformation in the horse heart structure, which immediately reverts to the whale conformation in molecular dynamics simulations excluding that structural water.

Columbite–Tantalite from Northern Scandinavia (Kaustinen, Kolmozero) Pegmatites: An Optical and Spectroscopic Properties

LCT (lithium–cesium–tantalum) pegmatites from the Kaustinen and Kolmozero regions contain columbite–tantalite mineralization, which has been presented in this study. Crystal structure, Raman microscopy, and optical property analyses of these minerals were performed. As a result of the structural studies and micro-area analyses, it was determined that these minerals in the pegmatites in question constitute a solid solution with numerous Mn-Fe and Nb-Ta substitutions within a single crystal. The ratio between Mn-Fe and Nb-Ta can change from crystal to crystal, which makes it impossible to find precise stechiometry between these ions. The crystallization conditions of these minerals were also determined by studying the associations of other rock-forming minerals and accessory minerals in the discussed rocks.

Influence of the Aromatic Ligand Nature and Synthesis Conditions on the Structures of the Copper Pentafluorobenzoate Complexes

New pentafluorobenzoate (Рfb) copper complexes with 2,3- and 3,5-lutidine (2,3- and 3,5-Lut, respectively), quinoline (Quin), and 1,10-phenanthroline (Рhen) ([Cu2(MeCN)2(Рfb)4] (I), [Cu(2,3-Lut)2(Pfb)2] (II), [Cu(3,5-Lut)4(Pfb)2] (III), [Cu(Quin)2(Pfb)2] (IV), and [Cu2(Phen)2(Pfb)4] (V)) are synthesized by the newly developed methods and characterized. The unusual heteroanionic pentafluorobenzoate benzoate (Вnz) ionic compound [Cu2(Рhen)2(Рfb)3]+(Рnz)– (VI) is synthesized. It is shown that the four-bridge binuclear metal cage of complex I is not retained in the reactions with various pyridine derivatives. In the case of such α-substituted pyridines as 2,3-lutidine and quinoline, the compositions and structures of the final products of the reactions with copper pentafluorobenzoate are independent of the initial ratio of the reagents and crystallization conditions. It is revealed by the Hirshfeld surface analysis that π···π, C–F···π, C–H···F, and F···F interactions make the major contribution to the stabilization of crystal packings of the synthesized complexes.

Crystallization conditions of plagioclase in volcanic complexes of Sulawesi island, Pacific Ocean

Mineralogical and thermobarogeochemical studies allowed us to reveal the crystallization conditions of plagioclase in volcanic complexes of Sulawesi Island (Pacific Ocean). The composition of plagioclases indicates the presence of three types of melts, which were involved in the formation of plagioclase phenocrysts in basalts, andesites and dacites, as well as crystallites in the groundmass of andesites and dacites. The analysis of glasses of heated melt inclusions in plagioclase indicates the involvement of two contrasting melts (mafic and felsic) in crystallization of phenocrysts. At the final stages of volcanic processes, plagioclase in matrix of andesites and dacites formed from another felsic melts with maximum alkali content. The presence of primary syngenetic melt and fluid inclusions in plagioclase phenocrysts indicates the phase separation of felsic magmas, which led to the crystallization of feldspar phenocrysts of different composition during the formation of dacites. Computational modeling in a program (Putirka, 2008) based on the composition of plagioclases, glasses of heated inclusions and glasses from the groundmass allowed us to estimate the crystallization temperatures of feldspar phenocrysts in basalts (1160–1120 ?С), andesites (930–890 ?С) and dacites (1020–950 ?С), as well as the feldspar microcrystals in the groundmass of andesites (875–810 ?С) and dacites (890–850 ?С). Keywords: crystallization conditions, plagioclase, melt inclusions, Sulawesi Island, Pacific Ocean.

498 Structural Determination of the CqsR CACHE Domain and its Autoinducer

OBJECTIVES/GOALS: Our goal is to determine the structure of the CACHE domain of the Vibrio cholerae quorum sensing receptor CqsR as well as its autoinducer (AI). We are performing X-ray crystallography on the protein in its apo form, with the fractions containing the AI, and with known ligand ethanolamine (ETA). METHODS/STUDY POPULATION: We have transformed BL21(DE3) E. coli cells with a pTB146 vector to contain the gene for the CqsR CACHE domain. We grow these cells to high optical density and induce protein expression, at which point we harvest them and purify the protein. This entails lysing the cells, separating the protein with Ni-NTA resin, cleaving our protein tag, and column chromatography. With purified protein, high-throughput screens are set up to find crystallization conditions of apo CqsR, CqsR-ETA, and CqsR-AI. We then determine conditions that best lead to crystal formation and optimize them. Crystals are then diffracted with X-rays, process the data, and determine the structure of protein and AI. RESULTS/ANTICIPATED RESULTS: We anticipate finding the structure of the CqsR CACHE domain to a high resolution in addition to the identity of its autoinducer. Previous results found that the structure is homologous to another V. cholerae chemoreceptor, Mlp37, and we expect the results from this project to confirm this. In addition, we know that the autoinducer weighs approximately 62 daltons, the same as the known ligand, ethanolamine. Given that CACHE domains bind specifically to their ligands, we anticipate that the autoinducer will be structurally similar to ethanolamine. DISCUSSION/SIGNIFICANCE: The results will reveal the structure of the CqsR CACHE domain and its autoinducer. This knowledge will better allow researchers to treat cholera, as both autoinducer identity and receptor conformational changes will be uncovered, allowing for drug development to inhibit cell growth.

Two new cases of polymorphism in diagonally substituted rubrene derivatives.

The crystal structures of two rubrene derivatives, 5,11-diphenyl-6,12-bis-[4-(tri-fluoro-meth-yl)phen-yl]tetra-cene, C44H26F6, and 5,11-bis-(4-tert-butyl-phen-yl)-6,12-di-phenyl-tetra-cene, C50H44, are presented. Each are substituted on diagonal (5/11) phenyl rings. Each derivative has one polymorph reported previously. A discussion of the differences between each derivative and its previously reported polymorph is provided. The triclinic packing of the CF3-substituted structure is similar to the packing of the parent rubrene's triclinic polymorph. In the tert-butyl-substituted structure, a planar tetra-cene core formed, which has been hypothesized but never published. Crystallization conditions are provided as they differ from previous reports.

Crystallization kinetics of Hf28Be18Ti17Zr17Cu7.5Ni12.5 high-entropy bulk metallic glass

Crystallization kinetics of Hf28Be18Ti17Zr17Cu7.5Ni12.5 high-entropy bulk metallic glass (HE-BMG) in the non-isothermal and isothermal conditions were investigated by differential scanning calorimetry (DSC). In non-isothermal crystallization condition, DSC traces exhibited three crystallization processes. The apparent activation energies of peak crystallization temperatures were calculated by Kissinger methods and found to be Ep1 > Ep2 > Ep3. The dependence of local activation energy on crystallized volume fraction was summarized by the Kissinger-Akahira-Sunose (KAS) method. The non-isothermal crystallization reaction was described mathematically using the Šesták-Berggren model. In the isothermal crystallization condition, with the increase of annealing temperature, the incubation time and crystallization time become shorter and the crystallization peak becomes higher. All Avrami indices were less than 2.5, indicating that crystallization of glassy alloy is dominated by a diffusion-controlled three-dimensional growth with a decreasing nucleation rate.

Effect of ultrasonic-induced selenium crystallization behavior during selenium reduction

In this work, the crystallization process of selenium was accelerated by ultrasonic wave. The effects of ultrasonic waves and conventional conditions of selenium crystallization were compared to understand the effects of different conditions on crystallization, including ultrasonic time, ultrasonic power, reduction temperature, and H2SeO3 concentration. The mechanism of ultrasound affecting selenium crystallization was also investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The experimental results showed that ultrasonic time, ultrasonic power, and reduction temperature significantly influenced the crystallization process and morphology of selenium. Ultrasonic time had a large effect on the completeness (all products have been crystallized) and integrity of the crystallization of the products. Meanwhile, ultrasonic power and reduction temperature had no effect on the completeness of crystallization. However, it had a significant effect on the morphology and integrity of the crystallized products, and different morphologies of the nano-selenium materials could be obtained by changing the ultrasonic parameters. Both primary and secondary nucleation are important in the process of ultrasound-accelerated selenium crystallization. The cavitation effect and mechanical fluctuant effects generated by ultrasound could reduce the crystallization induction time and accelerate the primary nucleation rate. The high-speed micro-jet formed in the rupture of the cavitation bubble generated is the most important reason to influence the secondary nucleation of the system.

Influence of Crystallization Conditions on the As-Cast Structure of Fe-Mn-Si Alloy with a Shape Memory Effect

Nowadays, smart materials with special functional properties, in particular shape memory alloys, are widely used in more and more units of various equipment. Fe-based alloys of the Fe-Mn-Si-Cr-Ni-X system, due to their relatively low cost and sufficiently high manufacturability, can be widely used in various fields. It is shown that in the studied alloys, alloying elements can be divided into system-forming (10–30 wt.% Mn and 3–10 wt.% Si), and additional (Cr, Ni, V, N, Cu, etc.) elements, which add to improve the shape memory effect. It is shown that the one problem of Fe-SMAs is the evaporation of manganese in the melting. Criteria for the selection of alloys considering the temperature regime of melting with minimal evaporation of manganese and satisfactory overheating above the liquidus temperature have been developed. The Fe-35Mn-8Si alloy were produced at laboratory scale. The effect of the cooling rate during solidification on the structural heterogeneity of the test ingots poured into a cast iron chill mold and into a sand mold is studied. Using pin molds, in which conditions are created that inhibit the shrinkage of the solidifying ingot and provoke cracking, their resistance to hot cracks has been studied. The secondary dendrite arm spacings and the segregation coefficients of manganese and silicon were determined depending on the crystallization conditions. Critical parameters of the technology have been determined, the optimization of which makes it possible to produce Fe-SMAs at industrial scale.

A Heptacene Analogue Entailing a Quinoidal Benzodi[7]annulene (7/6/7 Ring) Core with a Tunable Configuration and Multiple Redox Properties.

Non-benzenoid acenes containing heptagons have received increasing attention. We herein report a heptacene analogue containing a quinoidal benzodi[7]annulene core. Derivatives of this new non-benzenoid acene were obtained through an efficient synthetic strategy involving an Aldol condensation and a Diels-Alder reaction as key steps. The configuration of this heptacene analogue can be modulated from a wavy to a curved one by just varying the substituents from a (triisopropylsilyl)ethynyl group to a 2,4,6-triisopropylphenyl (Trip) group. When mesityl (Mes) groups are linked to the heptagons, the resulting non-benzenoid acene displays polymorphism with a tunable configuration from a curved to a wavy one upon varying the crystallization conditions. In addition, this new non-benzenoid acene can be oxidized or reduced by NOSbF6 or KC8 to the respective radical cation or radical anion. Compared with the neutral acene, the radical anion shows a wavy configuration and the central hexagon becomes aromatic.

A Heptacene Analogue Entailing a Quinoidal Benzodi[7]annulene (7/6/7 Ring) Core with a Tunable Configuration and Multiple Redox Properties

AbstractNon‐benzenoid acenes containing heptagons have received increasing attention. We herein report a heptacene analogue containing a quinoidal benzodi[7]annulene core. Derivatives of this new non‐benzenoid acene were obtained through an efficient synthetic strategy involving an Aldol condensation and a Diels–Alder reaction as key steps. The configuration of this heptacene analogue can be modulated from a wavy to a curved one by just varying the substituents from a (triisopropylsilyl)ethynyl group to a 2,4,6‐triisopropylphenyl (Trip) group. When mesityl (Mes) groups are linked to the heptagons, the resulting non‐benzenoid acene displays polymorphism with a tunable configuration from a curved to a wavy one upon varying the crystallization conditions. In addition, this new non‐benzenoid acene can be oxidized or reduced by NOSbF6 or KC8 to the respective radical cation or radical anion. Compared with the neutral acene, the radical anion shows a wavy configuration and the central hexagon becomes aromatic.