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We study properties of nitrogen at high pressure and temperature (100–120 GPa, 2000–3000 K) where molecular and polymeric phases compete both in solid and liquid phase. We employ ab initio MD simulations with the SCAN functional and study the pressure-induced polymerization in liquid nitrogen for system sizes up to 288 atoms in order to reduce finite-size effects. The transition is studied upon both compression and decompression, and at 3000 K, it is found to take place between 110 and 115 GPa, coming close to experimental data. We also simulate the molecular crystalline phase close to the melting line and analyze its structure. We show that the molecular crystal in this regime is highly disordered, in particular, due to pronounced orientational and also translational disorder of the molecules. Its short-range order and vibrational density of states are very close to those of the molecular liquid revealing that the system likely represents a plastic crystal with high entropy. [ABSTRACT FROM AUTHOR]

The many-body expansion (MBE) is promising for the efficient, parallel computation of lattice energies in organic crystals. Very high accuracy should be achievable by employing coupled-cluster singles, doubles, and perturbative triples at the complete basis set limit [CCSD(T)/CBS] for the dimers, trimers, and potentially tetramers resulting from the MBE, but such a brute-force approach seems impractical for crystals of all but the smallest molecules. Here, we investigate hybrid or multi-level approaches that employ CCSD(T)/CBS only for the closest dimers and trimers and utilize much faster methods like Møller–Plesset perturbation theory (MP2) for more distant dimers and trimers. For trimers, MP2 is supplemented with the Axilrod–Teller–Muto (ATM) model of three-body dispersion. MP2(+ATM) is shown to be a very effective replacement for CCSD(T)/CBS for all but the closest dimers and trimers. A limited investigation of tetramers using CCSD(T)/CBS suggests that the four-body contribution is entirely negligible. The large set of CCSD(T)/CBS dimer and trimer data should be valuable in benchmarking approximate methods for molecular crystals and allows us to see that a literature estimate of the core-valence contribution of the closest dimers to the lattice energy using just MP2 was overbinding by 0.5 kJ mol−1, and an estimate of the three-body contribution from the closest trimers using the T0 approximation in local CCSD(T) was underbinding by 0.7 kJ mol−1. Our CCSD(T)/CBS best estimate of the 0 K lattice energy is −54.01 kJ mol−1, compared to an estimated experimental value of −55.3 ± 2.2 kJ mol−1. [ABSTRACT FROM AUTHOR]

The structural evolution with pressure of icy mixtures of simple molecules is a poorly explored field despite the fundamental role they play in setting the properties of the crustal icy layer of the outer planets and of their satellites. Water and ammonia are the two major components of these mixtures, and the crystal properties of the two pure systems and of their compounds have been studied at high pressures in a certain detail. On the contrary, the study of their heterogeneous crystalline mixtures whose properties, due to the strong N–H⋯O and O–H⋯N hydrogen bonds, can be substantially altered with respect to the individual species has so far been overlooked. In this work, we performed a comparative Raman study with a high spatial resolution of the lattice phonon spectrum of both pure ammonia and water–ammonia mixtures in a pressure range of great interest for modeling the properties of icy planets' interiors. Lattice phonon spectra represent the spectroscopic signature of the molecular crystals' structure. The activation of a phonon mode in plastic NH3-III attests to a progressive reduction in the orientational disorder, which corresponds to a site symmetry reduction. This spectroscopic hallmark allowed us to solve the pressure evolution of H2O–NH3–AHH (ammonia hemihydrate) solid mixtures, which present a remarkably different behavior from the pure crystals likely to be ascribed to the role of the strong H-bonds between water and ammonia molecules characterizing the crystallites' surface. [ABSTRACT FROM AUTHOR]

To study the contribution of three-body dispersion to crystal lattice energies, we compute the three-body contributions to the lattice energies for crystalline benzene, carbon dioxide, and triazine using various computational methods. We show that these contributions converge quickly as the intermolecular distances between the monomers grow. In particular, the smallest value among the three pairwise intermonomer closest-contact distances, Rmin, shows a strong correlation with the three-body contribution to the lattice energy, and, here, the largest of the closest-contact distances, Rmax, serves as a cutoff criterion to limit the number of trimers to be considered. We considered all trimers up to R max = 15 A ̊ . The trimers with R min < 4 A ̊ contribute 90.4%, 90.6%, and 93.9% of the total three-body contributions for crystalline benzene, carbon dioxide, and triazine, respectively, for the coupled-cluster singles, doubles, and perturbative triples [CCSD(T)] method. For trimers with R min > 4 A ̊ , the second-order Møller–Plesset perturbation theory (MP2) supplemented with the Axilrod–Teller–Muto (ATM) three-body dispersion correction reproduces the CCSD(T) values for the cumulative three-body contributions with errors of less than 0.1 kJ mol−1. Moreover, three-body contributions are converged within 0.15 kJ mol−1 by R max = 10 A ̊ . From these results, it appears that in molecular crystals where dispersion dominates the three-body contribution to the lattice energy, the trimers with R min > 4 A ̊ can be computed with the MP2+ATM method to reduce the computational cost, and those with R max > 10 A ̊ appear to be basically negligible. [ABSTRACT FROM AUTHOR]

A new polymorph of 1,3-diacetylpyrene has been obtained from its melt and thoroughly characterized using single-crystal X-ray diffraction, steady-state UV–Vis spectroscopy and periodic density functional theory calculations. Experimental studies covered the temperature range from 90 to 390 K and the pressure range from atmospheric to 4.08 GPa. Optimal sample placement in a diamond anvil cell according to our previously presented methodology ensured over 80% data coverage up to 0.8 Å for a monoclinic sample. Unrestrained Hirshfeld atom refinement of the high-pressure crystal structures was successful and anharmonic behavior of carbonyl oxygen atoms was observed. Unlike the previously characterized polymorph, the structure of 2°AP-β is based on infinite π-stacks of antiparallel 2°AP molecules. 2°AP-β displays piezochromism and piezofluorochromism which are directly related to the variation in interplanar distances within the π-stacking. The importance of weak intermolecular interactions is reflected in the substantial negative thermal expansion coefficient of −55.8 (57) MK−1 in the direction of C—H...O interactions.

Crystallography is a quintessential method for determining the atomic structure of crystals. The most common implementation of crystallography uses single crystals that must be of sufficient size, typically tens of micrometres or larger, depending on the complexity of the crystal structure. The emergence of serial data-collection methods in crystallography, particularly for time-resolved experiments, opens up opportunities to develop new routes to structure determination for nanocrystals and ensembles of crystals. Fluctuation X-ray scattering is a correlation-based approach for single-particle imaging from ensembles of identical particles, but has yet to be applied to crystal structure determination. Here, an iterative algorithm is presented that recovers crystal structure-factor intensities from fluctuation X-ray scattering correlations. The capabilities of this algorithm are demonstrated by recovering the structure of three small-molecule crystals and a protein crystal from simulated fluctuation X-ray scattering correlations. This method could facilitate the recovery of structure-factor intensities from crystals in serial crystallography experiments and relax sample requirements for crystallography experiments.

A comprehensive series of mononuclear Ln(III) complexes based on N3-tridentate Schiff-base ligand L have been synthesized using triflate or nitrate lanthanide(III) metal salts. X-ray structural characterization shows that the obtained complexes exhibit a variety of coordination modes around the Ln(III) centers tuned through appropriate counterions and reaction conditions. Examination of the above-mentioned factors reveals that, in the case of all lanthanide assemblies, we observe anion-driven structural diversity. Tuning of the crystal structure of the formed supramolecular systems is also highly influenced by the lanthanide contraction phenomenon, directly resulting in a series of isostructural groups, with general formulae of [ML2(OTf)nX3−n](OTf)3−n, if n = 2, X = MeCN (except for Yb), and if n = 1, X = MeOH in the triflate series, and [ML(NO3)3(X)](Y), where X and Y represent MeOH, MeCN or H2O, respectively, in the nitrate series. The present study gives insight into the lanthanide contraction phenomenon within the tridentate N-heterocyclic coordination architectures of Ln(III) systems and can serve for targeted manipulation of properties through molecular tectonics and crystal engineering aspects in the domains, where subtle changes of the Ln(III) coordination spheres are important like molecular magnetism or catalysis. [ABSTRACT FROM AUTHOR]

Studies of graphene show that robust chemical bonds such as covalent bonds with trigonal‐planar atoms afford layered atomic 2D crystals possessing unique properties. Although layered molecular crystals are of interest to diversify elements and structures of 2D materials, the structural diversity of molecules as well as weak intermolecular interactions inevitably makes the design to be one‐off and individual. We herein report a versatile method to assemble layered molecular crystals. By developing a D3‐symmetry host at vertices to form a honeycomb layer, a diverse range of layered 2D host–guest crystals were obtained. Substituents on the host, elements/structures of the guest, the stereochemistry of the host and types of intercalants were diversified, which should allow for 6×32×3×2 combinations for structural diversification. [ABSTRACT FROM AUTHOR]

In this study LiFePO4/C composite particles were synthesized using five different carbon sources via a one-step sol-gel method. La-doped LiFePO4 was also synthesized using the sol-gel method. The XRD pattern of LixLayFePO4 (x = 0.9~1.0, y = 0~0.1) after being calcined at 700 °C for 10 h indicates that as the doping ratio increased, the sample's cell volume first increased then decreased, reaching a maximum value of 293.36 Å3 (x = 0.94, y = 0.06). The XRD patterns of Li0.92La0.08FePO4 after being calcined at different temperatures for 10 h indicate that with increasing calcination temperature, the (311) diffraction peak drifted toward a smaller diffraction angle. Similarly, the XRD patterns of Li0.92La0.08FePO4 after being calcined at 700 °C for different durations indicate that with increasing calcination times, the (311) diffraction peak drifted toward a larger diffraction angle. The infrared spectrum pattern of LixLayFePO4 (x = 0.9~1.0, y = 0~0.1) after being calcined at 700 °C for 10 h shows absorption peaks corresponding to the vibrations of the Li–O bond and PO43- group. An SEM analysis of LixLayFePO4 (x = 1, y = 0; x = 0.96, y = 0.04; x = 0.92, y = 0.08) after being calcined at 700 °C for 10 h indicates that the particles were irregular in shape and of uniform size. The hysteresis loops of Li0.92La0.08FePO4 after being calcined at 600 °C, 700 °C, or 800 °C for 10 h indicate that with increasing calcination temperature, the Ms gradually increased, while the Mr and Hc decreased, with minimum values of 0.08 emu/g and 58.21 Oe, respectively. The Mössbauer spectra of LixLayFePO4 (x = 1, y = 0; x = 0.96, y = 0.04; x = 0.92, y = 0.08) after being calcined at 700 °C for 10 h indicate that all samples contained Doublet(1) and Doublet(2) peaks, dominated by Fe2+ compounds. The proportions of Fe2+ were 85.5% (x = 1, y = 0), 89.9% (x = 0.96, y = 0.04), and 96.0% (x = 0.92, y = 0.08). The maximum IS and QS of Doublet(1) for the three samples were 1.224 mm/s and 2.956 mm/s, respectively. [ABSTRACT FROM AUTHOR]

Polyacrylamide (PAM) is a high-molecular-weight polymer with extensive applications. However, the inefficient natural degradation of PAM results in environmental accumulation of the polymer. Biodegradation is an environmentally friendly approach in the field of PAM treatment. The first phase of PAM biodegradation is the deamination of PAM, forming the product poly(acrylic acid) (PAA). The second phase of PAM biodegradation involves the cleavage of PAA into small molecules, which is a crucial step in the degradation pathway of PAM. However, the enzyme that catalyzes the degradation of PAA and the molecular mechanism remain unclear. Here, a novel monooxygenase PCX02514 is identified as the key enzyme for PAA degradation. Through biochemical experiments, the monooxygenase PCX02514 oxidizes PAA with the participation of NADPH, causing the cleavage of carbon chains and a decrease in the molecular weight of PAA. In addition, the crystal structure of the monooxygenase PCX02514 is solved at a resolution of 1.97 Å. The active pocket is in a long cavity that extends from the C-terminus of the TIM barrel to the protein surface and exhibits positive electrostatic potential, thereby causing the migration of oxygen-negative ions into the active pocket and facilitating the reaction between the substrates and monooxygenase PCX02514. Moreover, Arg10-Arg125-Ser186-Arg187-His253 are proposed as potential active sites in monooxygenase PCX02514. Our research characterizes the molecular mechanism of this monooxygenase, providing a theoretical basis and valuable tools for PAM bioremediation. [ABSTRACT FROM AUTHOR]

Semitransparent organic photodetectors (ST‐OPDs) show immense promise for integration into optoelectronic devices, offering adjustable absorption and see‐through functionalities. However, achieving high‐performance ST‐OPDs remains challenging, necessitating a delicate balance of low dark current density, high external quantum efficiency, and optimal visible light transmission. Here, a strategy is presented using anode interfacial materials (AIMs) as the donor and narrow bandgap non‐fullerene acceptors (NFAs) to formulate the donor: acceptor light‐sensitive layer. Critical to the approach is the incorporation of 1,8‐diiodooctane during film processing, enabling the formation of morphology with an NFA molecular crystal network embedded within the donor polymer matrix. This optimized morphology substantially boosted device external quantum efficiency and reduced dark current under reverse bias, yielding a remarkable special detectivity of over 1013 Jones at 840 nm under a bias of −0.1 V. ST‐OPDs are achieved with detectivity surpassing 1012 Jones and notable average visible transmittance of over 50%. These findings highlight the potential of AIM:NFA combinations for high‐efficiency ST‐OPDs by finely controlling morphology through multiple length scales, opening doors for various applications in transparent electronics and beyond. [ABSTRACT FROM AUTHOR]

A series of isostructural reticular frameworks with systematic differences on chemical structures allows us to disclose correlations between specific structural factors and properties, providing insights for designing novel porous materials. However, even slight differences in the molecular structure often lead to non‐isostructural polymorphic frameworks particularly in the case of hydrogen‐bonded organic frameworks (HOFs) because the structures of HOFs are based on a subtle balance of reversible interactions. In this study, we found that three simple analogues of tetracarboxylic acids with naphthalene, quinoxaline, and pyrazinopyrazine cores (NT, QX, and PP, respectively) yielded isostructural solvated HOFs (NT‐1, QX‐1, and PP‐1, respectively), where hydrogen‐bonded sql‐networked sheets were slip‐stacked with closely similar manners. More importantly, these isostructural HOFs underwent structural transformations in different manners upon removal of the guest solvents. Comparison of the crystal structures of the HOFs before and after the transformation revealed that intermolecular interactions of the core significantly affected on rearrangements of hydrogen bonds in the transformation. The results suggest the potential to control the properties and functions of isostructural HOFs by elements in the core. [ABSTRACT FROM AUTHOR]

Porous molecular crystals (PMCs) have gained significant importance as next-generation functional porous materials. However, the selective crystallisation of the PMC phase remains a challenge. Herein, we have systematically controlled the stability of the luminescent PMC phase prepared using the luminescent Pt(II) complex [Pt(pbim)(N^O)] (pbim = 2-phenylbenzimidazolate, N^O = N-heteroaryl carboxylate) with Pt⋯Pt electronic interactions. The PMC phase formation varied significantly among the complexes depending on the heteroaryl group of the ancillary N^O ligand; the oxazolyl-bearing complex did not form a PMC phase, whereas the pyrazyl- and 5-fluoropyridyl-bearing complexes spontaneously formed a porous structure. This difference was rationalised by the π-stacking capability of the heteroaryl group of the ancillary ligand. Furthermore, owing to the presence of the one-dimensional Pt⋯Pt chains in this PMC phase, the photophysical properties of PMCs resulting from the Pt⋯Pt interactions were also significantly changed by the ancillary ligands. [ABSTRACT FROM AUTHOR]

The title compound, bis­[di­thio­bis­(formamidinium)] hexa­bromido­ruthenium dibromide trihydrate, [(NH2)2CSSC(NH2)2]2[RuBr6]Br2·3H2O, crystallizes in the ortho­rhom­bic system, space group Cmcm, Z = 4. The [RuBr6]2− anionic complex has an octahedral structure. The Ru—Br distances fall in the range 2.4779 (4)–2.4890 (4) Å. The S—S and C—S distances are 2.0282 (12) and 1.783 (2) Å, respectively. The H2O mol­ecules, Br− ions, and NH2 groups of the cation are linked by hydrogen bonds. The conformation of the cation is consolidated by intra­molecular O—H⋯Br, O—H⋯O, N—H⋯Br and N—H⋯O hydrogen bonds. The [(NH2)2CSSC(NH2)2]2+ cations form a hydrogen-bonded system involving the Br− ions and the water mol­ecules. Two Br− anions form four hydrogen bonds, each with the NH2 groups of two cations, thus linking the cations into a ring. The rings are connected by water mol­ecules, forming N—H⋯O—H⋯Br hydrogen bonds. [ABSTRACT FROM AUTHOR]

The crystal structures of two inter­mediates, 4-amino-3,5-di­fluoro­benzo­nitrile, C7H4F2N2 (I), and ethyl 4-amino-3,5-di­fluoro­benzoate, C9H9F2NO2 (II), along with a visible-light-responsive azo­benzene derivative, diethyl 4,4′-(diazene-1,2-di­yl)bis­(3,5-di­fluoro­benzoate), C18H14F4N2O4 (III), obtained by four-step synthetic procedure, were studied using single-crystal X-ray diffraction. The mol­ecules of I and II demonstrate the quinoid character of phenyl rings accompanied by the distortion of bond angles related to the presence of fluorine substituents in the 3 and 5 (ortho) positions. In the crystals of I and II, the mol­ecules are connected by N—H⋯N, N—H⋯F and N—H⋯O hydrogen bonds, C—H⋯F short contacts, and π-stacking inter­actions. In crystal of III, only stacking inter­actions between the mol­ecules are found. [ABSTRACT FROM AUTHOR]

The crystal and molecular structures of the complex [99TcCl(CO)3(C5H8O2)]2 (C5H8O2 = Hacac = acetylacetone) formed in the course of prolonged standing of a [99Tc(acac)(CO)4] solution in ССl4/CDCl3 and of its analog containing no organic ligand, [99TcCl(CO)4]2, were determined. Both complexes contain a [Tc2(μ-Cl)2] four-membered ring. The remaining sites in the coordination sphere of the Tc atom are occupied by carbonyl ligands, and in the case of [99TcCl(CO)3(Hacac)]2, also by the neutral acetylacetone molecule in the enol form. The Hacac molecules in the binuclear complex are in the cis position to the Cl atoms in the octahedral surrounding of the Тс atoms and in the trans position to each other relative to the [Tc2(μ-Cl)2] ring. A comparative analysis of the geometries of the complexes and their known analogs was performed. [ABSTRACT FROM AUTHOR]

New 2-(4-carboxyphenylhydrazinylidene)[1,3]thiazolo[3,2-a]pyrimidine derivatives were synthesized in high yields by the reactions of 5-aryl-6-ethoxycarbonyl-7-methyl-3-oxo-2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidine with 4-carboxyphenyldiazonium chloride. The azo coupling occurs at the 2 position of the substrate. Different types of intra- and intermolecular non-covalent interactions can affect the supramolecular assembly of the molecules in the crystal structures and the molecular configuration of the synthesized compounds. The combined contribution of supramolecular non-covalent interactions leads to several types of the self-assembly in the crystalline phase, such as hydrogen-, chalcogen-, and π—π-bonded racemic dimers. In the case of compounds containing the m-chlorophenyl substituent at the C(5) position of the thiazolo[3,2-a]-pyrimidine scaffold, these interactions lead to the formation of halogen-bonded homochiral chains. Due to the π—π stacking between the electron-rich thiazolopyrimidine scaffold and the electron-deficient carboxyphenyl moiety, there occurs the formation of dense layers in the solid phase when selecting the appropriate substituents at the C(5) atom. The crystallization conditions (vapor diffusion and slow evaporation) were found to influence the configuration of the C=N-arylhydrazone moiety. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Molecular ferroelastics with the natural features of mechanical flexibility and switchable spontaneous strain have attracted widespread attention in the scientific community due to their potential applications in tunable gratings, flexible memorizers, strain sensors, and intelligent actuators. However, most designs of molecular ferroelastics remain in the stage of blind exploration, posing a challenge to achieve a functional ferroelastic more effectively. Herein, we have successfully obtained a molecular ferroelastic, [Me2NH(CH2)2NH3](ReO4)2 (Me2NH(CH2)2NH3 = N,N‐dimethylethylenediammonium), under the guidance of the mono‐/double‐protonation strategy. The double‐protonated [Me2NH(CH2)2NH3](ReO4)2 undergoes a paraelastic‐ferroelastic phase transition with the Aizu notation of 2/mF1¯ at 322 K. Meanwhile, the theoretical calculation and experimental measurement simultaneously show that [Me2NH(CH2)2NH3](ReO4)2 possesses good mechanical flexibility, because its elastic modulus (E) of 8.26 GPa and hardness (H) of 0.45 GPa are smaller than the average values of organic crystals (E of 12.05 GPa and H of 0.5 GPa), which makes it promising to apply in wearable pressure sensors, implantable medical sensors, high‐precision tuners, etc. This work further enriches the molecular ferroelastic family and demonstrates that mono‐/double‐protonation is one of the effective molecular modification strategies for designing ferroelastics. [ABSTRACT FROM AUTHOR]

Harnessing the photoinduced phase transitions in organic crystals, especially the changes in shape and structure across various dimensions, offers a fascinating avenue for exact spatiotemporal control, which is crucial for developing future smart devices. In our study, we report a new photoactive molecular crystal made from (E)-2-(3-phenyl-allylidene)malonate ((E)-PADM). When exposed to ultraviolet (UV) light at 365 nm, this compound experiences an E-to-Z photoisomerization in liquid solution and a crystal-to-liquid phase transition in solid crystals. Remarkably, nanoscopic crystalline rods boost their melting rate and degree compared to bulk crystals, indicating that miniaturization enhances the photoinduced melting effect. Our results demonstrate a simple approach to rapidly drive molecular crystals into liquids via photochemical reactions and phase transitions. [ABSTRACT FROM AUTHOR]

In order to discover a new antibiotic drug with better or similar activity of the already existing drugs, a series of novel cobalt(II) complexes with β-diketonate as ligands is synthesized and tested on four strains of bacteria and four species of fungi. All compounds showed notable antimicrobial activity against all tested strains. More importantly, some cobalt(II) complexes displayed greater activity than ketoconazole. It is important to notice that on the tested strains Mucor mucedo and Penicillium italicum complex 2B showed five times better activity compared to ketoconazole, while complex 2D had two times better activity on Penicillium italicum strain compared to ketoconazole. Moreover, investigations with bovine serum albumin were performed. Investigations showed that the tested complexes have an appropriate affinity for binding to bovine serum albumin. In addition, the molecular docking study was performed to investigate more specifically the sites and binding mode of the tested cobalt(II) complexes with β-diketonate as ligands to bovine serum albumin, tyrosyl-tRNA synthetase, topoisomerase II DNA gyrase, and cytochrome P450 14 alpha-sterol demethylase. In conclusion, all the results indicated the great prospective of the novel cobalt complexes for some potential clinical applications in the future. [ABSTRACT FROM AUTHOR]

In this work, we present simulations of the optical rotation (OR) for five molecular crystals at density functional theory level with periodic boundary conditions (DFT‐PBC). Calculations are compared with experimental measurements and show semi‐quantitative agreement with experimental data for three of the crystals: tartatic acid, benzil, and pentaerythritol. For the other two crystals, aspartic acid and glutamic acid, the calculated data are in qualitative agreement with, but two orders of magnitude smaller than, the experimental data. We provide some arguments that support the theoretical predictions and suggest that the experiments should be revisited. We also find that the position of H centers provided in experimental X‐ray data is not sufficiently reliable for simulating OR, and better results are obtained when H atoms are allowed to relax while keeping heavier elements fixed at the experimental positions. Comparison with molecular cluster calculations with a better functional and a larger basis set indicate that the role of intermolecular interactions (reproduced with the PBC technique) is as or more important than the choice of model chemistry. Despite the current limitations in the level of theory that can be employed, these simulations provide a promising avenue to investigate the effect of intermolecular interactions on this sensitive electronic property of molecules and materials. [ABSTRACT FROM AUTHOR]

Hybrid optical components and circuits that deal with multiple signal generation and processing are quintessential for neural networking systems. Herein, the study reports the fabrication of one such component, a hybrid directional coupler (HDC) from blue emissive (4,4′‐bis(2,6‐di(1H‐pyrazol‐1‐yl)pyridin‐4‐yl)biphenyl) (BPP) and green emissive (E)‐1‐(((5‐bromopyridin‐2‐yl)imino)methyl)naphthalen‐2‐ol (BPyIN) pseudo‐plastic molecular crystals. Initially, a BPyIN microcrystal optical waveguide (OW1) is shaped into a strained waveguide with five bends using an atomic force microscopy cantilever‐tip aided mechanophotonics approach. Later, a singly bent BPyIN waveguide (OW2) is integrated into one of the bends at the coupling region on a strained waveguide to produce a 2 × 2 monolithic directional coupler (DC). Later, this 2 × 2 DC is extended to a HDC by integrating a blue emissive BPP waveguide (OW3) at another bend on the deformed waveguide. The fabricated HDC can effectively split the incident light into three parts with different split ratios and deliver multi‐color outputs depending on the port receiving the input signal. The spontaneous generation and processing of various signals produced in the circuit helps in understanding the functioning of complex optical neural networks. The demonstration of such innovative optical components manifests their utility for diverse applications in neural networking and quantum computing systems. [ABSTRACT FROM AUTHOR]

Starting from [Mn(C5H4Br)(PPh3)(CO)2] (1a), the cymantrenyl thioethers [Mn(C5H4SMe)(PPh3)(CO)2] (1b) and [Mn{C5H4–nBr(SMe)n}(PPh3)(CO)2] (n = 1 for compound 2, n = 2 for 3 and n = 3 for 4) were obtained, using either n‐butyllithium (n‐BuLi), lithium diisopropylamide (LDA) or lithium tetramethylpiperidide (LiTMP) as base, followed by electrophilic quenching with MeSSMe. Stepwise consecutive reaction of [Mn(C5Br5)(PPh3)(CO)2] with n‐BuLi and MeSSMe led finally to [Mn{C5(SMe)5}(PPh3)(CO)2] (11), only the fifth complex to be reported containing a perthiolated cyclopentadienyl ring. The molecular and crystal structures of 1b, 3, 4 and 11 were determined and were studied for the occurrence of S...S and S...Br interactions. It turned out that although some interactions of this type occurred, they were of minor importance for the arrangement of the molecules in the crystal. [ABSTRACT FROM AUTHOR]

Context: Ammonium perchlorate (NH4ClO4, abbreviated as AP) has the advantages of high oxygen content, high density, and good compatibility, and has significant application prospects in the field of energetic materials. The crystal morphology has a great influence on the properties and sensibility of energetic materials, and a single experimental means is difficult in exploring the crystals; therefore, the crystal morphology of AP is investigated using molecular dynamics simulation complemented with experiments, to theoretically analyze the differences in AP crystal habit and the interactions between solvent molecules and the main growing crystal surfaces of AP. The results show that AP crystal is mainly composed of five independent crystal surfaces (0 0 1), (0 1 0), (1 0 0), (1 0 1), and (1 0 −1) in vacuum using the BFDH laws, with (0 0 1) surface being the main growth crystal surface. In contrast, in H2O solvent, the (1 0 1) and (1 0 −1) surfaces disappear, and the AP mainly consists of (0 0 1), (0 1 0), and (1 0 0) surfaces with a rectangular shape. The crystal morphology obtained from theoretical prediction is in good agreement with that obtained from experimental culture. This paper can provide a new idea for the cultivation and preparation of AP large crystals, and promote the application of AP crystals in energetic materials. Methods: The crystal morphologies of AP in vacuum and H2O solvent under Dreiding force field were predicted based on attachment energy model by using molecular dynamics method in Materials Studio 2019 software. The entire molecular dynamics simulation was carried out under the NTV system, the temperature control method was selected as Anderson, and the system temperature was set to 298 K. The simulation time was set to 40 ps, the step size was set to 1 fs, and the data were outputted every 5000 steps. [ABSTRACT FROM AUTHOR]

The study of the dynamics of nucleic acids in solution, their flow properties, and viscoelasticity is of great importance for understanding their biological functions. Many important properties of nucleic acids, such as DNA, depend on polymer concentration, CDNA, molecular weight (MW), rigidity, and external salt content, the latter parameter affecting electrostatic interactions. Furthermore, DNA molecular chains can organize, in vitro, into liquid crystalline phases at high CDNA. In this work, three DNA samples with different MW were studied in solution in a broad concentration range (CDNA from 0.025 to 200 mg mL−1, depending on DNA MW). Firstly, the intrinsic viscosities and MW for all DNA samples were determined through capillary and rheological measurements. Then, the overlap concentrations, C*, were estimated from the relation C* ≈ [η]−1. DNA chain characteristics were then analyzed in terms of the influence of DNA MW on the solution viscosities and on the overlap parameter, CDNA[η]. Flow birefringence appearance was identified by screening a wide CDNA range through visual observations with crossed polarizers. Finally, crossed‐light polarized microscopy was used to identify the appearance of liquid crystals at rest, confirming that higher CDNA are needed to obtain liquid crystals for low MW DNA samples. [ABSTRACT FROM AUTHOR]

The crystal and molecular structures of the complex [99TcCl(CO)3(C5H8O2)]2 (C5H8O2 = Hacac = acetylacetone) formed in the course of prolonged standing of a [99Tc(acac)(CO)4] solution in ССl4/CDCl3 and of its analog containing no organic ligand, [99TcCl(CO)4]2, were determined. Both complexes contain a [Tc2(μ-Cl)2] four-membered ring. The remaining sites in the coordination sphere of the Tc atom are occupied by carbonyl ligands, and in the case of [99TcCl(CO)3(Hacac)]2, also by the neutral acetylacetone molecule in the enol form. The Hacac molecules in the binuclear complex are in the cis position to the Cl atoms in the octahedral surrounding of the Тс atoms and in the trans position to each other relative to the [Tc2(μ-Cl)2] ring. A comparative analysis of the geometries of the complexes and their known analogs was performed. [ABSTRACT FROM AUTHOR]

X-ray diffraction (XRD) is used for characterizing the crystal structure of molecular sieves after synthetic experiments. However, for a high-throughput molecular sieve synthetic system, the huge amount of data derived from large throughput capacity makes it difficult to analyze timely. While the kernel step of XRD analysis is to search peaks, an automatic way for peak search is needed. Thus, we proposed a novel semantic mask-based two-step framework for peak search in XRD patterns: (1) mask generation, we proposed a multi-resolution net (MRN) to classify the data points of XRD patterns into binary masks (peak/background). (2) Peak search, based on the generated masks, the background points are used to fit an n-order polynomial background curve and estimate the random noises in XRD patterns. Then we proposed three rules named mask, shape, and intensity to screening peaks from initial peak candidates generated by maximum search. Besides, a voting strategy is proposed in peak screening to obtain a precise peak search result. Experiments show that the proposed MRN achieves the state-of-the-art performance compared with other semantic segmentation methods and the proposed peak search method performs better than Jade when using f1 score as the evaluation index. [ABSTRACT FROM AUTHOR]

The pressure response of crystalline trans‐cinnamic acid is studied by means of Raman spectroscopy up to 6 GPa. Pressure application causes the reversible shift of all the observed Raman peaks to higher frequencies and changes in their relative intensities, with the intermolecular vibrational modes being by far more sensitive to pressurization compared to the intramolecular ones. The present high‐pressure Raman data indicate the structural stability of the trans‐cinnamic acid crystal and molecular conformation up to the highest pressure attained in the experiments, the importance of the hydrogen bonding, as well as the considerable strengthening of the intermolecular interactions at elevated pressures. [ABSTRACT FROM AUTHOR]

Photonic and plasmonic hybrid nanostructures are the key solution for integrated nanophotonic circuits with ultracompact size but relative low loss. However, the poor tunability and modulability of conventional waveguides makes them cumbersome for optical multiplexing. Here we make use of two‐dimensional molecular crystal, α‐Sb2O3 as a dielectric waveguide via total internal reflection, which shows polarization‐sensitive modulation of the propagating beams due to its large polarization mode dispersion. Both experiments and simulations are performed to verify such concept. These Sb2O3 nanoflakes can be coupled with plasmonic nanowires to form nanophotonic beam splitters and routers which can be easily modulated by changing the polarization of the incidence. It thus provides a robust, exploitable and tunable platform for on‐chip nanophotonics. [ABSTRACT FROM AUTHOR]

Under the extreme conditions of high temperature and high pressure, molecular crystal nitrogen breaks the traditional three-bond mechanism and transforms into a single-bond polymerization state. The unique dissociation mechanism of nitrogen under high pressure makes the research significance of polymeric nitrogen beyond the scope of energetic materials, and also has profound scientific significance in the field of fundamental physics. Following the cubic gauche polymeric nitrogen cg-N (space group I213), the second experimentally discovered layered structure polymeric nitrogen LP-N (space group Pba2) has been controversial. The main problem is that, in addition to not being verified by other high-pressure X-ray diffraction experiments, LP-N structure has the similar synthesis temperature and pressure conditions and synthesis pathways, as well as almost the same Raman spectral characteristics as the subsequently discovered black phosphorus structure polymeric nitrogen BP-N (space group Cmca). The high-temperature and highpressure synthesis of LP-N is likely to have a unique phase transition kinetic barrier. In this work, we started from the low-temperature solid-state molecular nitrogen λ-N2, used double-sided laser-heated diamond anvil cell (LHDAC) technology, combined with high-pressure X-ray diffraction based on the synchrotron radiation and high-pressure Raman scattering spectroscopy, supplemented by first-principles calculations, and observed the Pba2 structure of polymeric nitrogen LP-N at the conditions of about 141 GPa and about 2 600 K. Combined with first-principles calculations, we compared and analyzed its pressure-dependent evolution of the volume per atom (p-V curve) and discussed the kinetic factors of LP-N synthesis at high temperature and high pressure. In addition to a more comprehensive understanding of LP-N, this paper further reveals the high-pressure path-dependent characteristics of polymeric nitrogen. [ABSTRACT FROM AUTHOR]

Context: Ammonium perchlorate (NH4ClO4, abbreviated as AP) has the advantages of high oxygen content, high density, and good compatibility, and has significant application prospects in the field of energetic materials. The crystal morphology has a great influence on the properties and sensibility of energetic materials, and a single experimental means is difficult in exploring the crystals; therefore, the crystal morphology of AP is investigated using molecular dynamics simulation complemented with experiments, to theoretically analyze the differences in AP crystal habit and the interactions between solvent molecules and the main growing crystal surfaces of AP. The results show that AP crystal is mainly composed of five independent crystal surfaces (0 0 1), (0 1 0), (1 0 0), (1 0 1), and (1 0 −1) in vacuum using the BFDH laws, with (0 0 1) surface being the main growth crystal surface. In contrast, in H2O solvent, the (1 0 1) and (1 0 −1) surfaces disappear, and the AP mainly consists of (0 0 1), (0 1 0), and (1 0 0) surfaces with a rectangular shape. The crystal morphology obtained from theoretical prediction is in good agreement with that obtained from experimental culture. This paper can provide a new idea for the cultivation and preparation of AP large crystals, and promote the application of AP crystals in energetic materials. Methods: The crystal morphologies of AP in vacuum and H2O solvent under Dreiding force field were predicted based on attachment energy model by using molecular dynamics method in Materials Studio 2019 software. The entire molecular dynamics simulation was carried out under the NTV system, the temperature control method was selected as Anderson, and the system temperature was set to 298 K. The simulation time was set to 40 ps, the step size was set to 1 fs, and the data were outputted every 5000 steps. [ABSTRACT FROM AUTHOR]

Starting from [Mn(C5H4Br)(PPh3)(CO)2] (1a), the cymantrenyl thioethers [Mn(C5H4SMe)(PPh3)(CO)2] (1b) and [Mn{C5H4–nBr(SMe)n}(PPh3)(CO)2] (n = 1 for compound 2, n = 2 for 3 and n = 3 for 4) were obtained, using either n‐butyllithium (n‐BuLi), lithium diisopropylamide (LDA) or lithium tetramethylpiperidide (LiTMP) as base, followed by electrophilic quenching with MeSSMe. Stepwise consecutive reaction of [Mn(C5Br5)(PPh3)(CO)2] with n‐BuLi and MeSSMe led finally to [Mn{C5(SMe)5}(PPh3)(CO)2] (11), only the fifth complex to be reported containing a perthiolated cyclopentadienyl ring. The molecular and crystal structures of 1b, 3, 4 and 11 were determined and were studied for the occurrence of S...S and S...Br interactions. It turned out that although some interactions of this type occurred, they were of minor importance for the arrangement of the molecules in the crystal. [ABSTRACT FROM AUTHOR]

Investigations into the construction of functional molecular crystals and their external stimuli-induced structural transformations represent compelling research topics, particularly for the advancement of sensors and memory devices. However, reports on the development of molecular crystals constructed from discrete mononuclear complex units and exhibiting structural transformations via the adsorption/desorption of guest molecules are scarce. In this study, we synthesised three molecular crystals composed of [Al(sap)(acac)(H2O)]·(solvent) (H2sap = 2-salicylideneaminophenol, acac = acetylacetonate, solvent = Me2CO (Al·Me2CO), MeCN (Al·MeCN), or DMSO (Al·DMSO)), and demonstrated solvent vapour-responsive reversible crystal-to-crystal structural transformations in Al·Me2CO and Al·MeCN. For Al·DMSO, exposure to DMSO vapour led to the formation of DMSO-coordinated compound [Al(sap)(acac)(DMSO)], indicating an irreversible structural transformation. This solvent vapour-responsive system incorporates a luminescent mononuclear aluminium(III) complex (λmax = 539–552 nm, Φem = 0.07–0.27) as the molecular building unit for the porous-like framework. Therefore, we synthesised a new functional molecular material and a potential molecular building unit that facilitates guest fixation through hydrogen-bonding. [ABSTRACT FROM AUTHOR]

The sensitivity and responsiveness of living cells to environmental changes are enabled by dynamic protein structures, inspiring efforts to construct artificial supramolecular protein assemblies. However, despite their sophisticated structures, designed protein assemblies have yet to be incorporated into macroscale devices for real-life applications. We report a 2D crystalline protein assembly of C98/E57/E66L-rhamnulose-1-phosphate aldolase (CEERhuA) that selectively blocks or passes molecular species when exposed to a chemical trigger. CEERhuA crystals are engineered via cobalt(II) coordination bonds to undergo a coherent conformational change from a closed state (pore dimensions <1 nm) to an ajar state (pore dimensions ~4 nm) when exposed to an HCN(g) trigger. When layered onto a mesoporous silicon (pSi) photonic crystal optical sensor configured to detect HCN(g), the 2D CEERhuA crystal layer effectively blocks interferents that would otherwise result in a false positive signal. The 2D CEERhuA crystal layer opens in selective response to low-ppm levels of HCN(g), allowing analyte penetration into the pSi sensor layer for detection. These findings illustrate that designed protein assemblies can function as dynamic components of solid-state devices in non-aqueous environments. Vijayakumar and coworkers report the integration of a designed, 2D crystalline protein assembly as a dynamic gatekeeper into mesoporous silicon photonic crystals for the selective sensing of hydrogen cyanide [ABSTRACT FROM AUTHOR]

The function of proteins depends on their correct structure and proper dynamics. Understanding the dynamics of target proteins facilitates drug design and development. However, dynamic information is often hidden in the spatial structure of proteins. It is important but difficult to identify the specific residues that play a decisive role in protein dynamics. Here, we report that a critical glycine residue (Gly463) dominates the motion of threonyl-tRNA synthetase (ThrRS) and the sensitivity of the enzyme to antibiotics. Obafluorin (OB), a natural antibiotic, is a novel covalent inhibitor of ThrRS. The binding of OB induces a large conformational change in ThrRS. Through five crystal structures, biochemical and biophysical analyses, and computational simulations, we found that Gly463 plays an important role in the dynamics of ThrRS. Mutating this flexible residue into more rigid residues did not damage the enzyme's three-dimensional structure but significantly improved the thermal stability of the enzyme and suppressed its ability to change conformation. These mutations cause resistance of ThrRS to antibiotics that are conformationally selective, such as OB and borrelidin. This work not only elucidates the molecular mechanism of the self-resistance of OB-producing Pseudomonas fluorescens but also emphasizes the importance of backbone kinetics for aminoacyl-tRNA synthetase-targeting drug development. Crystal structures and molecular dynamics simulations reveal that a critical glycine residue dominates the motion of threonyl-tRNA synthetase and the sensitivity of the enzyme to conformation selective inhibitors. [ABSTRACT FROM AUTHOR]

To investigate the effect of drilling speed on the molecular dynamics and subsurface defect evolution mechanism of 3C-SiC single crystals, a coupled molecular dynamic model for drilling is established. A multi-scale molecular dynamic potential energy function is established by combining the variational potential energy between C–Si bonds, based on this, the mechanical response coupling model is developed. By analyzing factors such as molecular dynamics temperature and periodic boundaries, a molecular dynamic differential ensemble environment drilling is constructed to achieve a constant temperature and pressure simulation environment for the evolution of sub-surface defects in single crystal 3C-SiC molecular dynamics. At drilling velocities of 30 m/s, 60 m/s, and 90 m/s, dislocation exchange occurs that the load stability is affected. When the drilling reaches a certain depth, the load tends to be constant, with values of 5.22 × 104 eV/Å, 3.36 × 104 eV/Å, and 0.58 × 104 eV/Å. Load changes during differential drilling impact single crystal 3C-SiC irreversibly. By comparing and analyzing the simulation results at different drilling speeds, it offers ideas for understanding the material response of single crystal 3C-SiC during high-speed machining from the point of view of dislocation energy changes. [ABSTRACT FROM AUTHOR]

Considering that regulation of thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) is necessary for a fluorophore to survive and properly show its characteristic features, it is successfully shown herein that a carefully designed novel pyrene derivative can exhibit remarkable aggregation‐induced emission (AIE) overcoming the characteristic fast excitonic decay of pyrene compounds. Moreover, it is established that J‐aggregation in the red‐emitting molecular crystals of the compound reduces the singlet‐triplet energy gap (∆EST), allowing TADF with a very high photoluminescence quantum yield (PLQY) of 72%. Whereas, anisotropic grinding of the same crystals generates well‐defined microcrystals that show RTP as the nature of aggregation changes. Impressively, under isotropic hydrostatic pressure, the crystals show near‐infra‐red (NIR) emission with a very high piezochromic luminescence sensitivity of 46.2 nm GPa−1. The results have established that formation of stable H‐aggregates in the microcrystals is responsible for the ultra‐long RTP. A highly sophisticated full‐spectrum Mueller‐matrix analysis is used for the first time in such systems to demonstrate the details of the effect of perturbation (pressure) on molecular conformation. [ABSTRACT FROM AUTHOR]

Atomistic calculations based on semi-classical dispersion-corrected density functional theory were performed to investigate bonding and elastic properties of low temperature polymorphs of three nitrile molecular crystals. For that purpose, the DFT-PBE-D3ijk method, which account for both pair and three-body interactions, was applied. The analysis of Hirshfeld surfaces demonstrated that the (C-N...H) hydrogen bonds are the strongest and the dominant ones in the three nitrile molecular crystals. The latter were found to share a common structural feature, consisting of an antiparallel orientation of the terminal nitrile groups at their constituent molecules. Our prediction of the elastic properties demonstrated that malonitrile has the highest Young modulus and succinonitrile has the lower one. The three nitrile crystals are expected to have similar resistance to volume variation while succinonitrle is predicted to exhibit the lowest resistance to shape change. Otherwise, succinonitrile was found to be ductile while malononitrile and acetonitrile were shown to be brittle. Elasticity anisotropy analysis demonstrated that the directions of maximum Young's modulus are always nearly parallel to the direction of alignment of strong (C-H...N) hydrogen bonds in the three nitrile crystals. The present analyses are relevant for understanding the structure and the properties of more complex high temperature phases. [ABSTRACT FROM AUTHOR]

High pressure shear band formation is a critical phenomenon in energetic materials due to its influence on both mechanical strength and mechanochemical activation. While shear banding is known to occur in a variety of these materials, the governing dynamics of the mechanisms are not well defined for molecular crystals. We conduct molecular dynamics simulations of shock wave induced shear band formation in the energetic material 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) to assess shear band nucleation processes. We find, that at high pressures, the initial formation sites for shear bands, "embryos", form in excess and rapidly lower deviatoric stresses prior to shear band formation and growth. This results in the suppression of plastic deformation. A local cluster analysis is used to quantify and contrast this mechanism with a more typical shear banding seen at lower pressures. These results demonstrate a mechanism that is reversible in nature and that supersedes shear band formation at increased pressures. We anticipate that these results will have a broad impact on the modeling and development of high-strain rate application materials such as those for high explosives and hypersonic systems. [ABSTRACT FROM AUTHOR]

The dense and ordered molecular arrangements endow dynamic molecular crystals with fast response, rapid energy conversion, low energy dissipation, and strong coupling between heat/light and mechanical energy. Most of the known dynamic crystals can only respond to a single stimulus, and materials that can respond to multiple stimuli are rare. Here, we report an organic crystalline material that can be bent plastically and is also thermosalient, as its crystals can move when they undergo a reversible phase transition. The crystals transmit light regardless of their shape or crystalline phase. The combination of light transduction and reversible thermomechanical deformation provides an opportunity to switch the waveguiding capability of the material in a narrow temperature range, which holds a tremendous potential for applications in heat‐averse electronic components, such as central processing units. Unlike existing electronics, the material we report here is completely organic and therefore much lighter, potentially reducing the overall weight of electronic circuits. [ABSTRACT FROM AUTHOR]

AbstractD-allulose, an epimer of D-fructose at C-3 position, is a low-calorie rare sugar with favorable physiochemical properties and special physiological functions, which displays promising perspectives in the food and pharmaceutical industries. Currently, D-allulose is extremely sparse in nature and is predominantly biosynthesized through the isomerization of D-fructose by D-allulose 3-epimerase (DAEase). In recent years, D-allulose 3-epimerase as the key biocatalyst for D-allulose production has received increasing interest. The current review begins by providing a summary of D-allulose regarding its characteristics and applications, as well as different synthesis pathways dominated by biotransformation. Then, the research advances of D-allulose 3-epimerase are systematically reviewed, focusing on heterologous expression and biochemical characterization, crystal structure and molecular modification, and application in D-allulose production. Concerning the constraint of low yield of DAEase for industrial application, this review addresses the various attempts made to promote the production of DAEase in different expression systems. Also, various strategies have been adopted to improve its thermotolerance and catalytic activity, which is mainly based on the structure-function relationship of DAEase. The application of DAEase in D-allulose biosynthesis from D-fructose or low-cost feedstocks through single- or multi-enzymatic cascade reaction has been discussed. Finally, the prospects for related research of D-allulose 3-epimerase are also proposed, facilitating the industrialization of DAEase and more efficient and economical bioproduction of D-allulose. [ABSTRACT FROM AUTHOR]

Boron, the element which is in close proximity with carbon in the periodic table has been hypothesized to produce diverse two‐dimensional structures that differ from well‐studied 2D materials. Icosahedron B12$$ {\mathcal{B}}_{12} $$, the monomers of which form the crystalline boron structure, appears as a recurring pattern in the chemistry of boron compounds, elemental boron and boron‐rich materials, functions as a building block in a majority of boron allotropes. The topological study of the icosahedral sheets is a necessary field to be investigated for the effective analysis and characterization of its physico‐chemical attributes without undertaking time‐consuming experimental research. The topological descriptors being expressed as numerical values enable scientists to compare and correlate data, which can be applied to quantitative structure‐activity relationships and quantitative structure‐property relationships modeling. In this study, various degree based molecular descriptors of the crystal boron icosahedral α$$ \alpha $$ sheet Bα(a,b)$$ {\mathcal{B}}_{\alpha}\left(\mathfrak{a},\mathfrak{b}\right) $$ has been formulated from a two‐dimensional lattice perspective using the 필‐polynomial approach. To establish the significance of these descriptors in the study of chemical attributes, an efficient linear regression modeling has also been performed, enabling the prediction of properties of several other boron sheets. [ABSTRACT FROM AUTHOR]

Dynamic molecular crystals are an emerging class of crystalline materials that can respond to mechanical stress by dissipating internal strain in a number of ways. Given the serendipitous nature of the discovery of such crystals, progress in the field requires advances in computational methods for the accurate and high–throughput computation of the nanomechanical properties of crystals on specific facets which are exposed to mechanical stress. Here, we develop and apply a new atomistic model for computing the surface elastic moduli of crystals on any set of facets of interest using dispersion–corrected density functional theory (DFT−D) methods. The model was benchmarked against a total of 24 reported nanoindentation measurements from a diverse set of molecular crystals and was found to be generally reliable. Using only the experimental crystal structure of the dietary supplement, L–aspartic acid, the model was subsequently applied under blind test conditions, to correctly predict the growth morphology, facet and nanomechanical properties of L–aspartic acid to within the accuracy of the measured elastic stiffness of the crystal, 24.53±0.56 GPa. This work paves the way for the computational design and experimental realization of other functional molecular crystals with tailor–made mechanical properties. [ABSTRACT FROM AUTHOR]

Semiconductor moiré superlattices provide a versatile platform to engineer quantum solids composed of artificial atoms on moiré sites. Previous studies have mostly focused on the simplest correlated quantum solid—the Fermi-Hubbard model—in which intra-atom interactions are simplified to a single onsite repulsion energy U. Here we report the experimental observation of Wigner molecular crystals emerging from multielectron artificial atoms in twisted bilayer tungsten disulfide moiré superlattices. Using scanning tunneling microscopy, we demonstrate that Wigner molecules appear in multielectron artificial atoms when Coulomb interactions dominate. The array of Wigner molecules observed in a moiré superlattice comprises a crystalline phase of electrons: the Wigner molecular crystal, which is shown to be highly tunable through mechanical strain, moiré period, and carrier charge type. [ABSTRACT FROM AUTHOR]

The new host materials are reported to boost the multiple resonance‐induced thermally activated delayed fluorescence (MR‐TADF) based pure deep‐blue organic light emitting diodes (OLEDs) toward further shortening the emission full width at the half maximum (FWHM). Based on an unusual asymmetric design concept, two new host compounds Bz2cb and Bz2cbz are synthesized. Despite possessing a compact and rigid molecular packing in crystal, Bz2cbz shows pure amorphous morphology via vapor deposition, as confirmed by the grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) analysis. Via incorporating a promising MR‐TADF emitter, ν‐DABNA‐O‐Me, into Bz2cb and Bz2cbz films, highly pure deep‐blue OLEDs are successfully demonstrated. Remarkably, the Bz2cbz device exhibits a 464 nm electroluminescence (EL) with narrow FWHM of 22 nm, accompanied by the reduction of the 0–1 vibronic sideband, and a maximum external quantum efficiency (EQEmax) of 28.2%, which, overall, reaches the true‐blue Commission Internationale de l'Eclairage coordinates (CIE) of (0.13, 0.07) and the high blue index of 253. The amorphous film formation turns out to be an important factor that is previously unrecognized to externally fine‐tune the MR‐TADF OLEDs toward even higher color purity. [ABSTRACT FROM AUTHOR]

We present the synthesis, characterization, and crystal structure of sodium tetrabenzylborate, a novel tetraalkoxyborate obtained via a direct mechanochemical reaction between benzaldehyde and sodium borohydride at room temperature. The molecular and crystal structures of this borate were investigated using 11B MAS NMR, IR spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction (XRD) analyses. Crystalline sodium tetrabenzylborate exists in two different crystal structures, which were elucidated using powder- and single-crystal-XRD analyses. At a low temperature (e.g., −100 °C), sodium tetrabenzylborate crystallizes in the monoclinic system with the space group P21 (No. 4), but at room temperature, it displays a crystallization in the tetragonal system with the space group I 4 ¯ (No. 82). According to the DSC analysis, the phase transition occurs at −45 °C. Upon hydrolysis, sodium tetrabenzylborate undergoes direct transformation into benzyl alcohol, thereby confirming the ability of sodium borohydride to convert an aldehyde into its primary alcohol analog. The key findings from our analyses are presented herein. [ABSTRACT FROM AUTHOR]

When solving a structure of a protein from single‐wavelength anomalous diffraction X‐ray data, the initial phases obtained by phasing from an anomalously scattering substructure usually need to be improved by an iterated electron‐density modification. In this manuscript, the use of convolutional neural networks (CNNs) for segmentation of the initial experimental phasing electron‐density maps is proposed. The results reported demonstrate that a CNN with U‐net architecture, trained on several thousands of electron‐density maps generated mainly using X‐ray data from the Protein Data Bank in a supervised learning, can improve current density‐modification methods. [ABSTRACT FROM AUTHOR]

Single crystals of the molecular compound, {Cu20Ir6Cl8(C21H24N2)6(C4H4N2)3]·3.18CH3OH or [({Cu10Ir3}Cl4(IMes)3(pyrazine))2(pyrazine)]·3.18CH3OH [where IMes is 1,3-bis (2,4,6-trimethylphenyl)imidazol-2-ylidene], with a unique heterometallic cluster have been prepared and the structure revealed using single-crystal X-ray diffraction. The molecule is centrosymmetric with two {Cu10Ir3} cores bridged by a pyrazine ligand. The polymetallic cluster contains three stabilizing N-heterocyclic carbenes, four Cl ligands, and a non-bridging pyrazine ligand. Notably, the Cu--Ir core is arranged in an unusual shape containing 13 vertices, 22 faces, and 32 sides. The atoms within the tridecametallic cluster are arranged in four planes, with 2, 4, 4, 3 metals in each plane. Ir atoms are present in alternate planes with an Ir atom featuring in the peripheral bimetallic plane, and two Ir atoms featuring on opposite sides of the non-adjacent tetrametallic plane. The crystal contains two disordered methanol solvent molecules with an additional region of non-modelled electron density corrected for using the SQUEEZE routine in PLATON [Spek (2015[Spek, A. L. (2015). Acta Cryst. C71, 9-18.]). Acta Cryst. C71, 9-18]. The given chemical formula and other crystal data do not take into account the unmodelled methanol solvent molecule(s). [ABSTRACT FROM AUTHOR]

The aryl diester compound, 2-methyl-1,4-phenylene bis(3,5-dibromobenzoate), C21H12Br4O4, was synthesized by esterification of methyl hydroquinone with 3,5-dibromobenzoic acid. A crystalline sample was obtained by cooling a sample of the melt (m.p. = 502 K/DSC) to room temperature. The molecular structure consists of a central benzene ring with anti-3,5-dibromobenzoate groups symmetrically attached at the 1 and 4 positions and a methyl group attached at the 2 position of the central ring. In the crystal structure (space group P1), molecules of the title aryl diester are located on inversion centers imposing disorder of the methyl group and H atom across the central benzene ring. The crystal structure is consolidated by a network of C--H...Br hydrogen bonds in addition to weaker and offset interactions involving the central benzene rings as well as the rings of the attached 3,5-dibromobenzoate groups. [ABSTRACT FROM AUTHOR]

Traditional heat conductive epoxy composites often fall short in meeting the escalating heat dissipation demands of large‐power, high‐frequency, and high‐voltage insulating packaging applications, due to the challenge of achieving high thermal conductivity (k), desirable dielectric performance, and robust thermomechanical properties simultaneously. Liquid crystal epoxy (LCE) emerges as a unique epoxy, exhibiting inherently high k achieved through the self‐assembly of mesogenic units into ordered structures. This characteristic enables liquid crystal epoxy to retain all the beneficial physical properties of pristine epoxy, while demonstrating a prominently enhanced k. As such, liquid crystal epoxy materials represent a promising solution for thermal management, with potential to tackle the critical issues and technical bottlenecks impeding the increasing miniaturization of microelectronic devices and electrical equipment. This article provides a comprehensive review on recent advances in liquid crystal epoxy, emphasizing the correlation between liquid crystal epoxy's microscopic arrangement, organized mesoscopic domain, k, and relevant physical properties. The impacts of LC units and curing agents on the development of ordered structure are discussed, alongside the consequent effects on the k, dielectric, thermal, and other properties. External processing factors such as temperature and pressure and their influence on the formation and organization of structured domains are also evaluated. Finally, potential applications that could benefit from the emergence of liquid crystal epoxy are reviewed. [ABSTRACT FROM AUTHOR]