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Structural DNA nanotechnology is an emerging field and is expected to be used for various applications in materials science. In this study, we designed a DNA tensegrity triangle to accommodate the bipyridine complexes with metal ions (Ni2+ and Fe2+) at the center of the space within the triangle. A metal–bipyridine-incorporated DNA tensegrity triangle was crystalized, and the presence of metals within it was confirmed through X-ray crystal structure analysis. A signal of the anomalous dispersion effect derived from metal was observed in the center of the DNA triangle. [ABSTRACT FROM AUTHOR]

Guanidine-containing molecules are an interesting class of compounds within both medicinal and material sciences. Having knowledge of their tautomerism is key in designing guanidines that interact with biological and chemical receptors. However, there are limited data on the solid-phase structure of N,N′-substituted guanidines. Thus, eleven guanidines bearing a 4,6-dimethylpyrimidyl at one end and substituents of varying sizes and electronic properties at the other side, were synthesised, crystallised, and analysed by X-ray crystallography. Calculations of isolated molecules of tautomer energies and bond lengths were performed for comparison. One class of guanidines crystallised as a cis–trans tautomer with the shorter bond directed towards the pyrimidyl unit. When more electron-deficient aniline substituents were inserted, the crystallised tautomer changed to a cis–cis form where the shorter bond was directed towards the aniline. The switch in the tautomer structure is concluded to be due to both the electronic properties of the substituents and the intermolecular hydrogen bonding in the crystal lattice. [ABSTRACT FROM AUTHOR]

Unconventional noncovalent interactions are ubiquitous in molecular crystals, supramolecular systems, and biomolecules, but their significance has often been overshadowed by stronger intermolecular interactions such as hydrogen bonding and π‐stacking. This study aims to emphasize the significance of nonclassical noncovalent interactions in crystal packing. The crystal structure of 1,1′‐(1‐chloro‐4‐methoxyphenyl)dibenzene was reported as a representative case. A network of weak interactions governs the arrangement of the molecules within the crystal, encompassing C−H⋅⋅⋅X hydrogen bonding (where X=O, Cl, or π), weak Cl⋅⋅⋅Cl symmetrical bonding (classified as Type I halogen–halogen bonding), and C−H...H−C homopolar dihydrogen contacts (dH...H=2.348 Å). The nature, energetics, and cooperativity of these interactions were evaluated using computational calculations based on dispersion‐corrected density functional theory (DFT/wB97X‐D/aug‐cc‐pVTZ). Our findings contribute to a comprehensive understanding of unconventional noncovalent interactions and their role in crystal packing. The methods and concepts employed are likely to be applicable to other molecular systems in biology, chemistry, and materials science. [ABSTRACT FROM AUTHOR]

Most of the fluorescent molecules among organic π -conjugated materials show blue or green emission in the solid phase but few of them emit red-shifted visible and near-infrared light in the material science. To create molecules emitting for this feature, two π-conjugated oxazol-5-one derivatives containing donor (OCH3) and acceptor groups (NO2) were synthesized. Their optical and charge-transport properties were investigated through experimental and theoretical methods including the single crystal X-ray crystallography, Hirshfeld Surface Analysis, photophysical studies and Density Functional Theory (DFT), respectively. In addition, FT-IR, 1H-NMR, 13C-NMR spectroscopy, cyclic voltammetry (CV) measurements were performed. According to our results, both molecules may provide the significant pathway of development of long wavelength visible and red emissive features in solid phase with the aggregation induced enhanced emission (AIEE) properties particularly in the fields of OLEDs, optical communication, defence and bioimaging. [ABSTRACT FROM AUTHOR]

Structural chemistry provides the foundation for progress in organic and inorganic chemistry with far-reaching consequences in medicine and in materials science and technology. New tools and concepts appear shaping together the progress in structural chemistry. [ABSTRACT FROM AUTHOR]

Despite various applications of alkylzinc complexes supported by N,N-bidentate ligands in chemistry and materials science, the corresponding organozinc amidinates still represent an insufficiently explored area. To gain a more in-depth understanding of factors controlling the structure and stability of alkylzinc amidinates, we selected benzamidinate and N,N′-diphenylformamidinate ligands as model N,N′-unsubstituted and N,N′-diaryl substituted ligands, respectively, to systematically modify the secondary coordination sphere of the Zn center. A series of new alkylzinc amidinates has been synthesized and their molecular structures identified in both the solid state (single-crystal X-ray crystallography) and solution (NMR and FTIR spectroscopy). The results indicate that [RZnL]x-type amidinate moieties are essentially unstable and tend to undergo Schlenk equilibria-mediated ligand scrambling leading to more thermodynamically stable non-stoichiometric [R2Zn3L4]- and [R3Zn4L5]-type complexes. This process is significantly influenced by the secondary coordination sphere noncovalent interactions as well as the steric hindrance provided by both zinc-bounded alkyl groups and the N-substituents. [ABSTRACT FROM AUTHOR]

Fluorochemistry is a field of tremendous developments and advances in several areas of science including materials, pharmaceuticals and agriculture. This makes the design and synthesis of fluorine-containing substances highly desirable research targets. The sub-area of synthetic perfluorinated chemistry proportionately attracts widespread interest by applying to all areas of chemistry including organic and inorganic. Particularly, the latter is much underdeveloped as metal complexes with perfluoroalkyl moieties are scarce, with the vast majority of perfluorinated analogs, of long known, halo and alkylated derivatives never having been synthesized. Focusing on the chemistry of trifluoromethyl group, which is the most important in the class of perfluoroalkyls, we set out to explore the possibility of synthesizing and completely characterizing a cyclohexadienyl metal complex. Upon utilizing a number of trifluorometylating reagents, we only arrived at an efficient preparation by the use of Morrison's trifluormethylating reagent. As a result, the new, air- and moisture-sensitive complex (η5-C6H7)Fe(CO)2CF3, was prepared in 71% yield, using a nucleophilic iodo-for-trifluoromethyl substitution, and was completely characterized including by X-ray crystallography. [ABSTRACT FROM AUTHOR]

Our recently developed gold‐catalyzed synthesis of indolo[1,2‐a]quinolines was successfully expanded towards bidirectional approaches, enabling access to two heptacyclic structural motifs. In the case of benzobispyrido[1,2‐a]indoles, previously inaccessible modifications of the only known representative were made possible. In addition, the synthesis of a new class of nitrogen‐containing heptacycles – namely benzobispyrrolo[1,2‐a]quinolines – was achieved by applying alkynylated benzodipyrrole derivatives as starting materials. All new compounds alongside with their corresponding precursors were fully characterized and their properties were investigated by X‐ray crystallography, photophysical measurements and computational methods. The study revealed important structure‐effect relationships between the solid‐state structures and the observed photophysical properties, e. g. aggregation‐induced emission and solid‐state fluorescence. [ABSTRACT FROM AUTHOR]

Perfluorinated aromatic compounds, the so-called perfluoroarenes, are widely used in materials science owing to their high electron affinity and characteristic intermolecular interactions. However, methods to synthesize highly strained perfluoroarenes are limited, which greatly limits their structural diversity. Herein, we report the synthesis and isolation of perfluorocycloparaphenylenes (PFCPPs) as a class of ring-shaped perfluoroarenes. Using macrocyclic nickel complexes, we succeeded in synthesizing PF[n]CPPs (n = 10, 12, 14, 16) in one-pot without noble metals. The molecular structures of PF[n]CPPs (n = 10, 12, 14) were determined by X-ray crystallography to confirm their tubular alignment. Photophysical and electrochemical measurements revealed that PF[n]CPPs (n = 10, 12, 14) exhibited wide HOMO–LUMO gaps, high reduction potentials, and strong phosphorescence at low temperature. PFCPPs are not only useful as electron-accepting organic materials but can also be used for accelerating the creation of topologically unique molecular nanocarbon materials. Synthetic methods for the preparation of perfluorinated aromatic compounds are desirable in materials science. Here, the authors synthesize perfluorocycloparaphenylenes, fully fluorinated carbon nanorings, through a nickel-mediated one-pot method. [ABSTRACT FROM AUTHOR]

N‐heterocyclic carbene ligands (NHC) are widely utilized in catalysis and material science. They are characterized by their steric and electronic properties. Steric properties are usually quantified on the basis of their static structure, which can be determined by X‐ray diffraction. The electronic properties are estimated in the liquid state; for example, via the 77Se liquid state NMR of Se‐NHC adducts. We demonstrate that 77Se NMR crystallography can contribute to the characterization of the structural and electronic properties of NHC in solid and liquid states. Selected Se‐NHC adducts are investigated via 77Se solid state NMR and X‐ray crystallography, supported by quantum chemical calculations. This investigation reveals a correlation between the molecular structure of adducts and NMR parameters, including not only isotropic chemical shifts but also the other chemical shift tensor components. Afterwards, the liquid state 77Se NMR data is presented and interpreted in terms of the quantum chemistry modelling. The discrepancy between the structural and electronic properties, and in particular the π‐accepting abilities of adducts in the solid and liquid states is discussed. Finally, the 13C isotropic chemical shift from the liquid state NMR and the 13C tensor components are also discussed, and compared with their 77Se counterparts. 77Se NMR crystallography can deliver valuable information about NHC ligands, and together with liquid state 77Se NMR can provide an in‐depth outlook on the properties of NHC ligands. [ABSTRACT FROM AUTHOR]

Laboratory X‐ray diffractometers play a crucial role in X‐ray crystallography and materials science. Such instruments still vastly outnumber synchrotron facilities and are responsible for most of the X‐ray characterization of materials around the world. The efforts to enhance the design and performance of in‐house X‐ray diffraction instruments benefit a broad research community. Here, the realization of a custom‐built multipurpose four‐circle diffractometer in the laboratory for X‐ray crystallography of functional materials at Tel Aviv University, Israel, is reported. The instrument is equipped with a microfocus Cu‐based X‐ray source, collimating X‐ray optics, four‐bounce monochromator, four‐circle goniometer, large (PILATUS3 R 1M) pixel area detector, analyser crystal and scintillating counter. It is suitable for a broad range of tasks in X‐ray crystallography/structure analysis and materials science. All the relevant X‐ray beam parameters (total flux, flux density, beam divergence, monochromaticity) are reported and several applications such as determination of the crystal orientation matrix and high‐resolution reciprocal‐space mapping are demonstrated. The diffractometer is suitable for measuring X‐ray diffraction in situ under an external electric field, as demonstrated by the measurement of electric‐field‐dependent rocking curves of a quartz single crystal. The diffractometer can be used as an independent research instrument, but also as a training platform and for preparation for synchrotron experiments. [ABSTRACT FROM AUTHOR]

The complex atomic structure of a high-order approximant to face-centered icosahedral quasicrystal in AlPdTM (TM = transition metal) systems can be deconvoluted into two kinds of atomic clusters pinned at the vertices of a tiling composed of four basic polyhedra, called the canonical cells. As a result, thousands of atoms per unit cell can be registered in fifteen orbits associated with vertices, edges, faces, and cells of the relevant canonical-cell tiling. This geometrical framework facilitates a rational guess of an atomic jungle in an unknown approximant structure, could an underlying tiling be postulated. A novel approximant phase in the AlPd(MoFe) system is discussed within the present framework. [ABSTRACT FROM AUTHOR]

Functionalized disiloxane units with defined structures are interesting molecular models for investigating the reactivity and chemoselectivity in transformations that are of interest in synthesis, surface chemistry, and materials science. (Mes)PhSi(OMe)2 (1) (Mes = mesityl) and (Mes)PhSiCl2 (5) were chosen as starting compounds for the controlled synthesis of methoxy‐, amino‐, and chloro‐functionalized unsymmetric disiloxanes. Two synthesis routes towards (Mes)PhSi(OMe)(OSiPh3) (3) were followed, one via the aminomethoxysilane (Mes)PhSi(OMe)(NC4H8) (2) and the other via the chlorodisiloxane (Mes)PhSiCl(OSiPh3) (6). The amino‐substituted disiloxane (Mes)PhSi(NC4H8)(OSiPh3) (4) was obtained from the chloro derivative 6 with N‐pyrrolidinyllithium, but the same reaction starting from compound 3 was not successful. All provided disiloxanes were structurally characterized by X‐ray crystallography. [ABSTRACT FROM AUTHOR]

Serial crystallography data can be challenging to index, as each frame is processed individually, rather than being processed as a whole like in conventional X‐ray single‐crystal crystallography. An algorithm has been developed to index still diffraction patterns arising from small‐unit‐cell samples. The algorithm is based on the matching of reciprocal‐lattice vector pairs, as developed for Laue microdiffraction data indexing, combined with three‐dimensional pattern matching using a nearest‐neighbors approach. As a result, large‐bandpass data (e.g. 5–24 keV energy range) and monochromatic data can be processed, the main requirement being prior knowledge of the unit cell. Angles calculated in the vicinity of a few theoretical and experimental reciprocal‐lattice vectors are compared, and only vectors with the highest number of common angles are selected as candidates to obtain the orientation matrix. Global matching on the entire pattern is then checked. Four indexing options are available, two for the ranking of the theoretical reciprocal‐lattice vectors and two for reducing the number of possible candidates. The algorithm has been used to index several data sets collected under different experimental conditions on a series of model samples. Knowing the crystallographic structure of the sample and using this information to rank the theoretical reflections based on the structure factors helps the indexing of large‐bandpass data for the largest‐unit‐cell samples. For small‐bandpass data, shortening the candidate list to determine the orientation matrix should be based on matching pairs of reciprocal‐lattice vectors instead of triplet matching. [ABSTRACT FROM AUTHOR]

Novel polyhedral structures were prepared with a butterfly‐shape composed of oligosiloxane wings and a double‐decker silsesquioxane (DDSQ) body. The compounds were synthesized in two steps from commercially available alkoxysilanes, and their structures were confirmed using spectroscopic methods and X‐ray crystallography. Not like other phenyl‐substituted cage silsesquioxanes, these butterfly cages show very good solubility in common organic solvents. The crystal structures clearly showed their unique features: a larger space with longer siloxane chains and a very flexible framework. Moreover, these compounds are thermally stable with a Td5 (5 % weight loss temperature) over 320 °C. [ABSTRACT FROM AUTHOR]

With the establishment of CAD/CAM technology, competing lithium silicate based formulations have been introduced for clinical use, but little is known about their phase composition. Here we investigate a commercially available SiO 2 -Al 2 O 3 -K 2 O-Li 2 O-P 2 O 5 -ZrO 2 system to evaluate the crystal phase evolution during the second heat treatment by changing the main crystallization parameters. With a focus on the final stage of crystallization, we characterized the dimensional changes in the crystallographic structure of the residual Li 2 SiO 3 and the lithium orthophosphate (Li 3 PO 4) phases with variations in crystallization parameters, i.e. time, temperature and cooling rate over the range of the glass transition temperature T g. The phase fractions (crystalline and glass) and the sizes of coherent scattering domains (CSDs) were resolved by means of quantitative X-Ray Diffraction using Rietveld refinement combined with an external standard method (G-factor). Biaxial flexure testing was conducted to evaluate the influence of crystallization parameters on the characteristic strength and natural defect distribution. An increase in crystallization temperature from 840 to 880 °C resulted in a significant reduction of the Li 2 Si 2 O 5 content, which indicated a reversion of the Li 2 SiO 3 to Li 2 Si 2 O 5 phase transformation. Reduction to 800 °C had no significant effect. Furthermore, the CSD sizes of Li 2 SiO 3 and Li 3 PO 4 continuously increased with increasing temperature, which was accompanied by an increase in strength parameters. Reducing the cooling rate over the range of T g resulted in an increased strength at low failure probabilities. These findings help to establish recommendations for adjustment of the crystallization protocol, which has potential to increase the clinical reliability of the material investigated. [ABSTRACT FROM AUTHOR]

The bulky supersilyl‐substituted (tBu3Si) silicon‐centered radical 1 was synthesized and fully characterized by single‐crystal X‐ray crystallography, cyclic voltammetry (CV), and EPR spectroscopy. With its extremely sterically encumbered radical center, 1 is stable in the solid state in air for 16 hours without showing signs of decomposition. Thus 1 is the most robust trisilyl‐substituted silyl radical to date and a promising candidate for application as electrode material in organic radical batteries. Furthermore, it was found to be a strong dehalogenation reagent and therefore might find application in organic syntheses. [ABSTRACT FROM AUTHOR]

Recent advancements in material science exploit non-covalent interactions, such as halogen bonding (XB) or π-stacking within solid-state molecular frameworks for application in organic electronic devices. Herein, we focus on these and other non-covalent interactions and the effect that furan and thiophene substituents play on the solid-state properties of co-crystals formed between pentafluoro(iodoethynyl)benzene (F5BAI; XB donor) and a pyridine disubstituted with either furans or thiophenes (PyrFur2 and PyrThio2; XB acceptors). Spectroscopic and thermal analyses of 1 : 1 mixtures provide indirect evidence of XB interactions, whereas X-ray crystallography provides direct evidence that XB and π-stacking are present in both co-crystals. Density functional theory (DFT) computations provide insight into the relative electronic energetics of each pair-wise contact observed in the experimental F5BAI-PyrFur2 and F5BAI-PyrThio2 co-crystals. [ABSTRACT FROM AUTHOR]

Due to the paucity of known RNA structures, experimental phasing is crucial for obtaining three-dimensional structures of RNAs by X-ray crystallography. Covalent attachment of heavy atoms to RNAs is one of the most useful strategies to facilitate phase determination. However, this approach is limited by the inefficiency or inability to synthesize large RNAs (>60 nucleotides) site-specifically labeled with heavy atoms using traditional methods. Here, we applied our recently reported method, PLOR (position-selective labeling of RNA) to incorporate 5-iodouridine at specific positions in the adenine riboswitch RNA aptamer domain, which was then used for crystallization and subsequent de novo SAD phasing. PLOR is a powerful tool to improve the efficiency of obtaining RNA structures de novo by X-ray crystallography. [ABSTRACT FROM AUTHOR]

A new scheme of two-beam X-ray diffractometry on the "X-Ray Crystallography and Physical Materials Science" (XCPM) beamline at the Kurchatov Synchrotron Radiation Source (KSRS) has been experimentally investigated. The scheme includes a standard double-crystal monochromator and a narrow slit installed in front of the sample. Measurements have been performed for the Si 111 and 311 reflections in the monochromator and the Si 111 and 220 reflections in the sample crystal. It is shown that this scheme allows one to obtain a near-proper diffraction reflection curve even in the case of symmetric diffraction if the Bragg angle for the monochromator exceeds the Bragg angle for the crystal sample by a factor of 2 or more. The experimental results coincide well with the theory. [ABSTRACT FROM AUTHOR]

In the histidine kinase family, the HAMP and DHp domains are considered to play an important role into the transmission of signal arising from environmental conditions to the auto-phosphorylation site and to the binding site of response regulator. Several conformational motions inside HAMP have been proposed to transmit this signal: (i) the gearbox model, (ii) α helices rotations, pistons and scissoring, (iii) transition between ordered and disordered states. In the present work, we explore by temperature-accelerated molecular dynamics (TAMD), an enhanced sampling technique, the conformational space of the cytoplasmic region of histidine kinase CpxA. Several HAMP motions, corresponding to α helices rotations, pistoning and scissoring have been detected and correlated to the segmental motions of HAMP and DHp domains of CpxA. [ABSTRACT FROM AUTHOR]

Acid sensing ion channels (ASICs) are proton-gated ion channels that are members of the degenerin/epithelial sodium channel superfamily and are expressed throughout central and peripheral nervous systems. ASICs have been implicated in multiple physiological processes and are subject to numerous forms of endogenous and exogenous regulation that include modulation by Ca2+ and Cl- ions. However, the mapping of ion binding sites as well as a structure-based understanding of the mechanisms underlying ionic modulation of ASICs have remained elusive. Here we present ion binding sites of chicken ASIC1a in resting and desensitized states at high and low pH, respectively, determined by anomalous diffraction x-ray crystallography. The acidic pocket serves as a nexus for divalent cation binding at both low and high pH, while we observe divalent cation binding within the central vestibule on the resting channel at high pH only. Moreover, neutralization of residues positioned to coordinate divalent cations via individual and combined Glu to Gln substitutions reduced, but did not extinguish, modulation of proton-dependent gating by Ca2+. Additionally, we demonstrate that anion binding at the canonical thumb domain site is state-dependent and present a previously undetected anion site at the mouth of the extracellular fenestrations on the resting channel. Our results map anion and cation sites on ASICs across multiple functional states, informing possible mechanisms of modulation and providing a blueprint for the design of therapeutics targeting ASICs. [ABSTRACT FROM AUTHOR]

Purpose: Rosuvastatin calcium (ROSCa) is a poorly soluble drug with bioavailability not exceeding 20%. Decreasing the particle size may enhance its solubility, dissolution rate and bioavailability. Therefore, the aim of the current study is to prepare ROSCa nanoparticles by wet milling technique using planetary ball mill. The codesign between formulation and stabilization of nanoparticles was studied to achieve both high dissolution as well as bioavailability. Methodology: ROSCa nanosuspensions was prepared by wet milling technique using planetary ball mill, by applying milling ball size of 0.1 mm at speed of 800 rpm for 3 cycles each cycle composed of 10 minutes. HPMC, PVP k-30, pluronic F-127, Tween 80 and PEG 6000 were used as stabilizers. The nanosuspensions were then freeze-dried, and the dried nanoparticles were evaluated for particle size, zeta potential, in-vitro dissolution test, XRPD and in-vivo study. Results: ROSCa nanoparticles stabilized with 10% PVP (P3) had a good stability with smallest particle size, which in turn enhanced the dissolution rate. The particle size of the leading formula was 461.8 ± 16.68 nm with zeta potential of -31.8 ± 7.22 mV compared to untreated drug that has a particle size of 618μm. The percent of ROSCa dissolved after 1 hour enhanced significantly which reached 72% and 58.25% for leading nanoparticle formula and untreated ROSCa, respectively (P < 0.05). The in-vivo study of ROSCa from the leading nanoparticle formula showed a significant enhancement in the Cmax after 2 h (82.35 ng/ml) compared to 9.2 ng/ml for untreated drug. Conclusion: Wet milling technique is a successful method to prepare ROSCa nanoparticles. From different stabilizer used, PVP (10%) was able to produce stable nanoparticle with small particle size which significantly enhance the dissolution rate and pharmacokinetics parameters of ROSCa. [ABSTRACT FROM AUTHOR]

The Machine Recognition of Crystallization Outcomes (MARCO) initiative has assembled roughly half a million annotated images of macromolecular crystallization experiments from various sources and setups. Here, state-of-the-art machine learning algorithms are trained and tested on different parts of this data set. We find that more than 94% of the test images can be correctly labeled, irrespective of their experimental origin. Because crystal recognition is key to high-density screening and the systematic analysis of crystallization experiments, this approach opens the door to both industrial and fundamental research applications. [ABSTRACT FROM AUTHOR]

Aiming at the design of an allosteric modulator of the neonatal Fc receptor (FcRn)–Immunoglobulin G (IgG) interaction, we developed a new methodology including NMR fragment screening, X-ray crystallography, and magic-angle-spinning (MAS) NMR at 100 kHz after sedimentation, exploiting very fast spinning of the nondeuterated soluble 42 kDa receptor construct to obtain resolved proton-detected 2D and 3D NMR spectra. FcRn plays a crucial role in regulation of IgG and serum albumin catabolism. It is a clinically validated drug target for the treatment of autoimmune diseases caused by pathogenic antibodies via the inhibition of its interaction with IgG. We herein present the discovery of a small molecule that binds into a conserved cavity of the heterodimeric, extracellular domain composed of an α-chain and β2-microglobulin (β2m) (FcRnECD, 373 residues). X-ray crystallography was used alongside NMR at 100 kHz MAS with sedimented soluble protein to explore possibilities for refining the compound as an allosteric modulator. Proton-detected MAS NMR experiments on fully protonated [13C,15N]-labeled FcRnECD yielded ligand-induced chemical-shift perturbations (CSPs) for residues in the binding pocket and allosteric changes close to the interface of the two receptor heterodimers present in the asymmetric unit as well as potentially in the albumin interaction site. X-ray structures with and without ligand suggest the need for an optimized ligand to displace the α-chain with respect to β2m, both of which participate in the FcRnECD–IgG interaction site. Our investigation establishes a method to characterize structurally small molecule binding to nondeuterated large proteins by NMR, even in their glycosylated form, which may prove highly valuable for structure-based drug discovery campaigns. [ABSTRACT FROM AUTHOR]