X-ray Structural Examination Research Articles

Large third-order nonlinear susceptibility of newly synthesized 3-amino-1H-1,2,4-triazolium p-toluene sulfonate (TPTSA) single crystal measured by the open and closed aperture of the Z-scan technique

The researchers employed the Slow Evaporation Solution Technique (SEST) to grow a third-order nonlinear optical 3-amino-1H-1,2,4-triazolium p-toluene sulfonate (TPTSA) crystal and subsequently conducted an X-ray structural examination. The resulting solution's monoclinic structure (P21/c space group) was confirmed and refined using the SHELXS 2018/3 program, and this marks the first instance of a TPTSA single-crystal structure being reported. To further investigate the optical qualities of the TPTSA crystals, including reflectance (R), bandgap (Eg), refractive index (n), and extinction coefficient (K), we utilized a UV–Vis–NIR spectrophotometer, which demonstrated a transmittance of 82%. Moreover, photoluminescence spectrum analysis revealed that the crystal emits light at 294 and 471 nm. Thermal properties of the TPTSA single crystals were also studied, and it was determined that TPTSA remains stable up to 197 °C. A Hirshfeld surface study showed various inter and intra molecular interactions within the TPTSA compound. Based on the crystal's Z-scan parameters, such as absorption coefficient (β = 1.02412 × 10−4 m/W), nonlinear refractive index (n2 = 9.7348 × 10−12 m2/W), and third-order linear optical susceptibility (χ3) of TPTSA, which was found to be 3 × 10−8 esu, it is evident that the nonlinear properties of this crystal make it suitable for third harmonic generation applications. The comprehensive structural analysis and physical characteristics of the TPTSA crystal demonstrate its potential for applications in harmonic generation.

Eco-friendly Bi(Ni2/5Ti2/5Fe1/5)O3 nanoceramics: Synthesis, dielectric and impedance studies

This investigation involves the synthesis and study of dielectric, structural and impedance properties of polycrystalline Bi(Ni2/5Ti2/5Fe1/5)O3 (symbolized as BNTF) nano-ceramic. The BNTF polycrystalline sample was fabricated through the use of a conventional solid-state reaction route. X-ray structural examination reveals that the parent compound (i.e., BiFeO3) crystallizes in the rhombohedral structure (space group-R3c) while that the BNTF compound crystallizes in orthorhombic symmetry. The substitution of NiTiO3 into BiFeO3 enhances various properties and reduces electrical leakage current. The average crystallite size is calculated to be 29 nm. The room temperature textures and surface morphologies of the specimen were verified by field-emission scanning electron microscope, and show uniform grains distribution on sample surfaces. Dielectric parameters (constant and tangent-loss) and impedance spectroscopy parameters of NiTiO3 modified BiFeO3 compound were investigated over a wide temperature range (25–500 °C) at different frequency (25 kHz-500 kHz), which offers several interesting features of BNTF material suitable for further device applications.

Sonochemical synthesis, crystal structure, and DFT calculation of an innovative nanosized Pb(II)-azido metal–organic coordination polymer as a precursor for preparation of PbO nanorod

A sonochemical synthesis was performed to synthesize nanosheets of an innovative lead (II) metal–organic coordination polymer (CP) [(PbN3Q)2]n (1) (Q– = 8-hydroxyquinolinate). For precise characterization, scanning electron microscopy, elemental analysis, IR spectroscopy, X-ray powder diffraction, and single-crystal X-ray diffraction scrutiny were conducted. The X-ray structural examination indicated that 1 was a 1D chain with the two neighboring Pb(II) centers bridged together by two O atoms from two Q− ligands and two N3− using their two terminal N atoms. Pb(II) had a coordination number of 7 with an asymmetrical coordination geometry. The contiguous chains were linked by the π–π interactions with the aromatic circles of Q− from the chains adjacent to each other. Therefore, these weak interactions facilitated the construction of a 3D metal–organic CP using the basic 1D building block. Density functional theory was used to optimize the title complex structure. The computed natural bond orbital burdens suggested that its ascription to the Pb…Pb contacts in the chains may have been attributed to the scant positive burden in the lead (II) ions. In summary, PbO nonorods were simply synthesized by thermolysis of 1 at 180 °C using oleic acid as the surfactant.

5-Hydroxymethylcytosine in E-box motifs ACAT|GTG and ACAC|GTG increases DNA-binding of the B-HLH transcription factor TCF4.

We evaluated DNA binding of the B-HLH family members TCF4 and USF1 using protein binding microarrays (PBMs) containing double-stranded DNA probes with cytosine on both strands or 5-methylcytosine (5mC) or 5-hydroxymethylcytosine (5hmC) on one DNA strand and cytosine on the second strand. TCF4 preferentially bound the E-box motif (CAN|NTG) with strongest binding to the 8-mer CAG|GTGGT. 5mC uniformly decreases DNA binding of both TCF4 and USF1. The bulkier 5hmC also inhibited USF1 binding to DNA. In contrast, 5hmC dramatically enhanced TCF4 binding to E-box motifs ACAT|GTG and ACAC|GTG, being better bound than any 8-mer containing cytosine. Examination of X-ray structures of the closely related TCF3 and USF1 bound to DNA suggests TCF3 can undergo a conformational shift to preferentially bind to 5hmC while the USF1 basic region is bulkier and rigid precluding a conformation shift to bind 5hmC. These results greatly expand the regulatory DNA sequence landscape bound by TCF4.

Characterization Of Oxide Layers Formed On 13CrMo4-5 Steel Operated For A Long Time At An Elevated Temperature

Abstract The paper contains results of studies into the formation of oxide layers on 13CrMo4-5 (15HM) steel long-term operated at an elevated temperature. The oxide layer was studied on a surface and a cross-section at the inner and outer surface of the tube wall. The 13CrMo4-5 steel operated at the temperature of 470°C during 190,000 hours was investigated. X-ray structural examinations (XRD) were carried out, microscope observation s using an optical, scanning microscope were performed. The native material chemical composition was analysed by means of emission spark spectroscopy, while that of oxide layers on a scanning microscope (EDS). The studies on the topography of the oxide layers comprised studies on the roughness plane, which were carried out using a AFM microscope designed for 2D and 3D studies on the surface. Mechanical properties of the oxide layer – steel (substrate) were characterised on the basis of scratch test. The adhesion of oxide layers, friction force, friction coefficient, scratching depth were determined as well as the force at which the layer was delaminated.

Studies on the adhesion of oxide layer formed on X10CrMoVNb9-1 steel

The paper contains results of studies on the formation of oxide layers on X10CrMoVNb9-1 (P91) steel long-term operated at an elevated temperature. X10CrMoVNb9-1 steel operated at the temperature of 595°C for 54,144h was the studied material. X-ray structural examinations (XRD) were carried out, microscope observations using an optical and scanning microscope were performed. The native material chemical composition was analysed by means of emission spark spectroscopy, while that of oxide layers on a scanning microscope (EDS). Mechanical properties of the oxide layer – steel (substrate) were characterised on the basis of scratch test. The adhesion of oxide layers, friction force, friction coefficient, scratching depth was determined as well as the force at which the layer was delaminated. It has been found that the oxide layer formed under the influence of applied pressure is more degradeted in the areas where are porous and cracks.

Molecular and crystal structure of 2,3-dimethyl-5-(2′-methylprop-1′-enyl)-6-(morpholyl-4′-carbonyl)-cyclohex-3-en-1-carboxylic acid

An X-ray structural examination is carried out for 2,3-dimethyl-5-(2′-methylprop-1′-enyl)-6-(morpholyl-4′-carbonyl)-cyclohex-3-en-1-carboxlic acid that is one of the products of the Diels-Alder reaction of an acyclic monoterpene alloocimene with maleic and citraconic anhydrides followed by the ring opening of adducts with morpholine to corresponding amides. The crystals are triclinic; a = 10.619(1) A, b = 12.784(2) A, c = 14.328(2) A; α = 65.752(1)°, β = 87.932(1)°, γ = 78.120(1)°; V = 1733.0(3) A3, P-1 space group, Z = 4 (two independent molecules). In both molecules, the anti-conformation of the carboxylic group is observed, the conformation being stabilized by an intramolecular hydrogen bond involving the carboxylic hydrogen atom and ketonic oxygen.

The correlation of processes of crystallization and changes of free electron density amorphous alloy powder Co80Ni20

Great attention is being given today to investigations on the capabilities and structural changes of amorphous and nanocrystal materials. Structural changes of the amorphous cobalt and nickel alloy powder obtained by electrochemical deposition were investigated in this paper. The crystallization process, as determined by the DSC method, occurred in two steps. The temperature dependence of electrical resistively and magnetic susceptibility in isothermal and non-isothermal conditions within the temperature range of room temperature to 700?C was determined for the powder samples pressed under pressure of 800 MPa. The X-ray structural examinations results correlate with those of the DSC analysis and the electrical resistively measuring.

Solidification microstructure of plasma sprayed and remelted carbide coatings (Cr3C2/ni-Al, W2C-WC/Co)

Carbide layers applied on the steel substrate by the plasma spraying method were remelted using high-energy heat sources. A diverse methodology of coating treatment was used: ranging from a single and multiple treatment with a continuous micro-plasma arc, through the treatment by the TIG (tungsten inert gas) welding method, to CO2 laser remelting. The quality of the remelted layers was evaluated based on macro- and microscopic structural examinations, x-ray phase analysis, tribological tests, and hardness measurements. The results of the investigations carried out confirmed the possibility of remelting sprayed coatings and obtaining layers free from faults and imperfections typical of plasma spraying. The micro- and x-ray structural examinations revealed, among other things, a significant reduction of porosity (both open and closed ones), homogenization of the chemical composition, smoothing of the surface, and the improvement of coating adhesion to the substrate. The present study is a continuation of the investigations carried out on thermally sprayed and micro-plasma remelted oxide layers, that were started at the beginning of the 1990s at the Material Engineering Institute of the Technical University of Częstochowa.

P53 Unfolding Detected by CD but Not by Tryptophan Fluorescence

Full-length human p53 protein was examined using tryptophan fluorescence and circular dichroism spectroscopy (CD) to monitor unfolding. No significant alteration in tryptophan fluorescence for the tetrameric protein was detectable over a wide range of either urea or guanidine hydrochloride concentrations, in contrast to results with the isolated DNA binding domain [Bullock et al. (1997) Proc. Natl. Acad. Sci. USA 94, 14338]. Under similar denaturant conditions, CD demonstrated significant protein unfolding for the full-length wild-type protein, with increased apparent structure loss compared to that detected during thermal denaturation [Nichols and Matthews (2001) Biochemistry 40, 3847]. Examination of X-ray structures containing two of the four tryptophan residues of a p53 monomer suggested local environments consistent with quenched fluorophores. Exploration of p53 fluorescence using potassium iodide as a quencher confirmed that these fluorophores are already substantially quenched in the native structure, and this quenching is not relieved during protein unfolding.

Topological chirality of iron-sulfur proteins.

An examination of x-ray structures of single-cluster [4Fe-4S] proteins in the Protein Data Bank has revealed that all redox proteins and the glutamine 5-phosphoribosyl-l-pyrophosphate amidotransferase from Bacillus subtilis have a topological configuration arbitrarily designated as D, whereas the DNA repair enzyme endonuclease III from Escherichia coli has the opposite topological configuration L. This is the first example in which both senses of topological chirality have been observed in a class of proteins.

Aryl-NNO-azoxy-?-nitroalkanes

Two methods of synthesis of aryl-NNO-azoxy-α-nitroalkanes bearing either one or two reactive hydrogen atoms α to the azoxy and nitro groups are described. These methods involve protection of the latter by easily removable groupings, those used being acetoxy-methyl and acetal fragments. The regiochemical nature of the diazene oxide groupings in aryl-NNO-azoxy-α-nitroalkanes obtained by oxidation of the appropriate diazenes has been established by heteronuclear NMR and x-ray structural examination. Some of the chemical properties of these diazene oxides have been examined.

A new ligand, BEDT-TTF: crystal and molecular structure of (BEDT-TTF)Cu3I4

X-ray structural examination of (BEDT-TTF)Cu3I4 crystals has shown for the first time that BEDT-TTF, previously known solely as a neutral molecule or cation-radical, acts as a bidentate ligand in binding Cu atoms.

Synthesis and x-ray structural examination of intracomplex boroxadiazolidines

The reaction between acetone monoalkylhydrazones and aldehydes in the presence of boric acid derivatives has given five-membered boron-nitrogen heterocycles, the stability of which is to a large extent dependent on the substituents in the ring. An x-ray structural examination of the boroxadiazolidine (VI) has been carried out.

Structure and properties of diphenylacetylbenzo-12-crown-4

It has been shown by x-ray structural examination and IR spectroscopy that conformations of diphenylacetylbenzo-12-crown-4 in which the lone pairs of oxygen are oriented on opposite sides of the plane of the macrocycle are stabilized in the crystal and in solution. From a comparison with the structure and anticonvulsant activity of benzo-12-crown-4 with those of its acetyl and diphenylacetyl derivatives, it is suggested that a condition for the possition of this type of activity is the presence of a conformation of the macrocycle in which the lone pairs of the three oxygen atoms are located on the same side.

Synthesis, molecular and crystal structure of 3-[(N-benzoyl) diaminomethylene]pentane-2,4-dione, a novel chelating ligand

1. Acetylacetone reacts with benzoylcyanamide in the presence of 5 mole% of Ni(acac)2 to give a novel chelating ligand, 3-[(N-benzoyl)diaminomethylene] pentane-2,4-dione (III). The key step in the reaction is addition of Ni(acac)2 to the C≡N group in benzoylcyanamide to give the chelate. 2. X-ray structural examination has shown that a characteristic feature of the molecule (III) is the involvement of all the O and N atoms in the formation of three intramolecular N-H...O=C hydrogen bonds.

Perfluorinated aliphatic enethiols and ?, ?-unsaturated sulfenyl chlorides

1. 2-Mercaptoperfluoro-3-isopropyl-4-methyl-2-pentene and perfluoro-3-isopropyl-4-methyl-2-pentenyl-2-sulfenyl chloride have been synthesized, and it has been shown that these compounds fail to undergo acid- or base-catalyzed isomerization to their thiocarbonyl forms. 2. Reaction of 2-mercaptoperfluoro-3-isopropyl-4-methyl-2-pentene with bases affords perfluoro 2,4,4-trimethyl-3-isopropyl-2-thiete by intramolecular cyclization. 3. Hydrolysis of perfluoro-3-isopropyl-4-methyl-2-pentenyl-2-sulfenyl chloride gives perfluoro-2,4,4-trimethyl-3-isopropyl-2-thiete oxide, the structure of which has been proved by X-ray structural examination. 4. Perfluoro-2,4,4-trimethyl-3-isopropyl-2-thiete oxide is reduced by triphenylphosphine to perfluoro-2,4,4-trimethyl-3-isopropyl-2-thiete.

Oxidation of transition metals in the liquid phase. 9. Direct synthesis and X-ray structural examination of complexes [(Me2S)AuBr] and [(Me2S)AuBr3

Oxidation of Au0 in the DMSO-HBr system has given dimethyl sulfide complexes of mono-and trivalent gold, [(Me2S)AuBr] and [(Me2S)AuBr3]. X-ray diffraction examination has shown that in the crystal of the first complex there are chain intermolecular contacts Au...Au (3.22 a), and in the crystal of the second, intermolecular Au...Br contacts which extend the square planar coordination of the gold atoms to distorted bipyramidal.

Structure of the rel(4R,6S)-5-thio-4,6-diisopropyl-2,5-diphenyl-2-bora-1,3,5-dioxaphosphorinane-pyridine complex

An x-ray structural examination of the rel(4R,6S)-5-thio-2,5-diphenyl-4,6-diisopropyl-2-bora-1,3,5-dioxaphosphorinane-pyridine complex has been carried out (diffractometer, lambdaMo, 2788 reflections, R = 0.035). The crystals are monoclinic, a = 9.422, b = 29.943, c = 17.607 A, ..beta.. = 94.57/sup 0/, Z = 8, space group P2/sub 1//n (two independent molecules). The six-membered heterocycles have the chair conformation flattened at the boron atom. The Ph substituent on the P atom and the pyridine on the boron atom occupy axial positions, and the Ph substituent on the P atom and the pyridine on the boron atom occupy axial positions, and the pH substituent on boron, the P=S bond, and the isopropyl groups attached to C(4) and C(6) are equatorial. The independent molecules differ in the inclination of the Ph substituents at boron to the plane to the principal heterocycle. The endocyclic valence angles CPC are reduced to 96.4/sup 0/.

Synthesis and X-ray structural examination of 2-phenylimino-4-(4-hydroxy-2-butynylidene)-l,3-oxathiolane

2,4-Hexadiyne-l,6-diol has been found to react with phenyl isothiocyanate to give 2-phenylimino-4-(4-hydroxybut-2-ynylidene)-l,3-oxathiolane, the structure of which was established by x-ray diffraction analysis and1H and13C NMR spectroscopy.