X-ray Structural Parameters Research Articles

Triel tris(aminoaryl)aluminum, gallium, and indium complexes and their homocoupling reactions mediated by NiBr2

Here, we present the synthesis, spectroscopic characterization, structural analysis, and studies on the bonding situation of group 13 tris(o-aminoaryl) complexes, [M(C6H4(o-NMe2))3] (1–3) and [M(C10H6(o-NMe2))3] (4–6) where M = Al, Ga, In. X-ray and DFT structural parameters, in conjunction with the inspection of the molecular electrostatic potential (MEP) of related triaryl, MAr3, models where Ar = C6H4, C10H6, suggest for 1–6 the presence of two partially polar covalent intramolecular M–N triel bonds. Interestingly, indium complexes 3 and 6 bind a third nitrogen atom with a Van der Waals type interaction. Stoichiometrical reactions of 1–3 with NiBr2 at 25 °C afforded the homocoupling product bi-o-dimethylaminophenyl (7) in up to 73 % isolated yield with 1 and 3 as the nucleophile. While 4–6 performed poorly under the same reaction conditions or at 100 °C providing either traces or at most 13 % of bi-o-dimethylaminonaphtyl (8) with 4 according to GC–MS. Hypothetical DFT bimetallic species [BrNi(μ-Br)M{C6H4(o-NMe2)}3] and [Ni(Br)2M{C10H6(o-NMe2}3] where M = Al (9, 12), Ga (10, 13), In (11, 14) are proposed reaction intermediates implied in the transmetalation/reductive elimination process that affords diaromatic amines 7 and 8.

Nanostructured Ag/NiO composites for supercapacitor and antibacterial applications, and in-silico theoretical investigation

In the current study, Ag/NiO nanocomposite performance, antibacterial properties, and in-silico theoretical method were examined utilizing Withania somnifera leaf extract. The ultraviolet–visible spectra showed distinct absorption peaks at 295 and 423 nm, confirming the presence of Ag and NiO. Morphological studies (scanning electron microscopy and high-resolution transmission electron microscopy) revealed mingled hexagonal and spherical structure, and energy-dispersive X-ray spectroscopy showed elemental composition of Ag/NiO. The crystal structure of Ag/NiO was confirmed by X-ray diffraction analysis and structural parameters were studied through Rietveld refinement analysis. Fourier transform infrared spectroscopy identified alkaloids as the main compounds responsible for the reduction of Ag and NiO. The occurrence of Ag, Ni, and O with compressed phytochemicals was identified using X-ray photoelectron spectrometry. The electrochemical performance and antimicrobial activities of Ag/NiO were investigated. The as-prepared Ag/NiO electrode exhibited specific capacitance of 872 F/g at a scan rate of 5 mV/s and revealed good cyclic retention of about 89.2 % even after 5000 cycles. Furthermore, admirable electrochemical properties of Ag/NiO provided an asymmetrical supercapacitor device with energy density of 46 Wh/kg and power density of 3501 W/kg. This indicates good prospects for utilization of biomass-derivable electrode material for energy storage applications. In addition, Ag/NiO had significant inhibitory effects (zone of inhibition: 15.4 mm, minimum inhibitory concentration: 12.5 μg/mL) against the human pathogen Klebsiella pneumoniae. The high probability of antibacterial action of the obtained complex was theoretically studied and the results correlated with experimental study.

STUDY OF COAL TAR PITCH MORPHOLOGY AND STRUCTURE

The morphology and structure of the mesophase in the series: coal tar pitch (CTP) - α-fraction of CTP - carbonised α-fraction after heating to 1200 °C, were studied by scanning electron microscopy, X-ray phase and X-ray structural analysis. The X-ray structural parameters were determined: longitudinal and transverse dimensions of the lamellae and the thickness of packages, the distance between the lamellae and the number of lamellae in the formed packages. It is shown that the two-dimensional structures of carbon mesophase are ordered into three-dimensional packages during the formation of semi-coke under CTP heating. It is established that the carbon structure of CTP and its α-fraction is represented by the turbostratic and graphite-like phases. The sizes of the packages formed by the lamellae during structuring in the transverse direction in the studied samples are of the order of 18-25 Å, in the longitudinal direction 46-63 Å, the average distance between the lamellae in the studied samples is 3.46-3.52 Å.

HYROGEN BOND IN CRYSTAL STRUCTURE OF SALTS OF SYMMETRIC POLYMETHYLFERRICINIUM CATİONS (SYM.[(CH3)mC5H5–m]2Fe+X – , m=3,4,5 or МеnFc+X – , n = 6, 8, 10; X– = PF6 – , BF4 – , Br3 – )

The article explains reasons of elongation (0.019 Å) of the bond between iron–cyclopentadienyl ring in the 1,2,4,1,2,4-hexamethylferricinium (sym. Ме6Fc+ ) cation formed due to the one-electron oxidation of iron atom of sym.1,2,4,1,2,4-hexamethylferrocene (sym. Ме6Fc) molecule which is 2-2.5 times smaller (0.04–0.05 Å) than that observed in pairs of ferrocene/ferricinium (Fc/Fc+ ), sym. octamethylferrocene/sym.octamethylferricinium (Ме8Fc/Me8Fc+ ) and decamethylferrocene/decamethylferricinium (Ме10Fc/Ме10Fc+ ). For this purpose, X-ray structural parameters characterizing the interaction between cation and anion in the sym.Ме6Fc+PF6 – complex was compared with appropriate parameters in Ме8Fc+BF4 – , Ме10Fc+Br3 and Ме10Fc+PF6 – complexes; and it was mooted that there is an F …H type hydrogen bond in this complex taking into account the length of the non-valent F…H contact (bond) in the sym. Ме6Fc+PF6 – complex. The lengths of Р–F bonds and F–P–F angles of the PF6 – anion in the listed 4 sandwich complexes were compared with appropriate parameters in the РF6 – anion of the LiРF6 crystal. It has been unequivocally proved that F…H hydrogen bonds exist in the sym.Ме6Fc+PF6 – complex.

Structural characterization, molecular docking assessment, drug-likeness study and DFT investigation of 2-(2-{1,2-dibromo-2-[3-(4-chloro-phenyl)-[1,2,4]oxadiazol-5-yl]-2-fluoro-ethyl1}-phenyl)-methyl 3-methoxy-acrylic ester

The structure of 2-(2-{1,2 dibromo-2-[3-(4-chloro-phenyl)- [1,2,4]oxadiazol-5-yl]-2-fluoro-ethyl1}-phenyl)-methyl 3-methoxy-acrylic ester (BCOD) was determined using X-ray single-crystal diffraction and theoretical. The BCOD compound crystallizes in the P-1 space group of the triclinic crystallographic system. The absolute structure has been refined to the final R of 5% for 3356 observed reflections. The evaluation of the theoretical parameters was performed using density functional theory (DFT) along with B3LYP and HSEH1PBE functionals at 6–311++G (d,p) basis set in the ground state. The theoretical geometries reproduce well the X-ray structural parameters. The 3D structure was analyzed through distances, bond and dihedral angles exposing that the BCOD molecule is non-planar. The HOMO and LUMO energy values, and reactivity descriptors were also studied and the molecular electrostatic surface potential (MEP) was calculated and mapped to highlight the positive and negative regions in the molecule. Furthermore, intermolecular interactions and their contributions in the crystal were analyzed by exploring Hirshfeld surface and 2D fingerprint results. The H⋅⋅⋅H and O⋅⋅⋅H intercontacts represent the main intermolecular interactions with contributions of 30.7% and 14%, respectively. Moreover, reduced density gradient was used to investigate non-bonded and weak interactions. The biological activity of this compound was extensively studied using molecular docking to identify the hydrogen bonds and binding energy with different proteins.

(Digital Presentation) Influence of Li2s on the Volume Expansion of Sn Particles during Lithiation of Tin Sulfides

In recent years tin sulfides, particularly SnS and SnS2, have attracted significant attention in the energy storage research community. Their high theoretical specific capacities (1111 mAhg-1 for SnS and 1209 mAhg-1 for SnS2) make this group of materials good candidates for anode active materials for Li-ion batteries. Moreover, their low cost and environmental benignity further contribute to the appeal. During lithiation, tin sulfides undergo a conversion reaction with Li in which Li2S and Sn are formed. Further lithiation triggers the alloying reaction between Sn and Li, resulting in the formation of various Sn-Li intermetallic phases. The newly formed Sn-Li phases have a significantly higher unit cell volume than their parent phases, causing cracking of particles on repeated alloying and dealloying. Ultimately, the continuous cracking of particles leads to pulverization of anode material, reduced contact between the particles and capacity fade.In our work, we explored the influence of Li2S formed during the conversion reaction on the stability of the solid electrolyte interphase (SEI) layer and the overall cycling performance of SnS and SnS2 materials. The precipitation reaction was used to synthesised both SnS and SnS2 materials. Furthermore, SnS2 was also synthesised via the widely used hydrothermal method. In all cases, SnClx ·yH2O (x= 2; y= 2 for SnS and x= 4; y= 5 for SnS2) was used as a Sn source and thioacetamide as a S source. The physio-chemical properties of the as-synthesised materials were examined by powder X-ray diffraction (PXRD) and structural parameters were extracted using Rietveld analysis of the measured patterns. Furthermore, the sample morphologies were characterized by scanning electron microscopy (SEM) and the crystallinity of the samples was further investigated by transmission electron microscopy (TEM). The presence of surface impurities which may formed during material synthesis, was examined by X-ray photoemission spectroscopy (XPS).The cycling performance of SnS2 prepared via the precipitation reaction was compared to SnS2 prepared via hydrothermal method as well as to SnS prepared via precipitation reaction. In this way we were able to draw comparisons between materials with the same chemical composition but different particle size and morphology as well as materials with different chemical composition and very similar morphology.The length changes of SnS and SnS2 electrodes during cycling were investigated by the in-situ dilatometry technique, and several ex-situ methods such as ex-situ XRD and ex-situ SEM were utilized to investigate the role of crystal chemistry and particle morphology on electrochemical performance post-mortem. The results showed that on alloying, the electrode comprised of partially amorphous SnS2 synthesised via the precipitation expands the least. Additionally, the cycling data show that partially amorphous SnS2 electrochemically outperformed both SnS and highly crystalline SnS2. This may be attributed to two effects. Firstly, thicker Li2S layers are generally formed on particles with lower surface areas, thereby better restraining the volume changes of Sn during cycling. Secondly, due to the intercalation step prior to the conversion reaction in SnS2, it is postulated that Li2S and Sn are homogeneously distributed on the atomic scale, which further helps to minimize the volume expansion during cycling.

Investigations of structural, spectral (IR and NMR) and in silico analyses of boron compounds as SERM inhibitor

• Detail computational analyses were done over the boron compounds. • Structural and spectral characterizations were done in detail. • SERM properties of boron compounds were investigated. • Active amino acid chain was determined in estrogen receptor. • Leucine was found as the most active amino acid. Computational analyses of selected boron compounds are performed at M06–2X/6–31+ G (d,p) level in vacuum and water. Simulated X-Ray structure and structural parameters are reported. In spectral analyses, IR spectrum are examined with VEDA program and vibration modes of selected peaks in IR spectrum are revealed. As for the NMR spectrum, chemical shift value of carbon, hydrogen, nitrogen and boron atoms are calculated for studied compounds. In addition to characterization studies, electronic properties of studied boron compounds are investigated by the calculation of contour plots and MEP maps of mentioned compounds. Finally, anticancer properties of studied compounds are investigated by molecular docking calculations. 6VPK, estrogen receptor, is selected as target protein in this study. Selective estrogen receptor modulator (SERM) properties of studied compounds are investigated due to the fact that inhibiting of the estrogen receptor is one of the cancer preventions. As a result, compound ( 2 ) and ( 4 ) are the best drug candidates due to the fact that their results are similar to each other. Amino acids between 525 and 539 in target protein are determined as effective in targeted drug development. Finally, leucine is identified as the most interacting amino acid.

The dynamics of hemoglobin-haptoglobin complexes. Relevance for oxidative stress

Haptoglobin (Hp) is a protein with role in oxidative stress prevention, which it fulfills by trapping hemoglobin (Hb) dimers in a strongly-bound complex, thus reducing Hb's ability to engage in oxidative stress reactions which are greatly enhanced when the Hb tetramer falls apart into dimers. A first molecular dynamics (MD) analysis is presented here for the Hb-Hp pair. Also, for the first time the tyrosyl (Tyr) radicals in globins are examined with MD calculations directed at comparing with electron paramagnetic resonance (EPR)-detected parameters, with the aim of identifying the location of free radicals on the globin. Such assignments are needed in order to complete our understanding of the manner in which globins deal with oxidative stress, as well as for the ways the organism deals with the oxidative stress occasionally accidentally amplified by the globins via their reactive heme and Tyr moieties. The EPR-detected free radical in Hb and in Hb:Hp is characterized experimentally by a measurable increase in hydrophobicity upon Hb:Hp complexation and by a constant ∼53° θ angle. The x-ray structure and MD-derived hydrophobicity-related parameters appear to support Y145, Y35 and Y24 as likely locations of the Hb radical – arguing strongly against Y42, Y130 and Y140. The θ values appear to favor Y42, with the MD data nevertheless also arguing in favor of Y35 and, to a lesser extent, Y145 and Y140. Y130 and Y24 appear the least likely candidates according to the θ values, especially in view of the MD data. Overall, Y35 and Y145 appear to be the two candidates with least arguments against them for satisfying the two criteria (θ values and hydrophobicity) for matching the experimentally-observed EPR radical in Hb and Hb:Hp.

Investigation of the structural characteristics of vitrinites of some coals of the Kuznetsk Basin

In this work, the structural parameters of vitrinites of coal of various degrees of metamorphism were investigated by X-ray diffraction methods. Vitrinite concentrates were obtained from coal of the Kuznetsk Basin by the method of fractional analysis of coals, according to which the studied fuel is stratified into fractions in liquids of different densities. The following X-ray structural parameters were analyzed: the number of carbon atoms in the lamellae (natC), the longitudinal size of the lamellae, the height of their stacking (La and Lc), the number of polyaromatic layers in the stack (N), and the packing density of the lamellae (ρ). It was shown that in vitrinite concentrates, an increase in all analyzed structural parameters (Lc, La, natC, N, ρ) is observed with an increase in the degree of metamorphism, at the same time, a decrease in the value of the interplanar distance (d002) is observed. The performed X-ray diffraction studies showed that the average number of layers in a package and carbon atoms per monolayer in the samples of vitrinite concentrates of bituminous coals of high stages of metamorphism (Ro, r = 1.41%) varies from 7 to 8 and 14-15, respectively. A correlation was found between the linear nature of the number of arene layers and the height of their packing. The results obtained are in good agreement with the literature data given for coals of various deposits.

Synthesis of nanostructured FePt systems

The paper compares some characteristics of nanoparticles of the FePt system obtained by the method of joint reduction of solutions of metal precursors using different reducing agents: an alkaline solution of hydrazine hydrate and sodium tetrahydroborate. The method of transmission electron microscopy is used to analyze the shape and morphology of the obtained nanosized particles, according to the data obtained by the methods of X-ray diffraction, phase analysis is carried out and the main X-ray structural parameters are evaluated. Thermal analysis in combination with mass spectrometry is used to characterize the state and purity of the surface of nanoparticles. It is shown in the work that nanoscale FePt systems obtained using the reductants selected in the work have similar physicochemical characteristics.

Сравнение методов синтеза наноструктурированной системы FePt

In this work, using the example of the synthesis of nanoparticles of the mutual FePt system, obtained in an aqueous medium by the method of co-reduction of solutions of metal precursors, the effect of reducing agents is considered: an alkaline solution of hydrazine hydrate and sodium tetrahydroborate in combination with a stabilizer of sodium-potassium tartrate. The main characteristics of the obtained nanosized particles of the iron-platinum system were studied by means of a complex of physicochemical methods of analysis. The shape and morphology of the obtained nanosized particles were studied by transmission electron microscopy, phase analysis and X-ray structural parameters – by X-ray diffraction methods. It was approached to reveal the dependence of the particle size on the type of reducing agent used. It was found that nanosized FePt particles obtained with different reducing agents have similar physicochemical characteristics. The use of sodium tetrahydroborate, in the presence of a stabilizer sodium-potassium tartrate, allowed to obtain more dispersed particles with a size of 14.3±2.1 nm. FePt nanoparticles reduced by hydrazine hydrate were characterized by large sizes of 16.7±4.0 nm, and the particles form large dense agglomerates. Chemical analysis showed that when reducing with sodium tetrahydroborate, the target product contained 0.4 mol. % boron. When reducing FePt nanoparticles with hydrazine hydrate, it was found that the target product was contaminated with iron oxide, which was also confirmed by X-ray phase analysis. X-ray diffraction analysis showed that the iron-platinum nanosystem was represented by a solid-solution phase with a face-centred cubic lattice. The parameters of the crystal lattice were estimated, 3.908 Å and 3.894 Å, respectively, for FePt nanoparticles obtained using NaBH4 and N2H4∙H2O.

Исследование структурных характеристик витринитов некоторых углей Кузнецкого бассейна

The article is devoted to research of the main structural parameters of vitrinites of bituminous coals of various metamorphism degrees carried out by methods of X-ray phase and X-ray structural analysis. Vitrinite concentrates were obtained from coal of the Kuznetsk Basin. The main X-ray structural parameters were estimated: the number of carbon atoms in the lamellae (natC), the longitudinal size of the lamellae, and the height of their stacking (La and Lc), the number of polyaromatic layers in the package (N), and the packing density of the lamellae (ρ). It is shown in the work that in vitrinite concentrates, an increase in all analyzed structural parameters (Lc, La, natC, N, ρ) is observed with an increase in the degree of metamorphism, at the same time, a decrease in the value of the interplanar distance (d002) is observed. The XRD analysis showed that for the average number of layers in a package and carbon atoms per monolayer, in the samples of vitrinite concentrates of bituminous coals of high stages of metamorphism (Ro, r = 1.41%) varies from 7 to 8 and 14-15, respectively. It was found a correlation between the linear nature of the number of polyarene-layers and the height of their stacking. The results obtained were in good agreement with the literature data given for coals of various deposits.

Effect of Accelerated Electrons on the Glow Structure of Nanosecond Diffuse Discharge in the Rod–Plane Air Gap

A diffuse discharge in a rod (cathode)–plane gap with an interelectrode spacing of 10 cm is studied in air at atmospheric pressure. The cathode voltage is 370–390 kV at a pulse FWHM of about 70 ns. It is shown that a pulse-to-pulse variation in delay time of the discharge formation in an interval of 3–15 ns leads to variations in the discharge current and X-ray pulse amplitude in intervals of 100–200 A and 20–250 relative units, respectively. A relationship of the amplitude of the X-ray pulse and structural parameters of the discharge glow is obtained. It is shown that fast electrons with energies of less 30 keV that are accelerated by strong electric field in the vicinity of the cathode play the key role in the formation of the longitudinal structure of glow at relatively large delay times of the discharge formation. Fast electrons ionize peripheral regions of the discharge, increase its cross section, and, hence, provide a decrease in the current density, specific energy deposition, and radiation intensity at a distance from the cathode that corresponds to electron path in air.

Role of W-site substitution on mechanical and electronic properties of cubic tungsten carbide

In order to understand the role of W-site substitution on properties of cubic tungsten carbide (-WC), we have investigated the structural, mechanical, and electronic properties of WXC2 (X = Si, Sc, Ti, V, Cr, Ge, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Sn, Hf, Ta, Re, Os, Ir, Pt, Th, U) using first principles calculations based on density functional theory, within generalized gradient approximation. The structural optimization has carried out for all these compounds using force as well as stress minimization. The optimized structural parameters for experimentally known compounds are in good agreement with the available x-ray diffraction measurements and structural parameters for nineteen WXC2 compounds are newly predicted. The W-site substitution of the above-listed elements into -WC reduces the symmetry of the primitive lattice to tetragonal structure. The heat of formation () and the mechanical stability studies are carried out to investigate the stability of these systems. The single-crystal elastic constants cij, elastic moduli of the polycrystalline aggregates, anisotropy in elastic constants and related properties of the WXC2 materials have calculated and discussed in detail. The hardness of the above materials is predicted using two different criteria, based on the softest elastic mode as well as the Pugh’s modulus ratio. There is a correlation in the hardness predicted from these two approaches except in the case of -WC. The chemical bonding interaction between the constituents is analysed using the density of states, crystal orbital Hamiltonian population, and charge density for selected systems. All these compounds are predicted to be metal and our calculations suggest that W-site substitutions do not improve the hardness of -WC. However, from the heat of formation studies, we have identified five new stable compounds such as CrWC2, NbWC2, ScWC2, YWC2, and UWC2 with reasonably good hardness and those need experimental verifications.

Influence of Iron Alloying on the Properties of Vanadium Dioxide

Results of investigations of the x-ray structural parameters of the crystal lattice and their temperature dependences in the vicinities of the metal-dielectric phase transition for V1–xFe x O2 solid solutions are reported together with results of comparison of x-ray and pycnometric densities of these materials. The defect concentration in the materials under study is estimated at room temperature.

Effect of Inter-Porphyrin Distance on Spin-State in Diiron(III) μ-Hydroxo Bisporphyrins.

The synthesis, structure, and properties of bischloro, μ-oxo, and a family of μ-hydroxo complexes (with BF4 (-) , SbF6 (-) , and PF6 (-) counteranions) of diethylpyrrole-bridged diiron(III) bisporphyrins are reported. Spectroscopic characterization has revealed that the iron centers of the bischloro and μ-oxo complexes are in the high-spin state (S=(5) /2 ). However, the two iron centers in the diiron(III) μ-hydroxo complexes are equivalent with high spin (S=(5) /2 ) in the solid state and an intermediate-spin state (S=(3) /2 ) in solution. The molecules have been compared with previously known diiron(III) μ-hydroxo complexes of ethane-bridged bisporphyrin, in which two different spin states of iron were stabilized under the influence of counteranions. The dimanganese(III) analogues were also synthesized and spectroscopically characterized. A comparison of the X-ray structural parameters between diethylpyrrole and ethane-bridged μ-hydroxo bisporphyrins suggest an increased separation, and hence, less interactions between the two heme units of the former. As a result, unlike the ethane-bridged μ-hydroxo complex, both iron centers become equivalent in the diethylpyrrole-bridged complex and their spin state remains unresponsive to the change in counteranion. The iron(III) centers of the diethylpyrrole-bridged diiron(III) μ-oxo bisporphyrin undergo very strong antiferromagnetic interactions (J=-137.7 cm(-1) ), although the coupling constant is reduced to only a weak value in the μ-hydroxo complexes (J=-42.2, -44.1, and -42.4 cm(-1) for the BF4 , SbF6 , and PF6 complexes, respectively).

Yes, one can obtain better quality structures from routine X-ray data collection.

Single-crystal X-ray diffraction structural results for benzidine dihydrochloride, hydrated and protonated N,N,N,N-peri(dimethylamino)naphthalene chloride, triptycene, dichlorodimethyltriptycene and decamethylferrocene have been analysed. A critical discussion of the dependence of structural and thermal parameters on resolution for these compounds is presented. Results of refinements against X-ray data, cut off to different resolutions from the high-resolution data files, are compared to structural models derived from neutron diffraction experiments. The Independent Atom Model (IAM) and the Transferable Aspherical Atom Model (TAAM) are tested. The average differences between the X-ray and neutron structural parameters (with the exception of valence angles defined by H atoms) decrease with the increasing 2θmax angle. The scale of differences between X-ray and neutron geometrical parameters can be significantly reduced when data are collected to the higher, than commonly used, 2θmax diffraction angles (for Mo Kα 2θmax > 65°). The final structural and thermal parameters obtained for the studied compounds using TAAM refinement are in better agreement with the neutron values than the IAM results for all resolutions and all compounds. By using TAAM, it is still possible to obtain accurate results even from low-resolution X-ray data. This is particularly important as TAAM is easy to apply and can routinely be used to improve the quality of structural investigations [Dominiak (2015 ▸). LSDB from UBDB. University of Buffalo, USA]. We can recommend that, in order to obtain more adequate (more accurate and precise) structural and displacement parameters during the IAM model refinement, data should be collected up to the larger diffraction angles, at least, for Mo Kα radiation to 2θmax = 65° (sin θmax/λ < 0.75 Å(-1)). The TAAM approach is a very good option to obtain more adequate results even using data collected to the lower 2θmax angles. Also the results of translation-libration-screw (TLS) analysis and vibrational entropy values are more reliable for 2θmax > 65°.

Infrared, Raman and NMR spectral analysis, vibrational assignments, normal coordinate analysis, and quantum mechanical calculations of 2-Amino-5-ethyl-1,3,4-thiadiazole

Raman (3500−55 cm−1) and infrared (4000–300 cm−1) spectra of 2-Amino-5-ethyl-1,3,4-thiadiazole (AET; C4H7N3S) have been recorded in the solid phase. In addition, the 1H and 13C NMR spectra of AET were obtained in DMSO-d6. As a result of internal rotations of either methyl and/or ethyl groups around the C–C bonds with NH2 moiety being planar (sp2) and/or non-planar (sp3) eight structures are theoretically proposed (1–8). The conformational energies and vibrational frequencies have been calculated using Density Functional Theory (DFT) with the methods of B3LYP and B3PW91 utilizing 6-31G (d) and 6-311++G(d,p) basis sets. And then S-4 (the only conformer with real frequencies) was optimized, to yield S-9, however the Thiadiazole ring slightly twisted (tilt angle is 0.9°). The 1H and 13C NMR chemical shifts were also predicted using a GIAO approximation at 6-311++G(d,p) basis set utilizing B3LYP and B3PW91 methods with solvent effects using PCM method. The computational outcomes favor S-9; the methyl group being staggered to the lone pair of N4 and reside trans position to the S atom, whereas NH2 is non-planar in good agreement with the current study. Aided by the above mentioned DFT computations, a complete vibrational assignment of the observed infrared and Raman bands along with NMR chemical shifts has been proposed. The vibrational interpretations have been supported by normal coordinate analysis and potential energy distributions (PEDs). Finally, NH2, CH3 and C2H5 barriers to internal rotations were carried out using B3LYP/6-31G(d) optimized structural parameters (S-9). The results are reported herein and compared with X-ray structural parameters.

X-Ray Diffraction Studies of some Structurally Modified Indian Coals and their Correlation with Petrographic Parameters

In order to study the X-ray structural parameters, five coals have been chosen from different coal basins of India. These coals have been demineralized by standard HF + HCl treatment and treated with nitric acid in aqueous and glacial acetic acid media. X-ray diffraction (XRD) patterns of the samples are recorded using a slow step scan (2 s/step) over an angular range 2θ ∼ 10-90°. TOPAS software has been used to determine the structural parameters like interlayer spacing ( d 002 ), crystallite size ( L c ), aromaticity ( f a ) and average number of aromatic layers ( N c ). The structural parameters have been correlated with chemical as well as petrographic parameters of coals. Mean random reflectance (MR r ) of the studied coals varies between 0.44% and 0.54% and the vitrinite, liptinite and inertinite contents vary between 17.8% and 66.4%, 9.2% and 20.3% and 20.7% and 62.9% respectively. Nitration in both the media has increased d 002 values. This study also shows that d 002 and fa values are dependent on the rank of the coal, rather than only the carbon content ( C dmf , dry mineral free basis). XRD rank parameter values have been directly correlated with the petrographic rank parameters. Nitration in both the media has induced similar kind of effect on individual macerals. Behaviour of the macerals to chemical treatment is also reported in this study.

Multinuclear magnetic resonance and X-ray characterization of platinum(II) complexes with substituted-1,2,4-triazolo[1,5-a]pyrimidines

Mononuclear, square-planar platinum(II) complexes having general formula cis-[PtI2(L)2], where L=7-isobutyl-5methyl-1,2,4-triazolo[1,5-a]pyrimidine (ibmtp) (1), 5,7-diethyl-1,2,4-triazolo[1,5-a]pyrimidine (detp) (2), 5,6,7-trimethyl-1,2,4-triazolo[1,5-a]pyrimidine (tmtp) (3) and 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one (HmtpO) (4) have been synthesized and characterized by infrared and multinuclear magnetic resonance (1H, 13C, 15N, 195Pt) spectroscopy. The solid-state structure of cis-[PtI2(dptp)2]·2dmf (5) has been determined by X-ray diffraction method. X-ray structure and spectroscopical parameters revealed that the heterocyclic ligands are coordinated to platinum(II) ion via N(3).