The Crystal Structure and Conformational Studies of Acridinedione Derivatives

Abstract  

Two crystal structures of acridinediones namely, TMHAD and MPHAD were studied by X-ray crystallographic method in view of their occurrence in numerous commercial products including pharmaceuticals, fragrances and dyes. Crystal data of TMHAD are: C₁₇H₂₃NO₂, orthorhombic, Fdd2, with cell parameters a = 40.417(6) ?, b = 5.744(1) ?, c = 12.979(2) ?, V = 3013.1(7) ?³, Z = 8, D_cal = 1.205 Mg/m³, μ = 0.078 mm⁻¹. Crystal data of MPHAD are: C₂₀H₁₈NO₃; monoclinic, P2₁/c with cell parameters a = 10.182(9) ?, b = 17.105(14) ?, c = 10.895(9) ?, β = 117.857(1)°, V = 1678(2) ?³, Z = 4, D_cal = 1.268 Mg/m³, μ = 0.085 mm⁻¹. Both data were collected using λ (MoK_α) = 0.71073 ?. The central ring in the acridinedione moieties tends to be planar while the outer two rings adopt sofa conformations. Intermolecular interactions of C–H···O type of hydrogen bond help the molecules to stabilize into the crystal packing. Interestingly, a week forces of C–H···π interactions also helps the molecules for stabilization.     

La3Ga5SiO14晶体电子结构及光学性质的第一性原理研究

采用基于密度泛函的第一性原理平面波赝势法对La3Ga5SiO14晶体基态的几何参量、能带结构、态密度和光学性质进行了系统的研究.优化了La3Ga5SiO14晶体中原子的内部坐标,利用精确计算的能带结构、态密度和电荷密度等值线分析了晶体的吸收谱、介电函数、折射率,计算结果与实验符合较好,为La3Ga5SiO14晶体材料的分子设计与应用提供了理论依据.     

Crystal Structure Studies of Two Regioisomers of Bromo-4-Aryloxymethylcoumarins

Abstract  

The 4-(2-bromo-4-methyl-phenoxymethyl)-6-methylcoumarin (1) have been synthesized from bromination of corresponding 4-aryloxymethyl coumarin, which is a regioisomer of 4-(2-bromo-4-methyl-phenoxymethyl)-7-methylcoumarin (2) (CCDC-695895). The compound 1 crystallizes with triclinic space group P-1, a = 8.0943(3) ?, b = 9.3502(3) ?, c = 10.1476(4) ?, α = 90.234(2)°, β = 94.065(2)°, γ = 95.106(2)°, Z = 2 and compound 2 crystallizes with monoclinic space group P2₁/n, a = 8.465(5) ?, b = 13.649(5) ?, c = 13.304(5) ?, α = 90.000(5)°, β = 90.740(5)°, γ = 90.000(5)°, Z = 4. Both the compounds are planar with variation in their intermolecular hydrogen bonds between C–H···O and C–H···π.     

Modern Methods of Neutron Radiography and Tomography in Studies of the Internal Structure of Objects

Crystallography Reports - The fundamentals, experimental possibilities, and applications of the methods of neutron radiography and tomography in studies of the structural features of large objects...     

Crystal Structure and Thermal Studies of Ruthenium(II) Bisimidazolylterpyridine Hexafluorophosphate Complex

Abstract  

A hexafluorophosphate salt of ruthenium(II) bis(4′-(1H-imidazol-2-yl)-2,2′:6′,2″-terpyridine) complex was synthesized. It crystallizes in the monoclinic space group C2₁/c with unit cell parameters, a = 18.5878(15) ?, b = 15.9546(11) ?, c = 16.1418(12) ?, β = 106.721(3)°, V = 4584.6(6) ?³ and Z = 4. The bond lengths, bond angles and torsional angles of hexafluorophosphate salt of the [Ru(itpy)₂]²⁺ cation show significant change from the nitrate salt of the same cation. Thermogravimetric analysis and differential scanning calorimetry confirm the loss of solvents of crystallization between 100 and 200 °C.     

Synthesis, Crystal Structure and ab initio Studies of Cyclohexyl N-Phenylcarbamate

Abstract  

Cyclohexyl N-phenylcarbamate, C₁₃H₁₇NO₂ (I), which is a useful target for biotransformations by fungi, has been synthesized and the structure has been solved by X-ray diffraction. The crystals are triclinic, space group P [`1] bar{1} , with a = 5.2581 (2) ?, b = 9.5080 (3) ?, c = 12.6165 (4) ?, α = 70.544 (2)°, β = 89.075 (2)°, γ = 80.447 (2)°, M _r = 219.28, V = 585.96 (3) ?³, Z = 2 and R = 0.065. In the title compound the phenyl ring makes a dihedral angle of 30.68(7)° with the carbamate group The molecules are linked into infinite chains via N–H···O hydrogen bonds along the a axis. These hydrogen-bonded chains are further linked by weaker C–H···π interactions. Quantum-mechanical ab initio calculations for the free molecule reproduce well the observed bond lengths and valency angles but show that the crystal packing might be responsible for the rotation of the phenyl ring out of the carbamate plane in the solid state conformation.     

Spectroscopic Studies and Structure of 4-(3-Benzoylthioureido)benzoic Acid

Abstract  

4-(3-Benzoylthioureido)benzoic acid has been synthesized from the reaction of 4-aminobenzoic acid with benzoyl isothiocyanate. The title compound has been characterized by elemental analysis, MS, FT-IR, ¹H-NMR, ¹³C-NMR and UV–Visible techniques. The structure of the compound has also been examined crystallographically. The title compound crystallizes in the triclinic space group P-1 with a = 3.969(1), b = 13.039(1), c = 13.504(1) ?, α = 96.50(1)°, β = 92.25(1)°, γ = 94.94(1), V = 691.0(1) ?³ and D _x  = 1.444 g cm⁻³, respectively. The crystal structure has been solved by direct methods and refined by full-matrix least squares and found R ₁ = 0.031 and wR ₂ = 0.081 for 2909 observed reflections [I > 2σ(I)].     

Studies on the Growth Rates of Crystals

The crystal growth rates are calculated from the nucleation rate of two-dimensional square shaped nucleus in four different models. In all these models, the growth is initiated by the birth of the critical nuclei. Two limiting values of the lateral spreading velocities perpendicular to the side of the growing island are considered in first two models and finite spreading velocities are treated in other two models.     

Electron Microscopy and Electron Diffraction Studies of Morphology and Crystal Structure of Natural Silicas

Crystallography Reports - The development of fundamental and applied geology requires an ever-increasing amount of data on the structures and properties of rocks at different scales. Of particular...     

Monomeric and Dimeric Erbium(III) Complexes: Crystal Structure and Photoluminescence Studies

Abstract  

The crystal structure and photoluminescence (PL) studies of the monomeric and dimeric Er(III) complexes with two different chelating ligands (anthracene-9-carboxylic acid, 9-ACA; pentaethylene glycol, EO5; and picric acid, HPic) are reviewed. The Er(III) metal ion was coordinated to the attached ligands in eight- and nine-coordination number. The dimeric [Er₂(9-AC)₆(DMF)₂(H₂O)₂] complex shows the presence of deprotonated 9-AC anions with the negatively charged oxygen atoms bridged two Er(III) ions leads to a great coordinative flexibility via three possibilities of coordination modes, i.e. monodentate, chelation bidentate, chelating–bridging tridentate, where 9-AC = anthracene-9-carboxylate anion. The monomeric [Er(Pic)₂(EO5)](Pic) complex displays the important flexible structure of the acyclic EO5 ligand and the role of Pic anions act as bidentate and monodentate chelations. The PL spectra of both Er(III) complexes show a broad band with the center peak position being dependent on the attached aromatic ligands. The heavier lanthanide complexes show the difference in structures, coordination geometry environment, and luminescence properties compared to the lighter lanthanide complexes. The energy transfer process in the complexes could be optimized with maximize the overlap between the emission spectrum of donor atom and absorption spectrum of acceptor atom.     

Studies on the Effect of Unsaturated Homologues on the Crystallization of Stearic Acid

The unsaturated fatty acids play decisive role in the activity of biological membranes. The interaction between saturated and unsaturated fatty acids during the condensation process is therefore of great importance. Studies on the crystallization of stearic acid (a typical saturated acid), in presence of oleic acid and linoleic acid (typical unsaturated acids), were carried out to determine the extent of interaction. Results indicated that interaction between saturated and unsaturated molecules is almost absent. It can be derived from the findings that these molecules might participate in biological or biochemical processes, as if they are entirely different types of molecules.     

EBIC/TEM Studies on the Relation between Electrical Properties,Crystallographic Structure,and Interaction with Point Defects of Epitaxial Stacking Faults in Silicon

Only after annealing, EBIC investigations on epitaxial layer defects partly gave contrasts. More information on the crystallographic structure of these defects was obtained in subsequent HVEM investigations. Experimental results confirmed the supposition that only the decoration of the crystallographic defects with additional recombination centres (impurity atoms), and not existence of the defects themselves, results in a detectable EBIC contrast. The observed getter efficiency of the various defect types is discussed. This efficiency is growing with increasing lattice distortion.     

Studies on two-dimensional nucleation

Assuming a square shaped two-dimensional nucleus, the expressions for critical size and critical free energy are derived. As an example of the relations derived, a system of ADP-water at 300 K has been considered. Also a graph connecting the critical size and the supersaturation is drawn. Using the McDonald theory, the nucleation rate of two dimensional nucleus is derived.     

Spectroscopic Studies and Crystal Structure of 3-[(2-morpholinoethylimino)methyl]benzene-1,2-diol

Abstract Schiff base 3-[(2-morpholinoethylimino)methyl]benzene-1,2-diol has been synthesized from the reaction of 4-(2-aminoethyl)morpholine with 2,3-dihydroxybenzaldehyde. The title compound has been characterized by elemental analysis, IR, ¹H-NMR, ¹³C-NMR and UV–visible techniques. The structure of the compound also has been examined crystallographically. For the compound exist as dominant form of enol-imines in both the solutions and solid state. The crystal structure has been solved by direct methods and refined by full-matrix least squares. The title compound crystallize in the monoclinic space group P2₁/n with a = 12.085(1), b = 8.256(1), c = 13.650(1) ?, β = 108.56(1)°, V = 1291.1(2) ?³, D _x = 1.288 g cm⁻³, respectively (R ₁ = 0.0336 and wR ₂ = 0.0922 for 2117 reflections [I > 2σ(I)]. Index abstract Intramolecular hydrogen bonding is important on the tautomeric properties and the type of aldehyde plays a vital role of the enol-imine and keto-amine properties of the Schiff base ligand.      

Effect of the Working Gas Pressure on the Structure of ZnO Layers

Crystallography Reports - Zinc oxide layers have been synthesized by magnetron sputtering of ZnO:Ga ceramic and ZnO:Ga + 10 wt % Zn cermet targets in an Ar atmosphere and by reactive sputtering of...