Study on Quality of Pair Distribution Function for Direct Space Approach of Structure Investigation

Study of the structure characteristics of solid materials is a key for development of technological applications. Potential of direct space approach for structure determination and refinement using powder X-ray diffraction data depend on the quality of pair distribution function (PDF) plot. So, the effect of data collection conditions and diffractogram characteristics on the quality of PDF plot has been investigated in detail. In addition, errors and possible tolerance have been estimated. Some parameters affect only either the X-ray diffractogram or PDF plots and others affect both. Considering the errors and tolerance, direct space approach can be confidently used for structure refinement, where the error did not exceed 10.0 % for inter-atomic radial distance longer than » 2.0 ? and 5.0 % for longer than » 4.0 ?, which is accepted for structure refinement. As tolerance is considered, every time the value of the lattice parameter is changed to smaller or larger than the correct value (+ 8.0 %), it comes back to the initial correct one. Although, advanced synchrotron radiation shows better data, conventional source can be used successfully for structure investigation applying direct space approach

2-((4-Amino-5-((2,4-dichlorophenoxy)methyl)-4<i>H</i>-1,2,4-triazol-3-yl)thio)-1-(5-methyl-1-(4-nitrophenyl)-1<i>H</i>-1,2,3-triazol-4-yl)ethan-1-one

The reaction of 2-bromo-1-(5-methyl-1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)ethan-1-one (1) with 4-amino-5-((2,4-dichlorophenoxy)methyl)-4H-1,2,4-triazole-3-thiol (2) in absolute ethanol in the presence of triethyl amine as catalyst gave 2-((4-amino-5-((2,4-dichlorophenoxy)methyl)-4H-1,2,4-triazol-3-yl)thio)-1-(5-methyl-1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)ethan-1-one (3) in 73% yield. The structure of the title heterocycle (3) was confirmed by X-ray single crystal diffraction and spectral analyses (NMR and IR)

THE STRUCTURE AND PROPERTIES OF Nd 0.66 (Sr 1-x Li x ) 0.34 FeO 3

Nd 0.66 (Sr 1-x Li x ) 0.34 FeO 3 series were synthesized using standard ceramic method. The properties of such materials were characterized by XRD and the results revealed that there are two phases; the major phase was neodymium iron oxide perovskite and the second phase was iron oxide. The crystal structure was refined by the Rietveld method using MAUD software. It was found that the fraction of neodymium iron oxide perovskite slightly decreases while the iron oxide phase increases with increasing Li concentration. The energy gap values of the samples have been calculated and it was found that it decreased as Li increased. The electrical conductivity increases with increasing both Li content and temperature. The activation energy has been calculated from the electrical conductivity and it was found that, it deceases with increasing Li content. The magnetic susceptibility shows non-linear variation with Li concentration

2-((5-(5-Methyl-2-phenyl-1<i>H</i>-imidazol-4-yl)-1,3,4-oxadiazol-2-yl)thio)-1-phenylethan-1-one

A promising imidazole compound was synthesized through the following route. The reaction of 5-methyl-2-phenyl-1H-imidazole-4-carbohydrazide (1) with carbon disulfide and potassium hydroxide in ethanol (80%) afforded potassium salt (2). Refluxing of (2) with phenacyl bromide (3) in ethanol/water (1:1) gave 2-((5-(5-methyl-2-phenyl-1H-imidazol-4-yl)-1,3,4-oxadiazol-2-yl)thio)-1-phenylethan-1-one (4) in a 76% yield. The structure of the title heterocycle (4) was confirmed by single-crystal X-ray diffraction and nuclear magnetic resonance

5-Chloro-5′′-(4-chlorobenzylidene)-4′-(4-chlorophenyl)-1′,1′′-dimethyldispiro[indoline-3,2′-pyrrolidine-3′,3′′-piperidine]-2,4′′-dione

The racemic title compound, C30H26Cl3N3O2, comprises two spiro links, the first connecting the piperidine and pyrrolidine rings and the other connecting the indole and pyrrolidine rings. The piperidine ring adopts a half-chair conformation, while the pyrrolidine ring has an envelope conformation with the unsubstituted C atom as the flap. The dihedral angles between the two p-Cl-substituted benzene rings and the indole ring are 33.13 (14) and 54.11 (14)°. In the crystal, molecules form inversion dimers through pairs of N—H...O hydrogen bonds [graph set R22(8)]. Aromatic C—H...O hydrogen bonds extend these dimers into a ribbon structure, enclosing R22(14) ring motifs, along the a-axis direction