Grain rotation and lattice deformation during photoinduced chemical reactions revealed by in situ X-ray nanodiffraction.

In situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) have been used to investigate many physical science phenomena, ranging from phase transitions, chemical reactions and crystal growth to grain boundary dynamics. A major limitation of in situ XRD and TEM is a compromise that has to be made between spatial and temporal resolution. Here, we report the development of in situ X-ray nanodiffraction to measure high-resolution diffraction patterns from single grains with up to 5 ms temporal resolution. We observed, for the first time, grain rotation and lattice deformation in chemical reactions induced by X-ray photons: Br(-) + hv → Br + e(-) and e(-) + Ag(+) → Ag(0). The grain rotation and lattice deformation associated with the chemical reactions were quantified to be as fast as 3.25 rad s(-1) and as large as 0.5 Å, respectively. The ability to measure high-resolution diffraction patterns from individual grains with a temporal resolution of several milliseconds is expected to find broad applications in materials science, physics, chemistry and nanoscience.

Omadacycline dihydrate, C29H40N4O7·2H2O, from X-ray powder diffraction data.

The crystal structure of the title compound {systematic name: (4S,4aS,5aR,12aR)-4,7-bis-(di-methyl-amino)-9-[(2,2-di-methyl-propyl-amino)-meth-yl]-1,10,11,12a-tetra-hydroxy-3,12-dioxo-4a,5,5a,6-tetra-hydro-4H-tetra-cene-2-carb-oxamide dihydrate, C29H40N4O7·2H2O} has been solved and refined using synchrotron X-ray powder diffraction data: it crystallizes in space group R3 with a = 24.34430 (7), c = 14.55212 (4) Å, V = 7468.81 (2) Å3 and Z = 9. Most of the hydrogen bonds are intra-molecular, but two classical N-H⋯O inter-molecular hydrogen bonds (along with probable weak C-H⋯O and C-H⋯N hydrogen bonds) link the mol-ecules into a three-dimensional framework. The framework contains voids, which contain disordered water mol-ecules. Keto-enol tautomerism is apparently important in this mol-ecule, and the exact mol-ecular structure is ambiguous.

Revealing the true crystal structure of L-phenylalanine using solid-state density functional theory.

Solid-state density functional theory can be used for crystal structure determination from powder X-ray diffraction data of molecular crystals that are too large and complex for conventional refinement methods.

Cynarine monohydrate from synchrotron powder X-ray diffraction data.

The crystal structure of cynarine monohydrate (systematic name: 1,3-bis{[(E)-3-(3,4-dihydroxyphenyl)prop-2-enoyl]oxy}-4,5-dihydroxycyclohexane-1-carboxylic acid monohydrate), C25H24O12·H2O, has been solved and refined using synchrotron powder X-ray diffraction data, and optimized using density functional techniques. Despite being purchased as anhydrous, cynarine crystallizes as a monohydrate and the crystal structure is characterized by alternating layers of hydrocarbon and hydrogen-bonding interactions parallel to the bc plane. Hydrogen bonds are significant in the crystal structure. The carboxylic acid group forms a strong intermolecular hydrogen bond to a hydroxy group of the quinic acid ring. Most of the hydroxy groups act as donors in O-H...O hydrogen bonding to carbonyl O atoms. One hydroxy group participates in bifurcated hydrogen bonds, one to a hydroxy group on the quinic acid ring and the other, an intramolecular interaction, to another hydroxy group. The powder pattern has been submitted to the International Centre for Diffraction Data (ICDD) for inclusion in the Powder Diffraction File (PDF-4).

Modulation of phase separation between spherical and rodlike molecules using geometric surfactancy.

A Dyad consisting of C(60) linked to a pi-conjugated oligomer by a propylene spacer was synthesized to explore its ability to modulate phase separation between OFTB and PCBM using differential scanning calorimetry, hot-stage polarizing optical microscopy, X-ray diffraction, and atomic force microscopy techniques. Upon thermal annealing at 10 degrees C above its T(g) for 12-48 h, the 1:1 blend of OFTB and PCBM resulted in a eutectic mixture. Thermal annealing of a OFTB:Dyad:PCBM film with a 9:2:9 mass ratio at 10 degrees C above its T(g) for 12 h resulted in an amorphous film. Its AFM phase image indicated phase separation into two interspersed 30 nm amorphous domains at approximately equal fractions. Geometric surfactancy is inferred from the formation of microemulsions in analogy to widely reported traditional oil-surfactant-water systems and ternary polymer blends. In contrast, thermal annealing of a 7:6:7 film under a similar condition resulted in an amorphous film with compositional uniformity.

Vapochromism and its structural basis in a luminescent Pt(II) terpyridine-nicotinamide complex.

A novel Pt(II) terpyridine complex that has a nicotinamide moiety linked to the terpyridyl ligand has been synthesized in good yield and studied structurally and spectroscopically. The complex, [Pt(Nttpy)Cl](PF(6))(2) where Nttpy = 4'-(p-nicotinamide-N-methylphenyl)-2,2':6',2' '-terpyridine, is observed to be brightly luminescent in the solid state at room temperature and at 77 K. The complex exhibits reversible vapochromic behavior and crystallographic change in the presence of several volatile organic solvents. Upon exposure to methanol vapors, the complex changes color from red to orange, and a shift to higher energy is observed in the emission maximum with an increase in excited-state lifetime and emission intensity. The crystal and molecular structures of the orange and red forms, determined by single-crystal X-ray diffraction on the same single crystal, were found to be equivalent in the molecular sense and only modestly different in terms of packing. In both forms, the cationic Pt(II) complexes possess distorted square planar geometries. Analysis of the orange form's crystal packing reveals the presence of solvent molecules in lattice voids, Pt...Pt separations averaging 3.75 A and a zigzag arrangement between nearest neighbor Pt atoms, whereas the red form is devoid of solvent within the crystal lattice and contains complexes stacked with a nearly linear arrangement of Pt(II) ions having an average distance of 3.33 A. On the basis of the crystallographic data, it is evident that sorption of methanol vapor induces a change in intermolecular contacts and Pt...Pt interactions in going from red to orange. Disruption of the d(8)-d(8) metallophilic interactions consequently alters the emitting state from (3)[(d)sigma*-pi*(terpyridine)] that is formally a metal-metal-to-ligand charge transfer (MMLCT) state in the red form to one in which the HOMO corresponds to a more localized Pt(d) orbital in the red form ((3)MLCT).

Three-dimensional structure determination of N-(p-Tolyl)-dodecylsulfonamide from powder diffraction data and validation of structure using solid-state NMR spectroscopy.

The three-dimensional structure, conformation, and packing of molecules in the solid state are crucial components used in the optimization of many technologically useful materials properties. Single-crystal X-ray diffraction is the traditional and most effective method of determining 3-D structures in the solid state. Obtaining single crystals that are sufficiently large and free of imperfections is often laborious, time-consuming, and, occasionally, impossible. The feasibility of an integrated approach to the determination and verification of a complete three-dimensional structure for a medium-sized organic molecule without using single crystals is demonstrated for the case of an organic stabilizer compound N-(p-tolyl)-dodecylsulfonamide. The approach uses a combination of powder XRD data, several computational packages involving Monte Carlo simulations and ab initio quantum mechanical calculations, and experimental solid-state NMR chemical shifts. Structure elucidation of N-(p-tolyl)-dodecylsulfonamide revealed that the Bravais lattice is monoclinic, with cell dimensions of a = 38.773 A, b = 5.507 A, c = 9.509 A, and beta = 86.35 degrees, and a space group of P21/c.