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41.
Tia Jarvis Carl Jacky Saint-Louis Alexander R. Fisch Korry L. Barnes Dolan Dean Luis A. Flores Thomas F. Hunt Lyndsay Munro Tyler J. Simmons Vincent J. Catalano Lei Zhu Alan K. Schrock Michael T. Huggins 《Tetrahedron》2018,74(14):1698-1704
Pyrrole β-amides are useful building blocks for the preparation of novel molecular architectures that can be used in supramolecular chemistry and sensor development. Under basic conditions, pyrrole β-amides with an α-aldehyde produce different condensation products when reacted with pyrrolinones depending on the amide substitution. Secondary amides form the expected dipyrrinones, but unexpectedly undergo a subsequent trans-amidation with the pyrrolinone nitrogen to produce an unsymmetrical imide (an N-confused fluorescent dipyrrinone). Under the same conditions, tertiary amides produce the expected dipyrrinone carboxylic acids, which have been shown to have strong self-association properties as determined by vapor pressure osmometry measurements, NMR studies, and X-ray crystal structure determination. Furthermore, an N-confused fluorescent dipyrrinone was produced from the same trans-amidation reaction during attempts to decarboxylate a dipyrrinone amide with a 9-carboxylic moiety. 相似文献
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Orde Q. Munro Nicole Pearson 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(10):m407-m412
The title salt, (1,4,7,10,13,16‐hexaoxacyclooctadecane‐κ6O)[(isothiocyanato)triphenylborato‐κS]potassium(I), [K(C19H15BNS)(C12H24O6)] or [K(SCNBPh3)(18‐crown‐6)], where 18‐crown‐6 is 1,4,7,10,13,16‐hexaoxacyclooctadecane and [SCNBPh3]− is the (isothiocyanato)triphenylborate anion, exhibits a supramolecular structure that is best described as a helical coordination polymer or molecular screw. This unusual supramolecular structure is based on a framework in which the SCN− ion bridges the chelated K+ ion and the B atom of BPh3 in a μ2 fashion. The X‐ray crystal structure of the title salt has been determined at 100 (1) and 293 (2) K. The K+ ion exhibits axial ligation by the S atom of the [SCNBPh3]− anion, with a K—S distance of 3.2617 (17) Å (100 K). The trans‐axial ligand is an unexpected η2‐bound C=C bond of a phenyl group (meta‐ and para‐C atoms) that belongs to the BPh3 moiety of a neighboring molecule. The K—C bond distances span the range 3.099 (3)–3.310 (3) Å (100 K) and are apparently retained in CDCl3 solution (as evidenced by 13C NMR spectroscopy). By virtue of the latter interaction, the supramolecular structure is a helical coordination polymer, with the helix axis parallel to the b axis of the unit cell. IR spectroscopy and semi‐empirical molecular orbital (AM1) calculations have been used to investigate further the electronic structure of the [SCNBPh3]− ion. 相似文献
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Orde Q. Munro Greville L. Camp 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(12):o672-o675
The title Schiff base compound, N,N′‐bis(pyrrol‐2‐ylmethylene)propane‐1,2‐diamine, C13H16N4, forms an interesting supramolecular structure (a one‐dimensional ladder‐like polymer) in the solid state that is based on the existence of complementary intermolecular N—H⋯N=C hydrogen bonds between the monomer units. The polymer axis is collinear with the c axis of the orthorhombic unit cell. Quantum‐chemical AM1 calculations clearly indicate that self‐recognition in this system by hydrogen bonding is favoured on electrostatic grounds, since the partial atomic charge on the H atom of the pyrrole NH group (0.274 e) complements the partial atomic charge of the N atom of the C=N group (−0.239 e) on a neighbouring molecule. 相似文献
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P. R. T. Munro 《Contemporary Physics》2017,58(2):140-159
Contemporary X-ray imaging techniques span a uniquely wide range of spatial resolutions, covering five orders of magnitude. The evolution of X-ray sources, from the earliest laboratory sources through to highly brilliant and coherent free-electron lasers, has been key to the development of these imaging techniques. This review surveys the predominant coherent X-ray imaging techniques with fields of view ranging from that of entire biological organs, down to that of biomolecules. We introduce the fundamental principles necessary to understand the image formation for each technique as well as briefly reviewing coherent X-ray source development. We present example images acquired using a selection of techniques, by leaders in the field. 相似文献
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1-Fluoronaphthalene was plasma polymerized and its composition and structure, as a function of position, power, and temperature, were examined by ESCA. The F:C ratio of the deposited film was lower than that of the starting monomer both at room temperature and at 150°C. An asymmetry of the main C1s photoionization peak was noted. Plasmas were also excited in fluoronaphthalene/hydrogen mixtures where extensive fluorine elimination and hydrogen incorporation occurred. This gave direct evidence that the height of step function or asymmetry of the main C1s peak is related to the degree of saturation in the compound. 相似文献
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