Rotaxanes comprising cyclic phenylenedioxydiacetamides and secondary mono- and bis-dialkylammonium ions: effect of macrocyclic ring size on pseudorotaxane formation

[2]Rotaxanes, stabilized through multiple and cooperative hydrogen bonding system, were synthesized from dialkylammonium ions and macrocycle possessing two phenylenedioxydiacetamide units and appropriate spacers.

Three differently coloured polymorphs of 3,6-bis(4-chlorophenyl)-2,5-dipropyl-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione

In this paper, the conformational polymorphism of a chlorinated diketopyrrolopyrrole (DPP) dye having flexible substituents in a non-hydrogen-bonding system is reported. The propyl-substituted DPP derivative (PR3C) has three polymorphic forms, each showing a different colour (red, orange and yellow). All polymorphs could be obtained concomitantly under various crystallization conditions. The results of the crystal structure analysis indicate that PR3C adopts different conformations in each polymorph. The packing effect caused by the difference in the arrangement of neighbouring molecules was found to play an important role in the occurrence of the observed polymorphism. The thermodynamic stability relationship between the three polymorphs was identified by thermal analysis and indicates that the yellow polymorph is the thermally stable form. The results indicate that the yellow form and orange form are enantiotropically related, and the other polymorph is monotropically related to the others.

The crystal structures of benzylammonium phenylacetate and its hydrate

The title compounds benzylammonium phenylacetate, C7H10N+·C8H7O2 − (1), and its monohydrate, C7H10N+·C8H7O2 −·H2O (2), can be obtained by evaporating methanolic solutions containing equimolar amounts of benzylamine and phenylacetic acid in the absence and presence of water, respectively. N—H...O hydrogen bonds in the crystal structure of 1 lead to the formation of hydrophilic channels running along the b-axis direction. The hydrogen-bonding system is best described by fused R 3 4(10) ring patterns, often observed in ammonium carboxylate salts. In 2, the presence of the crystal water leads to the formation of a two-dimensional hydrogen-bonding network. The benzyl moieties in 1 and 2 form hydrophobic layers in the crystal structures with the aromatic rings adopting edge-to-face arrangements.

The impact on the ring related vibrational frequencies of pyridine of hydrogen bonds with haloforms – a topology perspective

An intermolecular ring structure is identified for the hydrogen bonding system of pyridine and haloforms.

Strukturen zweier Salze des Bis(thioharnstoff)gold(I)-Kations

Attempts to isolate the compound (tu2Au)SCN 1 (tu=thiourea), first reported in 1949, at first led to [(tu)2Au]2SO4·CH3OH 2 after crystallization from methanol-petroleum ether. Crystallization from isopropanol led to the required compound 1. The crystal structure analysis of 1 confirmed its ionic nature, (tu2Au)+ SCN−. The tu ligands are mutually trans (torsion angle C–S···S–C 175.4(2)°), and the entire cation is approximately planar (r.m.s. deviation 0.08 Å). Eight classical hydrogen bonds connect the residues to form layers parallel to the bc plane at x≈⅛, ⅜, ⅝ and ⅞; the layers are connected by aurophilic contacts, which link the cations to form chains parallel to the a axis. In the structure of compound 2 the S=C groups are synclinal to each other; two NH2 groups are connected via a bifurcated hydrogen bonding system to a sulfate oxygen, forming a ring of graph set ${\rm{R}}_2^1(10).$ In a complex three-dimensional packing, the cations are connected by various interactions to form layers parallel to the ac plane at y≈½, whereas the sulfates are the centres of hydrogen-bonded double layers on both sides of the mirror plane at y≈¾. The structure contains a convincing example of a hydrogen bond to a gold centre.

Crystal structure of non-centrosymmetric bis(4-methoxybenzylammonium) tetrachloridozincate

The structure of the title non-centrosymmetric organic–inorganic hybrid salt, (C8H12NO)2[ZnCl4], consists of two 4-methoxybenzylammonium cations sandwiched between anionic layers, formed by isolated tetrachloridozincate tetrahedra. The double layers extend parallel to theacplane. The crystal packing is assured by Coulombic interactions and by a complex N—H...Cl and C—H...Cl hydrogen-bonding system mostly involving the positively charged ammonium groups and the chloride ligands of the isolated tetrahedral [ZnCl4]2−units. One of the methyleneammonium groups is disordered over two sets of sites in a 0.48 (2):0.52 (2) ratio. The crystal investigated was twinned by non-merohedry with a twin component ratio of 0.738 (2):0.262 (2).