2-Amino-anilinium 2-chloro-acetate

In the crystal structure of the title compound, C₆H₉N₂⁺·ClCH₂COO⁻, prepared by the reaction of OPDA (orthophenelynediamine) with chloro­acetic ­acid, N—H⋯O hydrogen bonds generate ladder-like chains and very weak inter­molecular C—H⋯Cl hydrogen-bonding inter­actions between the anions and cations lead to a supra­molecular network. C—H⋯O inter­actions also occur.

(R)-1-Phenyl-ethyl-ammonium trifluoro-acetate

In the crystal structure of the title salt, C(8)H(12)N(+)·C(2)F(3)O(2) (-), all of the ammonium H atoms serve as donors for hydrogen bonds to carboxyl-ate O atoms, forming an R(4) (3)(10) ring motif based on two cations and two anions. Since both cations and anions act as inter-ion bridging groups, R(10) rings aggregate in a one-dimensional supra-molecular network by sharing the strongest N-H⋯O bond. Edge-sharing motifs lie on the twofold screw axis parallel to [010], and anti-parallel packing of these 2(1)-column structural units results in the crystal structure. This arrangement is one of the most commonly occurring in conglomerates of chiral 1-phenyl-ethyl-amine with achiral monocarboxylic acids, confirming that these ionic salts are particularly robust supra-molecular heterosynthons useful in crystal engineering.

Hydrogen-bond quenching of photodecarbonylation in the solid state and recovery of reactivity by co-crystallization

Intermolecular H-bonding between C=O (ketone) and HO (4'-hydroxyphenyl) quenches photodecarbonylation of 2,2,4,4-tetramethyl-1,3-di(4'-hydroxyphenyl)acetone 1 in the crystalline solid state, its reactivity is recovered by co-crystallization with the small organic molecule 4,4'-bicyclohexanone.

From Nonfunctional Lamellae to Functional Nanotubes

[structure: see text] Long chain alkyl-alkyl interactions appears to be the main driving force in hydrogen bond isomerism induced transformation of lamellar architectures to nanotubular constructs in alkylammonium dicarboxylate salts; the syntheses of the nanotubes require no skill for typical organic synthesis, and they are functional materials displaying intriguing gelling properties.

Cis → trans and trans → cis isomerizations of styrylcoumarins in the solid state. Importance of the location of free volume in crystal lattices

We have examined the photobehavior of a set of isomers of 2-pyranone-annulated stilbenes (6-styrylcoumarin 1, 7-styrylcoumarin 2, 4-methyl-6-styrylcoumarin 3, and 4-methyl-7-styrylcoumarin, 4) in their crystalline phases. While the cis isomers of 1-3 undergo cis-->trans photoisomerizations in the solid state, cis-4 and the trans isomers of 1-3 do not; the trans isomer of 4 undergoes photo-induced intermolecular reactions. Solution-state irradiations of the trans isomers of 1-4 lead to the cis isomers quite readily, as does cis-4 lead to trans-4, which suggests that the absence of geometric isomerization of the trans isomers and the lack of reactivity of cis-4 in the solid state are due to molecular packing effects. X-Ray crystal structural analyses of 1-4 reveal interesting conformational preferences for the styrenic moieties and differences in the total 'free' volumes within the lattices, but neither factor explains satisfactorily why some of the molecules undergo geometric isomerizations in their single crystals and others do not. Using the PLATON program, we have located the sizes and positions of 'void volumes' within the crystal lattices, and identified trajectories necessary for atomic motions to lead to geometric isomerizations to understand the reactivities of 1-4. The voids in the reactive cis isomers of 1-3 crystals are located along the trajectories needed for geometric isomerization. The relevant voids in the crystals of cis-4 and the trans isomers of 1 and 2 (the non-isomerizing molecules for which suitable crystals could be grown for X-ray analyses) are located along a trajectory that does not permit isomerization. We hypothesize that the classical momentum gained from the initial motions that are facilitated due to the voids in the crystals of the cis isomers of 1-3, as well as the heat dissipated to the local environment by internal conversions and vibronic cascade of the Franck-Condon states, helps to drive the system over potential energy barriers that would not be possible otherwise. Cis-4 and the trans isomers of 1 and 2, as well as other examples from the literature in which geometric isomerizations do or do not occur in the solid state, also follow the predictions based upon the PLATON analyses. On these bases, it is suggested that the methodology described may be generally applicable for predicting when geometric isomerizations (and possibly other reactive processes) in crystalline materials will occur.

Synthesis and hierarchical self-assembly of cavity-containing facial amphiphiles

The synthesis and aggregation behavior of cavity-containing facial amphiphiles is described. The molecules consist of a glycoluril-based rigid cavity functionalized with two water-soluble benzoate groups. By specific molecular recognition processes in water, the amphiphilic hosts self-assemble in a hierarchical process to form arrays of molecules. Depending on the counterions, these arrays can be assembled into well-defined aggregates of mesoscopic size. The size and shape of the aggregates can be tuned by variations in the size and substitution pattern of the cavities of the host molecules.

Organic Layered Crystals with Adjustable Interlayer Distances of 1-Naphthylmethylammoniumn-Alkanoates and Isomerism of Hydrogen-Bond Networks by Steric Dimension

A series of 1-naphthylmethylammonium n-alkanoates from acetate to triacontanoate produce isomorphic layered structures in the crystalline state. The interlayer distances, d-spacings, are proportional to the lengths of the alkyl chains. This is attributed to synergic intermolecular interactions; pi-pi and CH-pi interactions of the naphthalene rings between the cations, hydrophobic interactions of the alkyl chains, and two-dimensional hydrogen-bond networks between the primary ammonium cations and the carboxylate anions. Salts made from carboxylic acids wider than 5.5 A in the cross sections produce another columnar structure with a one-dimensional ladder-type hydrogen-bond network. Steric parameters of the acid components provide an explanation for the isomerism of the hydrogen-bond network.