2-Amino­ethanaminium iodide

The title salt, [NH3CH2CH2NH2]+·I−, has an array structure based on strong inter­molecular N—H⋯N hydrogen bonding formed between the ammonium and amine groups of adjacent cations. This inter­action gives a helical chain of cations that runs parallel to the b axis. The four remaining NH group H atoms all form hydrogen bonds to the iodide anion, and these iodide anions lie in channels parallel to the cation–cation chains

catena-Poly[[(nitrito-κ2 O,O′)silver(I)]-μ-1,2-bis­[1-(pyridin-4-yl)ethyl­idene]hydrazine-κ2 N:N′]

The asymmetric unit of the title compound, [Ag(NO2)(C14H14N4)]n, contains half of the repeating formula unit (Z′ = 1/2). The AgI ion lies on a twofold rotation axis. The primary structure consists of a one-dimensional coordination polymer formed by the AgI ions and the bipyridyl azine ligand in which there is an inversion center at the mid-point of the N—N bond. The nitrite anion inter­acts with the AgI ion through a chelating μ2 inter­action involving both O atoms. In the crystal, the coordination chains are parallel and inter­act through Ag⋯π [3.220 (2) Å] and π–π [3.489 (3) Å] inter­actions

Dehydration mechanism of a small molecular solid: 5-nitrouracil hydrate

Previous studies of the dehydration of 5-nitrouracil (5NU) have resulted in it being classified as a ‘‘channel hydrate’’ in which dehydration proceeds principally by the exit of the water molecules along channels in the structure. We have re-examined this proposal and found that in fact there are no continuous channels in the 5NU structure that would contribute to such a mechanism. Product water molecules would be immediately trapped in unlinked voids in the crystal structure and would require some additional mechanism to break loose from the crystal. Through a detailed structural analysis of the macro and micro structure of the 5NU as it dehydrates, we have developed a model for the dehydration process based on the observed development of structural defects in the 5NU crystal and the basic crystallography of the material. The model was tested against standard kinetic measurements and found to present a satisfactory account of kinetic observations, thus defining the mechanism. Overall, the study shows the necessity of complementing standard kinetic studies with a parallel macro and micro examination of the dehydrating material when evaluating the mechanisms of dehydration and decomposition processes

1-Benz­yloxy-4-(2-nitro­ethen­yl)benzene

The title compound, C15H13NO3, crystallizes with three independent mol­ecules per asymmetric unit (Z′ = 3). One of these mol­ecules is found to have a configuration with a greater twist between its two aromatic rings than the other two [compare 70.26 (13) and 72.31 (12)° with 84.22 (12)°]. There are also differences in the number and nature of the weak inter­molecular C—H⋯O contacts formed by each of the three mol­ecules

The cobalt(II) salt of the azo dye Orange G

Crystallizing the cobalt(II) salt of the azo dye Orange G from water was found to give the solvent-separated ion-pair species hexa­aqua­cobalt(II) 7-oxo-8-(2-phenyl­hydrazin-1-ylidene)-7,8-dihydro­naphthalene-1,3-disulfonate tetra­hydrate, [Co(H2O)6](C16H10N2O7S2)·4H2O. The asymmetric unit of the cobalt(II) salt contains three independent octa­hedral [Co(OH2)6]2+ cations, three azo anions, all with similar configurations, and 12 uncoordinated water mol­ecules. The structure is closely related to that of one of the known magnesium analogues. Both structures have Z′ = 3, feature nearly planar azo anions [maximum displacement of azo-N atoms from the plane of the phenyl ring = 0.058 (7) Å] in their hydrazone tautomeric form, form layer structures with hydro­philic and hydro­phobic layers alternating along the b-axis direction, and are stabilized by an extensive network of hydrogen bonds.

4-(Benz­yloxy)benzaldehyde

The title compound, C14H12O2, has an essentially planar conformation with the two aromatic rings forming a dihedral angle of 5.23 (9)° and the aldehyde group lying in the plane of its aromatic group [maximum deviation = 0.204 (3) Å]. Weak inter­molecular C—H⋯O contacts are found to be shortest between the aldehyde O-atom acceptor and the H atoms of the methyl­ene group

Polymorphism and Hydrated States in 5‑Nitrouracil Crystallized from Aqueous Solution

The crystallization of 5-nitrouracil (5NU) from pure aqueous solution yields two anhydrous polymorphs and a monohydrate depending on the temperature at which the process is carried out. 5NU mimics true polymorphism in that, when retained in aqueous solution, both metastable (anhydrous) forms undergo solvent mediated phase transformations (SMPTs) into the more thermodynamically stable hydrated form as would be predicted by Ostwald’s rule of stages. The phase transformations can occur either in the classical manner of dissolution and recrystallization or, in one case, may in some circumstances be nucleated and morphologically templated by the original crystalline form. There is no appearance from aqueous solution of a known third acentric anhydrous form, previously prepared from acetonitrile solutions. Preliminary experiments suggest this nonappearance may result from the relatively high solubility of this form in aqueous solution