This investigation is a case study about the nature of the adiabatic organic solid-state reactions by kinetic measurements of the processes that occur during the dimerization of aromatic nitroso compounds under three different topochemical environments in crystals.

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The thermally induced E-Z isomerization of the benzeneazodioxide derivatives is studied in the solid polycrystalline state. The reactions are studied from the kinetic and mechanistic aspects. In contrast to the solution, where isomerizations of azodioxides occur through the formation of corresponding nitroso monomers, the topochemical effect in solid state lead to the mechanism that includes formation of the "torsional" transition state, as it is the case in other known cis-trans isomerizations. It is proposed that both the reactions in solid state, the nitroso monomer-dimer equilibrium, and isomerization about the azodioxide N¼N bond tentatively involve similar transition states.

Monomer-dimer equilibria of nitrosobenzene and 2-nitrosopyridine in gas phase and solution were studied by range of quantum chemical methods in an attempt to find the level of theory suitable for modeling dimerization reactions of aromatic C-nitroso compounds in general. The best agreement with the experimental standard reaction Gibbs energies was obtained with a combination of double-hybrid density functionals B2PLYP-D3, PBE0DH, and DSD-PBEB86, and basis sets of triple-ζ quality. Of all other tested functionals, global hybrid PBE0 behaved equally well, and proved to be more than adequate for at least preliminary work. Other tested methods either produced inferior results (MP2, MP4(SDQ), CCSD, G4(MP2), CBS-QBS, CBS-APNO), or were too demanding for practical use (CCSD(T)). Analysis of computationally obtained thermodynamic data reveal intricate details of these reactions. Both E- and Z-dimers have several different conformers, which all have different solvation energies. While in the gas phase the nitrosobenzene E-dimer is more stable that its Z-form, in chloroform, the Z-form is more stable. Gas-phase dimerization entropies are large and negative, so these reactions are strongly temperature dependent. In some cases, like with 2-nitrosopyridines, entropy and enthalpy terms essentially cancel each other out, allowing structural and media effects to significantly influence dimerization equilibria.

Three types of organic solid‐state reactions, dimerizations, dissociations, and Z‐E isomerizations were investigated by using the transformations of aromatic C‐nitroso compounds in crystalline solids as a convenient molecular model. Here we propose a conceptual frame for solid‐state organic reaction mechanisms by examining activation parameters obtained from kinetic measurements under specific experimental conditions. The possibility of the appearance of a sort of short‐lived intermediate liquid phase that constitutes a critical condition for initiating chemical reaction in crystalline solids, similarly to the mechanism for the thermal solid‐state reactions proposed by Paul and Curtin is discussed. The analogy of the proposed concept with the recent hypothesis about the variable rigidity/softness of the reaction cavity in the enzyme reactions, and with the newest molecular dynamic simulation studies of solid phase transformations was considered.

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The present study has identified molecular bending as an important factor that has a profound effect on the self-assembly of originally rod-shaped organic molecules on a (111) gold surface. This was demonstrated on three specifically designed rigid molecular rods carrying archetypal anchoring groups (pyridyl units and thiols) on one terminus. These rods were used to prepare corresponding self-assembled monolayers (SAMs), and a combination of various analytical techniques revealed that originally straight molecular rods that were bent once adsorbed on a metallic surface, acquiring a characteristic “J-shape”. Extensive density functional theory calculations, including in silico reconstruction of such SAMs on (111) gold, clearly confirmed experimental observations.

Since there are no products in the European market labelled as low-FODMAP (low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols), patients with irritable bowel syndrome and non-celiac wheat sensitivity often consume gluten-free products. These naturally contain little FODMAP, but have poorer sensory properties and lower nutritional value. This study aimed to develop sensory attractive crackers with high-fibre and low-FODMAP content. Various gluten-free flours (wholemeal buckwheat and millet, white maize), pumpkin seed meal, chia seeds, flax seeds, rice protein, sweet potato, sourdough, and spices were used to develop nine formulations. Using a nine-point hedonic scale and ranking test, four best-scored products were selected for which descriptive sensory analysis was performed and nutritional value and fructan content were determined. Crackers made from maize and millet flour mixtures (ratio 1:2.5) with sourdough and with chia or flax seed addition were rated highest for overall impression (8.2 and 7.0, respectively). Generally, high-fibre content, hardness, chewiness, dark colour, and bitterness lower the acceptability of crackers, but the addition of spices and sourdough can improve their acceptability and marketability. The crackers could be labelled as “gluten-free”, “low-FODMAP” (<0.12 g/100 g), “naturally high-fibre” (7–10 g/100 g of which 17–23% are soluble), and “high in protein” (24–26 g/100 g).