Reaction of isoniazid with benzoic acid, sebacic acid, suberic acid, and cinnamic acid results in formation of cocrystals. Two polymorphs of isoniazid–suberic acid and two polymorphs of isoniazid–cinnamic acid cocrystals were isolated. Crystal structure analysis shows the presence of a pyridine–carboxylic acid synthon in the studied cocrystals. The hydrazide group of isoniazid participates in N–H···O and N–H···N hydrogen bond formation, producing different supramolecular synthons. The stability study of isoniazid cocrystals has been performed over a 22 week period. A comparison of melting points of isoniazid–dicarboxylic acid 2:1 cocrystals shows the decrease of melting point with an increasing length of the acid. Solubility of isoniazid–carboxylic acid cocrystals tends to increase with increasing solubility of the acid.

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Cereal alkylresorcinols (ARs) are a group of phenolic lipids mainly found in the outer parts of grains of rye and wheat. They have been suggested for use as selective biomarkers for intake of whole grain and bran products of these cereals. Consumption of whole grains and whole grain products has been associated with reduced risk of developing chronic diseases, such as cardiovascular disease, diabetes type 2, obesity and some types of cancer. In this article a sensitive and rapid method of High Performance Liquid Chromatography with UV detection for quantitative determination of ARs in the cereals grown in Latvia is described. Instrument detection limits (IDL) were determined for C17:0, C19:0 and C21:0 homologues (coefficient of variation < 3%). According to the results of these studies, ARs were found in rye (87.1-112.0 mg/100 g), wheat (24.0-40.2 mg/100 g), triticale (32.1-74.4 mg/100 g), and in small amounts in barley (2.2-3.7 mg/100 g), but not in oats.

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This paper describes non-covalent complexes between zwitterionic 3-(1-alkyl-3N-imidazolio)-propane-1-sulfonates and different amines. Electrospray ionization (ESI) mass spectrometry and collision-induced dissociation were used to measure the stability of such complexes in solution and in the gas phase. Generally, zwitterionic sulfonates formed more abundant complexes with protonated 5-methylcytosine (5-MCH) than with aliphatic amines. The results show that the association constants and half-dissociation threshold energies of these complexes nonlinearly depend on the alkyl chain length of the zwitterion. It is shown that the complexes with the lowest stability exist in acetonitrile solution or in the gas phase. The factors responsible for this complicated behavior are discussed.The structure of the complexes was investigated by quantum chemical calculations using molecular mechanics and density functional theory. Hydrogen bonding is proposed as the main type of interaction responsible for the stability of ion-zwitterion complexes. In summary, the information obtained in this study could be used for the development of the new derivatization reagents for some compounds containing amidinium groups, like 5-MCH, to increase selectivity of ESI-based methods.