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The crystal structures of six novel salts of 4-nitrobenzoic acid — namely, 2-hydroxyethylammonium 4-nitrobenzoate (I), 2-hydroxypropylammonium 4-nitrobenzoate (II), 1-(hydroxymethyl)propylammonium 4-nitrobenzoate (III), 3-hydroxypropylammonium 4-nitrobenzoate (IV), bis-(2-hydroxyethylammonium) 4-nitrobenzoate (V), morpholinium 4-nitrobenzoate (VI) — containing the same anion but different cations have been studied. The ionic forms of I-VI serve as building blocks of the supramolecular architecture, and in crystals they are held together via ionic N-H···O and O-H···O hydrogen bonds. In the crystal packing the building blocks of I-III are self-assembled via N-H...O, O-H···O and C-H...O hydrogen bonds to form the chains which are further consolidated into two-dimensional layers by the same type of interactions. In IV-VI the chain-like structures have been generated by building blocks.

The salts of 1-naphthalene acetic acid and 2-naphthoxyacetic acid with ethanolamine have been synthetized. The two salts have been assessed using Tsibulskaya-Vassiliev biological test using agar-agar as the medium. Statistical processing of the data has been carried out. The good results of the bioassay indicate an auxinic growth-regulating activity of the two salts.

Benzoates and particularly, benzoic acids are known biologically for their effects in the regulation of seed germination. A series of monoethanolamine salts of para-substituted benzoic acids (MEASPBAs), the corresponding acids (BAs) and monoethanolamine (MEA) were tested at different concentrations, on Cucumis sativus L. germination in order to assess their biological activity. The correlation between the effects of different substituents of these salts and the corresponding acids with germination rate, root and shoot length, fresh and dry biomass, soluble protein content, isocitrate lyase (ICL, EC 4.1.3.1) and catalase (CAT, EC 1.11.1.6.) activity, was evaluated. Data showed that p-OH and p-CH3 substituents had a lower inhibitory effect compared to the halogenated substituents. Moreover, the inhibition of root and shoot lengths and the dramatic decrease of fresh biomass for halogenated (p-Cl, p-Br, p-I) MEASPBAs and BAs followed the increase of the atomic size of the substituent.