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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.

The aim of this paper was to find the simplest method for the synthesis of (aminoiminomethyl)thioacetic acid and some of its esters ( methyl- and ethyl-) in order to test them biologically as potential plant growth regulators.

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.

The relationship between the structure and biological activity (toxicity) SAR of the stoichiometric mixtures between anion and cation (or neutral species) proceeded at pH 8.2 from the different amine salts of benzoic, acetic, oxalic, naphthalene carboxylic acids was determined. Their toxicity was determined by using the metamorphosis (transformation) process of the marine invertebrate Hydractinia echinata (Hydrozoa, Cnidaria) from the freely swimming larva to a sessile polyp as a biological test system. The two components of the stoichiometric mixture, the anion and the cation or neutral species react independently, but in a parallel way, the effectiveness of the cation/neutral species being superior. The studied compounds were grouped by their cationic/neutral structure and measured toxicity. All of these series were also characterized by a calculated mean value of the toxicity. The marine organism, Hydractinia echinata was a good and advantageous alternative for the toxicity testing systems with vertebrate.