Krzysztof M. Borys

Lewis acidity and sugar receptor activity of 3-amino-substituted benzoxaboroles and their ortho-aminomethylphenylboronic acid analogues

The pKas as well as apparent binding constants of several 3-amino-substituted benzoxaboroles with alizarin red S (ARS) and some biologically important sugars have been evaluated and compared with that of the parent aminomethylphenylboronic acids. The investigated benzoxaboroles reveal lower acidity than the corresponding boronic acids. All the studied boronic compounds display the usual order of apparent binding constant values with glucose, galactose and fructose. The X-ray structure of the model catechol ester of the morpholinylmethylphenylboronic acid has been determined. The molecules are monomeric zwitterions with a tetracoordinated boron atom. The intermolecular interactions have been described with the aid of the Hirshfeld surface analysis.

Derivatives of phenyl tribromomethyl sulfone as novel compounds with potential pesticidal activity.

Summary A halogenmethylsulfonyl moiety is incorporated in numerous active herbicides and fungicides. The synthesis of tribromomethyl phenyl sulfone derivatives as novel potential pesticides is reported. The title sulfone was obtained by following three different synthetic routes, starting from 4-chlorothiophenol or 4-halogenphenyl methyl sulfone. Products of its subsequent nitration were subjected to the SNAr reactions with ammonia, amines, hydrazines and phenolates to give 2-nitroaniline, 2-nitrophenylhydrazine and diphenyl ether derivatives. Reduction of the nitro group of 4-tribromomethylsulfonyl-2-nitroaniline yielded the corresponding o-phenylenediamine substrate for preparation of structurally varied benzimidazoles.

Spectroscopic insight into supramolecular assemblies of boric acid derivatives and β-cyclodextrin

Interactions of select boric acid derivatives with β-cyclodextrin were investigated. All products were obtained employing the grinding-induced mechanochemical approach. It was found that phenylboronic acid, benzoxaborole and boric acid form non-covalent, hydrogen bonding-based systems with β-cyclodextrin, whereas catechol and pinacol esters of phenylboronic acid as well as ferroceneboronic acid form host-guest inclusion complexes. The interactions were probed using spectroscopic methods: 1H NMR, 1H-1H ROESY NMR, 1H DOSY NMR, FT-IR. Association constant values were evaluated by 1H DOSY NMR. The highest association constant was found for boric acid (117.5 ± 2.5 M-1), whilst the lowest for benzoxaborole (14.8 ± 0.3 M-1). The study shows the influence of boron compound structure on the nature of the assembly formed with β-cyclodextrin, laying up the basis for future work with such supramolecular systems.