3- and 4-pyridineboronic acids have been combined with trimesic and pyromellitic acids to give three molecular complexes.

The asymmetric unit of the title compound, C12H10BNO5·0.67H2O, contains three independent pyridinylboronic acid esters adopting zwitterionic forms and two water mol­ecules. The six-membered heterocyclic rings in the boronic esters have half-chair conformations and the deviations of the B atoms from the boronate mean planes range from 0.456 (3) to 0.657 (3) Å. All of the B atoms have tetra­hedral coordination environments, with B—O and B—C bond lengths of 1.446 (4)–1.539 (3) and 1.590 (5)–1.609 (5) Å, respectively. In the crystal, the ester and water mol­ecules are linked into a three-dimensional network by a large number of O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds. The crystal packing is further accomplished by π–π inter­actions, with centroid–centroid distances of 3.621 (4)–3.787 (4) Å.

In this work, we report the structural analysis of Cu+ and Cu2+ ions in zeolite as a nanoreactor with antibacterial applications. A simple one-step process was implemented to obtain Cu ions in zeolite A (ZA4) by controlling the temperature in the solutions to guarantee the ions’ stability. Samples were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy, showing the characteristic zeolite elements as well as the characteristic bands with slight modifications in the chemical environment of the zeolite nanoreactor attributed to Cu ions by FT-IR spectroscopy. In addition, a shift of the characteristic peaks of ZA4 in X-ray diffraction was observed as well as a decrease in relative peak intensity. On the other hand, the antibacterial activity of Cu ions in the zeolite nanoreactor was evaluated.

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