Nine new cocrystals of para-phenylenediboronic or para-hydroxyphenylboronic acids with a series of aromatic N-oxides are reported. All of the complexes form centrosymmetric crystal structures. They are stabilized by an extended net of hydrogen bonds further supported by effective π-stacking interactions. In the studied structures four main synthons were distinguished. Only in the 3,10-phenanthroline-3-N-oxide and 3,10-N,N-dioxide cocrystals from the series, an acid–acid dimeric motif characteristic for arylboronic acid crystals was observed. The majority of the obtained cocrystals exhibit layered architectures, where the N-oxide molecules are separated by boronic acid slabs. Furthermore, most of the cocrystals form hydrates, where water molecules play the role of a “molecular glue”. Water contribution to the lattice stability is significant, and energy gain per water molecule ranges from 66.8 to 117.6 kJ·mol–1. The cocrystal cohesive energies seem to be more favorable when compared to the corresponding values for crystals of their components. However, the presence of various asymmetric unit contents and numerous hydrated crystal structures indicates that the crystallization process and the final products are highly dependent on kinetic and entropy factors. Finally, the calculated energetic features are compared with the experimental thermogravimetric analysis–differential scanning calorimetry results obtained for selected cocrystals.

Photocrystallographic experiments provide valuable information on how crystalline samples interact with light, yielding light-induced structural changes. Studied processes include, among others, solid state chemical reactions, as well as isolation and characterization of various metastable states. Thus, some instrumentation development efforts in the field have been dedicated to facilitating such experiments using a home X-ray source. In this contribution, a portable, easy-to-use and adjustable light-delivery device for home single-crystal diffractometers is described. The whole system consists of adjustable laserfocusing optics and a holder, which can be conveniently attached to a goniometer, as an additional sample conditioning device. The light-delivery device was designed to reduce any goniometer movement limitations. It allows one to conveniently perform photocrystallographic experiments without violation of the X-ray safety protocols, even when changing the light source is necessary. Test in situ photocrystallographic experiments performed on the literature-reported Ni(NO 2 ) 2 (dppe) complex [dppe is bis(diphenylphosphino)ethane] confirm the effectiveness and applicability of the device for conducting linkage isomer single-crystal-to-single-crystal transformations.

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