The solid-state investigation of the diastereomeric salts (S)-ibuprofen (S-Ibu), (S)-naproxen, (S-Nap), and (S)-ketoprofen (S-Ket) with (R)-(+)- and (S)-(−)-1-phenylethylamine, R-PEA, and S-PEA respectively, has been carried out by using a combination of experimental and in-silico tools. The focus was on their crystal packing and on the stability/transformation of their solid forms under different experimental conditions with the final aim of extracting useful information on the forces/features which could be exploited for the chiral separation of the corresponding racemic compounds. All the salts are 2₁-column crystals, each column consisting of API and 1-phenylethylamine ions assembled via the 1-phenylethylammonium-carboxylate supramolecular heterosynthon which originates a R₄³ (10) pattern, the intercolumns contacts being definitely weaker. In spite of an overall similarity in the crystal packing forces and motifs of the anhydrous salts, the temperature stability range suggests that the homochiral species are the most stable. The fact that the homochiral salt of S-Ket (S-Ket_S-PEA) is stable toward the hydration, at variance with the heterochiral one (S-Ket_R-PEA), further confirms this hypothesis. On the other hand, preliminary sorption tests show that S-Ket and S-Ibu preferentially capture the homochiral PEA (S-Nap is not selective). This behavior has been correlated to the almost planar boundary surfaces which characterize and differentiate the 2₁ sheets in S-Ket_S-PEA and S-Ibu_S-PEA salts with respect to the corresponding heterochiral ones.

Formaldehyde (FA) is a toxic compound and a human carcinogen. Regulating FA-releasing substances in commercial goods is a growing and interesting topic: worldwide production sectors, like food industries, textiles, wood manufacture, and cosmetics, are involved. Thus, there is a need for sensitive, economical, and specific FA monitoring tools. Solid-phase microextraction (SPME), with O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine (PFBHA) on-sample derivatization and gas chromatography, is proposed for FA monitoring of real-life samples. This study reports the use of polydimethylsiloxane (PDMS) as a sorbent phase combined with innovative commercial methods, such as multiple SPME (MSPME) and cooling-assisted SPME, for FA determination. Critical steps, such as extraction and sampling, were evaluated in method development. The derivatization was performed at 60 °C for 30 min, followed by 15 min sampling at 10 °C, in three cycles (SPME Arrow) or six cycles (SPME). The sensitivity was satisfactory for the method’s purposes (LOD-LOQ at 11-36 ng L⁻¹, and 8-26 ng L⁻¹, for SPME and SPME Arrow, respectively). The method’s linearity ranges from the lower LOQ at trace level (ng L⁻¹) to the upper LOQ at 40 mg L⁻¹. The precision range was 5.7–10.2% and 4.8–9.6% and the accuracy was 97.4% and 96.3% for SPME and SPME Arrow, respectively. The cooling MSPME set-up applied to real commercial goods provided results of quality comparable to previously published data.

The reduction of aromatic nitro compounds has been performed employing a catalytic amount of Wang resin-supported phenyl(2-quinolyl)methanol (Wang-PQM) in the presence of an excess of NaBH₄ to regenerate the reactive reducing species at the end of the process. The reduction products are easily isolated through a simple filtration/extraction protocol, and the catalyst can be efficiently recovered and recycled. The condensation route is generally preferred, and azo- and/or hydrazo-arenes can be easily prepared in high yields.