Aromatic compounds bearing a nitro group are interesting models in environmental photochemistry. As an example, the photolysis of 4-nitrocatechol and 2,4-dinitrophenol was investigated by means of UV–vis spectroscopy in semisolid isomalt, in order to develop a new type of surrogate for glassy organic aerosols. The results have been compared to those obtained in water and alcohols. Interestingly, whereas 4-nitrocatechol undergoes photooxidation in organic solvents, irradiation of the model compounds in semisolid isomalt resulted in reduction and dimerisation (see Scheme 1).¹ 

The photochemistry of two nitro derivatives belonging to the class of neonicotinoids dinotefuran (DNF) and nitenpyram (NPM) when embedded in KBr pellets was investigated at different wavelengths (from 254 to 350 nm).²  The selective and versatile blue light driven reduction of nitroarenes (presumably via the formation of a electron donor–acceptor, or EDA, complex) was achieved by combining NaI and PPh₃. When o-nitrobiarenes were used, the irradiation resulted in a Cadogan-type reductive amination, affording the corresponding carbazole (Scheme 2).³  Similarly, nitroarenes were found to undergo PPh₃ mediated reductive amination to form, in the presence of boronic acids as the coupling partner, the corresponding diaryl amines.⁴