Lamellar, or layered, potassium niobium oxide perovskites are a class of underdeveloped semiconductors in organic photocatalysis that offer the inherent advantages of larger particle size and ease of recoverability as compared to traditional semiconductor materials.

Novel gold nanoparticle-doped niobium perovskites are synthesized using a chemical reduction technique, affording supported nanoparticles on the order of 8–10 nm. The UVA-initiated photocatalytic activity of the nanocomposites was studied using nitroarene reduction as a probe reaction which yielded the corresponding aminoarenes in as little as 3 hours with yields up to 92%. Analyses of kinetic data, using Hammett parameters and computational methods, show that electron-withdrawing groups accelerate the photocatalytic process and suggest that electron transfer from the gold nanoparticle surface to the nitro group is an integral part of the rate-limiting step of this reaction. The linearity of the Hammett plot shows that no change in the photocatalytic mechanism can be expected upon variation of the para-aryl substitution. Investigation of the reaction mechanism using CH₃OH-d₄ illustrates that CH₃OH is the most likely source of protons, as both electrons and protons are required for successful photoreduction. Moderate recyclability of the heterogeneous nanomaterial over three catalytic cycles is observed.

The development of quick and efficient methods for the detection of pathogenic bacteria is urgently needed for the diagnosis of infectious diseases and the control of microbiological contamination in global waterways, potable water sources and the food industry. This contribution will describe the synthesis of gold nanoparticles and their conjugation to broad spectrum, polypeptide and β-lactam antibiotics that function as both reducing agents and surface protectants (ATB@AuNP). Nanoparticle colloids examined using transmission electron microscopy are generally spherical in shape and range from 2–50 nm in size. Dynamic light scattering and infrared spectroscopy were also used to confirm encapsulation of the AuNP surface by antibiotic molecules. ATB@AuNP were then used to detect 3 common pathogenic bacterial species: Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. The colour of the AuNP colloid was monitored visually and using UV-visible spectroscopy. A red shift of the UV visible absorbance and a visible colour change following introduction of each pathogen is indicative of ATB binding to the bacteria surface, ascribed to AuNP agglomeration. This work demonstrates that ATB@AuNP may be an efficient and high throughput tool for the rapid detection of common bacterial contaminants.

The rarely recognized electron donating ability of the benzophenone triplet excited state provides an unusual route for the photochemical synthesis of gold nanoparticles.

Lignin is a promising renewable source of aromatic chemicals. Described herein is a new photocatalytic methodology for depolymerization of oxidized Kraft lignin to industrially relevant aromatic platform chemicals. The photooxidation route begins with oxidation of alcohol moieties using a gold nanoparticle/hydrotalcite composite. Next, the oxidized lignin is subjected to UVA irradiation in the presence of TiO₂, leading to a 3-fold decrease of its molecular weight and to the formation of various monolignols. The products obtained in both steps were characterized using FTIR, SEC, GC-MS, and 2D NMR spectroscopy, which confirm the depolymerization of lignin to smaller molecular weight products. This method offers both energetic and chemical advantages over thermochemical processing for lignin valorisation.

The photo-induced cytotoxicity of prodigiosenes is reported. One prodigiosene represents a synthetic analogue of the natural product prodigiosin, and two are conjugated to molecules that target the estrogen receptor (ER). A comparison of incubation and irradiation frameworks for the three prodigiosenes is reported, with activity against ER− and ER+ lines explored. Furthermore, the ability of the three prodigiosenes to photosensitise the production of singlet oxygen is demonstrated, shedding mechanistic light onto possible photodynamic therapeutic effects of this class of tripyrroles.