Photoinduced reversible-deactivation radical polymerization (photo-RDRP) techniques offer exceptional control over polymerization, providing access to well-defined polymers and hybrid materials with complex architectures. However, most photo-RDRP methods rely on UV/visible light or photoredox catalysts (PCs), which require complex multistep synthesis. Herein, we present the first example of fully oxygen-tolerant red/NIR-light-mediated photoinduced atom transfer radical polymerization (photo-ATRP) in a high-throughput manner under biologically relevant conditions. The method uses commercially available methylene blue (MB⁺) as the PC and [X-Cu^II/TPMA]⁺ (TPMA = tris(2-pyridylmethyl)amine) complex as the deactivator. The mechanistic study revealed that MB⁺ undergoes a reductive quenching cycle in the presence of the TPMA ligand used in excess. The formed semireduced MB (MB^•) sustains polymerization by regenerating the [Cu^I/TPMA]⁺ activator and together with [X-Cu^II/TPMA]⁺ provides control over the polymerization. This dual catalytic system exhibited excellent oxygen tolerance, enabling polymerizations with high monomer conversions (>90%) in less than 60 min at low volumes (50-250 μL) and high-throughput synthesis of a library of well-defined polymers and DNA-polymer bioconjugates with narrow molecular weight distributions (Đ < 1.30) in an open-air 96-well plate. In addition, the broad absorption spectrum of MB⁺ allowed ATRP to be triggered under UV to NIR irradiation (395-730 nm). This opens avenues for the integration of orthogonal photoinduced reactions. Finally, the MB⁺/Cu catalysis showed good biocompatibility during polymerization in the presence of cells, which expands the potential applications of this method.

Catalytic water oxidation has been investigated using five iridium complexes as precatalysts and NaIO₄ as an oxidant at various pH conditions. An increase in the activity of all complexes was observed with increasing pH. A detailed analysis of spectroscopic data together with O₂-evolution experiments using Cp*Ir(6,6′-dihydroxy-2,2′-bipyridine)(OH₂)²⁺ as a precatalyst indicate that the high catalytic activity is closely connected with transient species (A) that exhibits an absorption band at λ_max 590 nm. The formation of this active form is strongly dependent on reaction conditions, and the species was distinctly observed using a small excess of periodate. However, another species absorbing at 600 nm (B), which seems to be a less active catalyst, was also observed and was more prominent at high oxidant concentration. Dynamic light scattering analysis and transmission electron microscopy have identified species B as 120 nm nanoparticles. The ultrafiltration method has revealed that species A can be attributed to particles with size in the range of 0.5–2 nm, possibly small IrO_x clusters similar to those described previously by Harriman and co-workers (J. Phys. Chem., 1991, 95, 616–621).