Metalla-Aromatic Oligomers: Efficient Photocatalytic Activation for Phototherapy

Monodisperse oligomers, positioned as intermediates between polymers and small molecules, retain certain reactivities of small molecules while simultaneously displaying the initial aggregation characteristics of the polymers. This distinctive structure bestows on them with significant potential for a wide range of applications. In this study, a series of carbolong osmium oligomers (Os1-Os4) and corresponding polymer were evaluated as photocatalysts. It was discovered that their molar absorption coefficients and reactive oxygen species generation rose with π-conjugation length, peaking at a polymerization degree of 4. Moreover, Os4 facilitates the photocatalytic oxidation of nicotinamide adenine dinucleotide (NADH) to its oxided form, NAD⁺. In vitro experiments demonstrated that Os4 had the strongest phototoxicity index in cells in hypoxic conditions, highlighting its potential efficacy in hypoxic tumor. Metabolomic analyses indicated that Os4 exerted its photocytotoxicity by disrupting purine metabolism. These insights will guide the future design of π-conjugated metal oligomers for advancing photocatalytic applications.