First report of aggregation induced emission (AIE) in NIR-II region of a Pr(III) polymer chain with pyridine-2,6-dicarboxylic acid

Abstract

The captivating allure of lanthanide complexes, known for their NIR emissions, becomes even more mesmerizing when aggregation occurs, enhancing their luminescent properties. This novel property significantly boosts its potential for applications in theranostics, offering new opportunities for advancements. Complexation of Praseodymium (III) with pyridine-2,6-dicarboxylic acid (dipicH<inf>2</inf>) led to the formation of transparent green crystals of the 1-D polymer chain of [Pr(dipicH)(dipic)(OH<inf>2</inf>)<inf>2</inf>]·4H<inf>2</inf>O (DPr), which demonstrates this unique aggregation-induced emission in the NIR region. DipicH<inf>2</inf> being a versatile ligand offering diverse bridging modes in connecting metal centers, numerous complexes of lanthanides exist, displaying aggregation effects in the visible spectrum. Inspite of vast number of complexes, to the best of our knowledge, this is the first report of AIE behavior in lanthanide complexes in the NIR-II region, showcasing the potential applications that may emerge for lanthanide-based materials. © 2025 Elsevier B.V.