Constructing highly efficient dual-confinement phosphorescence supramolecular naphthalimide pyridinium networks via eco-friendly post-polymerization assembly

Abstract

Developing supramolecular network materials with controllable phosphorescence behavior constitutes a highly active research frontier. Herein, the preparation of a high-efficiency room-temperature phosphorescence (RTP) supramolecular polymer network (SPN) via the post-polymerization assembly strategy is reported, through sequential polymerization of naphthalimide pyridinium derivatives and spontaneous aqueous self-assembly with exfoliated LAPONITE® (LP) nanosheets. Initially, thermally initiated copolymerization of cationic naphthalimide pyridinium derivatives with acrylamide produces transparent swollen hydrogels by solvent replacement, exhibiting emergent RTP with a lifetime of 29.1 μs governed by hydrogen-bonding confinement. Subsequent electrostatic integration of negatively charged LP nanosheets into hydrogels can tightly anchor cationic naphthalimide pyridinium moieties, thus extending the phosphorescence lifetime to 923 μs by further suppressing the non-radiative transition of triplet excitons. Crucially, dual spatial confinement—from both interwoven hydrogen-bonding networks coupled with rigid LP nanosheet architectures—synergistically elevates the RTP lifetime to 316.0 ms with an excellent phosphorescence quantum yield of up to 67.5% in free-standing dehydrated SPN films, representing a 340-fold improvement over the pristine hydrogels by circumventing aqueous-mediated quenching pathways. This hierarchical confinement strategy enables dynamic information processing and penetrated bioimaging applications, offering a versatile platform for designing RTP materials with tailorable photophysics.