Energy-level Rule Guided Construction of Low-Coordinated LnOFs for Redox-Gated and Programmable Low-Bias Electrochemiluminescence
Electrochemiluminescence (ECL) platforms are often constrained by aggregation-caused quenching (ACQ), inefficient charge transfer, and instability under high driving potentials, thereby limiting their sensitivity and reproducibility. Herein, an energy-level rule-guided strategy is reported to construct a distinctive lanthanide-organic framework (LnOF), [Tb 2 ( µ 2 -OH) 2 (TBAPy)], through the controlled self-assembly of Tb 3+ and 4,4′,4″,4‴-(pyrene-1,3,6,8-tetrayl)tetrabenzoic acid (H 4 TBAPy). This LnOF features the rod-shaped [Tb( µ 2 -OH) 2 (-CO 2 ) 2 ] chains, a large π -stacking distance (6.685 Å) between pyrene rings, and a 3D sea topology, effectively suppressing ACQ and antenna-type energy transfer from the TBAPy triplet state to Tb 3+ , thereby preserving pyrene-based fluorescence while inhibiting the luminescence of Tb 3+ . Importantly, the low-coordinated [TbO 6 ] octahedron exposes multiple open metal sites to coordinate with coreactant S 2 O 8 2− and facilitate its decomposition to SO 4 •− radicals during electrochemical reactions. This process markedly reduces interfacial resistance and enables robust low-bias ECL amplification. Furthermore, a MnO 2 interfacial gate enables ratiometric ECL OFF/ON switching upon glutathione reduction, delivering internally referenced signal outputs with an ultralow limit of detection of 6.8 × 10 −4 n m across a wide range (0.01–500 n m ). This kind of functional material design establishes a generalizable blueprint for LnOF-based ECL systems, advancing programmable and low-bias luminescent sensing with exceptional sensitivity and stability.
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