Reticular assembly of 1D and 2D Cu10 cluster-assembled materials as a recyclable luminescent probe for highly sensitive creatinine detection

Abstract

Atomically precise metal cluster–assembled materials provide a powerful platform for engineering modular photophysical responses through well-defined cluster–linker interfaces. Here we report two copper cluster-assembled materials (CCAMs), Cu₁₀-bddi and Cu₁₀-dptp, obtained through the reticular integration of a decanuclear copper cluster with either a linear diisonicotinate linker (bddi) or a π-extended thiophene–dipyridyl linker (dptp). Single-crystal X-ray diffraction reveals distinct coordination chemistries: Cu₁₀-bddi features a Cu(I)-rich cluster bridged by thiolate and carboxylate donors to generate 1D chains, whereas Cu₁₀-dptp incorporates N-donor linkers to stabilize a Cu(I)-rich cluster environment assembled into fully extended 2D sheets. X-ray photoelectron spectroscopy corroborates these oxidation-state assignments and highlights the differing electronic structures of the two frameworks. Both CCAMs exhibit permanent microporosity arising from periodic cluster packing, enabling efficient molecular access to the luminescent cluster nodes. Optical studies disclose linker-to-cluster–coupled absorption features and distinct emission signatures in water. These properties render the materials effective luminescent probes for creatinine, an essential biomarker for kidney function. Cu₁₀-bddi undergoes strong fluorescence quenching upon creatinine binding, attributable to efficient photoinduced electron or energy transfer within its confined 1D channels. Conversely, Cu₁₀-dptp displays emission enhancement, consistent with rigidity-induced suppression of nonradiative decay within its 2D π-extended environment. Both sensing processes follow Stern–Volmer behavior and afford low detection limits. Importantly, each CCAM demonstrates excellent recyclability over fifteen sensing cycles, with FT-IR confirming structural integrity. This work shows that reticular Cu₁₀ cluster assembly enables robust, reusable luminescent sensors and underscores how oxidation state, dimensionality, and pore architecture govern aqueous analyte recognition.