Water‐Triggered Structural Transformation in a Silver Chalcogenolate Cluster‐Based MOF (SCC‐MOF) Enables Visually Readable Trace Water Sensing

Abstract

ABSTRACT Monitoring trace water is vital for chemical processes and moisture‐sensitive materials, but conventional electrical humidity sensors require complex instrumentation and lack intuitive visual readout. Luminescent metal‐organic frameworks (MOFs) offer optically driven water sensing; however, most existing systems still rely on traditional node‐linker structures, whereas cluster‐assembled frameworks may have potential due to their multisite existence and remain largely unexplored. Here, we introduce a silver chalcogenolate cluster‐based framework (SCC‐MOF), Ag 12 ‐TCNB 3D‐3D ( TCNB, 1,2,4,5‐tetracyanobenzene ) that exhibits a striking orange‐to‐yellow luminescence transition upon water exposure, enabling rapid, naked‐eye detection within relative humidity (RH) <1.26%. The atomically precise Ag 12 cluster node ( Ag 12 ‐TCNB 0D ), bridged by the electron‐deficient TCNB linker, forms a 2D network that achieve coordination with water molecules ( Ag 12 ‐TCNB 2D‐H 2 O ). Single‐crystal X‐ray diffraction (SCXRD) and powder X‐ray diffraction (PXRD) reveal that water induces lattice displacement and perturbs the cluster‐centered excited states, a conclusion further supported by electronic structure calculations. This work establishes cluster‐based MOFs as a promising platform for optically readable water‐vapor sensing.