Linker Flexibility-Dependent Cluster Transformations and Cluster-Controlled Luminescence in Isostructural Silver Cluster-Assembled Materials (SCAMs)

Abstract

Silver chalcogenolate clusters (SCCs) and silver cluster-assembled materials (SCAMs) are an important category of novel luminescent materials, the emission of which can be modulated by variation of the cluster nodes and linker species. Here, the successfully synthesis of two isostructural 2D SCAMs is reported: Ag 12 bpa and Ag 12 bpe are formed by using two linkers with different conformational freedom (bpa=1,2-bis(4-pyridyl)ethane, bpe=1,2-bis(4-pyridyl)ethylene), with dodenuclear silver chalcogenolate clusters as secondary building units (SBUs). Interestingly, nonluminescent Ag 12 bpa at room temperature could quickly transform into 1D Ag 10 bpa, with concomitant dissociation of two silver atoms and the remaining ten silver atoms rearranging in the cluster, thus exhibiting an intense yellow phosphorescence after being triggered by acetonitrile (CH 3 CN). Similarly, stimulating Ag 12 bpe with CH 3 CN, by contrast, gave another 2D structure Ag 12 bpe-1b with the distorted SBUs and different topology structure, and both of them are merely red-emissive at low temperature. To note, after exchanging ligands, room-temperature nonluminescent 2D Ag 12 bpe-1b can be transformed into intensely luminescent 1D Ag 10 bpa. This linker-flexibility-dependent structural transformation and cluster-based SBU controlled luminescence remains scarce. Our work provides new insights into structure–luminescence relationship in clustered metal–organic frameworks and intelligent stimulus-responsive luminescent materials.