Structural-transformation-induced drastic luminescence changes in an organic-inorganic hybrid [ReN(CN)${}_4$]${}^{2-}$ salt triggered by chemical stimuli

We synthesized a (1-propylpyridinium)${}_2$[ReN(CN)${}_4$]-type organic-inorganic hybrid exhibiting water-vapor-induced drastic structural changes of the [ReN(CN)${}_4$]${}^{2-}$ assemblies. Specifically, upon exposure to water vapor, dehydrated nitrido-bridged chains were converted to hydrated cyanido-bridged tetranuclear clusters via rearrangements of large molecular building units in the crystals. These switchable assembly forms display substantially different photo-physical properties, although in both cases the emission is caused by a metal-centered d-d transition. The nitrido-bridged chain exhibited a near-infrared (749 nm) emission, which blue-shifted as the temperature increased, while a visible (561 nm) emission and its red shift was demonstrated by the cyanido-bridged cluster. (© 2023 Wiley-VCH GmbH)