Luminescent cyanide coordination polymer based on {Mo6I8} and {Ag2(dppm)2} clusters: exceptional stability and efficient scintillation

First metal-organic coordination polymer based on [{Mo6I8}(CN)6]2– cluster anion was obtained using salts Cs1.3Na0.7[{Mo6I8}(CN)6]·2H2O (1) and K[Ag(CN)2], as well as bis(diphenylphosphino)methane (dppm) as precursors. In contrast to the previously reported coordination polymers based on octahedral cyanide cluster complexes, the 1D polymer [{Ag2(dppm)2}{Mo6I8}(CN)6] (2) demonstrated an order of magnitude increase in the cluster-centred photoluminescence quantum yield (Φem) in the solid state at 300 K in comparison with the ionic salt 1. Moreover, 2 displays bright X-ray induced emission, which is two orders of magnitude more intense than that of 1 and is characterized by a light yield of 10800 photons/MeV. Therefore, 2 represents the first effective scintillating compound, which is based on octahedral molybdenum clusters. The polymer have exceptional thermal, photo- and hydrolytic stability and displays minimal degradation upon X-ray irradiation, retaining its emission intensity following exposure to an air-equivalent dose of 2·103 Gray. It should be noted that no compounds based on octahedral molybdenum clusters have been previously obtained that would remain stable when exposed to such radiation doses. The high light yield and exceptional stability of the compound have enabled us to use it to manufacture scintillation screens for X-ray visualisation. These screens have a spatial resolution of up to 9 line pairs/mm, representing the first example of a scintillation device based on octahedral metal clusters.