Visible colorimetric dosimetry of UV and ionizing radiations by a dual-module photochromic nanocluster

Radiation dosimeters displaying conspicuous response of irradiance are highly desirable, owing to the growing demand of monitoring high-energy radiation and environmental exposure. Herein, we present a case of dosimetry based on a discrete nanocluster, [Th 6 (OH) 4 (O) 4 (H 2 O) 6 ](TPC) 8 (HCOO) 4 ∙4DMF∙H 2 O (Th-SINAP-100), by judiciously incorporating heavy Th 6 polynuclear centers as radiation attenuator and organic linkers as photo-responsive sensor. Interestingly, dual-module photochromic transitions upon multiple external stimuli including UV, β-ray, and γ-ray are integrated into this single material. The striking color change, and more significantly, the visible color transition of luminescence in response to accumulating radiation dose allow an on-site quantitative platform for naked-eye detection of ionization radiations over a broad range (1–80 kGy). Single crystal X-ray diffraction and density functional theory calculations reveal that the dual-module photochromism can be attributed to the π(TPC) → π*(TPC) intermolecular charge transfer driven by enhanced π-π stacking interaction between the adjacent TPC moieties upon irradiation.