A Three-Component Donor-Acceptor Hybrid Framework with Low-Power X-ray-Induced Photochromism

Donor-acceptor (D-A) hybrid frameworks with visual X-ray photochromism at room temperature are fascinating because of their promising applications as X-ray detectors. Herein, a 3-fold interpenetrated D-A hybrid framework, [Eu(bcbp)_1.5(DMF)(H₂O)₂][Co(CN)₆]·4H₂O·CH₃OH (1), has been obtained by incorporating electron-rich Co(CN)₆^3- into the electron-deficient europium viologen framework, which interestingly exhibits ultraviolet and low-power X-ray dual photochromism with a remarkable color change from brown to green. Experimental and theoretical studies revealed that the X-ray photochromic behavior of hybrid 1 could be attributed to its D-A hybrid structural feature increasing the extent of photoinduced electron transfer and thus photogenerated radical species upon X-ray irradiation. Meanwhile, due to the introduction of emissive lanthanide cations in the D-A system, hybrid 1 exhibits photomodulated luminescence properties.