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.