Photochromic and Room Temperature Phosphorescent Donor-Acceptor Hybrid Crystals Regulated by Core-Substituted Naphthalenediimides.

Donor-acceptor (D-A) hybrid crystals are an emerging kind of crystalline hybrid material composed of semiconductive inorganic donors and organic acceptors. Except for the intrinsic photochromism, recently we have reported that the anion-π polyoxometalate (POM)/naphthalenediimide (NDI) hybrid crystals could produce an interesting room temperature phosphorescence (RTP) quantum yield up to 7.2%. Herein, we extended into core-substituted NDIs and anticipated the regulation of their photochromic and RTP properties. Thus, two hybrid crystals, namely (H ₄ BDMPy-Br ₂ NDI)·(NMP) ₄ ·(HPW ₁₂ O ₄₀ ) ( 1 ) and (H ₄ BDMPy-I ₂ NDI)·(HPW ₁₂ O ₄₀ ) ( 2 ) (H ₂ BDMPy-Br ₂ NDI: N , N '-bis(3,5-dimethylpyrazolyl)-2,6-dibromo-1,4,5,8-naphthalenediimide and H ₂ BDMPy-I ₂ NDI: N , N '-bis(3,5-dimethylpyrazolyl)-2,6-diiodide-1,4,5,8-naphthalenediimide), have been synthesized from phosphotungstic anions (PW ₁₂ O ₄₀ ^3- ) and Br or I core-substituted NDIs. Compared to the core-unsubstituted analogues (H ₄ BDMPy-NDI)·(NMP) ₄ ·(HPW ₁₂ O ₄₀ ) ( 3 ), 2 with photosensitive iodine substituents is more sensitive to light, which can become discolored under natural light. As a result of the heavy-atom effect, hybrid 1 exhibits remarkable RTP with the quantum yield up to 10.2% and a lifetime of 1.14 ms.