The impact of metal ions on photoinduced electron-transfer properties: four photochromic metal–organic frameworks based on a naphthalenediimide chromophore

• Published in: CrystEngComm Vol. 20; no. 17; pp. 2430 - 2439
• Main Authors: Xu, Hui-Ling, Zeng, Xiao-Shan, Li, Jie, Xu, Yu-Ci, Qiu, Hai-Jiang, Xiao, Dong-Rong
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2018
• Subjects: Cations; Change detection; Color; Diamonds; Diffraction; Electrons; Infrared spectroscopy; Metal ions; Metal-organic frameworks; Photochromism; Photoluminescence; Photosensitivity; Properties (attributes); Self-assembly; Single crystals; X ray powder diffraction; X-ray diffraction
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/C8CE00213D

Four novel photochromic metal–organic frameworks (MOFs) self-assembled from a naphthalenediimide-based ligand and different metal cations, [Zn 2 (BINDI)(DMA) 2 ]·2DMA ( 1 ), [Cd(H 4 BINDI)(H 2 BINDI)]·4DMF ( 2 ), [Ca 2 (HBINDI)Cl(DMA) 3 ]·DMA ( 3 ), [Ba 4 (BINDI) 2 (DMF) 7 ]·7DMF ( 4 ) (H 4 BINDI = N , N ′-bis(5-isophthalic acid)naphthalenediimide), have been synthesized and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, elemental analyses, IR spectroscopy and TG analyses. Compound 1 exhibits a 3D porous framework with an lvt topology based on paddle-wheel Zn 2 (COO) 4 clusters and BINDI as four-connected nodes. Compound 2 features a porous threefold interpenetrating diamondoid framework. Compound 3 shows a microporous 2D double-layer architecture and compound 4 displays a porous twofold interpenetrated 3D network. Interestingly, these four MOFs exhibit reversible photochromic behaviors with a concomitant eye-detectable color change, but different coloration degrees. The comparison of these MOFs indicates that the electron-withdrawing capabilities of metal cations play a significant role in tuning the photosensitive properties of photochromic MOFs; this result may provide a feasible route for the design and synthesis of photochromic MOFs with controllable photoinduced electron-transfer properties. Moreover, the photomodulated photoluminescence properties of compounds 1–4 , as well as the solvatochromic behaviors of 3 and 4 were also investigated. Additionally, compounds 1–3 are found to be useful as indicators for the qualitative detection of nitrite by naked eye recognition of color change.