Framework Complexes of Group 2 Metals Organized by Homochiral Rods and 蟺路路路蟺 Stacking Forces: A Breathing Supramolecular MOF

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• 作者：Daniel L. Reger ; Andrew Leitner ; Perry J. Pellechia ; Mark D. Smith
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：September 15, 2014
• 年：2014
• 卷：53
• 期：18
• 页码：9932-9945
• 全文大小：1118K
• ISSN：1520-510X

文摘

The reactions of the potassium salts of the ligands (S)-2-(1,8-naphthalimido)propanoate (KL_ala), (S)-2-(1,8-naphthalimido)-3-hydroxypropanoate (KL_ser), and (R)-2-(1,8-naphthalimido)propanoate (KL_ala*), enantiopure carboxylate ligands containing a 1,8-naphthalimide 蟺路路路蟺 stacking supramolecular tecton, and, in the case of L_ser^鈥?/b>, an alcohol functional group with calcium or strontium nitrate under solvothermal conditions produce crystalline [Ca(L_ala)₂(H₂O)]路(H₂O) (1); [Ca(L_ser)₂]路(H₂O)₂ (2); [Sr(L_ala)₂(H₂O)]路(H₂O)₃ (3); [Sr(L_ala*)₂(H₂O)]路(H₂O)₃ (3*); and [Sr(L_ser)₂(H₂O)] (5). Placing 3 under vacuum removes the interstitial waters to produce [Sr(L_ala)₂(H₂O)] (4) in a single-crystal to single-crystal transformation; introduction of water vapor to 4 leads to the reformation of crystalline 3. Each of these new complexes has a solid-state structure based on homochiral rod secondary building unit (SBUs) central cores. Supramolecular 蟺路路路蟺 stacking interactions between 1,8-naphthalimide rings link adjacent rod SBUs into three-dimensional structures for 1, 3, 4, and 5 and two-dimensional structure for 2. Compounds 1 and 3 have open one-dimensional channels along the crystallographic c axis that are occupied by disordered solvent. For 3, these channels close and open in the reversible single-crystal conversion to 4; the 蟺路路路蟺 stacking interactions of the naphthalimide rings facilitate this process by rotating and slipping. Infrared spectroscopy demonstrated that the rehydration of 4 with D₂O leads to 3d₈, and the process of dehydration and rehydration of 3d₈ with H₂O leads to 3, thus showing exchange of the coordinated water in this process. These forms of 3 and 4 were characterized by ¹H, ²H, and ¹³C solid-state NMR spectroscopy, and thermal and luminescence data are reported on all of the complexes.