Rational Design and Control of the Dimensions of Channels in a Series of 3D Pillared Metal−Organic Frameworks: Synthesis, Structures, Adsorption, and Luminescence Properties

A systematic variation of diamine ligands, TED, Bipy, and Bpe [TED = triethylenediamine, Bipy = 4,4′-bipyridine, and Bpe = trans-bis(4-pyridyl)ethylene], pillaring 2-fold (6,3) layers constructed from metallic trinuclear SBUs and flexible CTC ligands gives rise to a series of porous metal−organic frameworks, Cd3(CTC)2(TED)(H2O)2·(H3O)2Cl2 (1), Cd3(CTC)2(Bipy)(DMF)2·(DMF)(H2O)2 (2), Cd3(CTC)2(Bpe)(DMF)2·(DMF)(H2O)2 (3), Zn3(CTC)2(Bipy)·(DMF)(H2O)2 (4), and Zn3(CTC)2(Bpe)·(DMF)(H2O)2 (5) (compounds 1–5 named JUC-34, JUC-44, JUC-45, JUC-46, JUC-47, respectively, JUC-Jilin University, China, CTC = cis,cis-1,3,5-cyclohexanetricarboxylate and DMF = N,N′-dimethylformamide). These open frameworks have been synthesized under mild conditions possessing three-dimensional connectivity with interconnecting pores and the same (43)2(46·618·84) topology. The water adsorption isotherms of these compounds show type Ι behavior with approximately 0.07, 0.10, 0.12, 0.17, and 0.19 mL/g pore volumes, respectively. Photoluminescence investigations reveal that they display strong emission in the blue/green regions.