Four new metal-organic frameworks (MOFs) containing chiral channels have been synthesized using an achiral, triazine-based trigonal-planar ligand, 4,4',4' '-s-triazine-2,4,6-triyltribenzoate (TATB), and an hourglass secondary building unit (SBU): Zn3(TATB)2(H2O)2.4DMF.6H2O (1); Cd3(TATB)2(H2O)2.7DMA.10H2O (2); [H2N(CH3)2][Zn3(TATB)2(HCOO)].HN(CH3)2.3DMF.3H2O (3); [H2N(CH3)2][Cd3(TATB)2(CH3COO)].HN(CH3)2.3DMA.4H2O (4). MOFs 1 and 2 are isostructural and possess (10,3)-a nets containing large chiral channels of 20.93 and 21.23 A, respectively, but are thermally unstable due to the easy removal of coordinated water molecules on the SBU. Replacement of these water molecules by formate or acetate generated in situ leads to 3 and 4, respectively. Formate or acetate links SBUs to form infinite helical chains bridged by TATB to create three-dimensional anionic networks, in which one of the two oxygen atoms of the formate or acetate is uncoordinated and points into the void of the channels. This novel SBU-stabilization and channel-functionalization strategy may have general implications in the preparation of new MOFs. Thermogravimetric analysis (TGA) shows that solvent-free 3' is thermally stable to 410 degrees C, while TGA studies on samples vapor-diffused with water, methanol, and chloroform show reversible adsorption. MOF 3 also has permanent porosity with a large Langmuir surface area of 1558 m2/g. All complexes exhibit similar strong luminescence with a lambdamax of approximately 423 nm upon excitation at 268.5 nm.
Two common radical anion reductants, potassium benzophenone ketyl (K(Ph(2)CO)) and potassium naphthalenide (K(2)(C(10)H(8))(2)(THF)), have been isolated and characterized for the first time in solvent-free form or with low solvent content, allowing their use as pure solid reactants in preparative redox chemistry in accurate stoichiometric amounts.
This article argues that central cities and their surrounding regions are highly interdependent, and that neither suburbs nor central cities are self-sufficient. For example, suburban per capita income is linked to central city per capital income, and the price of peripheral "edge city" office space is linked to the price of office space in the central business district. Not only do many suburbanites earn their incomes in central cities, but the authors also find that the amounts of income generated in core cities continue to grow. Overall, strong statistical evidence shows that suburbs benefit when their core cities are viable (densely populated and prosperous) and that when cities include a greater proportion of their metropolitan populations, they tend to be more prosperous.
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