A zeolitic imidazolate framework material of SOD topology possessing primarily unsubstituted imidazolate (im) linkers has been synthesized via solvent-assisted linker exchange (SALE) of ZIF-8. The structure of the new material, SALEM-2, has been confirmed through (1)H NMR and powder and single-crystal X-ray diffraction. SALEM-2 is the first example of a porous Zn(im)(2) ZIF possessing a truly zeolitic topology that can be obtained in bulk quantities. Upon treatment with n-butyllithium, the open analogue exhibits Brønsted base catalysis that cannot be accomplished by the parent material ZIF-8. Additionally, it displays a different size cutoff for uptake and release of molecular guests than does ZIF-8.

The present work is a critical review of metal exchange (transmetalation) involving metal nodes and metalated struts in metal-organic frameworks. Particular emphasis is given to drawing parallels between different examples of transmetalation in order to understand the influence of coordination environment, solvents, nature of the metals and other variables on the process. We hope that the present review will be of use to those involved in the incorporation of various metal centers to create isostructural MOFs and study their properties.

An efficient synthetic route to an A1/A2-difunctionalized pillar[5]arene containing resolvable planar chirality has been developed and the arene employed as a strut in the synthesis of P5A-MOF-1, which has been demonstrated by X-ray powder diffraction analysis--supported by modeling--to be isoreticular with MOF-5. This metal-organic framework has an active domain that expresses good and selective uptake of neutral and positively charged electron-poor aromatic guests, which effect color changes of the cubic crystals from faint yellow to deep orange, arising from charge transfer between the guests and active domain of P5A-MOF-1.

Control over catenation in a pillared paddlewheel metal−organic framework was achieved via solventassisted linker exchange. The linker exchange was demonstrated on the noncatenated structure of DO-MOF, by using 4,4′-bipyridine (L4) and 4,4′-azobis(pyridine) (L5) as linkers, leading to noncatenated materials SALEM-3 and SALEM-4. The de novo synthesized analogues of SALEM-3 and SALEM-4 can only be obtained as 2-fold interpenetrated frameworks. The reaction progress of the linker exchange was monitored by NMR spectroscopy, and structure and framework catenation were characterized by powder X-ray diffraction and thermogravimetric methods.

Metal imidazolates, an important class of constructs in metal−organic framework chemistry, are shown here to be precursors to N-heterocyclic carbene-like catalysts. By using n-butyl lithium to deprotonate tripodal imidazolate framework-1 (TIF-1), N-heterocyclic carbene (NHC) sites can be exposed. These sites are found to be remarkably competent as Brønsted-base-type NHC catalysts. An α,β-unsaturated ketone was converted to the corresponding benzyl ether with benzyl alcohol at a faster rate and in higher yield than with a traditional homogeneous NHC catalyst (1,3-bis-(2,4,6trimethylphenyl)imidazole)), despite lower overall loading. Varying the size of the alcohol in the conjugate addition reaction yielded no change in reaction rate, even when the size of the alcohol exceeded the diameter of the MOF pores, suggesting that catalysis occurs exclusively on the surface of the MOF crystals, as opposed to within the framework pores.