A superior bifunctional luminescent sensor for Al3+ and UO22+ was built based on a Co(ii) MOF with exposed Lewis basic pyrimidyl sites.

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Metal-organic frameworks (MOFs) provide highly designable platforms to construct complex coordination architectures for targeted applications. Herein, we demonstrate that trans-coordinated metal centers with exposed equatorial positions can be placed in a MOF matrix. A Zr-based MOF, namely, PCN-160, was initially synthesized as a scaffold structure. Postsynthetic linker labilization was subsequently implemented to partially remove the original dicarboxylate linkers and incorporate pyridinecarboxylates. A pair of neighboring pyridyl groups was arranged at proper proximity within the framework to form trans-binding sites that accommodate different metal cations including Mn, Fe, Co, Ni, Cu, and Pd. Furthermore, the trans-coordinated Ni sites in porous frameworks can be readily accessed by substrates along the equatorial plane, facilitating the catalysis as manifested by the superior activity in ethylene dimerization over that observed for a cis-chelated catalyst.

An unprecedentedr eversible dynamic transformation is reported in am etal-organic framework involving bond formation, which is accompanied by two important structural changes;achiral to chiral and two-to three-dimensions. Using two bent organic ligands (diimpym = 4,6-di(1H-imidazol-1-yl)pyrimidine;H 2 npta = 5-nitroisophthalic acid) and Co II (NO 3 ) 2 ·6H 2 Ot he coordination polymer Co(diimpym)(npta)·CH 3 OH, (1·CH 3 OH), was obtained solvothermally. Its structure consists of knitted pairs of square layers (4 4 -sql net) of five-coordinated Co and disordered methanol, and it crystallizedi nt he achiral Pbca space group at room temperature. It undergoes as ingle crystal to single crystal (SC-SC) transformation to a3 Di nterpenetrated framework (a-polonium-type net, pcu)o fs ix-coordinated Co and ordered methanol in the chiral P2 1 2 1 2 1 space group below 220 K. Most unusual is the dynamic temperature-dependent shortening of aC o···O connection from an on-bonded 2.640 (298 K) to ab onded2 .347 distance (100 K) transforming the square pyramidal cobalt polyhedron to ad istorted octahedron. The desolvated crystals( 1)o btained at 480 Kr etain the full crystallinitya nd crystallize in the achiral Pbca space group between 100 and 298 Kb ut the dynamic shorteningo ft he Co···O distance connecting the layers into the 3D pcu framework structure is observed. Following post-synthetic insertion of ethanol (1·CH 3 CH 2 OH)i td oes not exhibit the transformation and retains the knitted2 Da chiral Pbca structure for all temperatures (100-298 K) and the ethanol is always disordered. The structurala nalyses thusc oncludet hat the ordering of the methanol induces the chirality while the availables pace controlst he dynamic motion of the knitted 2D networks into the 3D interpenetrated framework. Consequently, 1 selectively adsorbs CO 2 to N 2 and exhibits Type-III isotherms indicating dynamic motion of the 2D networks to accommodate the CO 2 at 273 and 298 Ki nc ontrast to the rigidity of the 3D framework at 77 Kp reventing N 2 from penetrating the solid. The magnetic properties are also reported.

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