Versatile Tailoring of NH2 -Containing Metal-Organic Frameworks with Paddle-Wheel Units.

An amine-containing non-interpenetrating pillar-layer framework, [Zn2 (dbtcb)(L1)]⋅x solvent (1), has been synthesized from Zn(NO3 )2 and the ligands 1,4-dibromo-2,3,5,6-tetrakis(4-carboxyphenyl)benzene (H4 DBTCB) and 2,5-bis(4-pyridyl)aniline (L1). The [Zn2 (COO)4 ] secondary building units (SBUs) are bridged by DBTCB to form two-dimensional layers that are linked by L1 ligands acting as pillars to form a three-dimensional network. This NH2 -containing framework can undergo versatile tailoring through post-synthetic covalent modification, solvent-assisted linker exchange (SALE), and single-crystal-to-single-crystal (SC-SC) transmetalation reactions. Acetamide-functionalized [Zn2 (L2)(dbtcb)]⋅xsolvent (2) could be obtained by direct synthesis from Zn(NO3 )2 , N-acetyl-2,5-bis(4-pyridyl)aniline (L2) and H4 DBTCB. Importantly, compound 1 with pure NH2 ligands as pillars could be obtained by SALE of 2 with L1 in DMSO solution. The transmetalation reactions of 1 with CuII , NiII , and CoII were studied; inductively coupled plasma-atomic emission (ICP) analysis revealed that 1 underwent almost complete SC-SC transmetalation with CuII within 30 h, whereas with NiII and CoII only 70 and 80 % substitutions were achieved. Photoluminescence studies revealed that 1 and 2 display yellow-green and UV emission, respectively, under a UV lamp. Furthermore, the photoluminescent properties could be tuned by introducing mixed pillar amino ligands L1 and L2 into the MOF to produce multivariate (MTV) MOF 3 displaying overall orange emission.

Postsynthesis Modification of a Metallosalen-Containing Metal-Organic Framework for Selective Th(IV)/Ln(III) Separation.

An uncoordinated salen-containing metal-organic framework (MOF) obtained through postsynthesis removal of Mn(III) ions from a metallosalen-containing MOF material has been used for selective separation of Th(IV) ion from Ln(III) ions in methanol solutions for the first time. This material exhibited an adsorption capacity of 46.345 mg of Th/g. The separation factors (ß) of Th(IV)/La(III), Th(IV)/Eu(III), and Th(IV)/Lu(III) were 10.7, 16.4, and 10.3, respectively.

Enantioselective inclusion of alcohols by solvent-controlled assembled flexible metal-organic frameworks.

Through judicious choice of the ligands and patient regulation of the solvent conditions, three unique chiral coordination polymeric isomers have been synthesized. Their structures, gas adsorption, and structural interconversion have been studied. One of the isomers displays dynamic behavior, and its use in the enantioselective separation of chiral alcohols has also been reported.

Selective Th(iv) capture from a new metal-organic framework with O- groups.

Herein we report a new 4-fold interpenetrated metal-organic framework (MOF) functionalized with O- groups for selective Th(iv) capture, the activated samples 1a exhibited a high adsorption capacity for pure Th(iv) ions (Kd = 3.16 × 105 mL g-1) and the amount of metal ions adsorbed on the adsorbent was 165.61 mg g-1. A high removal efficiency of 99.75% was achieved within 10 min with an initial Th(iv) concentration of 100 mg L-1 and the adsorption data followed the pseudo-second-order model. In addition, the separation coefficient (S) of Th(iv) to metal ions with different valence states such as Th(iv)/La(iii), Th(iv)/Sm(iii), Th(iv)/Ho(iii), Th(iv)/Cd(ii) and Th(iv)/K(i) achieved values of 19.66, 26.83, 16.90, 11.26 and 255.79, respectively. Even given the fact that MOFs with O- groups showed high affinity for Pb(ii) ions, our adsorption studies for compound 1a revealed a separation coefficient (STh(IV)/Pb(II)) of 4.36. Further, the adsorption of Th(iv) ions to compound 1a was investigated by FT-IR, SEM-EDS and XPS.

Auxiliary ligand-directed synthesis of a series of Cd(II)/Co(II) coordination polymers with methylenebis(3,5-dimethylpyrazole): syntheses, crystal structures, and properties.

Using a flexible methylenebis(3,5-dimethylpyrazole) ligand (H2MDP) with different aromatic carboxylate ligands, six new complexes {[Cd(H2MDP)(OPh)](H2O)}n (1), {[Cd(H2MDP)(MPh)](H2O)(1/10)}n (2), {[Cd(H2MDP)(PPh)](H2O)(3/2)}n (3), {[Co(H2MDP)(OPh)](H2O)2}n (4), {Co(H2MDP)(MPh)}n (5), {Co(H2MDP)(HBTC)}n (6) (H2OPh = phthalic acid, H2MPh = isophthalic acid, H2PPh = terephthalic acid, H3BTC = benzene-1,3,5-tricarboxylic acid) have been isolated under hydrothermal conditions. The crystal structure analyses reveal that complexes 1 and 4 feature two-dimensional undulated sheets with 4(4)·6(2) topology. Both complexes 2 and 3 contain M2L2-type metallocyclic motifs composed of two H2MDP ligands and two metal atoms, while complex 2 features a two-dimensional 4(4)·6(2) network constructed from binuclear cadmium units as four connected nodes, and complex 3 shows a two-dimensional network with 6(3)-hcb topology. Complex 5 affords a one-dimensional chain structure, and complex 6 shows a two-dimensional (4,4) network further connected into a 3D supramolecular structure connected by intermolecular hydrogen bonds and by π-π interactions. In addition, the luminescent properties of complexes 2 and 3 as well as the magnetic properties of 4 and 5 were studied.