Dissolution/reorganization toward the destruction/construction of porous cobalt(II)- and nickel(II)-carboxylate coordination polymers.
The alkali-metal-cation-induced structural transformation of porous coordination polymers (CPs), {A(2)[M(3)(btec)(2)(H(2)O)(4)]}(n) (1, A = K, M = Co; 2, A = K, M = Ni; 3, A = Cs, M = Co; and 4, A = Cs, M = Ni; btec = benzene-1,2,4,5-tetracarboxylate), occurred via a unique dissolution/reorganization process in the presence of an alkali chloride (LiCl, NaCl) in water. Treatment of 1 or 2 in an aqueous solution of LiCl resulted in the formation of new metal-carboxylate species [Co(2)(btec)(H(2)O)(10)] x H(2)O (5 x H(2)O) and {Li(2)[Ni(3)(btec)(2)(H(2)O)(10)] x 3.5 H(2)O}(n) (6 x 3.5 H(2)O), respectively. When NaCl was used in place of LiCl under similar reaction conditions, similar dissolution/reorganization processes were observed. The cobalt species 1 and 3 were converted into the metal-carboxylate product [Na(2)Co(btec)(H(2)O)(8)](n) (7), whereas the nickel-carboxylate frameworks 2 and 4 were transformed into {[Na(4)Ni(2)(btec)(2)(H(2)O)(18)] x 3 H(2)O}(n) (8 x 3 H(2)O). Single-crystal X-ray diffraction analysis revealed that 5 x H(2)O is a discrete molecule, which extends to a hydrogen-bonded 3D porous supramolecular network including tetrameric water aggregates. Compound 6 x 3.5 H(2)O adopts a 3D polymeric structure with a novel (2,4,4)-connected net on the basis of a 4-connecting organic node of a btec ligand, a square-planar 4-connecting metallic trans-Ni(O(2)C)(4)(H(2)O)(2) node, and a 2-connecting octahedral metallic trans-Ni(O(2)C)(2)(H(2)O)(4) hinge. Compound 7 possesses a 3D polymeric structure comprised of two types of intercrossed (4,4)-layers, a [Co(II)(btec)]-based layer and a [Na(I)(btec)]-based layer, in a nearly perpendicular orientation (ca. 87 degrees). Compound 8 x 3 H(2)O adopted a 2D sheet network by utilizing heterometallic trinuclear clusters of Na(2)Ni(O(2)C)(5)(H(2)O)(9) as secondary building units. Each sheet is hydrogen-bonded to neighboring units, giving a 3D supramolecular network. It is noteworthy that the dissolution/reorganization process demonstrates the cleavage and reformation of metal-carboxylate bonds, leading to a destruction/construction structural transformation of CPs.
Ding
Miao-Tzu
MT
Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan.
Wu
Jing-Yun
JY
Liu
Yen-Hsiang
YH
Lu
Kuang-Lieh
KL