| 摘要: | The alkali-metal-ration-induced structural transformation of porous coordination polymers (CPs), {A(2)[M-3(btec)(2)(H2O)(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)(H2O)(10)]center dot H2O (5 center dot H2O) and {Li-2[Ni-3(btec)(2)(H2O)(10)]center dot 3.5H(2)O}(n)(6 center dot 3.5H(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 [Na2Co(btec)(H2O)(8)](n) (7), whereas the nickel-carboxylate frameworks 2 and 4 were transformed into {[Na4Ni2(btec)(2)(H2O)(18)]center dot 3H(2)O}(n) (8 center dot 3H(2)O). Single-crystal X-ray diffraction analysis revealed that 5 center dot H2O is a discrete molecule, which extends to a hydrogen-bonded 3D porous supramolecular network including tetrameric water aggregates. Compound 6 center dot 3.5H(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(O2C)(4)(H2O)(2) node, and a 2-connecting octahedral metallic trans-Ni(O2C)(2)(H2O)(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 center dot 3H(2)O adopted a 2D sheet network by utilizing heterometallic trinuclear clusters of Na2Ni (O2C)(5)(H2O)(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. |
