本文评述层状复合金属氢氧化物（lavered double hadroxides. LDHs）的化学及其应用。层状复合金属氢氧化物具有结合紧密的氢氧化物层和处于层间的阴离子、其比较突出的化学性质是可逆的阴离子交换和热分解性质。不过因为受到氢氧化物层的局限处于层间的阴离子表现出的特殊化学性质近年来也越来越受到重视。利用上述三个方面的性质人们发掘了层状复合金属氢氧化物在材料(包括有机无机复合材料)制备、离子交换与有害阴离子脱除、异构体化学分离、化学反应控制、阻燃材料、活性分子储存与缓释、局部化学反应合成、催化剂及催化剂载体等方面的应用。

Solid-state reaction of FeSO4 7H2O and 1,10-phenanthroline in a 1:1 molar ratio was investigated by time-resolved in-situ energy dispersive X-ray diffraction (EDXRD), DSC, TG/DTA, M?ssbauer and IR spectroscopy. The reaction of these solids takes place rapidly at around 70℃ and initially produces an intermediate crystalline phase, Fe(phen)3SO4 5H2O before cleanly converting to Fe(phen)(H2O)3SO4. This is in contrast to the product of the reaction of FeSO4 7H2O with 1,10-phenanthroline in aqueous solution which produces [Fe(phen)3 2][SO4 2]. All the spectral data suggest that the final product is a neutral Fe(II) complex. The coordination sphere around the Fe(II) ions is thought to be octahedral consisting of a unidentate sulfate ligand, a bidentate 1,10-phenanthroline ligand and three aquo ligands.

A series of pharmaceutically active compounds including diclofenac, gemfibrozil, ibuprofen, naproxen, 2-propylpentanoic acid, 4-biphenylacetic acid and tolfenamic acid can be reversibly intercalated into a layered double hydroxide, initial studies suggest that these materials may have application as the basis of a novel tuneable drug delivery system.

All six isomers of pyridinedicarboxylate (2,3-PDA; 2,4-PDA; 2,5-PDA; 2,6-PDA; 3,4-PDA; 3,5-PDA) can be intercalated by the layered double hydroxide [LiAl2(OH)6]Cl?H2O in water at 100 ?C to give the fully ionexchanged ?rst stage intercalation compounds [LiAl2(OH)6]G0.5?xH2O (G2,3-PDA; 2,4-PDA; 2,5-PDA; 2,6-PDA; 3,4-PDA; 3,5-PDA; X2±3.5). The observed interlayer separations for the intercalates vary from 10.9 A? for the high temperature form of [LiAl2(OH)6](3,5-PDA)0.5?2H2O to 14.8 A? for [LiAl2(OH)6](2,3-PDA)0.5?3H2O. When a solution containing an equal concentration of two or more of the pyridinedicarboxylate anions is added to a suspension of [LiAl2(OH)6]Cl?H2O in water then the host exhibits preferential anionexchange intercalation. Following an extensive series of competitive intercalation reactions involving two component through to six component mixtures we were able to determine the preference order for intercalation of all six PDA guests in [LiAl2(OH)6]Cl?H2O. The order was found to be 2,5-PDAw2,3-PDAw2,4-PDAw2,6-PDA#3,5-PDA#3,4-PDA in water at 100 ?C.