基于纳米多孔铬（III）的首批固体材料（MIL-53或Cr(III)(OH)x[O(2)C-C(6)H(4)-CO(2)]x[HO(2)C-C(6)H(4)-CO(2)H](x)xH(2)O(y)）中存在非常大的呼吸效应。

Very large breathing effect in the first nanoporous chromium(III)-based solids: MIL-53 or Cr(III)(OH) x [O(2)C-C(6)H(4)-CO(2)] x [HO(2)C-C(6)H(4)-CO(2)H](x) x H(2)O(y).

作者信息

Serre Christian, Millange Franck, Thouvenot Christelle, Noguès Marc, Marsolier Gérard, Louër Daniel, Férey Gérard

机构信息

Institut Lavoisier-Franklin, UFR 2483, Université de Versailles St-Quentin-en-Yvelines, 45 Avenue des Etats-Unis, 78035 Versailles Cedex, France.

出版信息

J Am Chem Soc. 2002 Nov 13;124(45):13519-26. doi: 10.1021/ja0276974.

DOI:10.1021/ja0276974

PMID:12418906

Abstract

The first three-dimensional chromium(III) dicarboxylate, MIL-53as or Cr(III)(OH) x [O(2)C-C(6)H(4)-CO(2)].HO(2)C-C(6)H(4)-CO(2)H, has been obtained under hydrothermal conditions (as: as-synthesized). The free acid can be removed by calcination giving the resulting solid, MIL-53ht or Cr(III)(OH) x [O(2)C-C(6)H(4)-CO(2)]. At room temperature, MIL-53ht adsorbs atmospheric water immediately to give Cr(III)(OH) x [O(2)C-C(6)H(4)-CO(2)] x H(2)O or MIL-53lt (lt: low-temperature form, ht: high-temperature form). Both structures, which have been determined by using X-ray powder diffraction data, are built up from chains of chromium(III) octahedra linked through terephthalate dianions. This creates a three-dimensional structure with an array of one-dimensional large pore channels filled with free disordered terephthalic molecules (MIL-53as) or water molecules (MIL-53lt); when the free molecules are removed, this leads to a nanoporous solid (MIL-53ht) with a Langmuir surface area over 1500 m(2)/g. The transition between the hydrated form (MIL-53lt) and the anhydrous solid (MIL-53ht) is fully reversible and followed by a very high breathing effect (more than 5 A), the pores being clipped in the presence of water molecules (MIL-53lt) and reopened when the channels are empty (MIL-53ht). The thermal behavior of the two solids has been investigated using TGA and X-ray thermodiffractometry. The sorption properties of MIL-53lt have also been studied using several organic solvents. Finally, magnetism measurements performed on MIL-53as and MIL-53lt revealed that these two phases are antiferromagnetic with Néel temperatures T(N) of 65 and 55 K, respectively. Crystal data for MIL-53as is as follows: orthorhombic space group Pnam with a = 17.340(1) A, b = 12.178(1) A, c = 6.822(1) A, and Z = 4. Crystal data for MIL-53ht is as follows: orthorhombic space group Imcm with a = 16.733(1) A, b = 13.038(1) A, c = 6.812(1) A, and Z = 4. Crystal data for MIL-53lt is as follows: monoclinic space group C2/c with a = 19.685(4) A, b = 7.849(1) A, c = 6.782(1) A, beta = 104.90(1) degrees, and Z = 4.

摘要

首个三维二羧酸铬（III），即MIL - 53as或Cr(III)(OH)ₓ[O₂C - C₆H₄ - CO₂].HO₂C - C₆H₄ - CO₂H，是在水热条件下（as：合成态）制得的。通过煅烧可除去游离酸，得到产物固体MIL - 53ht或Cr(III)(OH)ₓ[O₂C - C₆H₄ - CO₂]。在室温下，MIL - 53ht会立即吸附大气中的水，生成Cr(III)(OH)ₓ[O₂C - C₆H₄ - CO₂]·xH₂O或MIL - 53lt（lt：低温形式，ht：高温形式）。这两种结构均通过X射线粉末衍射数据确定，它们由通过对苯二甲酸二阴离子连接的铬（III）八面体链构成。这形成了一种三维结构，其中排列着一维大孔通道，通道中填充着游离的无序对苯二甲酸分子（MIL - 53as）或水分子（MIL - 53lt）；当游离分子被除去后，会得到一种朗缪尔表面积超过1500 m²/g的纳米多孔固体（MIL - 53ht）。水合形式（MIL - 53lt）与无水固体（MIL - 53ht）之间的转变是完全可逆的，且伴随着非常高的呼吸效应（超过5 Å），在有水分子存在时（MIL - 53lt）孔被夹住，通道为空时（MIL - 53ht）孔重新打开。使用热重分析（TGA）和X射线热衍射法研究了这两种固体的热行为。还使用几种有机溶剂研究了MIL - 53lt的吸附性能。最后，对MIL - 53as和MIL - 53lt进行的磁性测量表明，这两个相都是反铁磁性的，奈尔温度T(N)分别为65 K和55 K。MIL - 53as的晶体数据如下：正交空间群Pnam，a = 17.340(1) Å，b = 12.178(1) Å，c = 6.822(1) Å，Z = 4。MIL - 53ht的晶体数据如下：正交空间群Imcm，a = 16.733(1) Å，b = 13.038(1) Å，c = 6.812(1) Å，Z = 4。MIL - 53lt的晶体数据如下：单斜空间群C2/c，a = 19.685(4) Å，b = 7.849(1) Å，c = 6.782(1) Å，β = 104.90(1)°，Z = 4。