摘要:

Supramolecular assembly and molecular architecture have been areas of rapid growth in recent years.1Many supramolecular species with one­, two­ and three­dimensional networks of various sizes and shapes have been synthesized, and some show useful properties, such as in the areas of molecular recognition, electronic, optical, magnetic and catalytic fields.21,3,5­Benzenetricarboxylate anion (BTC3−) is often used as a building block due to its three equally spaced carboxylate groups and a rigid disk­like conformation. Thus, reactions of BTC3−with metal ions or metal complexes usually result in two­dimensional coordination polymers with large cavities and channels which can incorporate and recognize small guest molecules or ions.3However, two­dimensional coordination polymers with hydrophobic channels have so far not beenconstructed.We report here the synthesis and structure of a 2­D coordination polymer [NiL]3[BTC]2·6H2O formed by BTC3−with a macrocyclic nickel(ii) complex containing a hydrophobic pendant group, in which all the macrocyclic pendant groups point to the center of the cavity to form hydrophobic channelsviaedge­to­face aromatic interactions.The coordination polymer was synthesized by the reaction of the macrocyclic nickel(ii) complex[NiL](ClO4)2with BTC3−.4The results of an X­ray diffraction analysis (Table 1) indicate that the complex shows a 2­D brick wall structure. In the complex, each Ni(ii) ion lies on an inversion center and is six­coordinated with four nitrogen atoms from the macrocyclic ligand in the equatorial plane, and two carboxylate oxygen atoms from two different BTC3−anions in the axial position, forming a slightly distorted octahedral geometry (Fig. 1).Molecular structure of the complex [NiL]3[BTC]2·6H2O. Click image orhereto access a 3D representation.Crystallographic data for [NiL]3[BTC]2·6H2O,,,ParameterAll data were collected atT⊕=⊕293(2) K using a Bruker SMART 1000 CCD with MoKα radiation (λ⊕=⊕0.71073 Å).The atoms of the C1–C6 ring are disordered and were treated with restraints, and refined isotropically.Intensities were reduced using the SAINT6aprogram; the structure was solved by direct methods and refined by a full­matrix, least squares technique based onF2using SHELXL97.6bClickherefor full crystallographic data (CCDC 167896).Empirical formulaC90H132N18O18Ni3Crystal dimensions/mm0.26⊕×⊕0.07⊕×⊕0.05M1930.41Crystal systemTriclinicSpace groupP1&cmb.macr;a/Å14.217(3)b/Å14.439(3)c/Å14.914(3)α/°100.087(4)β/°96.311(4)γ/°109.958(3)U/Å32785.2(10)Z1Dc/Mg m−31.333μ(MoKα)/mm−10.587F(000)1188GoF0.991Number of reflections (unique)16 259 (11 936)Rint0.0216Number of observed reflections [I⊕>⊕2σ(I)]7274Number of refined parameters541R10.0709wR20.2316The Ni–N bond distances [ca.2.046(4)–2.067(4) Å] are slightly shorter than the Ni–O bond distances [ca.2.134(3)–2.173(3) Å]. Each BTC3−anion binds to three metal ions in aC1symmetry, resulting in a 2­D brick wall-like network along thebcplane (Fig. 2).Brick wall structure of the 2­D coordination polymer (macrocyclic and water molecules are omitted for clarity).In the 2­D network structure, six phenyl rings from six macrocyclic nickel(ii) complexes form a hydrophobic cavity (Fig. 3)viaedge­to­face aromatic interactions (distances from the plane of C6rings to the nearest C of neighboring phenyl rings are in the rangeca.3.80–4.32 Å). One of the water molecules forms a hydrogen bond with a free carbonyl oxygen atom of BTC3−(Ow3⋯O6⊕=⊕2.711 Å), while the rest of the water molecules are incorporated in the crystal lattice. (The hydrogen atoms of the water molecules are not located.)The hydrophobic cavity formed by six phenyl groupsviaedge­to­face aromatic interactions.The 2­D sheets stack along thea­axisviaπ⋯π interactions between two neighboring C25–C30 phenyl rings, forming a 3­D network with parallel hydrophobic channels along thea­axis (Fig. 4). The shortest intersheet separation is 9.427 Å. The size of the cavity is 6.0⊕×⊕9.8 Å, and no hydrophilic DMF or water guest molecules are located within these hydrophobic channels. The hydrophobic channels may selectively incorporate aromatic molecules such as benzene and toluene, and this guest inclusion property is being investigated.Space­filling view of the 2­D sheets packing along thea­axis and showing the hydrophobic channels. (Color scheme: C grey, H white, N blue, Ni green, O red.)

ISSN:1466-8033    

DOI:10.1039/b106490h

出版商:RSC    

年代:2001

数据来源: RSC