A Nanotubular 3D Coordination Polymer Based on a 3d–4f Heterometallic Assembly

Abstract

Interest in porous metal-coordination polymers that are constructed by self-assembly processes has mushroomed recently, [1] because of their use in, for example, redox catalysis, cathodic electrolysis, ion exchange, adsorption, separation, sensors, and molecular recognition. [2][3][4][5] However, much of the work has so far focused on coordination polymers containing transition metals, [2,6] while rare-earth metal compounds have received much less attention. [7] To date, no systematic investigation of zeolite-type structures containing metal atoms from the lanthanide series along with transitionmetal atoms has been documented. Furthermore, the pores or channels reported were mainly formed through either hydrogen bonding, [2b] or p-p packing, [1b] and only in a few cases were they formed through metal-ligand bonding alone.On the other hand, the construction of mesoporous metal--organic polymers suffers from difficulties in the control of the polymer dimensionality. Although ligands can be designed to create a large hole, the resulting coordination polymers are often plagued by lattice interpenetration, [8] or framework breakdown on removal of a guest molecule. [9] In addition, the variable and versatile coordination behavior of 4f-metal ions limits their selective introduction into highly ordered structures.Herein we report the syntheses and structures of three coordination polymers formed through hydrothermal synthesis: [{[Ln(dipic) 3 Mn 1.5 (H 2 O) 3 ]·n H 2 O} ¥ ], H 2 dipic = pyridine-2,6-dicarboxylic acid; Ln = Pr, n = 2 (1); Ln = Gd, n = 3.5 (2); Ln = Er, n = 3 (3). These compounds have the relatively large nanometer-sized tubes associated with selfassembly processes directed by metal-ligand coordination only, and the framework remains intact on removing water molecules trapped in the nanotube.The three compounds are stable in air and are insoluble in common solvents. Single-crystal X-ray diffraction analyses were performed on selected crystal of these compounds. The crystal structures of the polymers are isomorphous, comprising a 3D framework containing nine-coordinate lanthanidemetal centers and six-coordinate transition-metal centers, which results in a nanotubelike structure (Figure 1). All three polymers crystallized in the hexagonal crystal system, space group P6/mcc. The crystal structure is built up of two distinct types of building blocks, Ln(dipic) 3 and MnO 4 (H 2 O) 2 (Figure 2). The Ln atom is located at the intersection of a threefold and a twofold axis and is coordinated by three tridentate (ONO) dipic anions; for which each carboxy group coordinates through one oxygen atom. Three N atoms and six O atoms complete the coordination sphere of the Ln 3+ center, which conforms most closely to a tricapped trigonal prism. The coordination geometry around Mn 2+ center is a slightly distorted octahedron, the equatorial plane of which comprises four O atoms from the carboxy groups of the dipic molecules that are chelated to four neighboring Ln 3+ centers; two water molecules occupy the remaining apic...

Crystal structure of bis-(5-bromo-2-methyl-phenyl)-diazene, C14H12Br2N2

“…For the high coordination numbers, along with special magnetic elements for constructing CPs has attracted a lot of interest [4]. Designing solids with molecules that encode well defined non-covalent interactions has recently become a rapidly growing area of research due to their fascinating molecular and supramolecular structural diversity and potential applications for catalysis [5] and material sciences [6][7][8][9]. Substituted aromatic azo compounds are also important units in the area of nonlinear optics, optical storage media, chemo sensors, photochemical switches and electronic devices.…”

Crystal structure of tri-(1,4-bis(imidazol-1-yl)butane)-cadmium(II) dihexafluorophosphate, {[Cd(bimb)3](PF6)2}n, C30H42CdF12N12P2

“…In recent years, the design and synthesis of metal-organic frameworks (MOFs) with well-regulated architectures have caused increasing attention as they can be carried out as functional materials with potential applications in such fieldsasnonlinear optics, magnetism,m olecular separation, catalysis, luminescence, and gas sorption [1][2][3][4][5][6]. The ligands and metal centers both are the keys to the design and construction of metal-organic frameworks (MOFs) with fascinating topology and physicochemical properties [7,8].Flexible ligands are employed in the construction of metal-organic frameworks (MOFs) with variety of architectures and topologies because flexible ligands can adopt different conformations according to the geometric needs of the different metal ions [9,10].…”

Crystal structure of catena-diaqua(5-methoxyisophthalate)[1,2-bis-(imidazol-1’-yl)ethane]-cadmium(II)-water(1:1), C13H17CdN2O8

“…In recent yearsthe design and synthesis of metal-organic frameworks (MOFs) with well-regulated architectures have caused increasing attention because they can be used as functional materials with potential applications in such fields as nonlinear optics, magnetism, molecular separation, catalysis, luminesence, andgas sorption [1][2][3][4][5][6]. It is well known that carboxylate ligands play an important role in coordination chemistry, which may adopt diverse binding modes such as monodentate, chelating, and bridging in the syn-syn, syn-anti,and anti-anti configurations [7][8].Sofar,agreatmanymetal-carboxylate complexes, in the presence of rigidorflexibleN-donor bridging ligands, such as 4,4'-bipyridine andits derivativesorbis(imidazole)ligandshavebeen designed and characterized widely [9][10].…”