Molecular Tectonics of Metal–Organic Frameworks (MOFs): A Rational Design Strategy for Unusual Mixed‐Connected Network Topologies

Abstract

To systematically explore the higher-dimensional network structures with mixed connectivity, a series of two-dimensional (2D) and three-dimensional (3D) metal-organic frameworks (MOFs) with unusual (3,6)-connected net topologies are presented. These crystalline materials include [{[Mn(btza)2(H2O)2].2 H2O}n] (1), [{[Zn(btza)2(H2O)2].2 H2O}n] (2), [{[Cu(btza)2].H2O}n] (3), and [{[Cd(btza)2].3 H2O}n] (4), which have been successfully assembled through a predesigned three-connected organic component bis(1,2,4-triazol-1-yl)acetate (btza) with a variety of octahedral metal cores based on the modular synthetic methodology. The topological paradigms shown in this work cover the 2D CdCl2, 3D (4(2).6)2(4(4).6(2).8(7).10(2)), and pyrite (pyr) types. That is, when properly treated with the familiar first-row divalent metal ions, btza may perfectly furnish the coordination spheres for effective connectivity to result in diverse (3,6)-connected nets. Beyond this, a detailed analysis of network topology for all known 3D (3,6)-connected frameworks in both inorganic and inorganic-organic hybrid materials is described. Specific network connectivity of these MOFs indicates that the metal centers represent the most significant and alterable factor in structural assembly, although they show reliable and similar geometries. In this context, the combination of the distinct d10 AgI ion with btza in different solvents affords two isomorphous MOFs [{[Ag(btza)].glycol}n] (5) and [{[Ag(btza)]CH3OH}n] (6) with a binodal 4-connected 3D SrAl2 (sra) topology. The network structures of MOFs 1-3 and 5 turn out to be more complicated and interesting if one considers the hydrogen bonding between the host coordination frameworks and the intercalated solvent molecules. Furthermore, the role of the included solvents in the generation and stabilization of MOFs 1-6 is also investigated.

Crystal structure of 2-[4-(1H-imidazol-1-yl)phenyl]-1H-benzimidazol-3-ium [2-(carboxymethyl)phenyl]acetate monohydrate, C26H24N4O5

“…Thus, the investigation of compounds produced by the spontaneous aggregation among low-dimensional polymers through the intermolecular weak interactions may be a fascinating subject, that is worth studying. Among the reported studies, organic molecules with multi-carboxylate group are particularly interesting for this purpose because the do not only possess more than one donor atom to form an extended structure [5][6][7][8], but they can also act as hydrogen bond acceptors and hydrogen bond donors. o-Phenylenediacetic acid, captures our attention as this molecule contains a exible −CH 2 COOH group which can freely rotate to meet the requirement of the structure [9,10].…”

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 aqua-(1,10-phenanthroline)-(2-(1,2,4-triazol-1-yl)- acetate)copper(II)nitrate, C16H14CuN6O6

“…Studies on metal-organic frameworks (MOFs) have rapidly increased because of their intriguing variety of topologies and potential applications as functional materials [1][2][3][4]. The ligands and metal centers both are the key to the design and construction of metal-organic frameworks with fascinating topology and physicochemical properties.…”

“…The X-ray structural analysis shows that the title complex crystallizes monoclinic, space group P2 1 /c. The asymmetric unit of the title structure consists of a Cu 2+ ion, a 1,10-phenanthroline ligand (phen), a 2-(1,2,4-triazol-1-yl)acetate (tza) ligand, one coordinated water molecule and one NO 3 -counter anion. The central copper atom is distorted trigonal bipyramidal coordinated by two oxygen donors from one deprotonated tza -ligand, one coordinated water molecule, and three N atoms from one phen ligand and one triazole nitrogen atom from another tza -ligand.…”