Metal–organic macrocycles, metal–organic polyhedra and metal–organic frameworks

Abstract

Metal-organic macrocycles (MOMs), metal-organic polyhedra (MOPs) and metal-organic frameworks (MOFs) are metal-organic systems (MOSs) developed from appropriately designed ligands and selected metal ions. Metalladiazamacrocycles, a class of MOMs, are finite 2D MOSs formed from tricationic hexacoordinate metal ions and ditopic bridging ligands, N-acylsalicylhydrazide, containing diaza residues, where the size and shape of the systems have been modulated by controlling the steric repulsions between the ligands. The 2D MOM systems could be expanded to 3D MOP systems by self-assembling C(3) symmetric components and C(4) symmetric components to octahedral MOPs. By substituting some replaceable solvent sites of MOMs or MOPs, MOFs based on MOMs or MOPs as SBBs have been constructed, where the properties of the SBBs have been directly transferred to the MOF systems.

Self-assembled metal–organic polyhedra: An overview of various applications

“…The metal-ligand bond coordination is a cornerstone of various designing strategies such as directional bonding, symmetry interactions, molecular paneling, weak linking, and dimetallic building blocks. These strategies are predominantly used by Atwood [7], Cotton [8,9], Fujita [10][11][12], Lindoy [13][14][15][16], Mirkin [17][18][19], Nitschke [20][21][22], Raymond [23][24][25][26], Stang [27][28][29][30][31], Saalfrank [32,33], Ward [34,35], Yaghi [36][37][38], Zhou [39][40][41], and others [42][43][44][45] in designing 2D and 3D supramolecular architectures. The directional bonding approach relies on the angular orientation (0 to 180°) of binding sites and appropriate stoichiometric ratio of the precursor units.…”

Metallic macrocycles built-up from ferrocenedicarboxylate and ancillary nitrogen heterocycles: Hydrothermal synthesis, crystal structures and electrochemical properties

“…In addition, it was expected by introducing a ferrocene group into coordination macrocyclic systems not only incorporates a redox-active group but also leads to interesting assembled structures due to the conformational flexibility of the ferrocene moiety such as sinperiplanar, synclinal (staggered), synclinal (eclipsed) and so on [20]. Such factors could control the size of the MOMs, where the number of components is usually controlled by the bending torsion angle of ferrocenyl moieties [16]. Finally, it is well-known that the incorporation of a secondary ligand capable to coordinate in a chelate mode is also required; such condition provides a way to the passivation of metal sites by N donors, avoiding spatial propagation of the resulting metal-organic array [21,[23][24][25][26] prepared and most of them have shown a polymeric crystal structure [20][21][22][27][28][29][30][31][32][33].…”

“…The size of the MOMs can be modulated by length control of the ditopic exo-bidentate ligands [16][17][18][19]. On the other hand, the connectivity and geometrical environment of those metal centers which have a large coordination number are usually controlled by the number and stereochemistry of stable ligands bonded to the metal centers [16]. From the viewpoint of designing MOMs may be interesting incorporate functional ligands, which can combine flexibility with coordinating groups such as carboxylate group.…”

“…For the rational synthesis of MOMs some geometrical requirements are well recognized, as the use of at least one building block with bent geometry, which are intentionally introduced from the judicious choice of the metal centers and ligands [16]. The size of the MOMs can be modulated by length control of the ditopic exo-bidentate ligands [16][17][18][19]. On the other hand, the connectivity and geometrical environment of those metal centers which have a large coordination number are usually controlled by the number and stereochemistry of stable ligands bonded to the metal centers [16].…”

“…In particular the MOMs have attracted a special interest in Crystal Engineering because some of them have exhibited unique single magnetic properties [1][2][3], selective recognition for anions [4][5][6], and catalysis and controlled chemical reactivity inside of their cavities [7][8][9][10][11][12][13][14][15]. For the rational synthesis of MOMs some geometrical requirements are well recognized, as the use of at least one building block with bent geometry, which are intentionally introduced from the judicious choice of the metal centers and ligands [16]. The size of the MOMs can be modulated by length control of the ditopic exo-bidentate ligands [16][17][18][19].…”