Metal-Mediated Self-Assembly of a Twisted Biphenyl-Tetraacid Linker with Semi-rigid Core and Peripheral Flexibility: Concomitant Formation of Compositionally Distinct MOFs

Abstract

A semi-rigid organic linker, namely, 3,3′,5,5′-tetra­kis­(4-(α-carboxy)­meth­oxy­phenyl)-2,2′,6,6′-tetra­methoxy-1,1′-biphenyl (H 4 L), was designed and synthesized to access metal–organic frameworks (MOFs). While the ortho-methoxy substituents in the biphenyl core of H 4 L were surmised to twist the aromatic planes and impart porosity to the resultant MOFs, the (α-car­boxy)­meth­oxy­phenyl moieties at the periphery were envisaged to enable requisite flexibility for metal–ligand coordination polymerization. The reactions of H 4 L with Cd, Mn, and Zn salts indeed yielded MOFs, i.e., Cd-L, Mn-L, Zn-Lsqc, and Zn-Ldia, with interesting structural features and unusual inorganic SBUs. In particular, the reaction of H 4 L with ZnI2 in DMF at 90 °C over 2 days led to concomitant formation of a pair of compositionally distinct Zn-MOFs, i.e., Zn-Ldia and Zn-Lsqc, each of which could be accessed exclusively by controlling the reaction conditions. The diversity observed in the structures of MOFs formed with the linker H 4 L with a limited number of metal ions sufficiently emphasizes the importance of the attributes of the linker in the formation of 3D MOFs; the latter are desirable from the stability and exfoliation points of view when the MOFs are explored for applications such as gas storage, catalysis, etc. In corroboration of our previous results, it emerges that the flexibility that is built into the structure of the organic linker, both at the central core and at the periphery, leads to concomitant formation of compositionally distinct MOFs in addition to diverse SBUs and disparate framework topologies.

Cu(ii)/Ni(ii)–organic frameworks constructed from the homometallic clusters by 5-(2-carboxyphenoxy)isophthalic acid and N-ligand: synthesis, structures and visible light-driven photocatalytic properties

“…[1][2][3][4] MOFs, with interesting architectures, also have good physicochemical properties, which can be potentially applied to many elds such as catalysis, luminescence, gas adsorption, magnetic materials, etc. 3,[5][6][7][8][9][10] In the past few decades, MOFs have attracted wide attention. Transition metal cations have various coordination geometries which can be used in various crystal architectures.…”

“…Transition metal cations have various coordination geometries which can be used in various crystal architectures. 6,11,12 For example, Zn(II), Cd(II), Cu(II), Ni(II), and Co(II), with different electron congurations and coordination numbers, may form compounds in various architectures, which can be applied to catalysis and luminescence. [13][14][15][16][17][18] Among them, Cu (II) and Ni(II) complexes have shown to be effective chemical photocatalysts under visible light irradiation.…”

Solvent‐Ratio Dependency of Polymorphism of Silver(I) Complexes Containing 1,2,3‐Tris(Isoniconitoyloxy)Benzene

“…[6][7][8][9] In many cases, introduction of flexible organic ligands as spacers for supramolecular assemblies provides an opportunity to adopt at least two different conformations and various coordination modes together with their traditional role including the coordination to the central metal ions. [14][15][16][17] In this context, whereas there have been a number of reports on the formation of isomeric coordination polymers taking into account solvent-, template-, additive-, and temperature-dependency during last decades, [18][19][20][21][22] rational control of the construction of particular supramolecules formed from the same components by means of external conditions such as pH, additives, solvent, and crystallization temperature remains a significant challenge. [10][11][12][13] Systematic studies on supramolecular isomerism by the same molecular building blocks will allow us to obtain better insight into the factors influencing the structures and crystal growth of novel crystalline materials.…”

“…Systematic studies on supramolecular isomerism by the same molecular building blocks will allow us to obtain better insight into the factors influencing the structures and crystal growth of novel crystalline materials . In this context, whereas there have been a number of reports on the formation of isomeric coordination polymers taking into account solvent‐, template‐, additive‐, and temperature‐dependency during last decades, rational control of the construction of particular supramolecules formed from the same components by means of external conditions such as pH, additives, solvent, and crystallization temperature remains a significant challenge …”