Design and Generation of Extended Zeolitic Metal–Organic Frameworks (ZMOFs): Synthesis and Crystal Structures of Zinc(II) Imidazolate Polymers with Zeolitic Topologies

Abstract

Attempts to create metal-organic frameworks (MOFs) with zeolitic topologies, metal (zinc(II) and cobalt(II)) imidazolates have repeatedly been used as the metal-organic motifs of inorganic silicate analogues. By modulating the synthetic strategy based on the solvothermal and liquid diffusion method, seven further MOFs (including at least three zeolitic MOFs) of zinc(II) imidazolates, [Zn(im)2.x G] (G=guest molecule, x=0.2-1) 1 a-7 a, have been successfully synthesized. Of these, 1 a-3 a are isostructural with the previously reported cobalt analogues 1 b-3 b, respectively, while 4 a-7 a are new members of the metal imidazolate MOF family. Complex 4 a exhibits a structure related to silicate CaAl2Si2O8 of CrB4 topology, but with a higher network symmetry; complex 5 a has a structure with zeolitic DFT topology that was discovered in zeolite-related materials of DAF-2, UCSB-3, and UCSB-3GaGe; complex 6 a demonstrates an unprecedented zeolite-like topology with one dimensional channels with 10-rings; and 7 a displays a structure of natural zeolite GIS (gismondine) topology. All of these polymorphous MOFs were created only by using certain solvents as structure-directing agents (SDAs). Further extensive metal-organic frameworks with zeolitic topologies can be envisaged if other solvents were to be used.

Chemical structure, network topology, and porosity effects on the mechanical properties of Zeolitic Imidazolate Frameworks

“…5). On the whole, we note that ZIFs are relatively compliant and soft materials (i.e., low E and H values), which can be attributed to their flexible M-Im-M linkages (23) and large void spaces (Fig. 2).…”

“…Given that solvothermal synthesis of ZIFs involves the use of structure directing agents such as DMF (N,N-dimethylformamide) (23), it follows that products obtained contain solvent molecules trapped inside the pores (Fig. 2).…”

Investigation of zeolitic imidazolate frameworks using 13 C and 15 N solid-state NMR spectroscopy

“…It is noticeable for ZIF-8 that the agreement between experiment and calculation for Ω is poorer than for the other ZIFs, perhaps reflecting the dynamics of the -CH 3 group. More complex ZIFs can be synthesised using more than one type of linker, producing materials that not only have different pore shapes and sizes, but that can also have different chemical properties (e.g., hydrophobic or hydrophilic pores) [2,[4][5][6][7][8][9]. The 13 C CP MAS NMR spectra of ZIF-68, ZIF-70 and ZIF-78 are shown in Fig.…”

“…1a shows the structure of ZIF-65, which is synthesised with 2-nitroimidazolate as the linker, and exhibits the well-known sodalite (SOD) framework topology [3]. ZIFs have attracted considerable recent attention, owing to their potential applications in gas storage and separation, fluid separation, sensing, encapsulation and controlled delivery of drug molecules [2,[4][5][6][7][8][9]. The range of applications can be widened by using functionalised imidazolate linkers, altering the chemical nature of the pores produced, while maintaining the framework topology [10].…”

In situ static and dynamic light scattering and scanning electron microscopy study on the crystallization of the dense zinc imidazolate framework ZIF-zni

“…8,9 Metal imidazolate frameworks are most frequently prepared by precipitation from solution under sub-solvothermal or solvothermal conditions. Although some empirical rules have been established to guide this synthesis, [10][11][12] the preparation of new compounds is still mainly a trial-and-error approach. Thus, targeted synthesis of a new theoretically predicted and potentially existing 13 compound is currently not available.…”