A novel Zn₄O-based triazolyl benzoate MOF: synthesis, crystal structure, adsorption properties and solid state¹³C NMR investigations

Abstract

The newly synthesized Zn(4)O-based MOF (3)(∞)[Zn(4)(μ(4)-O){(Metrz-pba)(2)mPh}(3)]·8 DMF (1·8 DMF) of rare tungsten carbide (acs) topology exhibits a porosity of 43% and remarkably high thermal stability up to 430 °C. Single crystal X-ray structure analyses could be performed using as-synthesized as well as desolvated crystals. Besides the solvothermal synthesis of single crystals a scalable synthesis of microcrystalline material of the MOF is reported. Combined TG-MS and solid state NMR measurements reveal the presence of mobile DMF molecules in the pore system of the framework. Adsorption measurements confirm that the pore structure is fully accessible for nitrogen molecules at 77 K. The adsorptive pore volume of 0.41 cm(3) g(-1) correlates well with the pore volume of 0.43 cm(3) g(-1) estimated from the single crystal structure.

Synthesis, Crystal Structure, and Solid-State NMR Investigations of Heteronuclear Zn/Co Coordination Networks — A Comparative Study

“…25−27 Furthermore, using this method, it is easy to determine the presence of small mobile molecules, while X-ray analysis is more complicated or impossible. 28 In this paper, we report on the synthesis and detailed structural elucidation of two Zn MOFs together with their corresponding protonated ligands by means of X-ray structure analysis, 1 H and 13 C solid-state NMR, and quantum chemical calculations. Detailed assignments of NMR resonances were done, including the changes in individual chemical shifts with respect to the protonated ligands.…”

“…Solid-state NMR is a versatile tool for studying the different interactions present in porous coordination frameworks, which is increasingly used for the characterization of structure and dynamics in these materials. − NMR spectra of solid samples provide information on the detailed local electronic structure of each nucleus reflected as a chemical shift without the need of long-range order. Therefore, noncrystalline materials can be characterized with solid-state NMR, which is increasingly used for the characterization of structure and dynamics in these materials. − Furthermore, using this method, it is easy to determine the presence of small mobile molecules, while X-ray analysis is more complicated or impossible …”

“…[25][26][27] Furthermore, using this method it is easy to determine the presence of small mobile molecules, while X-ray analysis is more complicated or impossible. 28 In this paper, we report on the synthesis and detailed structural elucidation of two Zn MOFs together with their corresponding protonated ligands by means of X-ray structure analysis, 1 32 which has already been proven to be a reliable tool in characterizing the NMR properties of crystalline solids. [33][34][35][36][37][38][39][40] Heteronuclear MOFs with varying percentage of paramagnetic Co 2+ were also investigated with 1 H and 13 C NMR to study the influence of paramagnetic metal ions on the parent framework.…”

Cis and trans linkage of spin frustrated copper triangles creating Cu6 clusters

“…This behavior indicates a strong anti-ferromagnetic exchange coupling with a ground spin state of S = ½ within each triangle. Below 20 K, the χ M T value drops down sharply, which suggests the existence of weak intermolecular interactions between the two Cu 3 triangles in both complexes [27][28][29]. The field-dependence of the magnetization curves were also measured for Cu 6 and Cu 6 Cl under 2.0 K between 0−70 kOe (Figure S4 and Figure S5).…”

“…This phenomenon may be used to control molecular electronic quantum systems; actually, experimental evidence of such potential application has recently been reported [10][11][12][13][14]. The assembly of triangular units in larger aggregates has been accomplished by dimerization through Hbonds [15,16], bridging counteranions [17,18], bi-topic amines [19], carboxylate/bis-carboxylato linkers [20,21] and carboxylate functionalized N,N ligands [22][23][24][25][26][27]. However, planar tri-topic ligands with strict C 3 symmetry are still rare and to the best of our knowledge mostly limited to triaminoguanidinium-based ligands [8,[28][29][30].…”