Experimentally Validated Ab Initio Crystal Structure Prediction of Novel Metal–Organic Framework Materials

Abstract

First-principles crystal structure prediction (CSP) is the most powerful approach for materials discovery, enabling the prediction and evaluation of properties of new solid phases based only on a diagram of their underlying components. Here, we present the first CSP-based discovery of metal–organic frameworks (MOFs), offering a broader alternative to conventional techniques, which rely on geometry, intuition, and experimental screening. Phase landscapes were calculated for three systems involving flexible Cu­(II) nodes, which could adopt a potentially limitless number of network topologies and are not amenable to conventional MOF design. The CSP procedure was validated experimentally through the synthesis of materials whose structures perfectly matched those found among the lowest-energy calculated structures and whose relevant properties, such as combustion energies, could immediately be evaluated from CSP-derived structures.

Energetic isostructural metal imidazolate frameworks with a bridging dicyanamide linker towards high-performance hypergolic fuels

“…The energy densities ( E g ) of 1 and 2 are 27.97 and 25.90 kJ g −1 , respectively, and the volumetric energy densities ( E v ) of 1 and 2 are 42.91 and 41.98 kJ cm −3 , respectively. Compounds 1 and 2 occupy extraordinary energy densities (Table 1), which are not only higher than those of the reported CBA-CuAg (28.26 kJ cm −3 ), 1 CuBTA-1 (20.64 kJ cm −3 ), 26 QTZ-Zn(EtIm) 2 (37.20 kJ cm −3 ), 27 ANA-Zn(BuIm) 2 (36.30 kJ cm −3 ), 27 Cd(2-VIM) 2 (15.80 kJ cm −3 ), 32 Zn(2-VIM) 2 (18.90 kJ cm −3 ), 32 Co(2-VIM) 2 (18.40 kJ cm −3 ) 32 and Cu(2-VIM) 2 (34.10 kJ cm −3 ), 33 but also greater than that of the traditional explosive TNT (24.81 kJ cm −3 ). 38 The excellent energy densities of 1 and 2 can be attributed to the high energy N(CN) 2 − anions leading to the metal imidazolate frameworks.…”

“…In contrast, 1 and 2 exhibit excellent spontaneous combustion behaviours. Both of them display short ID times (ID ≤ 50 ms) 33 of 28(3) and 36(2) ms, respectively, and show steady flames after ignition (Fig. 3c and d).…”

“…In particular, the volumetric energy densities ( E v ) of 1 and 2 were as high as 42.91 and 41.98 kJ cm −3 , respectively, which were twice as high as those of ZIF-based Zn(2-VIM) 2 ( E v = 18.90 kJ cm −3 ), 32 Cd(2-VIM) 2 ( E v = 15.80 kJ cm −3 ), 32 Co(2-VIM) 2 ( E v = 18.40 kJ cm −3 ) 32 and Cu(2-VIM) 2 ( E v = 34.10 kJ cm −3 ). 33 Although compounds 1 and 2 have isomorphic structures, the droplet test shows that Cu-based 1 has a shorter ID time (ID = 28 ms) than that of Cd-based 2 (ID = 36 ms), which means that 1 displays superior self-ignition behaviours. Theoretical calculations reveal the smaller energy gap value of 1 , presumably resulting in 1 possessing higher reaction activity with WFNA than 2 , which is consistent with the experimental results of ID times.…”

Perturbation of the Classic Binary Adduct C6H6:C6F6 by Chlorine Substitution

“…CSP has enabled the crystal structures of relatively large organic molecules, such as those used in the pharmaceutical industry, to be predicted with ever increasing degrees of accuracy. In recent years, the field of CSP has expanded from small organic molecules to complex metal–organic frameworks and supramolecular solids . However, significant challenges still remain. , First, the minimum-energy landscapes encountered in CSP frequently predict many structures of similar energy and density .…”

Crystallographic and Compositional Dependence of Thermodynamic Stability of [Co(II), Cu(II), and Zn(II)] in 2-Methylimidazole-Containing Zeolitic Imidazolate Frameworks

“…In this work, we present a complementary approach to assess ZIF stability, by investigating the stabilizing effect of metal substitution across a series of topologically similar frameworks. Rather than investigating the effect of linker substituents in isostructural ZIFs, we investigate the enthalpic contribution of metal substitution on topologically similar ZIFs, namely, SOD-Co­(MeIm) 2 , SOD-Zn­(MeIm) 2 , dia -Co­(MeIm) 2 , dia -Cu­(MeIm) 2 , and dia -Zn­(MeIm) 2 (Figure ). This allows the direct assessment of the thermodynamic stability of these ZIFs.…”