A Flexible Hydrogen Bonded Organic Framework That Reversibly Adsorbs Acetic Acid: γ Trimesic Acid

Abstract

The elusive γ phase of trimesic acid (TMA, 1,3,5-benzenetricarboxylic acid) has been prepared by recrystallization of commercial α-TMA in acetic acid. This process yields a modified γ-TMA phase that contains guest acetic acid solvent molecules with an approximate stoichiometry of γ-TMA·1HAc. According to 1H NMR and crystal structure determination, guest molecules are located both in the channels and in relatively isolated cavities. Despite the constricted connection between channels and cavities, solvent guest molecules are easily removed, even at room temperature, yielding guest-free γ-TMA. This process is reversible, since pristine γ-TMA can reabsorb acetic acid vapor at room temperature, yielding again γ-TMA·1HAc. Conversely, γ-TMA only adsorbs negligible amounts of N2 at 77 K or CO2 at 273 K, denoting that the guest–adsorbent interaction is a key factor governing adsorption.

Mining predicted crystal structure landscapes with high throughput crystallisation: old molecules, new insights

“…The expense of searching the crystal packing space with multiple independent, conformationally exible molecules in the asymmetric unit limited us to predicting crystal structures with 1 and 2 molecules in the asymmetric unit (Z 0 ¼ 1 and 2). Hence, our landscape of predicted structures does not contain the known Z 0 ¼ 6 a-TMA, 43,44 nor the Z 0 ¼ 3 g-TMA structures. 42 For comparison to the CSP structures, the energies of aand g-TMA were calculated from ordered approximations of their high-Z 0 disordered structures (see Fig.…”

“…42 Herbstein also showed that TMA can be crystallised from the vapor, by condensation onto a cold surface, to produce a g-polymorph, 43 which was recently shown to adsorb acetic acid reversibly aer activation. 44 Zaworotko reported a 2 : 1 TMA : acetic acid solvate, which features triply inclined interpenetration between truncated 1D and hexagonal 2D nets. 45 The 2-D ordering of TMA on metal surfaces has also been investigated, 46 and TMA is an archetypal ligand for MOF synthesis (e.g., HKUST-1).…”

The Chemistry of Porous Organic Molecular Materials

“…However, TMA was recently revisited from a fresh perspective, after CSP calculations revealed an energetically stable, low-density polymorphic form, referred to as the δ-polymorph, which remained hidden, despite many groups studying the crystallization behavior of this molecule over the last 50 years. [285][286][287][288][289][290][291][292][293][294] In this study, a high throughput crystallization workflow was developed to screen 280 binary solvent crystallization conditions, of which less than 2% either yielded this δ-polymorph directly, or gave a structure that transformed to this form after activation of the crystal pores. [295] Unlike the nonporous α-polymorph reported by Duchamp et al, the computationally-identified δpolymorph of TMA had a SA BET 910 m 2 g -1 at 77.3 K. CSP was also used by Hisaki et al (Tp-apo, Figures 13 and 16) [296] to predict the structure of a carboxylic acid-based HOF material, that could not be determined directly from X-ray data alone.…”

“…The structure Duchamp reported is nonporous due to the nonplanar hydrogen‐bonded interactions between TMA molecules causing the hydrogen‐bonded networks to interlock. However, TMA was recently revisited from a fresh perspective, after CSP calculations revealed an energetically stable, low‐density polymorphic form, referred to as the δ−polymorph, which remained hidden, despite many groups studying the crystallization behavior of this molecule over the last 50 years 285–294. In this study, a high throughput crystallization workflow was developed to screen 280 binary solvent crystallization conditions, of which less than 2% either yielded this δ‐polymorph directly, or gave a structure that transformed to this form after activation of the crystal pores 295.…”

d2Dplot: 2D X-ray diffraction data processing and analysis for through-the-substrate microdiffraction

“…Another application under study is the crystal structure refinement of -trimesic acid at high pressure inside a diamond anvil cell. -Trimesic acid (orthorhombic, I222) is a flexible porous material (Sanchez-Sala et al, 2018) and the structural evolution with pressure has been followed by applying the tts-XRD methodology [ Fig. 6(b)].…”