Inherent Ethyl Acetate Selectivity in a Trianglimine Molecular Solid

Abstract

Ethyl acetate is an important chemical raw material and solvent. It is also a key volatile organic compound in the brewing industry and a marker for lung cancer. Materials that are highly selective toward ethyl acetate are needed for its separation and detection. Here, we report a trianglimine macrocycle (TAMC) that selectively adsorbs ethyl acetate by forming a solvate. Crystal structure prediction showed this to be the lowest energy solvate structure available. This solvate leaves a metastable, "templated" cavity after solvent removal. Adsorption and breakthrough experiments confirmed that TAMC has adequate adsorption kinetics to separate ethyl acetate from azeotropic mixtures with ethanol, which is a challenging and energy-intensive industrial separation.

Porous Organic Compounds – Small Pores on the Rise

“…Similar observations were made by Cooper and co‐workers, who recently studied the TA based macrocycle T2 in respect to its adsorption and separation properties (Figure 10 bottom) [26a] . When crystallizing T2 from ethyl acetate (EA), the group observed a 1 : 1 molar inclusion complex of EA @ T2 , in which EA is strongly bound inside the generated 1D pores, indicated also by the comparatively harsh activation conditions needed to remove the guest, ultimately yielding the guest‐free structure.…”

Creating porosity in a trianglimine macrocycle by heterochiral pairing

“…14 We reported a trianglimine macrocycle crystal that can separate ethyl acetate from its azeotropic mixture with ethanol. 15 Eddaoudi and co-workers reported a triangleamine-based supramolecular organic framework that showed permanent porosity and high affinity for CO 2 . 16 We also reported formally non-porous pillar [n]arenes that selectively adsorbed styrene from ethylbenzene 17 and para-xylene from its structural isomers.…”

Dynamic and solid-state behaviour of bromoisotrianglimine

“…[87][88][89][90][91] Cooper and co-workers invoked the possibility of chiral recognition to achieve the capsule head-to-head motif on the unsubstituted isotrianglimine. 21 Therefore, we explored the use of heterochiral co-crystallisation of bromo-isotrianglimine to investigate the effect on both the polymorphs obtained and the macrocycles present in the structure.…”

“…19,20 Incorporating terephthalaldehyde (1,4-dialdehyde), the unsubstituted trianglimine can selectively adsorb ethyl acetate from azeotropic mixtures with ethanol. 21 A heterochiral co-pairing strategy can be used to form a porous racemic crystal of the [3+3] unsubstituted isotrianglimine, formed using isophthalaldehyde (1,3-dialdehyde). 22 Finally, incorporation of additional functionality has resulted in substituted trianglimine macrocycles that can selectively separate industrially important molecular species.…”