Issue 11, 2022

Pillar[3]trianglamines: deeper cavity triangular macrocycles for selective hexene isomer separation

Abstract

The separation of α-olefins and their corresponding isomers continues to be a big challenge for the chemical industry due to their overlapping physical properties and low relative volatility. Herein, pillar[3]trianglamine (P-TA) macrocycles were synthesized for the molecular-sieving-like separation of 1-hexene (1-He) selectively over its positional isomer trans-3-hexene (trans-3-He) in the vapor and liquid state. This allyl-functionalized macrocycle features a deeper cavity compared to the previously reported trianglamine host molecules. Solid–vapor sorption experiments verified the successful separation of 1-He from an equimolar mixture of 1-He and trans-3-He. Single-crystal structures and powder X-ray diffraction patterns suggest that this selective adsorption arises from the formation of a thermodynamically stable host–guest complex between 1-He and P-TA. A reversible transformation between the nonporous guest-free structure and the guest-containing structure shows that 1-He separation can be carried out over multiple cycles without any loss of performance. Significantly, P-TA can separate 1-He directly from a liquid isomeric mixture and thus P-TA modified silica sieves (SBA-15) showed the ability to selectively separate 1-He when utilized as a stationary phase in column chromatography. This capitalizes on the prospects of employing macrocyclic hosts as molecular recognition units in real-life separations for sustainable and energy-efficient industrial practices.

Graphical abstract: Pillar[3]trianglamines: deeper cavity triangular macrocycles for selective hexene isomer separation

Supplementary files

Article information

Article type
Edge Article
Submitted
12 Janv. 2022
Accepted
23 Febr. 2022
First published
02 Marts 2022
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2022,13, 3244-3248

Pillar[3]trianglamines: deeper cavity triangular macrocycles for selective hexene isomer separation

Y. Ding, L. O. Alimi, J. Du, B. Hua, A. Dey, P. Yu and N. M. Khashab, Chem. Sci., 2022, 13, 3244 DOI: 10.1039/D2SC00207H

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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