Near-ideal xylene selectivity in adaptive molecular pillar[n]arene crystals

DOI: 10.1021/jacs.8b02621

Authors: Kecheng Jie (Zhejiang University) , Ming Liu (University of Liverpool) , Yujuan Zhou (Zhejiang University) , Marc A. Little , Angeles Pulido (University of Southampton) , Samantha Y. Chong (University of Liverpool) , Andrew Stephenson (University of Liverpool) , Ashlea R. Hughes (University of Liverpool) , Fumiyasu Sakakibara (Kanazawa University) , Tomoki Ogoshi (Kanazawa University) , Frédéric Blanc (University of Liverpool) , Graeme M. Day (University of Southampton) , Feihe Huang (Zhejiang University) , Andrew I. Cooper (University of Liverpool)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of The American Chemical Society

State: Published (Approved)
Published: May 2018
Diamond Proposal Number(s): 15777 , 12336 , 17193

Abstract: The energy-efficient separation of alkylaromatic compounds is a major industrial sustainability challenge. The use of selectively porous extended frameworks, such as zeolites or metal–organic frameworks, is one solution to this problem. Here, we studied a flexible molecular material, perethylated pillar[n]arene crystals (n = 5, 6), which can be used to separate C8 alkylaromatic compounds. Pillar[6]arene is shown to separate para-xylene from its structural isomers, meta-xylene and ortho-xylene, with 90% specificity in the solid state. Selectivity is an intrinsic property of the pillar[6]arene host, with the flexible pillar[6]arene cavities adapting during adsorption thus enabling preferential adsorption of para-xylene in the solid state. The flexibility of pillar[6]arene as a solid sorbent is rationalized using molecular conformer searches and crystal structure prediction (CSP) combined with comprehensive characterization by X-ray diffraction and 13C solid state NMR spectroscopy. The CSP study, which takes into account the structural variability of pillar[6]arene, breaks new ground in its own right and showcases the feasibility of applying CSP methods to understand and ultimately to predict the behaviour of soft, adaptive molecular crystals.

Journal Keywords: Adsorption; Crystal structure; Physical and chemical processes; Molecular structure; Cavities

Subject Areas: Chemistry, Energy, Environment


Instruments: I11-High Resolution Powder Diffraction , I19-Small Molecule Single Crystal Diffraction

Added On: 21/05/2018 15:10

Documents:
j45456acs.pdf

Discipline Tags:

Earth Sciences & Environment Sustainable Energy Systems Energy Climate Change Chemistry Organic Chemistry

Technical Tags:

Diffraction Single Crystal X-ray Diffraction (SXRD)