How Does Molecular Diameter Correlate with the Penetration Barrier of Small Gas Molecules on Porous Carbon-Based Monolayer Membranes?

Jing Wang; Ying Zhang; Wenhao Wang; Lina Yin; Mo Xie; Jin Yong Lee; Hu Shi; Hongguang Liu

doi:10.1021/acs.jpca.2c07554

How Does Molecular Diameter Correlate with the Penetration Barrier of Small Gas Molecules on Porous Carbon-Based Monolayer Membranes?

J Phys Chem A. 2023 Jan 19;127(2):517-526. doi: 10.1021/acs.jpca.2c07554.

Authors

Jing Wang¹, Ying Zhang¹, Wenhao Wang¹, Lina Yin¹, Mo Xie^{1

2}, Jin Yong Lee³, Hu Shi⁴, Hongguang Liu^{1

2

5}

Affiliations

¹ College of Chemistry and Materials Science, Jinan University, 601 Huang-Pu Avenue West, Guangzhou510632, China.
² Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications, Jinan University, 601 Huang-Pu Avenue West, Guangzhou510632, China.
³ Department of Chemistry, Sungkyunkwan University, Suwon440-746, Korea.
⁴ School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan030006, China.
⁵ School of Applied Physics and Materials, Wuyi University, Jiangmen529020, China.

PMID: 36600536
DOI: 10.1021/acs.jpca.2c07554

Abstract

Molecular diameter is an essential molecule-size descriptor that is widely used to understand, e.g., the gas separation preference of a permeable membrane. In this contribution, we have proposed two new molecular diameters calculated respectively by the circumscribed-cylinder method (D_n^') and the group-separated method (D_n), and compared them with the already known kinetic diameter (D_k), averaged diameters (D_pa), and maximum diameters (D_pm and D_mm) in correlating with the penetration barriers of small gas molecules on a total of 14 porous carbon-based monolayer membranes (PCMMs). D₁^' and D₂^' give the best barrier-diameter correlations with average Pearson's correlation coefficients of 0.91 and 0.90, which are markedly larger than those (0.77, 0.76, 0.60, 0.48, 0.33, and 0.32) for D₁, D₂, D_k, D_pa, D_pm, and D_mm. Our results manifest that the choice of vdW radii set does not drastically change the barrier-diameter correlation. Our newly defined D₁^', D₂^', D₁, and D₂, especially D₁^' and D₂^', show universal applicability in predicting the relative permeability of small gas molecules on different PCMMs. The circumscribed-cylinder method proposed here is a facile approach that considers the molecule's directionality and can be applicable to larger molecules. The excellent linear correlation between D_n^' and gas penetration barrier implies that the computationally less demanding molecular diameter D_n^' can be an alternative to the penetration barrier in diagnosing the gas separation preference of the PCMMs.