title: Insight into Ion Transfer through the Sub-Nanometer Channels in Zeolitic Imidazolate Frameworks.
abstract: A crack-free sub-nanometer composite structure for the study of ion transfer was constructed by in situ growth of ZIF-90 [Zn(ICA)2, ICA=Imidazole-2-carboxaldehyde] on the tip of a glass nanopipette. The potential-driven ion transfer through the sub-nanometer channels in ZIF-90 is strongly influenced by the pH of the solution. A rectification ratio over 500 is observed in 1 m KCl solution under alkaline conditions (pH 11.58), which is the highest value reported under such a high salt concentration. Fluorescence experiments show the super-high rectification ratio under alkaline conditions results from the strong electrostatic interaction between ions and the sub-nanometer channels of ZIF-90. In addition to providing a general pathway for further study of mass-transfer process through sub-nanometer channels, the approach enable all kinds of metal-organic frameworks (MOFs) to be used as ionic permselectivity materials in nanopore-based analysis.
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, Jiangsu, P.R. China.
authors.forename: Ze-Yu
authors.initials: ZY
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, Jiangsu, P.R. China.
authors.forename: Hai-Ling
authors.initials: HL
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, Jiangsu, P.R. China.
authors.forename: Saud Asif
authors.initials: SA
authors.lastname: Ahmed
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, Jiangsu, P.R. China.
authors.forename: Sumaira
authors.initials: S
authors.lastname: Hanif
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, Jiangsu, P.R. China.
authors.forename: Shi-Bin
authors.initials: SB
authors.lastname: Ren
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, Jiangsu, P.R. China.
authors.forename: Jing-Juan
authors.identifier: 0000-0001-9579-9318
authors.initials: JJ
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, Jiangsu, P.R. China.
authors.forename: Hong-Yuan
authors.initials: HY
authors.lastname: Chen
authors.forename: Xing-Hua
authors.initials: XH
authors.lastname: Xia
authors.forename: Kang
authors.identifier: 0000-0001-5170-5543
authors.initials: K
authors.lastname: Wang
keywords: ZIF-90; ion transport; nanopore analysis; rectification; zeolitic imidazolate frameworks