Kim, Hyojin Shin, Dong Yun Choe, Jong Hyeak Cheon, Gayoung Yun, Hongryeol Lee, Jung-Hoon Hong, Chang Seop 2026-01-15T09:30:54Z 2026-01-15T09:30:54Z 2026-01-12 2026-02 1613-6810 https://pubs.kist.re.kr/handle/201004/154032 Sigmoidal adsorption in flexible metal-organic frameworks (MOFs) can be achieved through a dramatic phase transition from narrow to large pores; however, such a unique phenomenon, which is not induced by abrupt phase changes, has rarely been reported. We report a series of flexible Hofmann-type MOFs, CoNi-Pipe, NiNi-Pipe, and CoPd-Pipe, pillared with a dimensional (3D) piperazine linker. Owing to the rotational flexibility and 3D dimensionality of the piperazine linker, CoNi-Pipe and CoPd-Pipe exhibited Xe-induced gate opening and the corresponding sigmoidal adsorption isotherms. CoNi-Pipe revealed not only excellent Xe/Kr separation but also Xe recovery performance, attributed to the greatest linker rotation and flexibility, along with moderate Xe binding strength, as validated by the machine learning potential-based molecular dynamics simulations and van der Waals-corrected DFT calculations. Thus, this work provides an effective approach for gaining a deeper understanding of the structural dynamics in flexible frameworks and expanding the repertoire of computational studies. English Wiley - V C H Verlag GmbbH & Co. Elucidating the Sigmoidal Adsorption Behavior of Xenon in Flexible Hofmann-Type MOFs Through Experiments and Molecular Dynamics with Machine Learning Potentials Article 10.1002/smll.202509479 1 Small, v.22, no.10 Small 22 10 N scie scopus 2-s2.0-105026181530 Chemistry, Multidisciplinary Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Physics, Applied Physics, Condensed Matter Chemistry Science & Technology - Other Topics Materials Science Physics Article; Early Access METAL-ORGANIC FRAMEWORK BREATHING BEHAVIOR SEPARATION FUNCTIONALITY FLEXIBILITY CRYSTAL CO2 kinetic analysis machine learning potential metal-organic frameworks rotational dynamics sigmoidal xenon adsorption