Shape-Memory Effect Triggered by π-π Interactions in a Flexible Terpyridine Metal-Organic Framework

Kornel Roztocki; Wiktoria Gromelska; Filip Formalik; Alessia Giordana; Luca Andreo; Ghodrat Mahmoudi; Volodymyr Bon; Stefan Kaskel; Leonard J Barbour; Agnieszka Janiak; Emanuele Priola

doi:10.1021/acsmaterialslett.3c00068

Shape-Memory Effect Triggered by π-π Interactions in a Flexible Terpyridine Metal-Organic Framework

ACS Mater Lett. 2023 Mar 23;5(4):1256-1260. doi: 10.1021/acsmaterialslett.3c00068. eCollection 2023 Apr 3.

Authors

Affiliations

¹ Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland.
² Department of Micro, Nano, and Bioprocess Engineering, Faculty of Chemistry, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland.
³ Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States.
⁴ Dipartimento di Chimica, Università degli Studi di Torino, Via Pietro Giuria 7, 10125, Torino, Italy.
⁵ Department of Chemistry, Faculty of Science, University of Maragheh, P.O. Box 55136-83111, Maragheh 83111-55181, Iran.
⁶ Chair of Inorganic Chemistry, Technische Universität Dresden, Bergstrasse 66, 01062 Dresden, Germany.
⁷ Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.

Abstract

Shape-memory polymers and alloys are adaptable materials capable of reversing from a deformed, metastable phase to an energetically favored original phase in response to external stimuli. In the context of metal-organic frameworks, the term shape-memory is defined as the property of a switchable framework to stabilize the reopened pore phase after the first switching transition. Herein we describe a novel flexible terpyridine MOF which, upon desolvation, transforms into a nonporous structure that reopens into a shape-memory phase when exposed to CO₂ at 195 K. Based on comprehensive in situ experimental studies (SC-XRD and PXRD) and DFT energetic considerations combined with literature reports, we recommend dividing shape-memory MOFs into two categories, viz responsive and nonresponsive, depending on the transformability of the gas-free reopened pore phase into the collapsed phase. Furthermore, considering the methodological gap in discovering and understanding shape-memory porous materials, we emphasize the importance of multicycle physisorption experiments for dynamic open framework materials, including metal-organic and covalent organic frameworks.