Guest Encapsulation Alters the Thermodynamic Landscape of a Coordination Host
Kuntrapakam Hema, Angela B. Grommet, Michał J. Białek, Jinhua Wang, Laura Schneider, Christoph Drechsler, Oksana Yanshyna, Yael Diskin‐Posner, Guido H. Clever, Rafał Klajn
Abstract
High Resolution Image Download MS PowerPoint Slide The architecture of self-assembled host molecules can profoundly affect the properties of the encapsulated guests. For example, a rigid cage with small windows can efficiently protect its contents from the environment; in contrast, tube-shaped, flexible hosts with large openings and an easily accessible cavity are ideally suited for catalysis. Here, we report a “Janus” nature of a Pd 6 L 4 coordination host previously reported to exist exclusively as a tube isomer ( T ). We show that upon encapsulating various tetrahedrally shaped guests, T can reconfigure into a cage-shaped host ( C ) in quantitative yield. Extracting the guest affords empty C, which is metastable and spontaneously relaxes to T, and the T ⇄ C interconversion can be repeated for multiple cycles. Reversible toggling between two vastly different isomers paves the way toward controlling functional properties of coordination hosts “on demand”.