Sequential Solid‐State Transformations Involving Consecutive Rearrangements of Secondary Building Units in a Metal–Organic Framework (MOF).

Solid‐state transformations in metal–organic frameworks (MOFs) are important and have led to the creation of new MOF structures. Solid‐state transformations from interpenetrated to non‐interpenetrated networks involving rearrangement of secondary building units (SBUs) in a single‐crystal‐to‐single‐crystal (SCSC) fashion have not been explored to date. Herein, we report the sequential, thermally stimulated solid‐state transformations in a barium‐organic framework (UPC‐600). The two‐fold interpenetrated framework of UPC‐600 is converted at 373 K into UPC‐601, a non‐interpenetrated framework. This proceeds in a SCSC fashion and involves the rearrangement of two proximate rod‐shaped SBUs in different nets to generate a new rod‐shaped SBU. At 473 K, a continuous solid‐state transformation involving a second rearrangement occurred, UPC‐601 converted into UPC‐602 by the rearrangement of the 1D rod‐shaped SBU to a 2D layer SBU. This is the first example of such a thermally driven stepwise transformation involving simultaneous cleavage and regeneration of multiple bonds. [ABSTRACT FROM AUTHOR]