Programmable Guest‐Induced 5‐Phase‐Transition Topological Reconstructions of Cobalt Formate Metal–Organic Frameworks

Structural dynamics in metal–organic frameworks (MOFs) typically rely on elaborate, flexible organic linkers. Here, we challenge this paradigm by demonstrating a rare, reversible 5‐phase‐transition cycle in a minimalist cobalt formate MOF system. Central to this evolution is the conceptual reframing of the amorphous state ( Co‐Amor ); rather than representing a structural dead‐end, Co‐Amor functions as a programmable, high‐energy reactive hub that lowers reorganization barriers. We show that specific guest molecules selectively direct the reconstruction of this amorphous matrix into distinct crystalline architectures, including chiral ( Co‐Hex ), perovskite‐like ( Co‐Trig ), diamondoid ( Co‐Mono1 ), and hydrated ( Co‐Mono2 ) frameworks, effectively ‘reprogramming’ the material's underlying lattice physics. The generality of the guest‐molecule selectivity is verified by Co‐Hex and Co‐Trig , which have different crystalline structures but share the same phase‐transition behavior, thereby further highlighting the adaptability and importance of this system. Most notably, we uncover a rare gas‐solid reconstruction where CO 2 acts as a morphogenic trigger, inducing a gradual amorphous‐to‐crystal transition to the rigid Co‐Mono1 phase. This chemoselectivity originates from a specific C–H···O hydrogen‐bond complementarity between the formate channel walls and CO 2 . This work highlights the untapped potential of amorphous intermediates in directing structural reconfigurations, offering a blueprint for designing highly adaptive materials from the simplest molecular building blocks.