Giant Atomic Displacement Driven Reconstructive Molecular Martensitic Structural Phase Transition in 1D Hybrid Metal Halide Actuator

ABSTRACT Dynamic molecular crystals driven by martensitic structural phase transitions can convert external stimuli into mechanical work, holding significant research importance in the fields of actuation and energy harvesting. However, the structural phase transition mechanisms in traditional martensitic actuators are primarily limited to small‐amplitude atomic displacements or molecular motions, rarely involving the breaking and reforming of chemical bonds. Herein, we report a Z‐type cyclic inorganic double‐chain hybrid (BMPD) 8 Pb 11 Br 30 (BMPD = N ‐butyl‐ N ‐methyl‐piperidinium). It undergoes an unprecedented reversible topological reconstruction that transforms the local face‐sharing linkage of [PbBr 6 ] 4− octahedra into edge‐sharing. Notably, the atomic displacement generated during the phase change exceeds 1.35 Å. This structural rearrangement induces interchain shearing and cooperative deflection of inorganic double chains, further triggering macroscopic deformation and fast (0.66 mm·s − 1 ) martensitic actuation behavior. Upon thermal stimulation, the crystal generates a kinetic energy of about 2.88 × 10 −10 J and a maximum thrust force of 3.97 × 10 −4 N. The corresponding average force density and work density are 6.39 × 10 6 N m −3 and 868.0 J m −3 , respectively. The actuator efficiency reaches 8.07 × 10 − 5 –2.63 × 10 − 4 . This work offers a promising strategy for the design of fast‐responsive and high‐efficiency molecular actuators.