Elastic Crystalline Fibers Composed of a Nickel(II) Complex

The generation of elastic crystalline fibers from a nonfibrous crystal of metal complex is demonstrated. Applying mechanical stimuli to a platelike crystal of Ni^II(salophen) [1; H₂salophen = N,N'-bis(salicylidene)-o-phenylenediamine] resulted in this complex being transformed into crystal fibers, which could be bent into a loop and demonstrated its high elasticity. Single-crystal X-ray diffraction analyses revealed that the transformation reflects the presence of molecular strands that are composed of a one-dimensional assembly of the slip-stacked arrangement by nearly planar Ni(salophen) molecules. The fiber flexibility was demonstrated to be lost upon the introduction of chloroform solvent molecules into the crystal lattice by recrystallization.