Water-triggered macroscopic structural transformation of a metal-organic framework

A millimeter-long metal-organic framework fiber has been successfully constructed. The fiber structure was unexpectedly found via the solvent vaporization process of a dispersion of a Zn-based MOF crystal. Detailed experiments and structural analysis indicate that a humid environment is a key to the growth of the fiber structure, inducing drastic transformation of the MOF crystal morphology from the nanoscopic to macroscopic scale. Synchrotron X-ray single-crystal diffraction analysis reveals that the complete crystal transformation from the Zn-MOF sheet to Zn-MOF fiber is accompanied by water coordination and ligand rearrangement. The highly anisotropic MOF fiber is easily converted to an electro conductive fiber while maintaining the long-fiber morphology.