Manipulating Light-Induced Dynamic Macro-Movement and Static Photonic Properties within 1D Isostructural Hydrogen-Bonded Molecular Cocrystals.

Smart molecular crystals with light-driven mechanical responses have received interest owing to their potential uses in molecular machines, artificial muscles, and biomimetics. However, challenges remain in control over both the dynamic photo-mechanical behaviors and static photonic properties of molecular crystals based on the same molecule. Herein, we show the construction of isostructural co-crystals allows their light-induced cracking and jumping behaviors (photosalient effect) to be controlled. Hydrogen-bonded co-crystals from 4-(1-naphthylvinyl)pyridine (NVP) with co-formers (tetrafluoro-4-hydroxybenzoic acid (THA) and tetrafluorobenzoic acid (TA)) crystallize as isostructural crystals, but have different static and dynamic photo-mechanical behaviors. These differences are due to alternations in the orientation of NVP and hydrogen-bonding modes of the co-formers. After light activation, the 1D NVP-TA crystal splits and shears off within 1 s. For NVP-THA, its photostability and high quantum yield give novel photonic properties, including low optical waveguide loss, highly polarized anisotropy, and efficient up-conversion fluorescence.