Organoferroelasticity Mediated by Water of Crystallization

Abstract

Despite the general conception of brittleness, organic single crystals composed of various kinds of molecules can show ferroelasticity by mechanical twinning. This is attributed to flexibilities in molecular structures, e.g., conformation, and noncovalent bonds, e.g., length and angle. Herein, we find ferroelasticity by mechanical twinning mediated by water of crystallization in a single crystal of a zwitterion: sulfanilic acid monohydrate. Shaping of an organic single crystal is demonstrated ferroelastically from linear to bent shape and from contracted to elongated shape. Rotation of sulfonate anions along with recombination and changes in lengths and angles in flexible hydrogen bonds of small water molecules helps ferroelastic mechanical twinning. Our findings demonstrate designability of mechanically twinnable organic crystals from the viewpoints of organic chemistry and crystal engineering based on hydrogen bonds.

An Organosuperelastic Mechanism with Bending Molecular Chain Bundles

“…The E d important for mechanical damping of vibrations is larger than that in most of the previously reported ferroelastic molecular crystals (Table S3). ,,,,− …”

Mechanical twinning in organic crystals

“…Other representative examples of tFE in multicomponent organic crystals are a clathrate of 26, [15][16][17] an organic salt of 5 by electrostatic interactions, 23 cocrystals of 12 67 and 14 69 by hydrogen bonding-based supramolecular synthesis, and a hydrate of a zwitterion of 13. 68 Among them, a biased ferroelastic hysteresis loop in 14 is noteworthy (Fig. 9a).…”

“…4). 11,12,[15][16][17]23,26,27,[61][62][63][64][65][66][67][68][69][70][71][72] Although some cases were reported with no stress-strain curves and no claims of tFE, optical observations of deformation behaviors by mechanical twinning indicate tFE. 14,18,19,73 In the case of a ferroelectric organic crystal of 2,2,6,6-tetramethylpiperidine 1-oxyl (or TEMPO), the crystal is potentially tFE due to movements of twin interfaces induced by thermal cycles and electric fields but the crystal is too soft to induce the movement mechanically at room temperature (r.t.).…”

Flexible organic crystals. Understanding the tractable co-existence of elastic and plastic bending

“…20,21 Layered molecular arrangement with an orthogonal distribution of strong and weak interactions ensue plasticity in the system. 22,23 Though the aforesaid factors are critical structural aspects that cause distinct mechanical characteristics of molecular crystals, various other factors-solvent of crystallization, [24][25][26] globularity of the molecules, 16,27 and aspect ratio of the crystals 3 -also could contribute to their mechanical properties. Also, one could employ crystal engineering strategies to tune the mechanical properties in molecular crystals.…”