TY - JOUR
T1 - Mechanically Responsive Crystals
T2 - Analysis of Macroscopic Strain Reveals "hidden" Processes
AU - Desta, Israel Tilahun
AU - Chizhik, Stanislav A.
AU - Sidelnikov, Anatoli A.
AU - Karothu, Durga Prasad
AU - Boldyreva, Elena V.
AU - Naumov, Panče
N1 - Funding Information:
This work was supported by Ministry of Science and Higher Education of the Russian Federation (project AAAA-A19-119020890025-3), and by a fund from New York University Abu Dhabi.
Publisher Copyright:
© 2019 American Chemical Society.
PY - 2020/1/16
Y1 - 2020/1/16
N2 - Mechanical response of single crystals to light, temperature, and/or force - an emerging platform for the development of new organic actuating materials for soft robotics - has recently been quantitatively described by a general and robust mathematical model (Chem. Rev. 2015, 115, 12440-12490). The model can be used to extract accurate activation energies and kinetics of solid-state chemical reactions simply by tracking the time-dependent bending of the crystal. Here we illustrate that deviations of the macroscopic strain in the crystal from that predicted by the model reveal the existence of additional, "hidden" chemical or physical processes, such as sustained structural relaxation between the chemical transformation and the resulting macroscopic deformation of the crystal. This is illustrated with photobendable single crystals of 4-hydroxy-2-(2-pyridinylmethylene)hydrazide, a photochemical switch that undergoes E-to-Z isomerization. The irreversible isomerization in these crystals results in amorphization and plastic deformation that are observed as poor correlation between the transformation extent and the induced strains. The occurrence of these processes was independently confirmed by X-ray diffraction and differential scanning calorimetry. An extended mathematical model is proposed to account for this complex mechanical response.
AB - Mechanical response of single crystals to light, temperature, and/or force - an emerging platform for the development of new organic actuating materials for soft robotics - has recently been quantitatively described by a general and robust mathematical model (Chem. Rev. 2015, 115, 12440-12490). The model can be used to extract accurate activation energies and kinetics of solid-state chemical reactions simply by tracking the time-dependent bending of the crystal. Here we illustrate that deviations of the macroscopic strain in the crystal from that predicted by the model reveal the existence of additional, "hidden" chemical or physical processes, such as sustained structural relaxation between the chemical transformation and the resulting macroscopic deformation of the crystal. This is illustrated with photobendable single crystals of 4-hydroxy-2-(2-pyridinylmethylene)hydrazide, a photochemical switch that undergoes E-to-Z isomerization. The irreversible isomerization in these crystals results in amorphization and plastic deformation that are observed as poor correlation between the transformation extent and the induced strains. The occurrence of these processes was independently confirmed by X-ray diffraction and differential scanning calorimetry. An extended mathematical model is proposed to account for this complex mechanical response.
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U2 - 10.1021/acs.jpca.9b10365
DO - 10.1021/acs.jpca.9b10365
M3 - Article
C2 - 31821761
AN - SCOPUS:85077945015
SN - 1089-5639
VL - 124
SP - 300
EP - 310
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 2
ER -