Open AccessRETRACTED ARTICLE: Mechanically interlocked architecture aids an ultra-stiff and ultra-hard elastically bendable cocrystal
Author(s) -
Somnath Dey,
Susobhan Das,
Surojit Bhunia,
Rituparno Chowdhury,
Amit Mondal,
Biswajit Bhattacharya,
Ramesh Devarapalli,
Nobuhiro Yasuda,
Toshimichi Moriwaki,
Kapil Mandal,
Goutam Dev Mukherjee,
C. Malla Reddy
Publication year - 2019
Publication title -
nature communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.559
H-Index - 365
ISSN - 2041-1723
DOI - 10.1038/s41467-019-11657-0
Subject(s) - materials science , bent molecular geometry , hardening (computing) , cocrystal , stacking , bimetal , hydrogen bond , crystal (programming language) , composite material , nanotechnology , molecule , chemistry , computer science , organic chemistry , layer (electronics) , programming language
Molecular crystals are not known to be as stiff as metals, composites and ceramics. Here we report an exceptional mechanical stiffness and high hardness in a known elastically bendable organic cocrystal [caffeine (CAF), 4-chloro-3-nitrobenzoic acid (CNB) and methanol (1:1:1)] which is comparable to certain low-density metals. Spatially resolved atomic level studies reveal that the mechanically interlocked weak hydrogen bond networks which are separated by dispersive interactions give rise to these mechanical properties. Upon bending, the crystals significantly conserve the overall energy by efficient redistribution of stress while perturbations in hydrogen bonds are compensated by strengthened π -stacking. Furthermore we report a remarkable stiffening and hardening in the elastically bent crystal. Hence, mechanically interlocked architectures provide an unexplored route to reach new mechanical limits and adaptability in organic crystals. This proof of concept inspires the design of light-weight, stiff crystalline organics with potential to rival certain inorganics, which currently seem inconceivable.