Large Local Internal Stress in an Elastically Bent Molecular Crystal Revealed by Raman Shifts.

Autor: Rahman A; Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, 110016, India.; School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia., Mondal S; Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, 110016, India., Modak M; High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Center, Mumbai, 400085, India., Singh A; Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, 110016, India., Thayat NS; Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, 110016, India., Singh H; Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, 110016, India., Clegg JK; School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia., Poswal HK; High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Center, Mumbai, 400085, India.; Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, India., Haridas V; Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, 110016, India.; Department of Chemistry, Indian Institute of Technology Palakkad, Kerala, 678623, India., Thomas SP; Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, 110016, India.
Jazyk: angličtina
Zdroj: Small (Weinheim an der Bergstrasse, Germany) [Small] 2024 Nov; Vol. 20 (45), pp. e2402120. Date of Electronic Publication: 2024 Jul 24.
DOI: 10.1002/smll.202402120
Abstrakt: The structural dynamics involved in the mechanical flexibility of molecular crystals and the internal stress in such flexible materials remain obscure. Here, the study reports an elastically bending lipidated molecular crystal that shows systematic shifts in characteristic vibrational frequencies across the bent crystal region - revealing the nature of structural changes during bending and the local internal stress distribution. The blueshifts in the bond stretching modes (such as C═O and C-H modes) in the inner arc region and redshifts in the outer arc region of the bent crystals observed via micro-Raman mapping are counterintuitive to the bending models based on intermolecular hydrogen bonds. Correlating these shifts with the trends observed from high-pressure Raman studies on the crystal reveals the local stress difference between the inner arc and outer arc regions of the bent crystal to be ≈2 GPa, more than an order of magnitude higher than the previously proposed value in elastically bending crystals. High local internal stress can have direct ramifications on the properties of molecular piezoelectric energy harvesters, actuators, semiconductors, and flexible optoelectronic materials.
(© 2024 Wiley‐VCH GmbH.)
Databáze: MEDLINE
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