Elucidating negative thermal expansion in MOF-5
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Date
2010-9-09
Journal Title
Journal ISSN
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Publisher
American Chemical Society
Abstract
Multi-temperature X-ray diffraction studies show that twisting, rotation, and libration cause negative thermal expansion (NTE) of the nanoporous metal−organic framework MOF-5, Zn4O(1,4-benzenedicarboxylate)3. The near-linear lattice contraction is quantified in the temperature range 80−500 K using synchrotron powder X-ray diffraction. Vibrational motions causing the abnormal expansion behavior are evidenced by shortening of certain interatomic distances with increasing temperature according to single-crystal X-ray diffraction on a guest-free crystal over a broad temperature range. Detailed analysis of the atomic positional and displacement parameters suggests two contributions to cause the effect: (1) local twisting and vibrational motion of the carboxylate groups and (2) concerted transverse vibration of the linear linkers. The vibrational mechanism is confirmed by calculations of the dynamics in a molecular fragment of the framework. © 2010, American Chemical Society
Description
Keywords
X-ray diffraction, Thermal expansion, Crystal lattices, Oscillation modes, Aromatics, Carboxylation
Citation
Lock, N., Wu, Y., Christensen, M., Cameron, L. J., Peterson, V. K., Bridgeman, A. J., Kepert. C. J., & Iversen, B. B.. (2010). Elucidating negative thermal expansion in MOF-5. Journal of Physical Chemistry C, 114(39), 16181-16186. doi:10.1021/jp103212z