Elucidating Negative Thermal Expansion in MOF-5

作者：Lock Nina; Wu Yue; Christensen Mogens; Cameron Lisa J; Peterson Vanessa K; Bridgeman Adam J; Kepert Cameron J; Iversen Bo B^*

来源：Journal of Physical Chemistry C, 2010, 114(39): 16181-16186.

DOI：10.1021/jp103212z

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.

• 出版日期2010-10-7