Elucidating the Mechanism of a Two-Step Spin Transition in a Nanoporous Metal−Organic Framework
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- 作者：Gregory J. Halder ; Karena W. Chapman ; Suzanne M. Neville ; Boujemaa Moubaraki ; Keith S. Murray ; Jean-Franois Ltard ; Cameron J. Kepert
- 刊名：Journal of the American Chemical Society
- 出版年：2008
- 出版时间：December 24, 2008
- 年：2008
- 卷：130
- 期：51
- 页码：17552-17562
- 全文大小：364K
- 年卷期：v.130,no.51(December 24, 2008)
- ISSN：1520-5126
文摘
The nanoporous metal−organic framework, Fe(bpe)2(NCS)2·3(acetone), SCOF-4(Ac) (where bpe is 1,2-bis(4′-pyridyl)ethane), displays a two-step spin crossover (SCO) transition (65−155 K) that is sensitive to the presence of acetone guest molecules. Structural analyses have revealed a structural phase transition, from tetragonal (P21c) to orthorhombic (P21212), associated with the spin transition that defines a checkerboard-like ordering of spin sites at the high-spin:low-spin plateau. The reversible desorption of the acetone guest species is accompanied by a complex series of structural phase transitions that describe a dramatic flexing of the structure. The thermal trapping of a metastable state with 20−25% high-spin character was observed both magnetically and structurally upon rapid quenching of SCOF-4(Ac) to 10 and 25 K, respectively. The light-induced excited spin state trapping (LIESST) effects for SCOF-4(Ac) show a 55% excitation of a metastable HS state at 10 K and a characteristic T(LIESST) value of 52 K.