Elucidating the mechanism of a two-step spin transition in a nanoporous metal-organic framework.
The nanoporous metal-organic framework, Fe(bpe){sub 2}(NCS){sub 2}{center_dot}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 (P{sub 4}2{sub 1}c) to orthorhombic (P2{sub 1}2{sub 1}2), 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 {approx}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.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); ARC Discovery Project Grant; Australian Synchrotron Research Program
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 953816
- Report Number(s):
- ANL/MSD/JA-62421; JACSAT; TRN: US201004%%575
- Journal Information:
- J. Amer. Chem. Soc., Vol. 130, Issue 51 ; 2008; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- ENGLISH
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