TY - JOUR
T1 - Solvent-induced transformation of single crystals of a spin-crossover (SCO) compound to single crystals with two distinct SCO centers
AU - Li, Bao
AU - Wei, Rong Jia
AU - Tao, Jun
AU - Huang, Rong Bin
AU - Zheng, Lan Sun
AU - Zheng, Zhiping
PY - 2010/2/10
Y1 - 2010/2/10
N2 - The long-sought-after crystal structure of Fe(tpa)(NCS)2 (1, tpa ) tris(2-pyridylmethyl)amine), an otherwise well-studied spin-crossover (SCO) complex, has been obtained, and its one-step, incomplete spin transition was correlated to its solid-state structures at different temperatures. Upon exposure to methanol vapor, single-crystal-to-single-crystal transformation of 1 to a new SCO compound, 2, formulated as {[Fe(tpa)(NCS)2] · [Fe(tpa)(NCS)2 · CH3OH]}, occurs with a dramatic color change from yellow to red. Crystallographic studies revealed that the asymmetric unit of the structure of 2 contains two independent Fe(II) centers. Studies by magnetic measurements and Mössbauer spectroscopy revealed a two-step complete spin transition for compound 2, between LS-LS and HS-HS, via an unambiguous intermediate LS-HS phase; the two SCO centers of disparate spin states were resolved crystallographically. That a significant portion of the original crystal structure is maintained indicates that the present approach is a more subtle means of altering the properties associated with SCO phenomenon than by changing counteranions or crystallization using different solvents. Furthermore, the dramatic changes in crystal structure and SCO behaviors triggered by mere solvent sorption suggest that this approach is rather efficient in modifying and hopefully fine-tuning and optimizing properties of SCO compounds. Coupled with the aforementioned gentleness and subtlety, the present approach of heterogeneously introducing perturbations to pre-existing supramolecular arrays of SCO units is more conducive to systematic studies aiming at the discovery of new SCO systems and phenomenon toward their ultimate materials applications.
AB - The long-sought-after crystal structure of Fe(tpa)(NCS)2 (1, tpa ) tris(2-pyridylmethyl)amine), an otherwise well-studied spin-crossover (SCO) complex, has been obtained, and its one-step, incomplete spin transition was correlated to its solid-state structures at different temperatures. Upon exposure to methanol vapor, single-crystal-to-single-crystal transformation of 1 to a new SCO compound, 2, formulated as {[Fe(tpa)(NCS)2] · [Fe(tpa)(NCS)2 · CH3OH]}, occurs with a dramatic color change from yellow to red. Crystallographic studies revealed that the asymmetric unit of the structure of 2 contains two independent Fe(II) centers. Studies by magnetic measurements and Mössbauer spectroscopy revealed a two-step complete spin transition for compound 2, between LS-LS and HS-HS, via an unambiguous intermediate LS-HS phase; the two SCO centers of disparate spin states were resolved crystallographically. That a significant portion of the original crystal structure is maintained indicates that the present approach is a more subtle means of altering the properties associated with SCO phenomenon than by changing counteranions or crystallization using different solvents. Furthermore, the dramatic changes in crystal structure and SCO behaviors triggered by mere solvent sorption suggest that this approach is rather efficient in modifying and hopefully fine-tuning and optimizing properties of SCO compounds. Coupled with the aforementioned gentleness and subtlety, the present approach of heterogeneously introducing perturbations to pre-existing supramolecular arrays of SCO units is more conducive to systematic studies aiming at the discovery of new SCO systems and phenomenon toward their ultimate materials applications.
UR - http://www.scopus.com/inward/record.url?scp=76149113936&partnerID=8YFLogxK
U2 - 10.1021/ja909695f
DO - 10.1021/ja909695f
M3 - Article
AN - SCOPUS:76149113936
SN - 0002-7863
VL - 132
SP - 1558
EP - 1566
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 5
ER -