An Investigation of Photo‐ and Pressure‐Induced Effects in a Pair of Isostructural Two‐Dimensional Spin‐Crossover Framework Materials |
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Authors: | Dr. Natasha F. Sciortino Dr. Suzanne M. Neville Dr. Cédric Desplanches Dr. Jean‐François Létard Dr. Victor Martinez Prof. José Antonio Real Dr. Boujemaa Moubaraki Prof. Keith S. Murray Prof. Cameron J. Kepert |
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Affiliation: | 1. School of Chemistry, The University of Sydney, NSW 2006 (Australia), Fax: (+61)?2‐9351‐5741;2. Laboratoire des Sciences Moléculaires, ICMCB (CNRS UPR 9048), Université Bordeaux I, 33608 Pessac (France);3. Edifici d'Instituts de Paterna, Apartat de Correus 22085, Universitat de Valéncia, 46071 Valéncia (Spain);4. School of Chemistry, Monash University, Clayton, Victoria 3800 (Australia) |
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Abstract: | Two new isostructural iron(II) spin‐crossover (SCO) framework (SCOF) materials of the type [Fe(dpms)2(NCX)2] (dpms=4,4′‐dipyridylmethyl sulfide; X=S ( SCOF‐6(S) ), X=Se ( SCOF‐6(Se) )) have been synthesized. The 2D framework materials consist of undulating and interpenetrated rhomboid (4,4) nets. SCOF‐6(S) displays an incomplete SCO transition with only approximately 30 % conversion of high‐spin (HS) to low‐spin iron(II) sites over the temperature range 300–4 K (T1/2=75 K). In contrast, the NCSe? analogue, SCOF‐6(Se) , displays a complete SCO transition (T1/2=135 K). Photomagnetic characterizations reveal quantitative light‐ induced excited spin‐state trapping (LIESST) of metastable HS iron(II) sites at 10 K. The temperature at which the photoinduced stored information is erased is 58 and 50 K for SCOF‐6(S) and SCOF‐6(Se) , respectively. Variable‐pressure magnetic measurements were performed on SCOF‐6(S) , revealing that with increasing pressure both the T1/2 value and the extent of spin conversion are increased; with pressures exceeding 5.2 kbar a complete thermal transition is achieved. This study confirms that kinetic trapping effects are responsible for hindering a complete thermally induced spin transition in SCOF‐6(S) at ambient pressure due to an interplay between close T1/2 and T(LIESST) values. |
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Keywords: | chalcogens coordination polymers iron magnetic properties spin crossover |
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