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Defying the inverse energy gap law: a vacuum-evaporable Fe(ii) low-spin complex with a long-lived LIESST state
The novel vacuum-evaporable complex [Fe(pypypyr)(2)] (pypypyr = bipyridyl pyrrolide) was synthesised and analysed as bulk material and as a thin film. In both cases, the compound is in its low-spin state up to temperatures of at least 510 K. Thus, it is conventionally considered a pure low-spin comp...
Autores principales: | , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The Royal Society of Chemistry
2023
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10321519/ https://www.ncbi.nlm.nih.gov/pubmed/37416721 http://dx.doi.org/10.1039/d3sc00561e |
Sumario: | The novel vacuum-evaporable complex [Fe(pypypyr)(2)] (pypypyr = bipyridyl pyrrolide) was synthesised and analysed as bulk material and as a thin film. In both cases, the compound is in its low-spin state up to temperatures of at least 510 K. Thus, it is conventionally considered a pure low-spin compound. According to the inverse energy gap law, the half time of the light-induced excited high-spin state of such compounds at temperatures approaching 0 K is expected to be in the regime of micro- or nanoseconds. In contrast to these expectations, the light-induced high-spin state of the title compound has a half time of several hours. We attribute this behaviour to a large structural difference between the two spin states along with four distinct distortion coordinates associated with the spin transition. This leads to a breakdown of single-mode behaviour and thus drastically decreases the relaxation rate of the metastable high-spin state. These unprecedented properties open up new strategies for the development of compounds showing light-induced excited spin state trapping (LIESST) at high temperatures, potentially around room temperature, which is relevant for applications in molecular spintronics, sensors, displays and the like. |
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