Auxiliary alkyl chain modulated spin crossover behaviour in [Fe(H2Bpz2)2(Cn-bipy)] complexes
(2021) Dalton Transactions — (2021)
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- Abstract
- Three new alkyl chain substituted complexes [Fe(H2Bpz2)2(Cn-bipy)] (pz = pyrazolyl, Cn-bipy = bipyridine alkyl chain diester, n = 3 (3), 4 (4) and 5 (5)) show versatile spin state switching behaviour with different “tail” length as revealed by structural and magnetic analysis. The most striking phenomenon is observed for 5 which undergoes an abrupt spin transition accompanied by thermal hysteresis of ca. 10 K, which is attributed to crystal packing effects derived from the competition between π···π and C-H···O interactions. Interestingly, each of the complexes exhibits similar gradual and complete spin crossover in methanol solution with a transition temperature around 249 K, as deduced from temperature-dependent UV-vis spectroscopy. This highlights the differences between solid state (ligand field; crystal packing) and solution (ligand field; solvation) effects on spin crossover. This work demonstrates that the length of the complex’s alkyl chain substituents on the complex can have a large impact on the transition temperature and profile of solid state spin crossover, offering a potential path to the fabrication of soft matter spin crossover materials.
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Guo, Y., Rotaru, A., Müller-Bunz, H., Morgan, G. G., Zhang, S., Xue, S., & Garcia, Y. (2021). Auxiliary alkyl chain modulated spin crossover behaviour in [Fe(H2Bpz2)2(Cn-bipy)] complexes. Dalton Transactions. Accepted/in-press. https://hdl.handle.net/2078.5/108883 (Original work published 2021)