Proton-Induced Spin State Switching in an FeIII Complex |
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| Authors: | Dr Conor T Kelly Sean Dunne Dr Irina A Kühne Dr Andrew Barker Dr Kane Esien Dr Solveig Felton Dr Helge Müller-Bunz Dr Yannick Ortin Prof Grace G Morgan |
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| Institution: | 1. School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland;2. Centre for Nanostructured Media, School of Mathematics and Physics, Queen's University Belfast, BT7 1NN Belfast, UK |
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| Abstract: | Reversible proton-induced spin state switching of an FeIII complex in solution is observed at room temperature. A reversible magnetic response was detected in the complex, FeIII(sal2323)]ClO4 ( 1 ), using Evans’ method 1H NMR spectroscopy which indicated cumulative switching from low-spin to high-spin upon addition of one and two equivalents of acid. Infrared spectroscopy suggests a coordination-induced spin state switching (CISSS) effect, whereby protonation displaces the metal-phenoxo donors. The analogous complex, FeIII(4-NEt2-sal2323)]ClO4 ( 2 ), with a diethylamino group on the ligand, was used to combine the magnetic change with a colorimetric response. Comparison of the protonation responses of 1 and 2 reveals that the magnetic switching is caused by perturbation of the immediate coordination sphere of the complex. These complexes constitute a new class of analyte sensor which operate by magneto-modulation, and in the case of 2 , also yield a colorimetric response. |
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| Keywords: | Colorimetric Host–Guest Systems NMR Spectroscopy Protonation Spin Crossover |
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