Spectroscopic in situ studies of the mechanochemical formation of luminescent complexes directly from metal (hydr)oxide precursors Thomas Auvray 1 , Tristan H. Borchers 1,2 , Christopher J. Barrett 2 and Tomislav Friščić 1,2* 1 School of chemistry, University of Birmingham, University Road W., Birmingham B15 2TT, UK 2 McGill University, Department of Chemistry, 801 Rue Sherbrooke O., Montréal (QC) H3A 0B8, Canada Due to their exciting photophysical properties, quinolin-8-olate coordination compounds have been thoroughly studied, with particular attention given to the tris-(quinolin-8-olate) Al(III) complex (AlQ 3 ) which is commonly used in organic light emissive devices (OLEDs). [1] As part of the on-going effort to develop faster, safer and cleaner synthetic protocols through mechanochemistry, relying on the use of mechanical forces to initiate and sustain chemical reactions, we decided to re-investigate the mechanochemical synthesis of this class of emissive complexes, previously explored by the James group using basic metal acetate precursors, leading to the formation of acetic acid solvates. [2] We chose to optimise a mechanochemical route based on oxide-hydroxide precursors to enhance the sustainability of the process, with water as the sole by-product. The mechanosynthesis of such complexes constitutes an exciting platform to further develop in situ Raman and fluorescence monitoring methods for mechanochemistry, [3,4] thanks to the strong correlation between solid-state structure and luminescent properties. By combining ex situ (NMR, PXRD) and in situ (fluorescence and Raman spectroscopies) monitoring, we optimised the solid-state synthesis conditions for the targeted luminescent complexes, with control over the final product properties based on reaction conditions. References 1. M. Brinkmann, G. Gadret, M. Muccini, C. Taliani, N. Masciocchi, and A. Sironi, J. Am. Chem. Soc., 2000, 122, 5147–5157. 2. X. Ma, G.K. Lim, K.D.M. Harris, D.C. Apperley, P.N. Horton, M.B. Hursthouse, and S.L. James, Cryst. Growth Des., 2012, 12, 5869–5872. 3. P.A. Julien, M.Arhangelskis, L.S. Germann, M. Etter, R. E. Dinnebier, A.J. Morris and T. Friščić, ChemRxiv, 2021, 10.26434/ chemrxiv-2021-lw8sm 4. P.A. Julien, I. Malvestiti and T. Friščić, Beilstein J. Org. Chem., 2017, 13, 2160–2168.
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