Theoretical investigation of transition metal complexes with mechanochromic properties Maria Jaworska University of Silesia in Katowice, Poland Mechanochromic luminescent (MCL) materials have emission properties which can be changed upon external force stimulus (e.g., grinding or heating). They are extensively studied due to their widespread applications. The MCL mechanisms are attributed to the physical phase transformations accompanied by a change in the molecular 3+ ( 2) exhibit mechanochromism and AIE (Aggregation Induced Emission) properties. The theoretical calculations were performed for 1 and 2 with the DFT method. In the calculations, the rotations inside the ligands of complexes 1 and 2 were studied. This allowed identifying molecular motions associated with low energy in the excited triplet state and lead to radiationless deactivation in the solvent. Their blocking due to aggregation increases the intensity of phosphorescence. The change in wavelength due to mechanical actions involves a conformation change from which luminescence occurs. References 1. Sathish, A. Ramdass, P. Thanasekaran, K.-L. Lu, S. Rajagopal, Aggregation-induced phosphorescence enhancement (AIPE) based on transition metal complexes—An overview, Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 23 (2015) 25-44, conformations or molecular packing modes. Complexes (ppy) 2 Ir(oz) ( 1) and [Ru(bpy) 2 (pzta)]
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