Journal of Materials Chemistry C 1 Carboxyl-functionalized ionic liquids: synthesis, characterization and synergism with rare earth ions Talita J. S. Ramos, a Guilherme H. Berton, b Tania M. Cassol, b Severino A. Júnior a* a Laboratório de Terras Raras, Departamento de Química, Centro de Ciências Exatas e da Natureza (CCEN), Universidade Federal de Pernambuco, Recife – PE, 50740-560, Brazil. b Grupo de Líquidos Iônicos e Metais, Departamento de Química e Biologia, Universidade Tecnológica Federal do Paraná, São Francisco Beltrão – PR, 85601-970, Brazil. *Corresponding author: salvesjr@ufpe.br Summary Experimental Procedure.................................................................................................02 Characterization Procedure............................................................................................03 NMR Studies...................................................................................................................04 Elemental Analysis..........................................................................................................10 Infrared Spectroscopy (FTIR)..........................................................................................10 Raman Spectroscopy......................................................................................................14 Physical-Chemical Properties.........................................................................................27 Thermogravimetric Analysis (TGA) ................................................................................28 UV-Vis Spectrophotometry.............................................................................................29 Photoluminescence Characterization.............................................................................31 Computational Modelling...............................................................................................41 References......................................................................................................................55 Electronic Supplementary Material (ESI) for Journal of Materials Chemistry C. This journal is © The Royal Society of Chemistry 2018