S1 Cationic Red-Emitting Probes for the Rapid and Selective Detection of SO 2 Derivatives in Aqueous and Cellular Environment Palash Jana # , Nishaben Patel § , Virupakshi Soppina § and Sriram Kanvah # * # Department of Chemistry and § Department of Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar Palaj-382355 *sriram@iitgn.ac.in; § vsoppina@iitgn.ac.in Supporting Information Fig. S1 Excitation spectra of dye 1 & 2 S2 Fig. S2 Real emission spectra of dye 1 & dye 2 S2 Fig. S3 The emission of dyes 1 and 2 obtained at the corresponding isosbestic points (450 nm for 1 and 475 nm for 2). S3 Fig. S4 Visual detection of dyes 1 & 2 with the different concentration of SO 3 2- anion S4 Fig. S5 Kinetic response of dyes 1 & 2 in PBS buffer solution S5 Fig. S6 Fluorescence spectra of dyes 1 & 2 (10M) in PBS buffer solution with the addition of different concentration of [SO 3 2- ]/M S5 Fig S7 Limit of Detection: Relationship between fluorescence intensity of dyes 1 & 2 with the concentration of sulfite from 0-30M SO 3 2- in PBS buffer solution S6 Fig. S8 a) Sulfite detection in H 2 O for dye 1 and b) dye 2 S6 Fig. S9 Absorbance spectra of dye 1 & 2 with various analytes in PBS buffer. S7 Fig. S10 Fluorescence spectra of dye 1 & 2 with various analytes in PBS buffer solution S7 Fig. S11 Competitive fluorescence spectra of dye 1 & 2 with various analytes including sulfite ion in PBS buffer solution S8 Fig. S12 Mass spectra of compound [1-SO 3 - + H + ] S9 Fig. S13 Mass spectra of compound [2-SO 3 H + H + ] S9 Fig. S14 Cytotoxicity S10 Fig. S15 Time dependent 1 H-NMR spectrum of dye 1 after 1hr S11 Fig. S16 Time dependent 1 H-NMR spectrum of dye2 after 1hr S11 Fig. S17-S22 NMR Spectral characterization of Compounds S12-S15 Electronic Supplementary Material (ESI) for New Journal of Chemistry. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2018