Supporting information Selective Recognition of Lithium (I) Ions using Biginelli based Fluorescent Organic Nanoparticles in aqueous medium Gaganpreet Kaur a , Amanpreet Singh, b P. Venugopalan, c Navneet Kaur* a,c , Narinder Singh* b a Centre for Nanoscience & Nanotechnology (UIEAST), Panjab University Chandigarh 160014, India. b Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001, India. c Department of chemistry, Panjab University, Chandigarh, 160014, India. *Corresponding authors. Table of contents Figure S1. (a) The absorbance and (b) the excitation spectra of compound 1 (5 µM) in DMSO and its nanoparticles, ONP (5 µM) in water. Figure S2. Changes in emission profile of ONP (5 μM) in water upon addition of 50 μM of particular metal nitrate salts (a) in absence of buffer (b) in presence of HEPES buffer, pH 7.4. Figure S3. Fluorescence spectra of ONP (a) before Li (I) binding (b) after Li (I) binding at different time intervals. (c) Absorbance spectra of ONP at different time intervals. Figure S4. (a) Absorbance spectra of ONP upon titration with Li (I); (b) Excitation spectra of ONP upon titration with Li (I) Figure S5. DLS histogram of ONP on interaction with (a) Li (I), 30 nm (b) Cs (I), 25 nm (c)Cr (III), 26nm (d) Al (III), 25 nm (e) Zn (II), 26 nm. Figure S6. Competitive experiment (a) in absence of buffer (b) in presence of HEPES buffer, pH 7.4. Figure S7. Fluorescence spectra of ONP at different pH values (a) acidic medium (b) basic medium (c) Fluorescence intensity vs pH profile (d) Absorbance spectra of ONP at different pH values. Figure S8. (a) DLS at pH=4.1, 25nm (b) DLS at pH= 8, 23nm (c) DLS at pH= 11, 25nm Figure S9. Fluorescence spectra of ONP on addition of different concentrations of tetrabutylammonium perchlorate to evaluate the salt effect. Figure S10. Packing diagram of 1. Figure S11. (a) 1-HNMR (b) 13C-NMR of compound 1. Electronic Supplementary Material (ESI) for RSC Advances. This journal is © The Royal Society of Chemistry 2015