1 Selective Zn 2+ sensing using a modified bipyridine complex Mahesh Akula, Patrick El Khoury, Amit Nag * and Anupam Bhattacharya * Birla Institute of Technology and Science-Pilani(Hyderabad Campus), Hyderabad-500078, Andhra Pradesh, India e-mail: anupam@hyderabad.bits-pilani.ac.in. amitnag@hyderabad.bits-pilani.ac.in. SUPPORTING INFORMATION Contents: Scheme & procedure for preparation of ligands S1-S6: Characterization ( 1 H & 13 C NMR) S7: MALDI of the complex (PPQ-Zn-PPQ) S8: Reversibility experiment S9: Fluorescence titration S10: pH titration S11: Ratiometric sensing S12-14: MALDI (with Co 2+ , Ni 2+ and Cu 2+ ) S15: UV-Visible spectra of PPQ S16: TD DFT studies of PPQ and PPQ-Zn 2+ -PPQ Electronic Supplementary Material (ESI) for RSC Advances. This journal is © The Royal Society of Chemistry 2014