1 Electronic Supplementary Information (ESI†) Modified mesoporous silica optical nanosensor for selective monitoring of multiple analytes in water Madhappan Santha Moorthy, Hun-Jeong Cho, Eun-Jeong Yu, Young-Sik Jung and Chang-Sik Ha* Department of Polymer Science and Engineering, Pusan National University, Busan-609-735, Korea. Experimental 4-aminomethylpyridine, salicylaldehyde, cetyltrimethylammonium bromide (CTAB), tetraethyl orthosilicate (TEOS), 3-(Triethoxysilyl)propylisocyanate (ICPTES) and ethylenediaminetetraacetic acid (EDTA) were analytical grade. All chemicals and reagents were obtained from Sigma-Aldrich, USA, and used as-received. Synthesis of sensor probe 1 1.77 g (0.016 mmol) of 4-aminomethylpyridine in 10 mL of methanol was slowly added into a reaction flask containing 2.0 g (0.016 mmol) salicylaldehyde in 40 mL of methanol, and the reaction mixture was stirred at room temperature for 3 h. Upon reaction completion, the solvent was removed under reduced pressure and the obtained product was then purified using silica gel by eluting with 3:7 ethyl acetate/hexane mixture. The yield of sensor probe 1 was 86 %. 1 H NMR (400 MHz, MeOH-d4): δ H 1.89 (t, 4H, CH 2 ), δ H 4.1 (t, 4H, CH=N), δ H 6.6–7.3 (m, 18H, aromatic). 13 C NMR (400 MHz, MeOH-d4): δ C 27.8 (CH 2 ), δ C 46.3 (CH=N), δ C 135–142 (aromatic). FTIR (KBr): 2848, 2916 cm -1 (υ C-H ), 1617 cm -1 (υ C=N ), 1454 cm -1 (υ C=C ), 1264 cm -1 (υ C-O-H ). Synthesis of silylated SAPy precursor 1.0 g (0.04 mmol) of sensor probe 1 was dissolved in 10 mL of dry tetrahydrofuran (THF). To this, 1.16 g (0.047 mmol) of ICPTES was added with vigorous stirring under nitrogen Electronic Supplementary Material (ESI) for Chemical Communications This journal is © The Royal Society of Chemistry 2013