2.1 Reagents and instruments
Reagents, solvents, and metal cationic samples (Na+, K+, Cs+, Cu+, Ca2+, Mg2+, Zn2+, Mn2+, Co2+, Pb2+, Ni2+, Cu2+, Fe2+, Hg2+, Cd2+, Ba2+, Fe3+, Y3+) used for synthesis and binding experiment. It was prepared with chloride, nitrate, and sulfate salts, and each reagent was purchased from Alfa Aesar (UK), Sigma-Aldrich (Munich, Germany), Samjeon Pure Chemical Industries (Daejeon, Korea), and Daejeonghwageum (Siheung, Korea). These reagents used without further purification. 13C and 1H NMR were measured at 126 MHz, 500 MHz, and 400 MHz with a Bruker Avance (Germany) NMR Spectrophotometer using DMSO-d6. Mass spectrometry (LC-MS) was measured using a 2975/ZQ2000 (waters) spectrometer. Infrared analysis was measured using a Frontier IR spectrophotometer (Perkin Elmer, USA). The process of the reaction was judged using TLC, and ultraviolet-visible absorption analysis was studied using a UV-2600 UV-Vis spectrophotometer of Shimadzu Corporation (Kyoto, Japan). Fluorescence analysis was measured using FluoroMate FS-2 from Scinco (Seoul, Korea).
2.2 Synthesis of ethyl 4-bromobenzoate b
4-bromobenzoic acid a (2.25 mmol) was added to ethanol with sulfuric acid and heated to 70-80°C for 5 hours. The progress of the reaction was confirmed by TLC. Thereafter, ethanol was obscure under concentrated pressure, 100 ml of water was added to the residue, the reaction mixture was neutralized with sodium carbonate, and take out with ethyl acetate. The organic layer was removed with anhydrous sodium sulfate, and the solvent was evaporated under concentrated pressure to attain a solid product b (yield 83%). These were used as such in the next step without purification.
2.3 Synthesis of 4-bromobenzohydrazide c
Ethyl-4-bromobenzoate b (1.0 mmol) produced in the previous step was dissolved in ethanol, hydrazine hydrate (1.5 mmol) was added, and the mixture was refluxed for 5 hours. After completion of the reaction, ethanol was removed under reduced pressure, and the resulting solid was put in methanol and heated to dissolve it, and insoluble matter was filtered and stored in a fume hood for recrystallization. After recrystallization, a solid product c was obtained (yield 75%)
2.4 Synthesis of 4-amino-5-(4-bromophenyl)-4H-1,2,4-triazole-3-thiol e
4-bromobenzhydrazide c (1.0 mmol) was added to ethanol together with potassium hydroxide (1.5 mmol) and carbon disulfide (1.2 mmol), followed by stirring at 0 °C for 5 minutes. When the mixture was dissolved, diethyl ether was added thereto and filtered to obtain an intermediate salt d. Then, hydrazine hydrate (2.0 mmol) and distilled water were added and reacted overnight at 120 °C. After the reaction was completed, the reaction mixture was poured into distilled water (50 ml) and acidified with 5N HCl solution. Then, the resulting solid was filtered, washed with distilled water, stored in a fume hood for recrystallization, and dissolved in methanol. After recrystallization, a solid triazole intermediate product e was obtained (yield 90%). It was used as it is in the next step without purification.
2.5 Synthesis of (E)-5-(4-bromophenyl)-4-((pyren-1-ylmethylene)amino)-4H-1, 2, 4-triazole-3-thiol, TP
4-amino-5-(4-bromophenyl)-4H-1,2,4-triazole-3-thiol e (0.337 mmol) and 1-pyrenecarboxy-aldehyde (0.337 mmol) were added to methanol together with hydrochloric acid (2 drops) and reacted at 70° C for 3 hours. After completion of the reaction, the solid product was filtered and washed with ethanol, methanol and distilled water. After that, a dry and pure solid product TP was obtained (yield 90%).
(E)-5-(4-bromophenyl)-4-((pyren-1-ylmethylene)amino)-4H-1,2, 4-triazole-3-thiol (TP)
Yellow Solid; yield: 90%; 1H NMR (500 MHz, DMSO-d6) δ 14.42 (s, 1H, SH), 10.91 (s, 1H. Imine CH), 8.74 (s, 1H. Ar), 8.69 – 8.66 (m, 1H, Ar), 8.47 – 8.40 (m, 4H, Ar), 8.38 (d, J = 8.9 Hz, 1H, Ar), 8.30 (d, J = 8.9 Hz, 1H, Ar), 8.18 (t, J = 7.6 Hz, 1H, Ar), 8.04 – 7.97 (m, 1H, Ar), 7.95 (d, J = 8.6 Hz, 2H, Ar), 7.81 (d, J = 8.6 Hz, 2H, Ar), 7.76 (d, J = 8.6 Hz, 1H, Ar). 13C NMR (126 MHz, DMSO) δ 164.60, 162.46, 147.95, 133.82, 131.78, 130.60, 130.55, 130.29, 129.90, 129.73, 129.69, 127.28, 126.83, 126.77, 126.51, 125.32, 125.16, 124.74, 124.34, 124.32, 123.82, 123.36, 122.06. IR (KBr) 3098.96, 2927.63, 1907.86, 1740.51, 1624.75, 1592.96, 1573.90, 1535.62, 1497.98, 1422.23, 1397.63, 1375.87, 1320.02, 1303.63, 1272.79, 1258.45, 1234.21, 1184.89, 1165.36, 1139.68, 1108.18, 1072.05, 1013.18, 974.63, 901.95, 843.80, 820.18, 790.81, 766.89, 756.76, 733.10, 682.73cm-1; (ESI, m/z), 485.4 [M+2].