3 amino 5 hydroxypyrazole

4-Bromo-2-(1H-pyrazol-3-yl)phenol (Pz1), 4-nitro-3-pyrazolecarboxylic acid (Pz2), N-(benzyloxycarbonyl)-1H-pyrazole-1-carboxamidine (Pz3), 3-amino-5-hydroxypyrazole (Pz4), and 3,5-pyrazoledicarboxylic acid monohydrate (Pz5) were commercial products purchased from Sigma-Aldrich Co.

3-Amino-5-hydroxypyrazole and m-anisaldehyde were purchased from Sigma Aldrich and were used as received. The solvents were purchased from Merck and used without further purification. The completion of reaction was monitored by thin layer chromatography (TLC) performed on pre-coated silica-gel plates (Merck, India) and spots were visualized by UV irradiation. FT-IR spectral measurements were recorded on Perkin-Elmer spectrometer version 10.03.09 (KBr pellet technique). ¹H and ¹³C NMR were obtained using a 500 MHz Bruker Avance DPX spectrometer with TMS as internal standard. HR-ESI-MS analysis was performed on a Thermo Scientific Exactive mass spectrometer by electrospray ionization technique. The electronic absorption spectra were recorded using UV1800 spectrophotometer (Shimadzu). Steady-state fluorescence experiments were performed with a SPEX Fluorolog F112X spectrofluorometer by using optically dilute solutions.