Click chemistry inspired synthesis of andrographolide triazolyl conjugates for effective fluorescent sensing of ferric ions.

The naturally occurring compound andrographolide was used as a substrate for the synthesis of a novel terminal alkyne which on copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction with azides , and furnished a series of regioselective andrographolide triazolyl conjugates and , respectively. A free glycoconjugate was also prepared by selective deprotection of compound in good yield. All the compounds were characterized by absorbance, FT-IR, NMR, and HR-MS analyses. The triazolyl conjugate was further investigated as a probe for selective detection of Fe ion in matrix. The mode of attachment of Fe ion to the compound was established by absorbance, fluorescence, infrared (IR), and nuclear magnetic resonance (NMR) spectroscopy, and high resolution mass-spectrometry (HR-MS). The logic gate circuits were constructed for the probe and ethylenediaminetetraacetic acid (EDTA). The environmental perspective of probe was investigated in real water samples.