Mechanistic Insight of Vanillin-BODIPY as a Potential Cyanide Colorimetric Sensor Rian Febriyana Putra, Yunita Purnamasari, Dikhi Firmansyah
Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology
Jalan Ganesha 10, Bandung 40132, Indonesia
*dikhfi[at]itb.ac.id
Abstract
Cassava primarily contains the cyanogenic glycoside linamarin, along with smaller amounts of lotaustralin, both of which contribute to its hydrogen cyanide content. The concentrations ranged from approximately 1 to 1550 ppm in the root parenchyma and from 900 to 2000 ppm in the root cortex. Meso-phenolic Boron dipyrromethene (BODIPY) is a promising cyanide detector that can undergo nucleophilic substitution. Phenolic BODIPY can undergo tautomerization under basic conditions, resulting in a red-shifted absorption. This study explored the mechanistic properties of BODIPY molecules substituted with vanillin in their function as cyanide sensors. BODIPY-based sensors have been extensively reported because of their advantageous photophysical and chemical properties, including exceptionally high molar absorptivity, remarkable photostability and chemical robustness, and superior fluorescence quantum yields. The syntheses of vanillin dipyrromethane and vanillin BODIPY afforded yields of 65% and 96% respectively. The addition of cyanide ions as the TBA salt (10 equivalents, 10 mM), followed by a color change from yellow to orange, caused the absorption peak in UV-Vis experiments to decrease from 495 to 477 nm, while an additional increase in absorption was observed at 573 nm. NMR studies of vanillin-BODIPY showed clear differences before and after the addition of TBACN, the signal intensity decreased, and both the pyrrolic and methoxy peaks shifted. These results indicate that upon interaction with cyanide ions, vanillin-BODIPY undergoes tautomerization to its phenolic form. The interaction of the cyanide ion with vanillin-BODIPY resulted in the reduction of the probe and subsequent quenching of emission in the luminescence spectra. The limit of detection (LoD) determined from titration experiments with TBACN at different concentrations was 3,82 ppm. This study opens up the potential for further development of BODIPY derivatives for the direct detection of cyanide ions.
