Tp Synthesis Lab Report
The structure and synthesis of TPC is outlined in Scheme 1. Briefly, the compound 1 was synthesized as per literature procedure. 2 was synthesized by reacting 1-methy pyrazole-4-boronic pinacol ester with 1 by suzuki-coupling, the final product TPC was synthesized by treating with malononitrile in the presence of piperidine as a base and ethanol as solvent. The detailed synthesis procedure given in the experimental section. The structure and purity of TPC was unambiguously confirmed by 1H and 13C NMR spectroscopy. The synthesized TPC is red in color and appeared non-fluorescent, the fluorescence of triphenylamine was completely switched-off in solid state. The UV-visible spectrum shows the strong absorbance at 460 nm and at 310 nm. In order to check the interference anions, sodium salt of various anions likes F‾, AcO‾, H2PO4‾, Cl‾, Br‾, I‾, NO3‾ were added and found no significant change, while adding CN‾ ion the peak at 460 nm completely decreased along with the peak at 310 nm enhanced (Figure S1). Further, the titration of cyanide addition to TPC was conducted, during the addition by increasing cyanide ion concentration the peak at 460 nm gradually decreased with the simultaneous enhancement of peak at 310 nm, the color also changes from red to colorless in fraction of seconds (Figure 1a, 1b). This remarkable color and spectral changes happened with cyanide is due to the addition of cyanide ion at the β-position of vinyl
…show more content…
malononitrile attached with triphenylamine, due to this addition the conjugation between the triphenylamine fluorphore and malononitrile acceptor was disturbed and result in the change in spectral and color. The detection limit of TPC for CN‾ was found to be 44 nM (Figure S2), which is much lower than the permissible level of WHO (1.9 µM).
TPC exhibit moderate fluorescence intensity at 400 nm when excited at 320 nm.
Upon the addition of CN‾ ion, increase in the fluorescence intensity of TPC at 400 nm was observed (Figure 2a). TPC exhibits strong yellow color under the 365 nm light and the color switched to blue fluorescence after the immediate addition of CN‾ anion (Figure 2b), so TPC exhibits the fluorogenic sensing for CN‾ anion, this further support our mechanism by the fluorophore is switching its fluorescence nature after the breaking of conjugation to the
acceptor.
malononitrile attached with triphenylamine, due to this addition the conjugation between the triphenylamine fluorphore and malononitrile acceptor was disturbed and result in the change in spectral and color. The detection limit of TPC for CN‾ was found to be 44 nM (Figure S2), which is much lower than the permissible level of WHO (1.9 µM).
TPC exhibit moderate fluorescence intensity at 400 nm when excited at 320 nm.
Upon the addition of CN‾ ion, increase in the fluorescence intensity of TPC at 400 nm was observed (Figure 2a). TPC exhibits strong yellow color under the 365 nm light and the color switched to blue fluorescence after the immediate addition of CN‾ anion (Figure 2b), so TPC exhibits the fluorogenic sensing for CN‾ anion, this further support our mechanism by the fluorophore is switching its fluorescence nature after the breaking of conjugation to the
acceptor.