Synthesis and Chemosensory Studies of a Heterocyclic Thiosemicarbazone as a New Tributyltin Optical Chemosensor

Abstract

Thiosemicarbazones are a versatile type of organic compounds which are known for their coordination ability with different types of analytes, due to the presence of sulfur and nitrogen heteroatoms. Therefore, the functionalization of thiosemicarbazones with heterocyclic moieties can be a promising route to developing new optical chemosensors. Tributyltin (TBT) is an antifouling component of paints that is acutely toxic to aquatic environments, being quickly absorbed by microorganisms and causing problems such as imposex. Herein, the synthesis of a novel heterocyclic thiosemicarbazone, functionalized with a quinoline moiety, is reported to assess the potential of this recognition moiety for TBT optical chemosensing. A preliminary chemosensory study in acetonitrile solution was performed showing that 50 equivalents of TBT were needed to induce a change of color from colorless to yellow. Spectrophotometric titration was performed to assess the concentration of TBT necessary for a maximum optical signal, revealing that 100 equivalents of TBT were necessary to reach maximum absorbance, although it was able to respond with a detectable color change to a TBT concentration as low as 10 µM.