Synthesis and Chemosensing Properties of Indole Based Donor–π–Acceptor Dye Material

In this work, we have designed and synthesized a new chemosensor for the detection of various metal ions. The chemosensor named 2-[2-(1 H-indole-2-ylmethylene)-3-oxo-indan-1-yliden]-malononitrile was synthesized using 3-formyl indole and 2-(3-oxo-indan-1-yliden)-malononitrile. This chemosensor has been investigated the properties which are able to detect and recognize the detection function of heavy metal ions. D–π–A system of dye chemosensor between electron withdrawing malononitrile and electron donating indole moieties provides the functions to interact with target metal ions. These recognizing sensing effects were studied using the absorption behaviors. Furthermore, cyclic voltammogram was used to determine HOMO/LUMO energy levels from their redox onset points. Measured energy levels of HOMO/LUMO were compared with computational calculation and discussed in details. Finally, the interaction type of metal ions binding was determined by Job's plot measurements.