TAGRA 2025

Persistent radical-anions generating electrochemically or photochemically offer an exciting platform for investigation due to easily generation, structure–stability correlation, colour modulation and etc. A wide range of applications including molecular magnets, sensors, polymerization initiators, CO2 reduction and etc., have been developed recently for these intermediates [1-3]. Carbonyl compounds such as diimides or dianhydrides possessing low-lying frontier orbitals and known as organic π-acids, participate generally in electron transfer (ET) processes which engender persistent radical-anions. Herein, tetrachloroperylene dianhydride (TCP) is presented as a simple and capable electron accepting material that generate its colourful radical anion. This capability was utilized as a powerful and selective colorimetric sensing method to identify and determine some analytes. Many different anions including CN-, Halide anions, SCN- and etc., as well as different types of amines were investigated as electron donor in solution ET to TCP. Upon exposer to CN- and primary aliphatic amines, TCP solution was changed to a colourful state enabled colorimetric identification and determination of these species. Only CN- could participate in ET to TCP in between twenty examined anions and only primary aliphatic amines in between different various amines perform such a redox reaction, made TCP as a selective sensing agent. The response time of emerging detectable coloration was immediate in the case of CN-, while the amines have a two-step interaction with the substrate comprising a fast complexation followed by ET process with a 3h period. The ET process was followed using absorption and emission along with H NMR spectroscopy techniques. In order to evaluate the effect of the chemical structure of TCP comprising chlorine atoms and anhydride functionality on the ET interaction, the pristine perylene dianhydride and two imide counterparts were also checked which did not showed any comparable results. The following figure illustrates a representative scheme for the thermal ET process.