Pyridinium-based symmetrical diamides as chemosensors in visual sensing of citrate through indicator displacement assay (IDA) and gel formation.

The design and synthesis of pyridinium-based symmetrical diamides 1 and 2 along with their anion binding studies through 'indicator-diplacement assay' are reported. Both the chemosensors effectively respond in in CH(3)CN-H(2)O (4 : 1 v/v) at pH = 6.3 for the selective naked-eye detection of citrate. Additionally, chemosensor 2 (c = 6.29 × 10(-3) M) forms a stable gel only with citrate in CH(3)CN, which validates its visual sensing.