The metal catalyzed oxidation reaction in a simple rhodamine–carbazole dyad (a carbazole nucleus flanked by two rhodamine moieties) was carried out in the presence of CAN. This sensor displays a very fast response (<1 min) toward CAN at room temperature with a ‘naked-eye’ change. This TBET based sensor is also highly selective and sensitive towards CAN. The chemosensor showed excellent performance in the “dip-stick” method.