Abstract An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran- 2-ones, benzo [h] chromene and thiochromeno [4, 3-b] pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ...