Expanded porphyrins are macrocyclic compounds where pyrrole and/or heterocyclic rings are connected to each other through meso carbon bridges. The interests in such systems are two-fold; (a) their potential applications as anion, cation and neutral substrate receptors, photosensitizers, MRI contrasting agents and non-linear optical materials; (b) they exhibit range of structures such as normal (i), inverted (ii), fused (iii) and bridged (iv), depending on how the heterocyclic rings are linked to each other. The electronic structure of the macrocycle varies according to the structure, the macrocycle crystallizes and hence both aromatic and non-aromatic systems have been isolated. This talk will focus on the structural diversity exhibited by macrocycles (i – iv) and their applications as; (i) anion/Cation receptors, (ii) non linear optical materials, and (iii) photosensitizers for photodynamic therapy (PDT).