The present book is especially designed for the students working in the field of synthesis and ionophore studies of macromolecules. These macromolecules have cations recognizing property and subsequently can be used to selectively transport cations across apolar membrane. Synthesis is of podands with two pyrimidinedione units linked at N1 & N3 with a carbon chain, which is structurally varied to incorporate heteroatoms or aryl groups have been discussed. These macro molecules have cation recognizing property and subsequently can be used to selectively transport cations across apolar membrane. Podands possessing two pyrimidinedione units and other ligating sites (o,s etc.) have been studied for their transport and extraction properties towards Li+, Na+, K+, Tl+ and NH4+ metal picrates. Ionophore character of benzimidazol 2 (1H)- one based Sulphur and/ nitrogen containing podands have also been studied. Ionophore character of ether -ester podands and macrocycles possessing ethyleneurea and benzimidazol-2 (1H) one units.