Synthesis and Phase Behaviour of Some New Isoflavone Derivatives

Abstract

An overview on new isoflavones comprising 7- and 3-disubsituted-4H-1-benzopyran-4-ones has been carried out. The derivatives thus obtained exhibit different molecular orientation and phase sequences as evident by texture observation under polarized light as well as differential scanning calorimetry. Typical examples from these newly derived isoflavones include those compounds possessing butanoyloxy and hexanoyloxy groups at both 7- and 3-position in benzopyran-4-ones which favour the nematic phases. The compounds attached by heptanoyloxy and longer side chains at both 7- and 3-positions show SmC phase. The monotropic SmC phase has been observed for the compound with octadecanoyloxy moiety only. The analogues 7-decanoyloxy-3-(4′-substitutedphenyl)- 4H-1-benzopyran-4-one possessing different substituents at 4′-position exhibiting various polymorphism. The results on the structural changes, the electronic polarizability, the presence of lateral dipole associated with the intermolecular interaction within the mesophase and the crystal structure at solid phase in the derivatives containing 3-methylbutyloxy group at 4′-position will also be discussed.