10.1016/j.cclet.2011.03.006
The research investigates the influence of a bromoalkyloxy side chain on the mesomorphic behavior of a new homologous series of isoflavone-based ethers, specifically 7-(4-bromoalkyloxy)-3-(4'-decyloxyphenyl)-4H-1-benzopyran-4-ones. The purpose is to understand how structural modifications, particularly the presence of a bromine atom in the alkyloxy side chain, affect the liquid crystalline properties of these compounds. Resorcinol (1,3-dihydroxybenzene) is used as a core reactant in the synthesis of the isoflavone-based ethers. 1-Bromodecane is used as a reactant to introduce the decyloxy (C10H21O) side chain into the molecular structure of the target compounds. Differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) were employed to study the mesomorphic properties. The results showed that all homologues exhibited a stable enantiotropic smectic A (SmA) phase, independent of the side chain length. The bromine atom in the alkyloxy chain was found to facilitate lamellar packing due to its polarizability and polarity, leading to the formation of the SmA phase. However, it also prevented the formation of the smectic C (SmC) phase due to steric effects when molecules are tilted. The study concluded that the stability of the mesophase is due to the polar bromine atom, the planarity and enhanced polarity of the ether linkages, and the heterocyclic central moiety. This research provides insights into the structure–property relationships in liquid crystalline compounds, which can be useful for designing materials with specific mesomorphic behaviors.