Synthesis, mesomorphic properties and X-ray diffraction studies on7-alkyloxy-3-(4-alkyloxypheny1-4H-1-benzopyran-4-one: Crystal structureof 7-hexyloxy-3-(4-hexyloxypheny1)-4H-1-benzopyran-4-one

摘要

Eight new compounds, 7-alkyloxy-3-(4-alkyloxyphenyl)-4H-1-benzopyran-4-one incorporating isoflav-one core and identical terminal side chains, OR (where R = C?H2n+1 with n ranging from 4 to 18 ineven parity) have been synthesized and isolated. The thermal stability in relation to the phase behav-iour and respective enthalpy values of these compounds were analyzed using differential scanningcalorimetry. The texture of the preferred molecular orientation at different temperatures wasobserved under polarized light wherein all compounds exhibited nematic (N), smectic A (SmA) andsmectic C (SmC) phases. The difference in mesogenicity of these compounds was also investigatedfrom the viewpoints of conformation and polarity of the side chains which contributed remarkablytowards the change in the intermolecular interaction within the mesophase. X-ray diffraction tech-nique was employed to investigate the molecular packing associated with the intermolecular interac-tion as well as the correlation between the thermal behaviour of these compounds with theiranisotropy properties within a mesophase. The molecular structure of compound 7-hexyloxy-3-(4-hexyloxyphenyl)-4H-1-benzopyran-4-one in crystal phase was confirmed by single-crystal X-raydiffraction.