Physico-Chemical Properties of New Liquid Crystals Incorporating a Benzofuran-2-one Skeleton

The liquid crystal properties of 3H-2-oxobenzofuran-6-yl 4-(n-C n H 2n+1 O)benzoates (1-n, n = 5-12), 4'-(n-C n H 2n+1 O)biphenyl-4-carboxylates (2-n, n = 6-10), and 4-(n-C n H 2n+1 )benzoates (3-n, n = 4-6) are described. The n = 5-8 homologues of 1-n exhibit a nematic (N) phase, and the n = 8-12 homologues exhibit a smectic A (SmA) phase, where the layer spacing is ca. 1.3 times of the calculated molecular length. The homologues of 2-n show a complex phase-transition behavior involving a smectic C (SmC), two kinds of SmA, reentrant nematic, and N phases, where the SmC phase is exhibited by the n = 6-8 homologues. The layer spacings of SmA phases formed at high and low temperature regions correspond to 1.3 and 1.0 times of the molecular lengths, respectively. The polar interactions around the terminal lactone moiety are assumed to play important roles for the complex polymesomorphism and diversity of the smectic layer structure.