No abstract

The olefin cross-metathesis reaction using the second-generation Grubbs catalyst was employed to prepare non-symmetrical thermotropic liquid crystals from various mesomorphic or nonmesomorphic type I and type II olefinic constructs, including linear, chiral, dendritic and ferrocenyl olefins. Smectic C, smectic A and nematic phases, as well as chiral smectic

A liquid-crystalline mixed [5 : 1]hexa-adduct of [60]fullerene was synthesized by addition of two different malonate derivatives onto C 60 . The hexa-adduct derivative 2 was prepared by a stepwise synthetic procedure (fullerene ! mono-adduct of C 60 ! hexa-adduct of C 60 ). Cyanobiphenyl and octyloxybiphenyl derivatives were selected as mesogens. The malonate derivatives showed either a monotropic nematic phase or a monotropic smectic A phase, and the hexa-adduct derivative gave rise to an enantiotropic smectic A phase. The versatile chemistry of C 60 prompted us to design liquid-crystalline hexa-adducts to explore the behavior of mesogens in a spherical environment. The first hexa-adduct of C 60 was synthesized previously from malonate 1 (see Scheme below), which gave rise to a smectic A phase [2c]. Recently, we described a chiral hexa-adduct of C 60 , which was prepared from a laterally-branched optically active mesogen. A chiral nematic phase was observed [2m]. Besides our work, other mesomorphic hexa-adducts of C 60 were reported. Diederich and co-workers described a hexa-adduct containing eight Et groups and four mesogenic cyanobiphenyl units. This compound afforded a nematic phase during the first heating run [3]. Felder-Flesch et al. reported two hexa-adducts of C 60 containing either twelve mesogenic cholesterol units, or ten mesogenic cholesterol units and two non-mesogenic groups. Both compounds showed a smectic A phase [6]. In all the above-mentioned cases, the observed liquid-crystalline properties are in