title: Effects of auxiliary ligands of Pd(II) dimers on induction of chiral nematic phases: chirality inversion and the photo-responsive structural change.
abstract: Dinuclear square planar palladium(ii) complexes, [{Pd(ii)La}2(baet)] (La(-) = β-diketonato and baet(2-) = 1,2-diacetyl-1,2-bis(3-methylbutanoyl)ethanato), were prepared and used as chiral dopants to induce chiral nematic phases. The following β-diketones were used as LaH: pentane-2,4-dione (acacH), dibenzoylmethane (dbmH), di-4-nonyloxybenzoylmethane (C9-dbmH) and 3-[4'-(4''-(octyloxy)phenylazo)phenyl]-2,4-dione (C8-azoacacH). When the enantiomers were doped in a nematic liquid crystal, they induced a chiral nematic phase with a helical twisting power (HTP) of 5-50 μm(-1). In particular, the sample doped with [{Pd(ii)(C8-azoacac)}2(baet)] exhibited a reversible change of the circular dichroism spectrum under alternate irradiation at 350 nm and 460 nm. It implied that the HTP changed reversibly in response to the cis-trans isomerization of the coordinated C8-azoacac ligand.
authors.affiliation: National Institute of Materials Science, Tsukuba 305-0044, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Tamura
authors.forename: Jun
authors.initials: J
authors.lastname: Yoshida
authors.forename: Masahiro
authors.initials: M
authors.lastname: Taniguchi
authors.forename: Takafumi
authors.initials: T
authors.lastname: Kitazawa
authors.forename: Akihiko
authors.initials: A
authors.lastname: Yamagishi
authors.forename: Hisako
authors.initials: H
authors.lastname: Sato