title: A molecular leverage for helicity control and helix inversion.
abstract: The helical tetranuclear complex [LZn(3)La(OAc)(3)] having two benzocrown moieties was designed and synthesized as a novel molecular leverage for helicity control and helix inversion. Short alkanediammonium guests H(3)N(+)(CH(2))(n)NH(3)(+) (n = 4, 6, 8) preferentially stabilized the P-helical isomer of [LZn(3)La(OAc)(3)], while the longer guest H(3)N(+)(CH(2))(12)NH(3)(+) caused a helix inversion to give the M-helical isomer as the major isomer. The differences in the molecular lengths were efficiently translated into helical handedness via the novel molecular leverage mechanism using the gauche/anti conversion of the trans-1,2-disubstituted ethylenediamine unit.
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki, Japan. akine@chem.tsukuba.ac.jp
authors.forename: Shigehisa
authors.initials: S
authors.lastname: Akine
authors.forename: Sayaka
authors.initials: S
authors.lastname: Hotate
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Nabeshima
mesh_terms: D001554:Benzene / Q000737:chemistry*; D040761:Biomimetic Materials / Q000737:chemistry*; D002942:Circular Dichroism; D047248:Crown Compounds / Q000737:chemistry*; D007811:Lanthanum / Q000737:chemistry*; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D047248:Crown Compounds; D000644:Quaternary Ammonium Compounds; D007811:Lanthanum; D001554:Benzene