Toshikazu Takata

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTOptically Active Poly(aryl carbonates) Consisting of Axially Chiral Units. Chiral Binaphthyl Group Induced Helical PolymerToshikazu Takata, Yoshio Furusho, Ken-ichi Murakawa, Takeshi Endo, Hideo Matsuoka, Takashi Hirasa, Jyuho Matsuo, and Masahiko SisidoView Author Information Department of Applied Chemistry, College of Engineering, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan Research Laboratory of Resources Utilization, Tokyo Insti

Break it down: Gels formed from rotaxane cross-linkers with end groups that are size-complementary to the macrocyclic cavity of wheel components (see picture) were prepared. The network structure was maintained in polar organic solvents or in the presence of a base to prevent hydrogen bonding. Anion exchange enabled the selective and efficient de-cross-linking of the gels.

The synthesis and dynamic nature of macromolecular systems controlled by rotaxane macromolecular switches are introduced to discuss the significance of rotaxane linking of polymer chains and its topological switching. Macromolecular switches have been synthesized from macromolecular [2]rotaxanes (M2Rs) using <i>sec</i>-ammonium salt/crown ether couples. The successful synthesis of M2Rs possessing a single polymer axle and one crown ether wheel, constituting a key component of the macromolecular

Effective induction of preferred-handed helicity of polyacetylenes by pendant mechanically chiral rotaxanes is discussed. Polyacetylenes possessing optically active mechanically chiral rotaxanes in the side chains were synthesized by the polymerization of the corresponding enantiopure [2]rotaxane-type ethynyl monomers prepared by the chiral-phase HPLC separations. The CD Cotton effects revealed that the polyacetylenes took preferred-handed helical conformations depending on the rotaxane chiralit

A fifteen-year riddle has been settled: neutralization, the most popular chemical event, of a crown ether/sec-ammonium salt-type rotaxane has been achieved and a completely nonionic crown ether/sec-amine-type rotaxane isolated. A [2]rotaxane was prepared as a typical substrate from a mixture of dibenzo[24]crown-8 ether (DB24C8) and sec-ammonium hexafluorophosphate (PF(6)) with a terminal hydroxy group through end-capping with 3,5-dimethylbenzoic anhydride in the presence of tributylphosphane as

Rotaxane cross-linked (RC) microgels that exhibit a decoupled thermo- and pH-responsive volume transition were developed. The pH-induced changes of the aggregation/disaggregation states of cyclodextrin in the RC networks were used to control the swelling capacity of the entire microgels. Different from conventional thermo- and pH-responsive microgels, which are usually obtained from copolymerizations involving charged monomers, the RC microgels respond to temperature as intended, even in the pre

Rotaxane-structure-specific Pd-catalyzed rearrangement of propargyl or allyl urethane groups to oxazolidinone moieties proceeded efficiently. The conversion took place successively by the translation of the wheel along the axle, thus providing a novel macrocyclic catalytic system.

Linear-cyclic polymer structural transformation and its reversibility are demonstrated by a simple but rational strategy using the structural characteristics of crown ether-based rotaxanes. The structure of a polymer containing a [1]rotaxane unit at one end was controlled by conventional protection-deprotection reactions, giving rise to a reversible linear-cyclic polymer structural transformation.

The first poly[3]rotaxane was synthesized from a dumbbell-shaped compound with a disulfide linkage at the center and a bifunctional 24-crown-8 ether derivative through a reversible thiol–disulfide interchange reaction.

Abstract Several poly(arylene thioether)s ( PTEs ) containing a fluorene moiety were synthesized by the polycondensation of masked dithiols such as 9,9‐bis(4‐( N,N ‐dimethyl‐ S ‐carbamoyl)phenyl)fluorene and various difluoroarenes. All PTEs were obtained in quantitative yields. The PTEs showed good thermal stability: the 10% weight loss temperature was over 480 °C under both nitrogen and air atmosphere by TGA, and glass temperature was within a range of 204–275 °C by DSC. Most PTEs exhibited rem

Three component mobility controlling vinylic rotaxane crosslinkers with two radically polymerizable vinyl groups (RC_Rs) were synthesized to prove that the mobility of the components of the RC_Rs plays a crucial role in determining the properties of rotaxane-crosslinked polymers (RCPs). RC_Rs (R=H, Me, or Et) were obtained from living ring-opening polymerization. RCP_Et was prepared using RC_Et, which exhibits the lowest component mobility. The low component mobility is reflected in inferior mec

Polyacetylene bearing a pendant rotaxane moiety with an optically active wheel component was synthesized to realize reversible structural control of its helical structure by position control of the wheel component. Polyacetylene formed a one-handed helical structure only when the optically active wheel component moved close to the main chain.