Biological macromolecules, such as DNA and proteins, possess a unique specific ordered structure, right-handed double helix or single alpha-helix. Those structures direct the sophisticated functions of these molecules in living systems. Inspired by biological helices, chemists have worked to synthesize polymers with controlled helicity, not only mimic helices but also realize their functions. Although numerous synthetic that fold into single-handed been reported, double-stranded helical are...

No metal required: Double-helical assemblies can be constructed through hydrogen bonds upon formation of amidinium–carboxylate salt bridges (see schematic representation). The double-helical structures formed including the helix sense are predictable by this approach.

We describe the construction of first double-stranded metallosupramolecular helical polymers. designed and synthesized a supramolecular duplex comprised complementary m-terphenyl-based strands bearing chiral amidine or achiral carboxylic acid together with two pyridine groups at four ends. Supramolecular polymerization cis-PtPh2(DMSO)2 in 1,1,2,2-tetrachloroethane produced polymer controlled helicity which metallostrands are intertwined through amidinium-carboxylate salt bridges. The...

We report the first double helices with a controlled helicity in water based on oligoresorcinols as new, simplest water-soluble structural motif. The molecular strands of self-assemble into aid aromatic interactions characterized by 1H NMR and absorption spectroscopies together X-ray crystallographic study pentamer. helix formation is sensitive to chain length, solvent composition, temperature. Moreover, bias screw sense was achieved covalently attaching chiral substituents both ends strands.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTChirality-Memory Molecule: A D2-Symmetric Fully Substituted Porphyrin as a Conceptually New Chirality SensorYoshio Furusho, Takayuki Kimura, Yukitami Mizuno, and Takuzo AidaView Author Information Department of Chemistry Biotechnology Graduate School Engineering The University Tokyo Hongo, Bunkyo-ku, 113, JapanCite this: J. Am. Chem. Soc. 1997, 119, 22, 5267–5268Publication Date (Web):June 4, 1997Publication History Received10 February...

A through-space superexchange mechanism appears to be responsible for charge recombination (CR) following photoexcitation and separation (CS) in rotaxanes containing zinc porphyrin C60 moieties (see picture), as suggested by the low activation energy of this process. Furthermore, charge-separated state is relatively long-lived. Supporting information article available on WWW under http://www.wiley-vch.de/contents/jc_2002/2003/z19881_s.pdf or from author. Please note: The publisher not...

The artificial sequential strands consisting of two, three, or four m-terphenyl groups joined by diacetylene linkers with complementary binding sites, either the chiral amidine (A) achiral carboxyl (C) group, were synthesized in a stepwise manner. Using circular dichroism and (1)H NMR spectroscopies along liquid chromatography, we showed that, when three dimeric molecular (AA, CC, AC) six trimeric (AAA, CCC, AAC, CCA, ACA, CAC) mixed solution, sequence-specifically hybridized to form...

We report the dual memory of both enantiomeric right- and left-handed helical conformations induced in a polyacetylene based on temperature-stimulated helicity inversion polymer. The folds into one-handed helix by noncovalent bonding interactions with single amine. underwent reversible temperature. diastereomeric helices obtained at different temperatures could be further memorized when optically active amine was replaced an achiral diamine, generating mirror images each other. Consequently,...

Two complementary homopolymers of chiral amidines and achiral carboxylic acids with m-terphenyl-based backbones were synthesized by the copolymerization a p-diiodobenzene derivative diethynyl monomers bearing amidine group carboxyl using Sonogashira reaction, respectively. Upon mixing in THF, homopolymer strands assembled into preferred-handed double helix through interstrand amidinium-carboxylate salt bridges, as evidenced its absorption, circular dichroism, IR spectra. In contrast, when...

Two twisted: Optically active double helices were synthesized through a twist-sense bias induced by chiral phosphine ligand on one of the complementary metallostrands followed ligand-exchange reaction with an achiral bidentate ligand, which replaces to bridge two strands. Furthermore, can efficiently catalyze asymmetric cyclopropanation.

We report on the oligosaccharide recognition through noncovalent interactions in water based a unique supramolecular homoduplex-to-heteroduplex transformation of oligoresorcinol nonamer as fully artificial receptor. The forms double helix water, which unravels and entwines upon complexation with specific oligosaccharides particular chain length glucosidic linkage pattern, thus generating heteroduplex an excess one-handed helical conformation that can be readily monitored further quantified...

A series of dimer strands consisting m-terphenyl backbones bearing complementary chiral or achiral amidines and carboxylic acid residues connected by various types linkers, such as diacetylene, Pt(II)-acetylide, p-diethynylbenzene linkages, were synthesized a modular strategy, their chiroptical properties on the double helix formations investigated absorption, circular dichroism (CD), (1)H NMR spectroscopies. The thermodynamic kinetic stabilities helices assisted amidinium-carboxylate salt...

A series of complementary molecular strands from 2-mer to 5-mer that are composed m-terphenyl units bearing chiral/achiral amidine or achiral carboxyl groups linked via Pt(II) acetylide complexes were synthesized by sequential stepwise reactions, and their chiroptical properties on the double-helix formation investigated circular dichroism (CD) (1)H NMR spectroscopies. In CHCl(3), "all-chiral" consisting (R)- (S)-amidine formed preferred-handed double helices with carboxylic acid through...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTOptically Active Poly(aryl carbonates) Consisting of Axially Chiral Units. 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 Applied Chemistry, College Engineering, Osaka Prefecture University, Sakai, 599-8531, Japan Research Laboratory Resources Utilization, Tokyo Institute Technology,...

Double Twist: The first spiroborate-based helicate was synthesized and shown to be stable in the solid state as well solution. double-stranded structure (see picture) characterized by 1H NMR spectroscopy, ESI MS, X-ray crystallographic studies. racemic helicates were resolved formation of a diastereomeric, optically active ammonium salt. Supporting information for this article is available on WWW under http://www.wiley-vch.de/contents/jc_2002/2006/z504326_s.pdf or from author. Please note:...

Abstract A dynamic covalent approach to disulfide‐containing [2]‐ and [3]rotaxanes is described. Symmetrical dumbbell‐shaped compounds with two secondary ammonium centers a central located disulfide bond were synthesized as components of rotaxanes. The rotaxanes from the dibenzo‐[24]crown‐8 (DB24C8) catalysis by benzenethiol. yields isolated reached about 90 % under optimized conditions. kinetic study on reaction forming [2]rotaxane 2 [3]rotaxane 3 suggested plausible mechanism comprising...

The double helix of the oligoresorcinol nonamer formed in water was unwound by β-cyclodextrin (β-CD), and resulting single strands threaded β-CD to form a twisted [3]pseudorotaxane with controlled helicity. Upon addition an adamantane, strand expelled out wheels, thus regenerating helix. This supramolecularly controlled, reversible unwinding rewinding is unique can be readily monitored spectroscopic techniques.

Going straight: A luminescent composite of poly(p-phenylenevinylene) (PPV) and amylose was synthesized by direct polymerization the precursor monomer in aqueous media presence amylose. The PPV–amylose consists a rigid-rod PPV segment threaded into flexible tube self-assembles liquid-crystalline phases. Supporting information for this article is available on WWW under http://www.wiley-vch.de/contents/jc_2002/2006/z602134_s.pdf or from author. Please note: publisher not responsible content...

We previously reported that the oligoresorcinols formed double-stranded helices in neutral water through interstrand aromatic interactions. In present study, we synthesized a new series of oligomers from 2mer to 15mer explore thermodynamics, kinetics, and mechanism double helix formation water. The was dependent on chain length significantly affected by solvent, pH, salt, temperature. free energy change (−ΔG) for linearly increased with 4mer 11mer (ΔΔG = −0.94 kcal mol−1 unit−1), whereas it...

Salty catenane: An optically active [2]catenane was synthesized by utilizing an amidinium carboxylate salt bridge (see picture). The relative motion of the two macrocyclic components completely controlled acid/base or Zn2+/cryptand couple.