Synthesis, structural analysis, and visualization of poly(2‐ethynyl‐9‐substituted carbazole)s and poly(3‐ethynyl‐9‐substituted carbazole)s containing chiral and achiral minidendritic substituents

Percéc, Virgil; Obata, Makoto; Rudick, Jonathan G.; De, Binod B.; Glodde, Martin; Bera, Tushar Kanti; Magonov, Sergei; Balagurusamy, Venkat; Heiney, Paul A.

doi:10.1002/pola.10458

Cited by 181 publications

(155 citation statements)

References 45 publications

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“…71 The detailed AFM study 73 of another of those dendronized PPAs (i.e., poly-21) deposited on HOPG ( Figure 15) showed individual macromolecules as oblate cylindrical objects. Their orientation in the first layer, the one directly adsorbed on the HOPG, reflected the underlying lattice symmetry due to the adsorption of the long alkyl tails.…”

Section: Spin Coating and Thermal Annealingmentioning

confidence: 99%

Chiral nanostructure in polymers under different deposition conditions observed using atomic force microscopy of monolayers: poly(phenylacetylene)s as a case study

2017

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This is the peer reviewed version of the following article: Freire, F. Quiñoá, E.; Riguera, R.; "Chiral nanostructure in polymers under different deposition conditions observed using atomic force microscopy of monolayers: poly(phenylacetylene)s as a case study" Chemical Communications, 2017, 53, 481-492 PPAs by atomic-force microscopy (AFM) are presented, with special attention to the methods for the preparation of monolayers, and their consequences in the quality of the AFM images. Thus, monolayers formed by drop casting, spin coating followed by crystallization or annealing, Langmuir-Blodgett and Langmuir-Schaefer methods, onto highly oriented pyrolytic graphite (HOPG) or mica are described, together with the AFM images and the resulting helical structure obtained for different PPAs. Also, some conclusions are assessed both on the adequacy of the different techniques for the formation of monolayers and on the solid supports employed to elucidate the secondary structure of different PPAs.

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Section: Spin Coating and Thermal Annealingmentioning

confidence: 99%

Chiral nanostructure in polymers under different deposition conditions observed using atomic force microscopy of monolayers: poly(phenylacetylene)s as a case study

2017

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“…[18] We conclude, then, that the redshift results from the approach of the bulky wheel component to the main chain during N-acylation, as we expected. [18] That the redshift does not result simply from N-acylation is confirmed by the following experimental results for non-rotaxane-type polyacetylenes poly-4 and poly-4 Ac: a UV/Vis absorption maximum is observed at 475 nm for poly-4 and at 448 nm for poly-4 Ac ( Figure 1); in addition, a large blueshift ( % 30 nm) due to N-acylation is observed for both, in contrast to the redshift observed for the rotaxane-type polymers. These phenomena suggest that the steric and/or electronic repulsions of the sec-ammonium groups are larger than those of the NÀAc groups.…”

mentioning

confidence: 54%

“…This prediction is justified by their absorption maxima for which poly-(R,R)-3 Bz (488 nm) is at a shorter wavelength than that of poly-(R)-2 Ac (492 nm), despite its bigger pendant group. [18] Therefore, the degree of approach to the main chain is significant.…”

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confidence: 99%

A Rational Design for the Directed Helicity Change of Polyacetylene Using Dynamic Rotaxane Mobility by Means of Through‐Space Chirality Transfer

Ishiwari

Fukasawa

Sato

et al. 2011

Chemistry A European J

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Directed helicity control of a polyacetylene dynamic helix was achieved by hybridization with a rotaxane skeleton placed on the side chain. Rotaxane-tethering phenylacetylene monomers were synthesized in good yields by the ester end-capping of pseudorotaxanes that consisted of optically active crown ethers and sec-ammonium salts with an ethynyl benzoic acid. The monomers were polymerized with [{RhCl(nbd)}(2)] (nbd=norbornadiene) to give the corresponding polyacetylenes in high yields. Polymers with optically active wheel components that are far from the main chain show no Cotton effect, thereby indicating the formation of racemic helices. Our proposal that N-acylative neutralization of the sec-ammonium moieties of the side-chain rotaxane moieties enables asymmetric induction of a one-handed helix as the wheel components approach the main chain is strongly supported by observation of the Cotton effect around the main-chain absorption region. A polyacetylene with a side-chain rotaxane that has a shorter axle component shows a Cotton effect despite the ammonium structure of the side-chain rotaxane moiety, thereby suggesting the importance of proximity between the wheel and the main chain for the formation of a one-handed helix. Through-space chirality induction in the present systems proved to be as powerful as through-bond chirality induction for formation of a one-handed helix, as demonstrated in an experiment using non-rotaxane-based polyacetylene that had an optically active binaphthyl group. The present protocol for controlling the helical structure of polyacetylene therefore provides the basis for the rational design of one-handed helical polyacetylenes.

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“…The helix seems tight in THF compared with that in the other three solvents judging from the UV-vis spectra, because largely twisted helical polyacetylenes have a shorter conjugation length than loosely twisted ones. 22 THF has the highest donor ability among the solvents, so it may interact with the polymer differently from the other ones, leading to the CD spectroscopic difference. However, detailed explanation of the solvent effect is difficult as commonly recognized.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Glutamic Acid-based Dendritic Helical Poly(phenylacetylene)s

Liu

Sanda

et al. 2007

Polym J

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L-Glutamic acid-based novel dendritic phenylacetylene derivatives 1 and 2 were synthesized and polymerized with a rhodium catalyst to afford the corresponding polymers [poly(1) and poly(2)] with high molecular weights in 83-95% yields. Poly(1) formed a helical structure with predominantly one-handed screw sense in DMF, CHCl 3 , and MeOH, and poly(2) did in DMF. The helical conformation of poly(1) and poly(2) could be tuned by temperature. Poly(1) underwent solvent-driven helix-helix transition in CHCl 3 /DMF.KEY WORDS: Dendritic Polymer / Glutamic Acid / Helical Polyacetylene / Amino acids are constituents of proteins and peptides, and not only are biologically important but also are useful substances for chiral auxiliaries and building blocks in organic synthesis.1 Amino acid-based synthetic polymers are expected to show biocompatibility and biodegradability similarly to polypeptides. Among varieties of amino acid-based synthetic polymers, amino acid-substituted polyacetylenes have attracted much attention due to the ability to form regulated secondary structures and responsiveness to external stimuli. Poly(phenylacetylene) derivatives with amino acid pendants show liquid crystalline properties based on the helical structure.2,3 They also exhibit self-assembling properties, form superhelical fibers, and change the helical sense by medium. [4][5][6][7][8] We have synthesized a series of amino acid-based poly(N-propargylamide)s 9-12 and poly(propargy ester)s 13 to find that they undergo helix inversion and/or transformation from a helix to a random coil according to external stimuli such as pH, 14 heat, and solvent. [15][16][17] On the other hand, dendrimers and dendritic polymers belong to a new class of macromolecules consisting of a cascade-branched structure. They gather interest due to their highly three-dimensional structure and a synthetic point of view. Recently, they are finding wide applications such as nanoscopic building blocks, catalysts, optoelectronic materials, and drug delivery systems.18 Dendronized helical poly(phenylacetylene)s form interesting architectures including ultra-high density arrays of helical wires, porous protein mimics, and exhibit permselectivity and self-healing. 19 In this article, we report the synthesis and chiroptical properties of glutamic acid-based novel helical dendritic poly(phenylacetylene)s (Scheme 1). EXPERIMENTAL Measurements1 H (400 MHz) and 13 C (100 MHz) NMR spectra were recorded on a JEOL EX-400 spectrometer. IR spectra were measured on a JASCO FTIR-4100 spectrophotometer. Melting points (mp) were measured on a YANACO micro melting point apparatus. High-resolution mass spectra were recorded on a JEOL JMS-HX110A and a JMS-SX102A spectrometers. Specific rotations (½ D ) were measured on a JASCO DIP-1000 digital polarimeter with a sodium lamp as a light source. Number-and weigh-average molecular weights (M n and M w ) of polymers were determined by gel permeation chromatography (GPC) on a JASCO Gulliver system (PU-980, CO-965, RI-930, and UV-1570) equipped with po...

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Synthesis, structural analysis, and visualization of poly(2‐ethynyl‐9‐substituted carbazole)s and poly(3‐ethynyl‐9‐substituted carbazole)s containing chiral and achiral minidendritic substituents

Cited by 181 publications

References 45 publications

Chiral nanostructure in polymers under different deposition conditions observed using atomic force microscopy of monolayers: poly(phenylacetylene)s as a case study

Chiral nanostructure in polymers under different deposition conditions observed using atomic force microscopy of monolayers: poly(phenylacetylene)s as a case study

A Rational Design for the Directed Helicity Change of Polyacetylene Using Dynamic Rotaxane Mobility by Means of Through‐Space Chirality Transfer

Synthesis of Glutamic Acid-based Dendritic Helical Poly(phenylacetylene)s

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