Sequence-Modification in Copoly(ester-Imide)s: A Catalytic/supramolecular Approach to Writing/reading Copolymer Sequence-Information

2020 ◽  
Author(s):  
Marcus Knappert ◽  
Howard Colquhoun
Keyword(s):  
Ring Current ◽  
Sequence Information ◽  
Nmr Analysis ◽  
Ester Interchange ◽  
H Nmr ◽  
Sequence Exchange ◽  
Supramolecular Complexation ◽  
Different Levels ◽  
Sequence Modification ◽  
Interchange Reactions

Catalytic ester-interchange reactions, analogous to mutation and recombination, allow new sequence-information to be written, statistically, into NDI-based poly(ester-imide) chains. Thus, insertion of the cyclic ester cyclopentadecanolide ("exaltolide") into an NDI-based homopolymer, and quantitative sequence-exchange between two different homopoly(ester-imide)s, are catalysed by di-<i>n</i>-butyl tin(IV) oxide. Emerging sequences are identified at the triplet and quintet levels by <sup>1</sup>H NMR analysis, using supramolecular complexation of pyrene-<i>d</i><sub>10</sub> at the NDI residues to amplify the separation of resonances associated with different sequences. In such systems, pyrene is able to act as a "reader-molecule" by generating different levels of ring-current shielding from the different patterns of supramolecular binding to all the NDI-centred sequences of a given length.

Sequence-Modification in Copoly(ester-Imide)s: A Catalytic/supramolecular Approach to Writing/reading Copolymer Sequence-Information

2020 ◽  
Author(s):  
Marcus Knappert ◽  
Howard Colquhoun
Keyword(s):  
Ring Current ◽  
Sequence Information ◽  
Nmr Analysis ◽  
Ester Interchange ◽  
H Nmr ◽  
Sequence Exchange ◽  
Supramolecular Complexation ◽  
Different Levels ◽  
Sequence Modification ◽  
Interchange Reactions

Catalytic ester-interchange reactions, analogous to mutation and recombination, allow new sequence-information to be written, statistically, into NDI-based poly(ester-imide) chains. Thus, insertion of the cyclic ester cyclopentadecanolide ("exaltolide") into an NDI-based homopolymer, and quantitative sequence-exchange between two different homopoly(ester-imide)s, are catalysed by di-<i>n</i>-butyl tin(IV) oxide. Emerging sequences are identified at the triplet and quintet levels by <sup>1</sup>H NMR analysis, using supramolecular complexation of pyrene-<i>d</i><sub>10</sub> at the NDI residues to amplify the separation of resonances associated with different sequences. In such systems, pyrene is able to act as a "reader-molecule" by generating different levels of ring-current shielding from the different patterns of supramolecular binding to all the NDI-centred sequences of a given length.

scholarly journals Sequence modification in copoly(ester-imide)s: a catalytic/supramolecular approach to the evolution and reading of copolymer sequence information

2021 ◽  
Author(s):  
Marcus Knappert ◽  
Howard M. Colquhoun
Keyword(s):  
Ring Current ◽  
Cyclic Ester ◽  
Sequence Information ◽  
Ester Interchange ◽  
H Nmr ◽  
Sequence Exchange ◽  
Supramolecular Complexation ◽  
Different Levels ◽  
Sequence Modification ◽  
Interchange Reactions

AbstractCatalytic ester-interchange reactions, analogous to mutation and recombination, allow new sequence information to be written statistically into poly(ester-imide) chains based on NDI (1,4,5,8-naphthalenetetracarboxylic diimide) units. Thus, both the insertion of the cyclic ester cyclopentadecanolide (“exaltolide”) into an NDI-based homopolymer and quantitative sequence exchange between two different homopoly(ester-imide)s are catalyzed by di-n-butyl tin(IV) oxide. Emerging sequences are identified at the triplet and quintet levels using supramolecular complexation of pyrene-d10 at the NDI residues to amplify the separation of 1H NMR resonances associated with different sequences. In such systems, pyrene is able to act as a “reader molecule” by generating different levels of ring-current shielding from the different patterns of supramolecular binding to all NDI-centered sequences of a given length.

scholarly journals Supramolecular complexation between chain-folding poly(ester-imide)s and polycyclic aromatics: a fractal-based pattern of NMR ring-current shielding

2019 ◽  
Vol 10 (48) ◽  
pp. 6641-6650 ◽  
Author(s):  
Marcus Knappert ◽  
Tianqi Jin ◽  
Scott D. Midgley ◽  
Guanglu Wu ◽  
Oren A. Scherman ◽  
...  
Keyword(s):  
Ring Current ◽  
Polycyclic Aromatics ◽  
Chain Folding ◽  
H Nmr ◽  
Type Character ◽  
A Chain ◽  
Supramolecular Complexation

Supramolecular complexation of pyrene with a chain-folding, NDI-based co-poly(ester-imide) generates a 1H NMR pattern showing fractal-type character.

Synthesis and Structure Assignment of 2-(4-Methoxybenzyl)cyclohexyl β-D-Glucopyranoside Enantiomers

2006 ◽  
Vol 71 (10) ◽  
pp. 1470-1483 ◽  
Author(s):  
David Šaman ◽  
Pavel Kratina ◽  
Jitka Moravcová ◽  
Martina Wimmerová ◽  
Zdeněk Wimmer
Keyword(s):  
Analytical Data ◽  
Chiral Hplc ◽  
Nmr Analysis ◽  
Target Structure ◽  
Enantiomerically Pure ◽  
Whole Cells ◽  
H Nmr ◽  
Structure Assignment ◽  
Related Compounds ◽  
C Nmr

Glucosylation of the cis- and trans-isomers of 2-(4-methoxybenzyl)cyclohexan-1-ol (1a/1b, 2a/2b, 1a or 2a) was performed to prepare the corresponding alkyl β-D-glucopyranosides, mainly to get analytical data of pure enantiomers of the glucosides (3a-6b), required for subsequent investigations of related compounds with biological activity. One of the employed modifications of the Koenigs-Knorr synthesis resulted in achieving 85-95% yields of pure β-anomers 3a/3b, 4a/4b, 3a or 4a of protected intermediates, with several promoters and toluene as solvent, yielding finally the deprotected products 5a/5b, 6a/6b, 5a or 6a as pure β-anomers. To obtain enantiomerically pure β-anomers of the target structure (3a, 4a, 5a and 6a) for unambiguous structure assignment, an enzymic reduction of 2-(4-methoxybenzyl)cyclohexan-1-one by Saccharomyces cerevisiae whole cells was performed to get (1S,2S)- and (1S,2R)-enantiomers (1a and 2a) of 2-(4-methoxybenzyl)cyclohexan-1-ol. The opposite enantiomers of alkyl β-D-glucopyranosides (5b and 6b) were obtained by separation of the diastereoisomeric mixtures 5a/5b and 6a/6b by chiral HPLC. All stereoisomers of the products (3a-6b) were subjected to a detailed 1H NMR and 13C NMR analysis.

1H-NMR Analysis of Degree of Substitution in N,O-Carboxymethyl Chitosans from Various Chitosan Sources and Types

2012 ◽  
Vol 506 ◽  
pp. 158-161 ◽  
Author(s):  
A. Jaidee ◽  
Pornchai Rachtanapun ◽  
S. Luangkamin
Keyword(s):  
Chemical Structure ◽  
Carboxymethyl Chitosan ◽  
Degree Of Substitution ◽  
Resonance Spectroscopy ◽  
Nmr Analysis ◽  
Reaction Conditions ◽  
H Nmr ◽  
Fourier Transformed Infrared Spectroscopy ◽  
Chitosan Oligomer ◽  
Ft Ir

N,O-Carboxymethyl chitosans were synthesized by the reaction between shrimp, crab and squid chitosans with monochloroacetic acid under basic conditions at 50°C. The mole ratio of reactants was obtained from various reaction conditions of shrimp chitosan polymer and oligomer types. The mole ratio 1:12:6 of chitosan:sodium hydroxide:monochloroacetic acid was used for preparing carboxymethyl of chitosan polymer types while carboxymethyl of chitosan oligomer types were used the mole ratio 1:6:3 of chitosan:sodium hydroxide:monochloroacetic acid. The chemical structure was analyzed by fourier transformed infrared spectroscopy (FT-IR) and proton nuclear magnatic resonance spectroscopy (1H-NMR). The FT-IR was used for confirm the insertion of carboxymethyl group on chitosan molecules. The 1H-NMR was used for determining the degree of substitution (DS) of carboxymethylation at hydroxyl and amino sites of chitosans. Carboxymethyl chitosan samples had the total DS of carboxymethylation ranging from 1.0-2.2. The highest of DS of carboxymethylation was from shrimp chitosan oligomer type.

scholarly journals Offsets in the geomagnetic indices of the magnetospheric ring current

2021 ◽  
Vol 7 (3) ◽  
pp. 31-38
Author(s):  
Georgy Makarov
Keyword(s):  
Ring Current ◽  
Magnetic Disturbance ◽  
Absolute Value ◽  
Daily Average ◽  
Geomagnetic Indices ◽  
Asymmetric Component ◽  
Different Levels

The paper considers changes in the daily average values of the Dst, SYM-H, ASY-H, and ASY-D indices and their dependence on the level of magnetic disturbance for the period 1981–2016. These indices are geomagnetic characteristics of the magnetospheric ring current. It has been established that the indices of the asymmetric component of the ring current ASY-H and ASY-D during relatively magnetically quiet periods are not equal to zero. The values of the offsets in the dependences of the ASY-H and ASY-D indices on the level of magnetic disturbance have been determined. The behavior of the index of the degree of symmetry of the ring current, the ratio SYM-H / ASY-H, is analyzed during the year at different levels of disturbance. This ratio has been found to grow in absolute value with increasing disturbance and to exceed 1 at large disturbances (at Dst <–50).

Prediction of physical-chemical properties of crude oils by 1 H NMR analysis of neat samples and chemometrics

2012 ◽  
Vol 50 (11) ◽  
pp. 729-738 ◽  
Author(s):  
Alice Masili ◽  
Sonia Puligheddu ◽  
Lorenzo Sassu ◽  
Paola Scano ◽  
Adolfo Lai
Keyword(s):  
Chemical Properties ◽  
Crude Oils ◽  
Nmr Analysis ◽  
H Nmr ◽  
Physical Chemical
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