Determination of Molecular Weight Distributions for Polymers by Diffusion-Ordered NMR

Chen, Aidi; Wu, Donghui; Johnson, Charles S.

doi:10.1021/ja00135a015

Cited by 192 publications

(211 citation statements)

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“…DOSY NMR can classify the spectrum of each ingredient according to the differences in the hydrodynamic volumes (or diffusion coefficients) of the ingredients which are melted into the solution. This process is especially well known for having the advantage of classifying blended mixtures existing in a solution without any special preliminary treatment [105][106][107][108][109][110]. Theoretically, the same element size of a molecule connected by a combined reaction in the DOSY NMR spectrum appears on the same line of the y-axis.…”

Section: Copolymer Formationmentioning

confidence: 99%

Design and Synthesis of Cross-Linked Copolymer Membranes Based on Poly(benzoxazine) and Polybenzimidazole and Their Application to an Electrolyte Membrane for a High-Temperature PEM Fuel Cell

et al. 2013

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Elevated-temperature (100~200 °C) polymer electrolyte membrane (PEM) fuel cells have many features, such as their high efficiency and simple system design, that make them ideal for residential micro-combined heat and power systems and as a power source for fuel cell electric vehicles. A proton-conducting solid-electrolyte membrane having high conductivity and durability at elevated temperatures is essential, and phosphoric-acid-containing polymeric material synthesized from cross-linked polybenzoxazine has demonstrated feasible characteristics. This paper reviews the design rules, synthesis schemes, and characteristics of this unique polymeric material. Additionally, a membrane electrode assembly (MEA) utilizing this polymer membrane is evaluated in terms of its power density and lifecycle by an in situ accelerated lifetime test. This paper also covers an in-depth discussion ranging from the polymer material design to the cell performance in consideration of commercialization requirements. OPEN ACCESSPolymers 2013, 5 78

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Section: Copolymer Formationmentioning

confidence: 99%

Design and Synthesis of Cross-Linked Copolymer Membranes Based on Poly(benzoxazine) and Polybenzimidazole and Their Application to an Electrolyte Membrane for a High-Temperature PEM Fuel Cell

et al. 2013

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“…to provide MW information for samples being analyzed [32,[34][35][36][37][38][39]. Different forms of diffusion NMR experiments have been applied for diverse varieties of systems including inorganic materials [37,[40][41][42], organic molecules [17,23,24,28,[43][44][45][46][47][48][49] and polymers of different kinds (inorganic and organic polymers, polysaccharides, proteins) [21,37,[50][51][52][53][54][55][56][57][58][59][60][61][62]. Application for nucleic acids has been rather limited because the well-defined double helical structures have been investigated for most cases.…”

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confidence: 99%

Diffusion-ordered nuclear magnetic resonance spectroscopy for analysis of DNA secondary structural elements

Ambrus¹,

Yang²

2007

Analytical Biochemistry

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Structure determination of secondary DNA structural elements, such as G-quadruplexes, gains an increasing importance as fundamental physiological roles are being associated with the formation of such structures in vivo. A truncated native DNA sequence generally requires further optimization to obtain a candidate with desired NMR properties for structural analysis in solution. The optimum sequence is expected to form one dominant, stable molecular entity in solution with well-resolved NMR peaks. However, DNA sequences are prone to form structures composed of one, two, three or four strands depending on sequence and solution conditions. The thorough characterization of the molecularity (stoichiometry and molecular weight) and appropriate solution conditions for sequences with different modifications traditionally applies analytical techniques that generally do not represent the solution conditions for NMR structure determination. Here we present the application of diffusion ordered NMR spectroscopy as a useful analytical tool for the optimization and analysis of DNA secondary structural elements, specifically, the DNA G-quadruplex structures, including those formed in the human telomeric sequence and in the promoter regions of bcl-2 and c-myc genes. KeywordsDNA; NMR; DOSY; quadruplex; bcl-2; human telomere; c-myc Structural analysis of unusual DNA motifs with particular emphasis on G-quadruplexes and imotifs has a central role in the identification and characterization of molecular targets related to these structures [1][2][3][4][5][6][7]. Such structures are implicated in several physiologically important regulatory processes, with special emphasis on carcinogenesis [4][5][6][7][8][9][10][11][12]. Most of the structural studies on these elements have been performed by NMR spectroscopy. In most cases the related nucleotide sequence bearing the actual physiological function in vivo needs to be truncated/ elongated and/or mutated in order to obtain a successful candidate for NMR structure determination [3][4][5][6][7]13]. This NMR candidate should be a well-defined molecular entity in physiologically relevant solution conditions (ionic strength, pH, temperature) representing the same conformation as the original sequence. Appropriate modification of the sequence by mutation/truncation/elongation will force the molecule to form a single stable structure without altering crucial connectivities (conformation) of the structure.* To whom correspondence should be addressed at the Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, 1703 E. Mabel St., P.O. Box 210207, room 101/406, Tucson, Arizona 85721, USA; Tel: +1 520 626 6749/626 5969, Fax: +1 520 626 2466, E-mail: ambrus@pharmacy.arizona.edu, yangd@pharmacy.arizona.edu.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of ...

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“…More quantitative information can be useful in determining the molecular weight distribution for polymers [78], the purity and composition of functionalized carbon nanotubes [79], the formation of ion pairs and quadruples [80][81][82][83], or, in the case of neutral species, of supramolecular adducts [84,85].…”

Section: = ( + ( ) • ) (8)mentioning

confidence: 99%

Characterization of Halogen Bonded Adducts in Solution by Advanced NMR Techniques

Ciancaleoni

2017

Magnetochemistry

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Abstract:In the last 20 years, a huge volume of experimental work into halogen bonding (XB) has been produced. Most of the systems have been characterized by solid state X-ray crystallography, whereas in solution the only routine technique is titration (by using 1 H and 19 F nuclear magnetic resonance (NMR), infrared (IR), ultraviolet-visible (UV-Vis) or Raman spectroscopies, depending on the nature of the system), with the aim of characterizing the strength of the XB interaction. Unfortunately, titration techniques have many intrinsic limitations and they should be coupled with other, more sophisticated techniques to provide an accurate and detailed description of the geometry and stoichiometry of the XB adduct in solution. This review will show how crucial information about XB adducts can be obtained by advanced NMR techniques, nuclear Overhauser effect-based spectroscopies (NOESY, ROESY, HOESY . . . ) and diffusion NMR techniques (PGSE or DOSY).

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Determination of Molecular Weight Distributions for Polymers by Diffusion-Ordered NMR

Cited by 192 publications

References 0 publications

Design and Synthesis of Cross-Linked Copolymer Membranes Based on Poly(benzoxazine) and Polybenzimidazole and Their Application to an Electrolyte Membrane for a High-Temperature PEM Fuel Cell

Design and Synthesis of Cross-Linked Copolymer Membranes Based on Poly(benzoxazine) and Polybenzimidazole and Their Application to an Electrolyte Membrane for a High-Temperature PEM Fuel Cell

Diffusion-ordered nuclear magnetic resonance spectroscopy for analysis of DNA secondary structural elements

Characterization of Halogen Bonded Adducts in Solution by Advanced NMR Techniques

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