244 research outputs found
Supplemental material for Analysis of monodisperse, sequence-defined, and POSS-functionalized polyester copolymers by MALDI tandem mass spectrometry
No full textSupplemental Material for Analysis of monodisperse, sequence-defined, and POSS-functionalized polyester copolymers by MALDI tandem mass spectrometry by Jialin Mao, Wei Zhang, Stephen ZD Cheng and Chrys Wesdemiotis in European Journal of Mass Spectrometry</p
Multidimensional Mass Spectrometry of Synthetic Polymers and Advanced Materials
No full textMultidimensional mass spectrometry interfaces a suitable ionization technique and mass analysis (MS) with fragmentation by tandem mass spectrometry (MS2) and an orthogonal online separation method. Separation choices include liquid chromatography (LC) and ion‐mobility spectrometry (IMS), in which separation takes place pre‐ionization in the solution state or post‐ionization in the gas phase, respectively. The MS step provides elemental composition information, while MS2 exploits differences in the bond stabilities of a polymer, yielding connectivity and sequence information. LC conditions can be tuned to separate by polarity, end‐group functionality, or hydrodynamic volume, whereas IMS adds selectivity by macromolecular shape and architecture. This Minireview discusses how selected combinations of the MS, MS2, LC, and IMS dimensions can be applied, together with the appropriate ionization method, to determine the constituents, structures, end groups, sequences, and architectures of a wide variety of homo‐ and copolymeric materials, including multicomponent blends, supramolecular assemblies, novel hybrid materials, and large cross‐linked or nonionizable polymers.More dimensions for MS: Multidimensional mass spectrometry combines mass analysis with tandem mass spectrometry fragmentation and an orthogonal separation method, such as liquid chromatography (LC) fractionation or ion‐mobility spectrometry (IMS), to achieve top‐down characterization of the composition, end groups, connectivity, and architecture of synthetic materials. CCS=collision cross‐section; CE=collision energy.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137445/1/anie201607003.pd
Schiff base polymers derived from 2,5-diformylfuran
No full textPolymerization of 2,5-diformylfuran with two primary amines was carried out in acetonitrile and ethanol at room temperature. The reaction was characterized using a combination of mass spectroscopy and NMR spectroscopy, which revealed the clean formation of the imine -CH N-functional group. Although some cyclic products were detected from mass spectroscopy, the ring size was limited to products that have the -CH N-group only in anti-geometry. The furan Schiff bases exhibit good thermal stability. While mass spectra evidenced oligomers of different lengths, cross-polarization magic angle spinning 13C NMR spectra of the insoluble polymer revealed the linear structure as proposed. (C) 2013 Society of Chemical Industr
Electronic Supporting Information (ESI) for: Separation, identification, and confirmation of cyclic and tadpole macromolecules via UPLC‐MS/MS
No full textPeer reviewe
Mehrdimensionale Massenspektrometrie von synthetischen Polymeren und modernen Materialien
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α-glycyl cation, radical, and anion (H2NCH+/·/−COOH): generation and characterization in the gas phase
No full textAbstractThe title species are synthesized in the gas phase and their unimolecular chemistry is determined by a combination of tandem mass spectrometry methods. Dissociative electron ionization of the α-amino acids valine, leucine, isoleucine, or serine produces the α-glycyl cation, H2NCH+COOH, in high yield and purity. At threshold, this ion dissociates by CO loss to form the proton-bound complex HCN⋯H+⋯OH2 via a tight 1,4-H migration that is associated with a high reverse barrier. After collisional activation, additional channels open, most notably the formation of the complementary and structure-characteristic fragments H2NCH+· (ionized aminocarbene) and +COOH and the elimination of OH·. Charge reversal and neutralization–reionization of H2NCH+COOH conclusively show that α-glycyl anion, H2NCH−COOH, and α-glycyl radical, H2NCH·COOH, are stable species residing in deep potential energy wells. In the microsecond time window of the experiments, a small fraction of the α-glycyl radical decomposes by sequential elimination of H2O and CO. The α-glycyl anions arising by charge reversal of the cation or reionization of the radical partly undergo rearrangement losses of H2 and H2O, direct cleavages to −COOH, OH−, and H2N−, and consecutive fragmentation of these primary product anions
Non-covalent complexes between single-stranded oligodeoxynucleotides and poly(ethylene imine)
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