<sup>2</sup>H Solid-State NMR of Mobile Protons:  It Is Not Always the Simple Way

Lee, Young Joo; Murakhtina, Tatiana; Sebastiani, Daniel; Spiess, Hans Wolfgang

doi:10.1021/ja0754857

Cited by 63 publications

(90 citation statements)

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“…According to this understanding, in a fully polymeric system containing high concentrations of phosphonic acid or imidazole, fast proton diffusion does exist exclusively due to rapid hydrogen bond breaking and forming processes. [28,29] Poly(vinyl phosphonic acid) (PVPA) has been extensively studied. [5,28,29] Water content and selfcondensation of the phosphonic acid group (anhydride formation) was found to have a profound influence on the conductivity of this system.…”

Section: Introductionmentioning

confidence: 99%

“…[28,29] Poly(vinyl phosphonic acid) (PVPA) has been extensively studied. [5,28,29] Water content and selfcondensation of the phosphonic acid group (anhydride formation) was found to have a profound influence on the conductivity of this system. [30] There have been reports on the concept of mixing proton acceptors (like imidazole) with proton donors like phosphonic acid.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Polymer Composition and Water Content on Proton Conductivity in Vinyl Benzyl Phosphonic Acid—4‐Vinyl Pyridine Copolymers

Jiang

Kaltbeitzel

Fassbender

et al. 2008

Macro Chemistry & Physics

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The proton conductivities of poly(vinylbenzyl phosphonic acid) (PVBPA) homopolymer and its statistical copolymers with 4‐vinyl pyridine [poly(VBPA‐stat‐4VP)s] are comprehensively studied in this work. Temperature and composition‐dependent “dry” proton conductivities of the copolymers have been determined and the self‐condensation of phosphonic acid groups has been quantified. The results show that the intrinsic proton conductivities of poly(VBPA‐stat‐4VP)s and PVBPA are quite low at 150 °C and exhibit time‐dependent changes due to anhydride formation at elevated temperatures. The effect of polymer composition on proton conduction shows a minimum at a 1:1 molar ratio of proton donor and acceptor groups and is discussed on the basis of the pKa values of the electrolyte species. A trace amount of water significantly increases conductivity probably due to additional hydronium ion diffusion and water bridging effects. Water content and proton conductivities of poly(VBPA‐stat‐4VP)s are determined at different relative humidities. High amounts of water are absorbed at high humidities leading to high proton conductivities.magnified image

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Polymer Composition and Water Content on Proton Conductivity in Vinyl Benzyl Phosphonic Acid—4‐Vinyl Pyridine Copolymers

Jiang

Kaltbeitzel

Fassbender

et al. 2008

Macro Chemistry & Physics

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“…It could be shown that the so‐called “condensation defects,” which tend to be traps for H + conduction, have a unique 31 P NMR signal that allows a quantitative estimate of their density 52. In addition, the computed distribution of hydrogen bond orientations could be compared against experiment by means of variable‐temperature NMR spectroscopy 45.…”

Section: Complex Hydrogen Bond Network In Condensed Phasesmentioning

confidence: 99%

“… (online color at: http://www.pss-b.com/) Poly‐vinyl‐phosphonic acid (PVPA) and its local hydrogen bonding network 44, 45. There are both inter‐ and intra‐chain hydrogen bonds between phosphonic acid groups, as well as intercalated water molecules which can bridge small interstitial gaps of the network.…”

Section: Complex Hydrogen Bond Network In Condensed Phasesmentioning

confidence: 99%

Hydrogen bond networks: Structure and dynamics via first‐principles spectroscopy

Schiffmann¹,

Sebastiani²

2011

Physica Status Solidi (b)

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Different hydrogen bonding networks, same principle: hydrogen bonds are the most common fundamental structural driving forces, which determine structural and dynamical properties of numerous functional materials. First-principles calculations of spectroscopic parameters can help to understand local geometric motifs, but also more complex processes such as hydrogen bond lifetimes and ion transport processes in condensed phases. In this feature article, we review the relevance of structure-spectroscopy-relationships, we discuss recent ab initio calculations eludicating the structure of supramolecular assemblies, and highlight the importance of incorporating atomic and molecular mobility by means of molecular dynamics (MD) simulations.Complex hydrogen bonding networks: vinyl-phosphonic acid polymers (left) and aqueous hydrochloric acid (right).1 Sensitivity of spectroscopic signatures to structure Any simulation of a molecular system is based on the computed potential energy surface (PES). This surface, however, is not directly experimentally accessible. One of the first actual observables in a numerical calculation is the atomic structure, be it at equilibrium or as an ensemble average. As a consequence, approximations and errors in the calculation of the PES propagate immediately to structural parameters. Even a highly corrugated landscape is full of local energy minima, at which the atomic forces vanish; hence, the PES is locally quadratic in all coordinates at those points. This in turn results in a strong effect of small perturbative forces on computed geometries near equilibrium.It turns out that many spectroscopic observables exhibit a very different behavior close to the equilibrium geometry: small structural variations can lead to considerable changes in (experimental as well as computed) spectra. As an example from nuclear magnetic resonance spectroscopy (NMR), the 1 H NMR chemical shift calculated for the H-bonding proton in an imidazole dimer is shown in Fig. 1 (top). The slope of d H at equilibrium (indicated by the dashed line) is about 8 ppm/Å ; assuming a conservative estimate for the theoretical/experimental resolution of 0.1 ppm, this corresponds to a spectroscopic distance resolution of almost 0.01 Å [1]. In comparison to this, the energetic resolution of a standard ab initio calculation (assuming a systematic error of 1 kcal/mol and a typical H-bond strength) is roughly 0.1 Å . It is not feasible to reliably compute the energy differences due to small geometric changes more accurately than this, except by means of very resource-intensive quantumchemical reference methods. Hence, the variation of the NMR chemical shift considerably magnifies alterations of Phys. Status Solidi B 249, No. 2, 368-375 (2012)

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“…1D double‐quantum filtered (DQF) NMR spectra give information about the mobility of protons in the system, through which the proton conduction can be performed 12. Recent studies showed the power of solid‐state MAS NMR in similar systems 14–18…”

Section: Introductionmentioning

confidence: 99%

Proton‐Conducting Properties of Acid‐Doped Poly(glycidyl methacrylate)‐1,2,4‐Triazole Systems

Çelik

Akbey

Bozkurt

et al. 2008

Macro Chemistry & Physics

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Abstract1,2,4‐triazole‐functional PGMA polymers have been synthesized and their anhydrous proton‐conducting properties were investigated after doping with phosphoric acid and triflic acid. PGMA was prepared by solution polymerization and then modified with 1H‐1,2,4‐triazole (Tri) and 3‐amino‐1,2,4‐triazole (ATri). FT‐IR, 13C NMR and elemental analysis verify the high immobilization of the triazoles in the polymer chain. Phosphoric‐acid‐doped polymers showed lower Tg and higher proton conductivities. PGMA‐Tri 4 H3PO4 showed a maximum water‐free proton conductivity of approximately 10−2 S · cm−1 while that of PGMA‐ATri 2 H3PO4 was 10−3 S · cm−1. The structure and dynamics of the polymers were explored by 1H MAS and 13C CP‐MAS solid‐state NMR.magnified image

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²H Solid-State NMR of Mobile Protons: It Is Not Always the Simple Way

Cited by 63 publications

References 14 publications

Effect of Polymer Composition and Water Content on Proton Conductivity in Vinyl Benzyl Phosphonic Acid—4‐Vinyl Pyridine Copolymers

Effect of Polymer Composition and Water Content on Proton Conductivity in Vinyl Benzyl Phosphonic Acid—4‐Vinyl Pyridine Copolymers

Hydrogen bond networks: Structure and dynamics via first‐principles spectroscopy

Proton‐Conducting Properties of Acid‐Doped Poly(glycidyl methacrylate)‐1,2,4‐Triazole Systems

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2H Solid-State NMR of Mobile Protons: It Is Not Always the Simple Way

Cited by 63 publications

References 14 publications

Effect of Polymer Composition and Water Content on Proton Conductivity in Vinyl Benzyl Phosphonic Acid—4‐Vinyl Pyridine Copolymers

Effect of Polymer Composition and Water Content on Proton Conductivity in Vinyl Benzyl Phosphonic Acid—4‐Vinyl Pyridine Copolymers

Hydrogen bond networks: Structure and dynamics via first‐principles spectroscopy

Proton‐Conducting Properties of Acid‐Doped Poly(glycidyl methacrylate)‐1,2,4‐Triazole Systems

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²H Solid-State NMR of Mobile Protons: It Is Not Always the Simple Way