In Situ NMR Insights into the Electrochemical Reaction of Cu₃P Electrodes in Lithium Batteries

This study reports a multinuclei in situ (real-time) NMR spectroscopic characterization of the electrochemical reactions of a negative Cu₃P electrode toward lithium. Taking advantage of the different nuclear spin characteristics, we have obtained real-time ³¹P and ⁷Li NMR data for a comprehensive understanding of the electrochemical mechanism during the discharge and charge processes of a lithium battery. The large NMR chemical shift span of ³¹P facilitates the observation of the chemical evolutions of different lithiated and delithiated Li_<i>x</i>Cu_3–<i>x</i>P phases, whereas the quadrupolar line features in ⁷Li enable identification of asymmetric Li sites. These combined NMR data offer an unambiguous identification of four distinct Li_<i>x</i>Cu_3–<i>x</i>P phases, Cu₃P, Li_0.2Cu_2.8P, Li₂CuP, and Li₃P, and the characterization of their involvement in the electrochemical reactions. The NMR data led us to propose a delithiation process involving the intercalation of metallic Cu⁰ atomic aggregates into the Li₂CuP structure to form a Cu⁰-Li_2–<i>x</i>Cu_1+<i>x</i>P phase. This process might be responsible for the poor capacity retention in Cu₃P lithium batteries when cycled to a low voltage

Linewidth narrowing of solid-state adamantane spectrum for higher rotational speeds.

<p>NMR spectra at 500 MHz for two different spinning speeds: 0.9 ppm at 10 kHz vs. 1.5 ppm at 5 kHz.</p

Successful tuning of the microfabricated NMR insert at 500 MHz.

<p>Successful tuning of the microfabricated NMR insert at 500 MHz.</p

500 MHz ¹H NMR spectrum of 330 nl water spun at 110 Hz.

<p>The isotropic central peak is split in sidebands spaced at 110 Hz, i.e., 0.22 ppm at 500 MHz. The inset shows the central water peak which has a non-Gaussian shape due to the field inhomogeneities (see <i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0042848#s4" target="_blank">Discussion</a></i> section).</p

¹H NMR spectra of Drosophila pupae.

<p>The spectra was acquired with a total of three pupae in a 400 µm-microcoil coupled with a standard 7-mm MAS probe, spinning at 500 Hz for the single-pulse experiment, and at 371 Hz for the PASS experiment. The total experimental time for the PASS experiment is about 1 hour. Peak assignment (1) Lipid –CH₃ (2) fatty acid –(CH₂)_n (3) lactate CH₃ (4) Lipid –CH₂-CH₂-CO– (5) Lipid–CH = CH-CH₂-CH₂– (6) Lipid –CH₂-CH₂-CO–.</p

Figure 1

<p>a) Microscope image of the microfabricated NMR insert. b) Profile of the electroplated on-chip capacitor. c) Schematic of the magic angle coil spinning (MACS) experimental set-up.</p

Sensitivity of the microfabricated NMR insert.

<p>¹H spectrum at 700 MHz of a mixture of 99.9% D₂O and 0.1% H₂O.</p

<i>N</i>^ε‑Acryloyllysine Piperazides as Irreversible Inhibitors of Transglutaminase 2: Synthesis, Structure–Activity Relationships, and Pharmacokinetic Profiling

Transglutaminase 2 (TGase 2)-catalyzed transamidation represents an important post-translational mechanism for protein modification with implications in physiological and pathophysiological conditions, including fibrotic and neoplastic processes. Consequently, this enzyme is considered a promising target for the diagnosis of and therapy for these diseases. In this study, we report on the synthesis and kinetic characterization of <i>N</i>^ε-acryloyllysine piperazides as irreversible inhibitors of TGase 2. Systematic structural modifications on 54 new compounds were performed with a major focus on fluorine-bearing substituents due to the potential of such compounds to serve as radiotracer candidates for positron emission tomography. The determined inhibitory activities ranged from 100 to 10 000 M^–1 s^–1, which resulted in comprehensive structure–activity relationships. Structure–activity correlations using various substituent parameters accompanied by covalent docking studies provide an advanced understanding of the molecular recognition for this inhibitor class within the active site of TGase 2. Selectivity profiling of selected compounds for other transglutaminases demonstrated an excellent selectivity toward transglutaminase 2. Furthermore, an initial pharmacokinetic profiling of selected inhibitors was performed, including the assessment of potential membrane permeability and liver microsomal stability

<i>N</i>^ε‑Acryloyllysine Piperazides as Irreversible Inhibitors of Transglutaminase 2: Synthesis, Structure–Activity Relationships, and Pharmacokinetic Profiling

Transglutaminase 2 (TGase 2)-catalyzed transamidation represents an important post-translational mechanism for protein modification with implications in physiological and pathophysiological conditions, including fibrotic and neoplastic processes. Consequently, this enzyme is considered a promising target for the diagnosis of and therapy for these diseases. In this study, we report on the synthesis and kinetic characterization of <i>N</i>^ε-acryloyllysine piperazides as irreversible inhibitors of TGase 2. Systematic structural modifications on 54 new compounds were performed with a major focus on fluorine-bearing substituents due to the potential of such compounds to serve as radiotracer candidates for positron emission tomography. The determined inhibitory activities ranged from 100 to 10 000 M^–1 s^–1, which resulted in comprehensive structure–activity relationships. Structure–activity correlations using various substituent parameters accompanied by covalent docking studies provide an advanced understanding of the molecular recognition for this inhibitor class within the active site of TGase 2. Selectivity profiling of selected compounds for other transglutaminases demonstrated an excellent selectivity toward transglutaminase 2. Furthermore, an initial pharmacokinetic profiling of selected inhibitors was performed, including the assessment of potential membrane permeability and liver microsomal stability

<i>N</i>^ε‑Acryloyllysine Piperazides as Irreversible Inhibitors of Transglutaminase 2: Synthesis, Structure–Activity Relationships, and Pharmacokinetic Profiling

Transglutaminase 2 (TGase 2)-catalyzed transamidation represents an important post-translational mechanism for protein modification with implications in physiological and pathophysiological conditions, including fibrotic and neoplastic processes. Consequently, this enzyme is considered a promising target for the diagnosis of and therapy for these diseases. In this study, we report on the synthesis and kinetic characterization of <i>N</i>^ε-acryloyllysine piperazides as irreversible inhibitors of TGase 2. Systematic structural modifications on 54 new compounds were performed with a major focus on fluorine-bearing substituents due to the potential of such compounds to serve as radiotracer candidates for positron emission tomography. The determined inhibitory activities ranged from 100 to 10 000 M^–1 s^–1, which resulted in comprehensive structure–activity relationships. Structure–activity correlations using various substituent parameters accompanied by covalent docking studies provide an advanced understanding of the molecular recognition for this inhibitor class within the active site of TGase 2. Selectivity profiling of selected compounds for other transglutaminases demonstrated an excellent selectivity toward transglutaminase 2. Furthermore, an initial pharmacokinetic profiling of selected inhibitors was performed, including the assessment of potential membrane permeability and liver microsomal stability