Search results for: Johannes Hunger

Items from 1 to 20 out of 33 results

article

Ion and Molecular Sieving With Ultrathin Polydopamine Nanomembranes

Jiyao Yu, Tommaso Marchesi D'Alvise, Iain Harley, Adam Krysztofik, more

Advanced Materials > 36 > 29 > n/a - n/a

In contrast to biological cell membranes, it is still a major challenge for synthetic membranes to efficiently separate ions and small molecules due to their similar sizes in the sub‐nanometer range. Inspired by biological ion channels with their unique channel wall chemistry that facilitates ion sieving by ion‐channel interactions, the first free‐standing, ultrathin (10–17 nm) nanomembranes composed...

article

Direct Probe of Electrochemical Pseudocapacitive pH Jump at a Graphene Electrode**

Yongkang Wang, Takakazu Seki, Xuan Liu, Xiaoqing Yu, more

Angewandte Chemie International Edition > 62 > 10 > n/a - n/a

Molecular‐level insight into interfacial water at a buried electrode interface is essential in electrochemistry, but spectroscopic probing of the interface remains challenging. Here, using surface‐specific heterodyne‐detected sum‐frequency generation (HD‐SFG) spectroscopy, we directly access the interfacial water in contact with the graphene electrode supported on calcium fluoride (CaF₂). We find...

article

Direkte Visualisierung elektrochemischer pseudo‐kapazitiver pH Sprünge an einer Graphenelektrode**

Yongkang Wang, Takakazu Seki, Xuan Liu, Xiaoqing Yu, more

Angewandte Chemie > 135 > 10 > n/a - n/a

Molekulare Einblicke in Wasser an Elektrodengrenzflächen sind für die Aufklärung vieler elektrochemischer Phänomene, unter Anderem der elektrokatalytischen Wasserspaltung und der kapazitiven Energiespeicherung, von wesentlicher Bedeutung, aber die spektroskopische Untersuchung dieser Grenzflächen bleibt eine Herausforderung. Mit Hilfe der oberflächenspezifischen heterodyn‐detektierten Summenfrequenzspektroskopie...

article

Ionenadsorption und ‐desorption an der CaF₂‐Wasser‐Grenzfläche untersucht mit Flussexperimenten und Schwingungsspektroskopie

Patrick Ober, Johannes Hunger, Sophia H. Kolbinger, Ellen H. G. Backus, more

Angewandte Chemie > 134 > 46 > n/a - n/a

Die Auflösung von Mineralien in Kontakt mit Wasser spielt eine entscheidende Rolle in der Geochemie. Einblicke in die Grenzflächenchemie auf molekularer Ebene zu erhalten, gestaltet sich jedoch schwierig. Beim Auflösen werden typischerweise Ionen an der Oberfläche freigesetzt, die eine geladene Mineraloberfläche entstehen lassen. Diese Ladung beeinflusst die Ausrichtung der Wassermoleküle an der Grenzfläche,...

article

Ion Adsorption and Desorption at the CaF₂‐Water Interface Probed by Flow Experiments and Vibrational Spectroscopy

Patrick Ober, Johannes Hunger, Sophia H. Kolbinger, Ellen H. G. Backus, more

Angewandte Chemie International Edition > 61 > 46 > n/a - n/a

The dissolution of minerals in contact with water plays a crucial role in geochemistry. However, obtaining molecular insight into interfacial chemistry is challenging. Dissolution typically involves the release of ions from the surface, giving rise to a charged mineral surface. This charge affects the interfacial water arrangement, which can be investigated by surface‐specific vibrational Sum Frequency...

article

Probing Water State during Lipidic Mesophases Phase Transitions

Yang Yao, Sara Catalini, Bence Kutus, Johannes Hunger, more

Angewandte Chemie International Edition > 60 > 48 > 25274 - 25280

We investigate the static and dynamic states of water network during the phase transitions from double gyroid (

I a \overline{3} d

) to double diamond (

P n \overline{3} m

) bicontinuous cubic phases and from the latter to the reverse hexagonal (H_II) phase in monolinolein based lipidic mesophases by combining FTIR and broadband dielectric spectroscopy (BDS). In both cubic(s) and H_II phase, two dynamically different fractions...

article

Probing Water State during Lipidic Mesophases Phase Transitions

Yang Yao, Sara Catalini, Bence Kutus, Johannes Hunger, more

Angewandte Chemie > 133 > 48 > 25478 - 25484

We investigate the static and dynamic states of water network during the phase transitions from double gyroid (

I a \overline{3} d

) to double diamond (

P n \overline{3} m

article

Hydrogen‐Bond Structure and Dynamics of TADDOL Asymmetric Organocatalysts Correlate with Catalytic Activity

Seoncheol Cha, Bogdan Marekha, Manfred Wagner, Johannes Hunger

Chemistry – A European Journal > 25 > 42 > 9984 - 9990

The catalytic efficiency of diol‐based organocatalysts has been shown to strongly depend on the diols molecular structure including hydrogen‐bonding, yet, the underlying molecular‐level origins have remained elusive. Herein a study on the inter‐ and intramolecular hydrogen‐bonding of two isomeric diol‐based catalysts (TADDOLs) in solution is presented: 1‐Naphthyl substituted TADDOL (1nTADDOL), which...

article

Specific Ion Effects on an Oligopeptide: Bidentate Binding Matters for the Guanidinium Cation

Vasileios Balos, Bogdan Marekha, Christian Malm, Manfred Wagner, more

Angewandte Chemie International Edition > 58 > 1 > 332 - 337

Ion–protein interactions are important for protein function, yet challenging to rationalize owing to the multitude of possible ion–protein interactions. To explore specific ion effects on protein binding sites, we investigate the interaction of different salts with the zwitterionic peptide triglycine in solution. Dielectric spectroscopy shows that salts affect the peptide's reorientational dynamics,...

article

Spezifische Ionen‐Effekte am Beispiel eines Oligopeptids: die Rolle zweizähniger Koordination beim Guanidinium‐Kation

Vasileios Balos, Bogdan Marekha, Christian Malm, Manfred Wagner, more

Angewandte Chemie > 131 > 1 > 338 - 343

Ion‐Protein‐Wechselwirkungen sind wegen der zahlreichen möglichen Proteinbindungsstellen schwierig zu verstehen. Um spezifische Ionen‐Effekte auf Proteinbindungsstellen zu erfassen, untersuchen wir den Einfluss von Salzen auf des zwitterionische Peptid Triglycin. Dielektrische Spektren zeigen, dass Salze die Rotationsdynamik des Peptids beeinflussen, wobei der Effekt von stark denaturierenden Kationen...

article

Complexity in Acid–Base Titrations: Multimer Formation Between Phosphoric Acids and Imines

Christian Malm, Heejae Kim, Manfred Wagner, Johannes Hunger

Chemistry – A European Journal > 23 > 45 > 10853 - 10860

Solutions of Brønsted acids with bases in aprotic solvents are not only common model systems to study the fundamentals of proton transfer pathways but are also highly relevant to Brønsted acid catalysis. Despite their importance the light nature of the proton makes characterization of acid–base aggregates challenging. Here, we track such acid–base interactions over a broad range of relative compositions...

article

Hofmeister‐Effekte unter der Lupe: Die direkte Anion‐Amid‐Bindung ist schwächer als die Kation‐Amid‐Bindung

Vasileios Balos, Heejae Kim, Mischa Bonn, Johannes Hunger

Angewandte Chemie > 128 > 28 > 8257 - 8261

Trotz vermehrter Hinweise auf direkte Wechselwirkungen als Ursache für die Destabilisierung von Proteinen durch Ionen blieb die Frage nach der Stärke der Bindung von Anionen zu Proteinen im Vergleich zu jener von Kationen offen. Die Rotation eines Modellamids wurde nun als Maß für die Wechselwirkung verschiedener Anionen mit der Amidgruppe verwendet. Die Untersuchungen zeigen, dass Protein‐stabilisierende...

article

Dissecting Hofmeister Effects: Direct Anion–Amide Interactions Are Weaker than Cation–Amide Binding

Vasileios Balos, Heejae Kim, Mischa Bonn, Johannes Hunger

Angewandte Chemie International Edition > 55 > 28 > 8125 - 8128

Whereas there is increasing evidence for ion‐induced protein destabilization through direct ion–protein interactions, the strength of the binding of anions to proteins relative to cation–protein binding has remained elusive. In this work, the rotational mobility of a model amide in aqueous solution was used as a reporter for the interactions of different anions with the amide group. Protein‐stabilizing...

article

Ionische Flüssigkeiten: nicht nur strukturell, sondern auch dynamisch heterogen

Zhuan‐Ping Zheng, Wen‐Hui Fan, Soham Roy, Kamila Mazur, more

Angewandte Chemie > 127 > 2 > 697 - 700

Die komplexe und heterogene Struktur von ionischen Flüssigkeiten wurde in den vergangenen Jahren aufgezeigt, ihre Auswirkung auf die Dynamik blieb jedoch offen. Hier verwenden wir Femtosekunden‐IR‐Spektroskopie, um die lokale strukturelle Dynamik in protischen Alkylammonium‐basierten ionischen Flüssigkeiten aufzuklären. Die Strukturrelaxation nach einem ultraschnellen Temperatursprung, der auf die...

article

Ionic Liquids: Not only Structurally but also Dynamically Heterogeneous

Zhuan‐Ping Zheng, Wen‐Hui Fan, Soham Roy, Kamila Mazur, more

Angewandte Chemie International Edition > 54 > 2 > 687 - 690

In recent years, the complex and heterogeneous structure of ionic liquids has been demonstrated; however, the consequences on the dynamics have remained elusive. Here, we use femtosecond IR spectroscopy to elucidate the local structural dynamics in protic alkylammonium‐based ionic liquids. The structural relaxation after an ultrafast temperature increase, following vibrational excitation and subsequent...

article

Heterogenität der Luft/Wasser‐Grenzfläche gezeigt durch 2D‐HD‐SFE‐Spektroskopie

Cho‐Shuen Hsieh, Masanari Okuno, Johannes Hunger, Ellen H. G. Backus, more

Angewandte Chemie > 126 > 31 > 8284 - 8288

Wassermoleküle wechselwirken stark miteinander durch Wasserstoffbrücken. Diese effiziente intermolekulare Kopplung verursacht eine starke Delokalisierung der Molekülschwingungen im Inneren des Wassers. Wir untersuchen die intermolekulare Kopplung der Schwingungen an der Luft/Wasser‐Grenzfläche und beobachten, dass die intermolekulare Kopplung 1) signifikant reduziert ist und 2) für verschiedene Wassermoleküle...

article

Aqueous Heterogeneity at the Air/Water Interface Revealed by 2D‐HD‐SFG Spectroscopy

Cho‐Shuen Hsieh, Masanari Okuno, Johannes Hunger, Ellen H. G. Backus, more

Angewandte Chemie International Edition > 53 > 31 > 8146 - 8149

Water molecules interact strongly with each other through hydrogen bonds. This efficient intermolecular coupling causes strong delocalization of molecular vibrations in bulk water. We study intermolecular coupling at the air/water interface and find intermolecular coupling 1) to be significantly reduced and 2) to vary strongly for different water molecules at the interface—whereas in bulk water the...

article

Dynamics of RTILs: A comparative dielectric and OKE study

Thomas Sonnleitner, David A. Turton, Stefan Waselikowski, Johannes Hunger, more

Journal of Molecular Liquids > 2014 > 192 > Complete > 19-25

The dynamics of room-temperature ionic liquids (RTILs) were studied by investigating their dielectric relaxation (DR) and time-resolved optical Kerr-effect (OKE) spectra in the frequency range of ~10MHz to ~20THz. For the studied RTILs the OKE and DR spectra are dominated by a relaxation in the GHz region and extend to a relatively sharp band at around 10THz. Whilst the first feature is mainly associated...

article

Hydration Dynamics of Hyaluronan and Dextran

Johannes Hunger, Anja Bernecker, Huib J. Bakker, Mischa Bonn, more

Biophysical Journal > 2012 > 103 > 1 > L10-L12

Hyaluronan is a polysaccharide, which is ubiquitous in vertebrates and has been reported to be strongly hydrated in a biological environment. We study the hydration of hyaluronan in solution using the rotational dynamics of water as a probe. We measure these dynamics with polarization-resolved femtosecond-infrared and terahertz time-domain spectroscopies. Both experiments reveal that a subensemble...

article

Energy Relaxation Dynamics of the Hydration Complex of Hydroxide

Liyuan Liu, Johannes Hunger, Huib J. Bakker

The Journal of Physical Chemistry A > 2011 > 115 > 51 > 14593 - 14598

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Keywords

DIELECTRIC SPECTROSCOPY (4)
ADSORPTION (2)
DIELECTRIC RELAXATION (2)
DIELEKTRISCHE SPEKTROSKOPIE (2)
GRENZFLÄCHENWASSER (2)
INTERFACES (2)
INTERFACIAL WATER (2)
IR SPECTROSCOPY (2)
LIPIDIC MESOPHASE (2)
ORGANOCATALYSIS (2)
PHASE TRANSITIONS (2)
ROOM-TEMPERATURE IONIC LIQUIDS (2)
SUMMENFREQUENZERZEUGUNG (2)
WATER DYNAMICS (2)
AMIDE (1)
AMIDES (1)
ANIONEN (1)
ANIONS (1)
BRØNSTED ACID CATALYSIS (1)
COOPERATIVE DYNAMICS (1)
DENATURATION (1)
DENATURIERUNG (1)
DIELECTRIC RELAXATION SPECTROSCOPY (1)
ELECTROLYTE (1)
FISCHER CLUSTERS (1)
FLOW (1)
GRAPHEN (1)
GRAPHENE (1)
HOFMEISTER EFFECTS (1)
HOFMEISTER-EFFEKTE (1)
HYDROGEN BONDING (1)
ION SIEVING (1)
IONIC LIQUIDS (1)
IONISCHE FLÜSSIGKEITEN (1)
IR‐SPEKTROSKOPIE (1)
JAMMING (1)
MESOSCOPIC (1)
MINERAL-WASSER-GRENZFLÄCHE (1)
MINERAL-WATER INTERFACE (1)
MOLECULAR DYNAMICS SIMULATIONS (1)
MOLEKÜLDYNAMIKSIMULATIONEN (1)
NANOMEMBRANES (1)
NANOSCALE (1)
NICHTLINEARE SPEKTROSKOPIE (1)
NMR SPECTROSCOPY (1)
NMR TITRATION (1)
NOBLE GAS LIQUIDS (1)
NON-LINEAR SPECTROSCOPY (1)
OPTICAL KERR EFFECT (1)
PH‐RESPONSIVE (1)
POLYDOPAMINE (1)
PRECISE SEPARATION (1)
PROTEIN DENATURATION (1)
PROTEINDENATURIERUNG (1)
PROTON TRANSFER (1)
PSEUDOCAPACITANCE (1)
PSEUDOKAPAZITÄT (1)
RAMAN (1)
SCHWINGUNGSDYNAMIK (1)
SCHWINGUNGSSPEKTROSKOPIE (1)
SPECIFIC ION EFFECTS (1)
SPECTRAL DIFFUSION (1)
SPECTROSCOPY (1)
SPEKTRALE DIFFUSION (1)
SPEZIFISCHE IONENEFFEKTE (1)
STRÖMUNG (1)
SUM-FREQUENCY GENERATION (1)
SUM‐FREQUENCY GENERATION (1)
TERAHERTZ (1)
TERAHERTZ FIELD-INDUCED SECOND-HARMONIC GENERATION (1)
THERMAL EQUILIBRATION (1)
THERMISCHE ÄQUILIBRIERUNG (1)
TRANSPORT MECHANISMS (1)
TRIGLYCIN (1)
TRIGLYCINE (1)
TWO‐DIMENSIONAL SPECTROSCOPY (1)
ULTRA-FAST OPTICAL KERR-EFFECT (1)
ULTRAFAST (1)
VIBRATIONAL DYNAMICS (1)
VIBRATIONAL SPECTROSCOPY (1)
WATER (1)
ZWEIDIMENSIONALE SPEKTROSKOPIE (1)
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Wiley (17)
ACS (11)
Elsevier (5)

Journal

Angewandte Chemie (7)
Angewandte Chemie International Edition (7)
Journal of Chemical & Engineering Data (4)
The Journal of Physical Chemistry B (4)
Chemistry – A European Journal (2)
Journal of Molecular Liquids (2)
Journal of the American Chemical Society (2)
Advanced Materials (1)
Biophysical Journal (1)
Chemical Physics Letters (1)
Studies in History and Philosophy of Modern Physics (1)
The Journal of Physical Chemistry A (1)
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INFONA - science communication portal

Search results for: Johannes Hunger

Ion and Molecular Sieving With Ultrathin Polydopamine Nanomembranes

Direct Probe of Electrochemical Pseudocapacitive pH Jump at a Graphene Electrode**

Direkte Visualisierung elektrochemischer pseudo‐kapazitiver pH Sprünge an einer Graphenelektrode**

Ionenadsorption und ‐desorption an der CaF₂‐Wasser‐Grenzfläche untersucht mit Flussexperimenten und Schwingungsspektroskopie

Ion Adsorption and Desorption at the CaF₂‐Water Interface Probed by Flow Experiments and Vibrational Spectroscopy

Probing Water State during Lipidic Mesophases Phase Transitions

Probing Water State during Lipidic Mesophases Phase Transitions

Hydrogen‐Bond Structure and Dynamics of TADDOL Asymmetric Organocatalysts Correlate with Catalytic Activity

Specific Ion Effects on an Oligopeptide: Bidentate Binding Matters for the Guanidinium Cation

Spezifische Ionen‐Effekte am Beispiel eines Oligopeptids: die Rolle zweizähniger Koordination beim Guanidinium‐Kation

Complexity in Acid–Base Titrations: Multimer Formation Between Phosphoric Acids and Imines

Hofmeister‐Effekte unter der Lupe: Die direkte Anion‐Amid‐Bindung ist schwächer als die Kation‐Amid‐Bindung

Dissecting Hofmeister Effects: Direct Anion–Amide Interactions Are Weaker than Cation–Amide Binding

Ionische Flüssigkeiten: nicht nur strukturell, sondern auch dynamisch heterogen

Ionic Liquids: Not only Structurally but also Dynamically Heterogeneous

Heterogenität der Luft/Wasser‐Grenzfläche gezeigt durch 2D‐HD‐SFE‐Spektroskopie

Aqueous Heterogeneity at the Air/Water Interface Revealed by 2D‐HD‐SFG Spectroscopy

Dynamics of RTILs: A comparative dielectric and OKE study

Hydration Dynamics of Hyaluronan and Dextran

Energy Relaxation Dynamics of the Hydration Complex of Hydroxide

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