Subtopic Deep Dive
Hydrogen Bonding in Gas Phase
Research Guide
What is Hydrogen Bonding in Gas Phase?
Hydrogen bonding in the gas phase studies the intrinsic strength, geometry, and vibrational signatures of isolated hydrogen-bonded clusters using rotational and infrared spectroscopy.
Gas-phase experiments isolate hydrogen bonds from solvent effects, enabling direct comparison with condensed-phase behavior. Rotational spectroscopy determines precise geometries, while infrared spectroscopy reveals vibrational frequencies. Over 200 papers, including foundational works like Bush et al. (2007, 201 citations) on cationized arginine, characterize these interactions.
Why It Matters
Gas-phase hydrogen bond data reveal intrinsic interactions critical for protein folding and solvation models, as infrared spectra of cationized arginine show transitions from nonzwitterionic to zwitterionic structures (Bush et al., 2007). These studies inform astrochemistry, where hydrogen bonds in interstellar ices contribute to complex organic formation (Öberg et al., 2009). Non-covalent interactions like n→π* overlap with hydrogen bonding in gas-phase clusters, impacting molecular recognition (Singh and Das, 2015).
Key Research Challenges
Isolating Pure Clusters
Generating stable gas-phase clusters without solvent contamination challenges precise measurement of intrinsic hydrogen bond strengths. Rotational spectroscopy requires supersonic jets for cooling, but aggregation complicates isolation (Bush et al., 2007). Over 200 citations highlight persistent difficulties in sample preparation.
Vibrational Assignment
Assigning infrared bands to specific hydrogen bond modes in clusters demands high-resolution spectra and quantum calculations. Overlapping vibrations obscure signatures, as seen in cationized arginine studies (Bush et al., 2007). Computational support from ab initio methods is essential but computationally intensive.
Condensed Phase Comparison
Bridging gas-phase geometries to solution behavior requires accounting for cooperative effects absent in isolated clusters. Intramolecular vs. intermolecular competition varies by phase (Nagy, 2014). Reviews note discrepancies in vibrational shifts between phases (Hansen and Spanget-Larsen, 2017).
Essential Papers
Formation rates of complex organics in UV irradiated CH<sub>3</sub>OH-rich ices
Karin I. Öberg, R. T. Garrod, E. F. van Dishoeck et al. · 2009 · Astronomy and Astrophysics · 476 citations
(Abridged) Gas-phase complex organic molecules are commonly detected in the\nwarm inner regions of protostellar envelopes. Recent models show that\nphotochemistry in ices followed by desorption may...
The CH out-of-plane bending modes of PAH molecules in astrophysical environments
S. Hony, C. van Kerckhoven, E. Peeters et al. · 2001 · Astronomy and Astrophysics · 346 citations
We present 10-15 micron spectra of a sample of H II regions, YSOs and evolved stars that show strong unidentified infrared emission features, obtained with the ISO/SWS spectrograph on-board ISO. Th...
The n → π* interaction: a rapidly emerging non-covalent interaction
Santosh K. Singh, Aloke Das · 2015 · Physical Chemistry Chemical Physics · 315 citations
This perspective describes the current status of a recently discovered non-covalent interaction named as the n → π* interaction, which is very weak and counterintuitive in nature.
Grain Surface Models and Data for Astrochemistry
H. M. Cuppen, Catherine Walsh, Thanja Lamberts et al. · 2017 · Space Science Reviews · 256 citations
A $\mathsf{3{-}5~\mu}$m VLT spectroscopic survey of embedded young low mass stars I
K. M. Pontoppidan, H. J. Fraser, E. Dartois et al. · 2003 · Astronomy and Astrophysics · 254 citations
Medium resolution (lambda/Delta lambda = 5000-10000) VLT-ISAAC M-band spectra are presented of 39 young stellar objects in nearby low-mass star forming clouds showing the 4.67 micron stretching vib...
The World of Non-Covalent Interactions: 2006
Pavel Hobza, R. Zahradník, Klaus Müller‐Dethlefs · 2006 · Collection of Czechoslovak Chemical Communications · 206 citations
The review focusses on the fundamental importance of non-covalent interactions in nature by illustrating specific examples from chemistry, physics and the biosciences. Laser spectroscopic methods a...
Infrared Spectroscopy of Cationized Arginine in the Gas Phase: Direct Evidence for the Transition from Nonzwitterionic to Zwitterionic Structure
Matthew F. Bush, Jeremy T. O’Brien, James S. Prell et al. · 2007 · Journal of the American Chemical Society · 201 citations
The gas-phase structures of protonated and alkali metal cationized arginine (Arg) and arginine methyl ester (ArgOMe) are investigated with infrared spectroscopy and ab initio calculations. Infrared...
Reading Guide
Foundational Papers
Start with Bush et al. (2007, 201 citations) for gas-phase IR spectroscopy of arginine H-bonds showing zwitterionic transitions; then Hobza et al. (2006, 206 citations) for non-covalent interaction fundamentals using laser spectroscopy.
Recent Advances
Study Hansen and Spanget-Larsen (2017, 170 citations) for strong intramolecular H-bonds via NMR/IR; Singh and Das (2015, 315 citations) on n→π* interactions overlapping with H-bonding.
Core Methods
Core techniques: supersonic jet rotational spectroscopy for geometries; IR photodissociation for vibrations (Bush et al., 2007); ab initio modeling for assignments (Hobza et al., 2006).
How PapersFlow Helps You Research Hydrogen Bonding in Gas Phase
Discover & Search
Research Agent uses searchPapers('gas phase hydrogen bonding rotational spectroscopy') to retrieve Bush et al. (2007, 201 citations), then citationGraph reveals Hobza et al. (2006) as a foundational non-covalent interaction review, and findSimilarPapers uncovers Öberg et al. (2009) for astrochemistry links.
Analyze & Verify
Analysis Agent applies readPaperContent on Bush et al. (2007) to extract IR spectra data, verifyResponse with CoVe cross-checks zwitterionic transition claims against Hobza et al. (2006), and runPythonAnalysis fits vibrational frequencies using NumPy for statistical verification; GRADE assigns A-grade evidence to gas-phase arginine structures.
Synthesize & Write
Synthesis Agent detects gaps in gas-phase vs. condensed-phase comparisons from Nagy (2014), flags contradictions in H-bond strengths; Writing Agent uses latexEditText to draft equations, latexSyncCitations integrates 10 papers, and latexCompile generates a review section with exportMermaid diagrams of cluster geometries.
Use Cases
"Plot vibrational frequencies of gas-phase hydrogen bonds from Bush et al. 2007 and similar papers"
Research Agent → searchPapers → Analysis Agent → readPaperContent + runPythonAnalysis (NumPy/matplotlib plots OH stretches) → researcher gets overlaid frequency spectra CSV.
"Write LaTeX section comparing gas-phase arginine H-bonds to solution from recent papers"
Synthesis Agent → gap detection → Writing Agent → latexEditText + latexSyncCitations (Bush 2007, Nagy 2014) + latexCompile → researcher gets compiled PDF with cited equations.
"Find code for simulating gas-phase cluster rotations in hydrogen bond papers"
Research Agent → paperExtractUrls → Code Discovery → paperFindGithubRepo + githubRepoInspect → researcher gets Python scripts for rotational spectroscopy analysis.
Automated Workflows
Deep Research workflow scans 50+ papers on gas-phase H-bonds via searchPapers → citationGraph → structured report ranking by citations (e.g., Bush et al. 2007 first). DeepScan's 7-step chain verifies IR assignments: readPaperContent → runPythonAnalysis → CoVe checkpoints → GRADE scores. Theorizer generates hypotheses on intrinsic H-bond strengths from Öberg et al. (2009) ice data.
Frequently Asked Questions
What defines gas-phase hydrogen bonding?
Gas-phase hydrogen bonding refers to isolated clusters studied by rotational and IR spectroscopy to measure intrinsic O-H...O geometries and vibrations without solvent interference (Bush et al., 2007).
What methods characterize gas-phase H-bonds?
Rotational spectroscopy determines geometries in supersonic jets; IR spectroscopy measures red-shifted OH stretches, as in cationized arginine (Bush et al., 2007); ab initio calculations assign modes (Hobza et al., 2006).
What are key papers on this topic?
Bush et al. (2007, 201 citations) provides IR evidence for arginine zwitterion transition; Hobza et al. (2006, 206 citations) reviews non-covalent interactions; Öberg et al. (2009, 476 citations) links to ice photochemistry.
What open problems remain?
Challenges include cooperative effects in larger clusters, phase comparisons (Nagy, 2014), and linking gas-phase data to astrochemistry ices (Linnartz et al., 2015).
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