Transition from Water Wires to Bifurcated H-Bond Networks in 2-Pyridone·(H₂O)_n, n = 1–4 Clusters

Abstract

Mass-selective two-color resonant two-photon ionization (2C-R2PI), UV/UV hole-burning, and infrared (IR) depletion spectra of supersonic jet-cooled 2-pyridone·(H2O) n clusters with n = 1–4 have been measured to investigate the local hydration patterns around 2-pyridone (2PY) as a function of cluster size. As shown by others, the IR frequencies of the OH and NH stretches of the n = 1, 2 clusters are characteristic of water wires stretching from the NH to the CO group of 2PY. We identify two isomers (3A and 3B) of the n = 3 cluster in the 2C-R2PI spectrum and separate them by IR/UV and UV/UV hole-burning techniques. Isomer 3A exhibits a three-membered water wire, extending the n = 1, 2 structural motif. Isomer 3B exhibits bifurcated water wires with the first H2O donating to two waters that form H-bonds to the CO group. This increases the H-bond strength between the NH group of 2PY and the proximal H2O molecule, lowering the NH stretch to ∼2800 cm–1. The n = 4 cluster is also bifurcated with two water wires between the bifurcating H2O and the CO group. The cluster-selective IR spectra are complemented with density-functional calculations using the PW91, B3LYP, B97-D, and M06-2X functionals, where the latter two include long-range dispersive interactions, and with the ab initio correlated SCS-CC2 method. The calculated IR spectra provide firm assignments of the structures of the n = 1–4 cluster structures and allow us to understand the evolution of individual H-bond strengths with increasing cluster size.

Disentangling the Complex Vibrational Spectra of Hydrogen-Bonded Clusters of 2-Pyridone with Ab Initio Structural Search and Anharmonic Analysis

“…In 2013, Leutwyler and co-workers measured the vibrational spectra of 2PY-(NH 3 ) n in the NH and CH stretch fundamental region (2400–3700 cm –1 ) using infrared (IR) laser depletion spectroscopy for n = 1–3 . In 2018, Leutwyler and co-workers measured the vibrational spectra of 2PY-(H 2 O) n for n = 3 and 4 with an emphasis on the IR signatures of the different H-bond structural motifs using mass- and isomer-specific two-color resonant two-photon ionization for cluster size and isomer identification …”

“…16 In 2018, Leutwyler and co-workers measured the vibrational spectra of 2PY-(H 2 O) n for n = 3 and 4 with an emphasis on the IR signatures of the different H-bond structural motifs using mass-and isomer-specific two-color resonant two-photon ionization for cluster size and isomer identification. 17 When 2PY is solvated by water, methanol, or ammonia molecules, it is not surprising to see the complex vibrational spectra at 3 μm as a result of formation of hydrogen-bond networks. For example, Zwier and co-workers have analyzed the spectra of 2PY-(H 2 O) 1 and 2HP-(H 2 O) 3 and speculated the origin of their complex vibrational features at 3 μm to be (1) the existence of multiple conformers, (2) H-atom transfer, and (3) inherent anharmonic coupling in water hydrogen-bond networks.…”

Non‐conventional Hydrogen Bonding and Aromaticity: A Systematic Study on Model Nucleobases and Their Solvated Clusters

“…[10] Herein we tried to explain such aromatic behavior of 2PY analogs surrounded by water molecules through H-bonded network. Recent work from Leutwyler's group [30] discussed the evolution of water cluster (n = to 4) around 2-pyridone moiety. With the help of supersonic jet-cooled gas-phase spectroscopy and quantum calculations, the authors concluded that clusters with one and two water molecules are characteristics of sequential H-bonded water-wires.…”

SILVER SULFATE (Ag2SO4): MOLECULAR ANALYSIS AND ION TRANSPORT

“…Gambar 1. Fishbone Perak Sulfat (Ag2SO4) (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) Penelitian dilakukan dalam beberapa tahapan, yaitu (1) Analisis 2D molekul Ag2SO4 secara dua dimensi menggunakan ChemDraw 2D; (2) Analisis molekul (103,(115)(116)(117)(118)(119)(120)(121)(122)(123)(124) Ag2SO4, secara 3 dimensi menggunakan Chem 3D. Molekul Ag2SO4 dilukis dengan menggunakan ChemDraw dengan cara memilih Structure dan Convert Name to Structure.…”

“…Molekul Ag2SO4 dibuat dengan menggunakan Chemdraw 2D dan kemudian di pindahkan ke dalam bentuk 3 dimensi menggunakan Chem 3D. Proses ini dapat membantu melihat pola pergerakan molekul (103,(115)(116)(117)(118)(119)(120)(121)(122)(123)(124) secara optimal dan kemungkinan dinamika air selama berinteraksi (164)(165)(166)(167)(168)(169)(170)(171)(172) di lingkungan saat proses splitting berlangsung. Dengan bantuan Chem3D dapat dilihat bentuk surface dari molekul Ag2SO4.…”