Please use this identifier to cite or link to this item:
http://dx.doi.org/10.14279/depositonce-8454
Main Title: | Microhydration of protonated 5-hydroxyindole revealed by infrared spectroscopy |
Author(s): | Klyne, Johanna Dopfer, Otto |
Type: | Article |
Is Part Of: | 10.14279/depositonce-8344 |
Language Code: | en |
Abstract: | Controlled microsolvation of protonated aromatic biomolecules with water is fundamental to understand proton transfer reactions in aqueous environments. We measured infrared photodissociation (IRPD) spectra of mass-selected microhydrates of protonated 5-hydroxyindole (5HIH+–Wn, W = H2O, n = 1–3) in the OH and NH stretch ranges (2700–3800 cm−1), which are sensitive to the spectroscopic characteristics of interior solvation, water network formation, and proton transfer to solvent. Analysis of the IRPD spectra by dispersion-corrected density functional theory calculations (B3LYP-D3/aug-cc-pVTZ) reveals the coexistence of C3- and C4-protonated carbenium ions, 5HIH+(C3) and 5HIH+(C4), as well as the O-protonated oxonium ion, 5HIH+(O). Monohydrated 5HIH+–W2/3 clusters are formed by hydrogen-bonding (H-bonding) of the first water to the most acidic functional group, namely, the NH group in the case of 5HIH+(C3), the OH group for 5HIH+(C4), and the OH2 group for 5HIH+(O). The latter benefits from its twofold degeneracy and the outstandingly high binding energy of D0 ∼ 100 kJ mol−1. Larger 5HIH+–W2/3 clusters preferably grow (i) by H-bonding of the second water to the remaining vacant functional group and and/or (ii) by formation of W2 water chains at the respective most acidic functional group. Our IRPD spectra of 5HIH+–Wn do not indicate any proton transfer to the solvent up to n = 3, in line with the proton affinities of 5HI and Wn. Comparison of 5HIH+–Wn to neutral 5HI–W and cationic 5HI+–Wn clusters elucidates the impact of different charge states on the topology of the initial solvation shell. Furthermore, to access the influence of the size of the arene ion and a second functional group, we draw a comparison to microhydration of protonated phenol. |
URI: | 10.14279/depositonce-8454 |
Issue Date: | 8-Jan-2019 |
Date Available: | 30-Apr-2019 |
DDC Class: | 540 Chemie und zugeordnete Wissenschaften |
Sponsor/Funder: | TU Berlin, Open-Access-Mittel - 2019 |
License: | https://creativecommons.org/licenses/by-nc/3.0/ |
Journal Title: | Physical Chemistry Chemical Physics |
Publisher: | Royal Society of Chemistry |
Publisher Place: | Cambridge |
Volume: | 21 |
Issue: | 5 |
Publisher DOI: | 10.1039/C8CP06950F |
Page Start: | 2706 |
Page End: | 2718 |
EISSN: | 1463-9084 |
ISSN: | 1463-9076 |
Appears in Collections: | FG Lasermolekülspektroskopie und Umweltphysik » Publications |
Files in This Item:
File | Description | Size | Format | |
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c8cp06950f.pdf | 4.33 MB | Adobe PDF | View/Open |
This item is licensed under a Creative Commons License