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Issue 30, 2017
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Gas-phase vibrational spectroscopy of triphenylamine: the effect of charge on structure and spectra

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Abstract

The effect of ionization by oxidation and protonation on the structure and IR spectrum of isolated, gas-phase triphenylamine (TPA) has been investigated by infrared multiple photon dissociation (IRMPD) spectroscopy in the fingerprint range from 600 cm−1 to 1800 cm−1 using an infrared free electron laser. IR spectra calculated using density functional theory (DFT) convincingly reproduce the experimental data. Spectral and structural differences are identified among neutral TPA, TPA˙+ and protonated TPA and qualitatively related to effects of resonance delocalization. As a consequence of electron delocalization, computed structural parameters for TPA remain virtually unchanged upon removal of an electron. Nonetheless, CC and CN stretching vibrations in the IR spectra of TPA˙+ undergo a red shift of up to 52 cm−1 as compared to those in TPA. Since ionization also strongly influences the relative band intensities, a vibrational projection analysis was used to correlate vibrational modes of TPA with those of TPA˙+. The experimental IR spectrum of gas-phase protonated TPA indicates that protonation occurs on the nitrogen atom, despite delocalization of the lone electron pair. Upon protonation, the structure changes from the nearly planar geometry to a near-tetrahedral configuration.

Graphical abstract: Gas-phase vibrational spectroscopy of triphenylamine: the effect of charge on structure and spectra

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Publication details

The article was received on 21 Apr 2017, accepted on 10 Jun 2017 and first published on 12 Jun 2017


Article type: Paper
DOI: 10.1039/C7CP02638B
Citation: Phys. Chem. Chem. Phys., 2017,19, 19881-19889
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    Gas-phase vibrational spectroscopy of triphenylamine: the effect of charge on structure and spectra

    M. U. Munshi, G. Berden, J. Martens and J. Oomens, Phys. Chem. Chem. Phys., 2017, 19, 19881
    DOI: 10.1039/C7CP02638B

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