A Molecular Cluster Study on Activated CH/π Interactions: Infrared Spectroscopy of Aromatic Molecule-Acetylene Clusters

Asuka Fujii, So Ichi Morita, Mitsuhiko Miyazaki, Takayuki Ebata, Naohiko Mikami

Research output: Contribution to journalArticlepeer-review

63 Citations (Scopus)

Abstract

CH stretching vibrations of jet-cooled benzene-acetylene and several aromatics-acetylene clusters were observed in order to characterize the intermolecular interaction, so-called activated CH/π interaction between an acidic CH group and π-electrons. The infrared-ultraviolet double resonance spectroscopic techniques were used for measuring their vibrational spectra. The antisymmetric CH stretching vibration of the acetylene moiety exhibits a remarkable low-frequency shift upon the cluster formation with the aromatic molecules, indicating such a cluster structure that the acetylenic CH group is bound to π-electrons of the aromatic ring. The low-frequency shifts observed for the clusters show a positive correlation with the π-electron density of the ring, as expected for an ordinary π-hydrogen bond. On the other hand, the polarizability of the proton-accepting molecules showed a weakly negative correlation with the CH frequency shifts. These results show that the intermolecular interaction between the activated CH group and π-electrons is characterized as a π-hydrogen bond rather than as a van der Waals interaction.

Original languageEnglish
Pages (from-to)2652-2658
Number of pages7
JournalJournal of Physical Chemistry A
Volume108
Issue number14
DOIs
Publication statusPublished - 2004 Apr 8

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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