A Combined Spectroscopic and ab Initio Investigation of Phenylacetylene−Methylamine Complex. Observation of σ and π Type Hydrogen-Bonded Configurations and Fluorescence Quenching by We

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• 作者：Surajit Maity ; Arghya Dey ; G. Naresh Patwari ; S. Karthikeyan ; Kwang S. Kim
• 刊名：Journal of Physical Chemistry A
• 出版年：2010
• 出版时间：October 28, 2010
• 年：2010
• 卷：114
• 期：42
• 页码：11347-11352
• 全文大小：194K
• 年卷期：v.114,no.42(October 28, 2010)
• ISSN：1520-5215

文摘

Two distinct isomers for the binary complex between phenylacetylene and methylamine were observed. The first complex is characterized by the presence of a C−H···N hydrogen bond between the acetylenic C−H group and the N atom of methylamine. In the second complex the N−H group of methylamine interacts with the π electron density of the benzene ring accompanied by a peripheral interaction between the methyl C−H group and the π electron density of the C≡C bond. Stabilization energies and Gibbs free energies at the complete basis set (CBS) limit of the coupled cluster theory with single, double, and perturbative triple excitations [CCSD(T)] suggest that while the C−H···N hydrogen bonded complex is the global minimum, the N−H···π hydrogen bonded complex is a high energy local minimum. The formation of the N−H···π complex could be related to kinetic trapping or higher accessibility. Comparison of the laser induced fluorescence (LIF) excitation and the one-color-resonant two-photon ionization (1C-R2PI) spectra suggests that formation of C−H···N hydrogen bonding leads to fluorescence quenching in phenylacetylene, most probably due to dipolar coupling in the excited state. The binary complex between the phenylacetylene and methylamine shows interesting isomer-dependent fluorescent properties.