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Simultaneous enhancement of transition dipole strength and vibrational lifetime of an alkyne IR probe viaπ-d backbonding and vibrational decoupling.
Kossowska, Dorota; Lee, Giseong; Han, Hogyu; Kwak, Kyungwon; Cho, Minhaeng.
Afiliación
  • Kossowska D; Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Korea. kkwak@korea.ac.kr mcho@korea.ac.kr and Department of Chemistry, Korea University, Seoul 02841, Korea. hogyuhan@korea.ac.kr.
  • Lee G; Department of Chemistry, Korea University, Seoul 02841, Korea. hogyuhan@korea.ac.kr.
  • Han H; Department of Chemistry, Korea University, Seoul 02841, Korea. hogyuhan@korea.ac.kr.
  • Kwak K; Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Korea. kkwak@korea.ac.kr mcho@korea.ac.kr and Department of Chemistry, Korea University, Seoul 02841, Korea. hogyuhan@korea.ac.kr.
  • Cho M; Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Korea. kkwak@korea.ac.kr mcho@korea.ac.kr and Department of Chemistry, Korea University, Seoul 02841, Korea. hogyuhan@korea.ac.kr.
Phys Chem Chem Phys ; 21(45): 24919-24925, 2019 Dec 07.
Article en En | MEDLINE | ID: mdl-31696881
Alkyne infrared (IR) probes 1-6 with Si and S (or Se) atoms incorporated into the C[triple bond, length as m-dash]C bond were synthesized, and the vibrational properties of their C[triple bond, length as m-dash]C stretch mode were studied using Fourier transform infrared (FTIR) and femtosecond IR pump-probe (IR PP) spectroscopies in combination with quantum chemical calculations. From FTIR studies, the transition dipole strengths (in units of 10-2 D2) of 1-3 having the Si atom were measured to be 1.85, 3.32, and 2.52, whereas those of 4-6 having no Si atom were measured to be 0.13, 0.20, and 0.17, respectively, in CHCl3. Thus, the increase in the transition dipole strength of the C[triple bond, length as m-dash]C stretch mode upon incorporation of the Si atom into the C[triple bond, length as m-dash]C bond is by a factor of about 14 or higher. The large increase in the transition dipole strength of the C[triple bond, length as m-dash]C stretch mode upon such Si incorporation is attributed to π-d backbonding between the C[triple bond, length as m-dash]C group's π and Si atom's d orbitals. From IR PP experiments, the vibrational lifetimes of the C[triple bond, length as m-dash]C stretch mode in 1-3 having none, S, and Se atoms were determined to be 5.7 ± 0.7, 13.0 ± 1.1, and 94.2 ± 5.8 ps, respectively, in CHCl3. Thus, the increase in the vibrational lifetime of the C[triple bond, length as m-dash]C stretch mode upon incorporation of the S (or Se) atom between the phenyl ring and the C[triple bond, length as m-dash]C bond is by a factor of about 2 (or 16) or higher. The large increase in the vibrational lifetime of the C[triple bond, length as m-dash]C stretch mode upon such S (or Se) incorporation is attributed to its heavy atom effect impeding vibrational couplings between the C[triple bond, length as m-dash]C stretch and phenyl ring vibrations. From two-dimensional infrared (2DIR) experiments, the large transition dipole strength and long vibrational lifetime of 3 containing the Si and S (or Se) atoms were shown to enable the measurement of its 2DIR spectra up to 500 ps. The strongly absorbing alkynes with long vibrational lifetimes will be a promising probe of molecular dynamics in nonlinear vibrational spectroscopy and imaging on an extended time scale.

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: Phys Chem Chem Phys Asunto de la revista: BIOFISICA / QUIMICA Año: 2019 Tipo del documento: Article Pais de publicación: Reino Unido

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: Phys Chem Chem Phys Asunto de la revista: BIOFISICA / QUIMICA Año: 2019 Tipo del documento: Article Pais de publicación: Reino Unido