Nitrobenzene anti-parallel dimer formation in non-polar solvents
We investigated the dielectric and depolarized Rayleigh scattering behaviors of nitrobenzene (NO2-Bz), which is a benzene mono-substituted with a planar molecular frame bearing the large electric dipole moment 4.0 D, in non-polar solvents solutions, such as tetrachloromethane and benzene, at up to 3...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
AIP Publishing LLC
2014-06-01
|
| Series: | AIP Advances |
| Online Access: | http://dx.doi.org/10.1063/1.4884393 |
| _version_ | 1811232212255768576 |
|---|---|
| author | Toshiyuki Shikata Yuji Sakai Junji Watanabe |
| author_facet | Toshiyuki Shikata Yuji Sakai Junji Watanabe |
| author_sort | Toshiyuki Shikata |
| collection | DOAJ |
| description | We investigated the dielectric and depolarized Rayleigh scattering behaviors of nitrobenzene (NO2-Bz), which is a benzene mono-substituted with a planar molecular frame bearing the large electric dipole moment 4.0 D, in non-polar solvents solutions, such as tetrachloromethane and benzene, at up to 3 THz for the dielectric measurements and 8 THz for the scattering experiments at 20 °C. The dielectric relaxation strength of the system was substantially smaller than the proportionality to the concentration in a concentrated regime and showed a Kirkwood correlation factor markedly lower than unity; gK ∼ 0.65. This observation revealed that NO2-Bz has a tendency to form dimers, (NO2-Bz)2, in anti-parallel configurations for the dipole moment with increasing concentration of the two solvents. Both the dielectric and scattering data exhibited fast and slow Debye-type relaxation modes with the characteristic time constants ∼7 and ∼50 ps in a concentrated regime (∼15 and ∼30 ps in a dilute regime), respectively. The fast mode was simply attributed to the rotational motion of the (monomeric) NO2-Bz. However, the magnitude of the slow mode was proportional to the square of the concentration in the dilute regime; thus, the mode was assigned to the anti-parallel dimer, (NO2-Bz)2, dissociation process, and the slow relaxation time was attributed to the anti-parallel dimer lifetime. The concentration dependencies of both the dielectric and scattering data show that the NO2-Bz molecular processes are controlled through a chemical equilibrium between monomers and anti-parallel dimers, 2NO2-Bz ↔ (NO2-Bz)2, due to a strong dipole-dipole interaction between nitro groups. |
| first_indexed | 2024-04-12T10:59:39Z |
| format | Article |
| id | doaj.art-006df432e4c54d3091dd75c064ae8e9d |
| institution | Directory Open Access Journal |
| issn | 2158-3226 |
| language | English |
| last_indexed | 2024-04-12T10:59:39Z |
| publishDate | 2014-06-01 |
| publisher | AIP Publishing LLC |
| record_format | Article |
| series | AIP Advances |
| spelling | doaj.art-006df432e4c54d3091dd75c064ae8e9d2022-12-22T03:36:00ZengAIP Publishing LLCAIP Advances2158-32262014-06-0146067130067130-1310.1063/1.4884393028406ADVNitrobenzene anti-parallel dimer formation in non-polar solventsToshiyuki Shikata0Yuji Sakai1Junji Watanabe2Division of Natural Resources and Eco-materials, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, JapanGraduate School of Frontier Bioscience, Osaka University, Suita, Osaka 565-0871, JapanGraduate School of Frontier Bioscience, Osaka University, Suita, Osaka 565-0871, JapanWe investigated the dielectric and depolarized Rayleigh scattering behaviors of nitrobenzene (NO2-Bz), which is a benzene mono-substituted with a planar molecular frame bearing the large electric dipole moment 4.0 D, in non-polar solvents solutions, such as tetrachloromethane and benzene, at up to 3 THz for the dielectric measurements and 8 THz for the scattering experiments at 20 °C. The dielectric relaxation strength of the system was substantially smaller than the proportionality to the concentration in a concentrated regime and showed a Kirkwood correlation factor markedly lower than unity; gK ∼ 0.65. This observation revealed that NO2-Bz has a tendency to form dimers, (NO2-Bz)2, in anti-parallel configurations for the dipole moment with increasing concentration of the two solvents. Both the dielectric and scattering data exhibited fast and slow Debye-type relaxation modes with the characteristic time constants ∼7 and ∼50 ps in a concentrated regime (∼15 and ∼30 ps in a dilute regime), respectively. The fast mode was simply attributed to the rotational motion of the (monomeric) NO2-Bz. However, the magnitude of the slow mode was proportional to the square of the concentration in the dilute regime; thus, the mode was assigned to the anti-parallel dimer, (NO2-Bz)2, dissociation process, and the slow relaxation time was attributed to the anti-parallel dimer lifetime. The concentration dependencies of both the dielectric and scattering data show that the NO2-Bz molecular processes are controlled through a chemical equilibrium between monomers and anti-parallel dimers, 2NO2-Bz ↔ (NO2-Bz)2, due to a strong dipole-dipole interaction between nitro groups.http://dx.doi.org/10.1063/1.4884393 |
| spellingShingle | Toshiyuki Shikata Yuji Sakai Junji Watanabe Nitrobenzene anti-parallel dimer formation in non-polar solvents AIP Advances |
| title | Nitrobenzene anti-parallel dimer formation in non-polar solvents |
| title_full | Nitrobenzene anti-parallel dimer formation in non-polar solvents |
| title_fullStr | Nitrobenzene anti-parallel dimer formation in non-polar solvents |
| title_full_unstemmed | Nitrobenzene anti-parallel dimer formation in non-polar solvents |
| title_short | Nitrobenzene anti-parallel dimer formation in non-polar solvents |
| title_sort | nitrobenzene anti parallel dimer formation in non polar solvents |
| url | http://dx.doi.org/10.1063/1.4884393 |
| work_keys_str_mv | AT toshiyukishikata nitrobenzeneantiparalleldimerformationinnonpolarsolvents AT yujisakai nitrobenzeneantiparalleldimerformationinnonpolarsolvents AT junjiwatanabe nitrobenzeneantiparalleldimerformationinnonpolarsolvents |