DICP OpenIR
Conformational preferences and isomerization upon excitation/ionization of 2-methoxypyridine and 2-N-methylaminopyridine
Dai, Wenshuai1,2; Liu, Sheng1,2; Zhang, Zhe1,2; Chi, Xiaoping1,2; Cheng, Min1; Du, Yikui1; Zhu, Qihe1
Source PublicationPHYSICAL CHEMISTRY CHEMICAL PHYSICS
2018-03-07
ISSN1463-9076
DOI10.1039/c7cp07854d
Volume20Issue:9Pages:6211-6226
Indexed BySCI
SubtypeArticle
WOS HeadingsScience & Technology ; Physical Sciences
WOS SubjectChemistry, Physical ; Physics, Atomic, Molecular & Chemical
WOS Research AreaChemistry ; Physics
WOS KeywordTHRESHOLD IONIZATION SPECTROSCOPY ; METHYL VINYL ETHER ; CIS-TRANS ISOMERIZATION ; SET MODEL CHEMISTRY ; 1ST EXCITED-STATE ; THEORETICAL CALCULATIONS ; MICROWAVE-SPECTRUM ; INTERNAL-ROTATION ; MATI SPECTROSCOPY ; HYPERCONJUGATION
AbstractConformers from the rotations of the methyl group and the methoxy or methylamino group, namely staggered (s)/eclipsed (e)-cis/trans 2-methoxypyridine (2MOP) and 2-N-methylaminopyridine (2NMP), are studied using theoretical calculations in combination with one-color resonance-enhanced two-photon ionization (1C-R2PI) and mass-analyzed threshold ionization (MATI) spectroscopies. The calculations predict that, for cis 2MOP, trans 2MOP and trans 2NMP, only the s conformers are stable in the S-0, S-1 and D-0 states. However, for cis 2NMP, the stable conformer is staggered in the S-0 state but eclipsed in the S-1 and D-0 states, indicating an isomerization upon the excitation or ionization from the S-0 state. This is experimentally supported by the 1C-R2PI and MATI spectra of 2NMP. Due to the relative instability, the number density of trans 2MOP is too low in the sample to be detected. All the bands in the 1C-R2PI and MATI spectra of 2MOP are assigned to s-cis 2MOP. The energy differences between cis and trans conformers are derived from excitation and ionization energies, indicating another conformational isomerization: stable trans 2NMP in the S-0 and S-1 states but stable cis 2NMP in the D-0 state. For 2MOP, the so-called syn preference previously found for the S-0 state is also observed in the S-1 and D-0 states. The conformational preference and isomerization are discussed with natural bond orbital calculations and reduced density gradient analysis. For 2MOP, the syn preferences are mainly caused by the exchange repulsion among several s-orbitals of the OCH3 group and the pyridine ring. While the relative stabilities of the s and e conformers of cis 2MOP and cis 2NMP are simultaneously influenced by steric repulsion and orbital interactions.
Language英语
WOS IDWOS:000429280100022
PublisherROYAL SOC CHEMISTRY
Citation statistics
Cited Times:1[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://cas-ir.dicp.ac.cn/handle/321008/169129
Collection中国科学院大连化学物理研究所
Corresponding AuthorDu, Yikui
Affiliation1.Chinese Acad Sci, Inst Chem, State Key Lab Mol React Dynam, Beijing Natl Lab Mol Sci, Beijing 100190, Peoples R China
2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China
Recommended Citation
GB/T 7714
Dai, Wenshuai,Liu, Sheng,Zhang, Zhe,et al. Conformational preferences and isomerization upon excitation/ionization of 2-methoxypyridine and 2-N-methylaminopyridine[J]. PHYSICAL CHEMISTRY CHEMICAL PHYSICS,2018,20(9):6211-6226.
APA Dai, Wenshuai.,Liu, Sheng.,Zhang, Zhe.,Chi, Xiaoping.,Cheng, Min.,...&Zhu, Qihe.(2018).Conformational preferences and isomerization upon excitation/ionization of 2-methoxypyridine and 2-N-methylaminopyridine.PHYSICAL CHEMISTRY CHEMICAL PHYSICS,20(9),6211-6226.
MLA Dai, Wenshuai,et al."Conformational preferences and isomerization upon excitation/ionization of 2-methoxypyridine and 2-N-methylaminopyridine".PHYSICAL CHEMISTRY CHEMICAL PHYSICS 20.9(2018):6211-6226.
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