Ultrafast conformation-dependent charge transfer in N, N, N′, N′-tetramethyl-1,3-propanediamine: Effect of flexible carbon skeleton on electron lone pair interactions

被引:1
|
作者
Abulimiti, Bumaliya [1 ,2 ]
Ma, Jiajun [1 ]
Wei, Jie [2 ]
An, Huan [1 ]
Wang, Xiaoning [1 ]
Yang, Jie [1 ]
Xiang, Mei [1 ]
Long, Jinyou [2 ]
Zhang, Song [2 ]
Zhang, Bing [2 ]
机构
[1] Xinjiang Normal Univ, Sch Phys & Elect Engn, Xinjiang Key Lab Luminescence Minerals & Opt Funct, Urumqi 830054, Peoples R China
[2] Chinese Acad Sci, Innovat Acad Precis Measurement Sci & Technol, State Key Lab Magnet Resonance & Atom & Mol Phys, Wuhan 430071, Peoples R China
关键词
Photoelectron spectroscopy; Conformational dynamics; Rydberg state; Charge transfer; Electron lone pair interaction; RYDBERG FINGERPRINT SPECTROSCOPY; STRUCTURAL DYNAMICS; THROUGH-SPACE; ENERGY-FLOW; IONIZATION; MOLECULES;
D O I
10.1016/j.saa.2024.124628
中图分类号
O433 [光谱学];
学科分类号
0703 ; 070302 ;
摘要
Flexible three-carbon skeleton makes N, N, N ' , N ' -tetramethyl-1,3-propanediamine (TMPDA) an important diamine system to investigate the conformation-dependent electron lone pair interactions and charge delocalization. The charge transfer process linked to structural motions of the three-carbon skeleton has been monitored in real time by the Rydberg electron binding energy (BE) spectra of TMPDA coupled with quantum chemical calculations. Optical excitation to the 3p state with a 200 nm pump pulse initially generated a localized charge on one of the two nitrogen atoms that may partially transfer to the other one. Rapid internal conversion (IC) from the 3p to 3s state occurred within 430 fs, resulting in an initial charge delocalized 3s_h/3s_l population ratio of 23.6 %/76.4 %. A final 3s_h/3s_l (51.9 %/48.1 %) equilibrium proceeded within about 2.64 ps. The 3s_h (TTTT + , GG ' TG + and G ' GG ' G + ) and 3s_l (GG ' GG ' + and GG ' G ' G + ) (see text for structure definitions) are identified as the extended and folded conformers, respectively. Two types of electron lone pair interactions, i.e., through-space interaction (TSI) and through-bond interaction (TBI), are found to coexist in TMPDA to drive charge transfer. The GG ' GG ' + and GG ' G ' G + structures exhibit TSI, while the TTTT + structure shows TBI. The GG ' TG + and G ' GG ' G + structures exhibit both TSI and TBI. Flexible three -carbon skeleton provide more opportunities for the two Nelectron lone pairs to overlap in space (i.e., TSI), making TMPDA to be favorable for the most stably folded conformation.
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页数:9
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