Synthesis and Photoinduced Intramolecular Charge Transfer of trans-3-Aminostilbenes
Date Issued
2007
Date
2007
Author(s)
Li, Chun-Yi
DOI
zh-TW
Abstract
This thesis is about the synthesis and the photoinduced intramolecular charge transfer (ICT) behavior of a series of trans-3-aminostilbenes. We recently reported that trans-4-(N-aryl-amino)stilbenes undergo ICT in the excited state. The ICT state of trans-4-(N-arylamino)-stilbenes could be planar (PICT) or twisted (TICT), depending on the substituent in the N-phenyl group. For instance, when the substituent is 4-OMe or 4-CN, a TICT state is present. The TICT state formation leads to low fluorescence quantum yields. Whereas a PICT state is favored by the electron delocalization effect, a TICT state possesses a larger dipole moment and gains better solvation in polar solvents.
We have designed a series of trans-3-(N-arylamino)stilbenes to investigate the meta effect on ICT properties and compare with the corresponding para isomers. The results show that m1OM and m1Me undergo TICT formation, but m1CN doesn’t. The distinct propensity of torsional motion toward TICT between the para and meta isomers of 1CN and 1Me are due to the difference in intramolecular charge delocalization ability. On the basis of the ring-bridged model compounds m1MeB3 and m1OMB3, the TICT state for m1OM and m1Me results from the twisting of the stilbenyl-anilino C-N bond.
We have also investigated the photochemical behavior of 3,4’-DDS and its derivatives. According to the data in literature, 3,4’-DDS might have a TICT state. However, through the reexamination of the data and investigation of the related compounds 34DDSB3 and 34DDSB4, we conclude that these diaminostilbenes do not undergo TICT state formation. However, those having the N-(4-methoxy)phenyl group (D3AAS and AA3DS) display the TICT behavior.
Moreover, we have synthesized compound DNSB2. The synthesis of DNSB2 is more difficult compared to that of the other aminostilbenes. The results show that restriction of the twisting of the styryl-anilino C-C bond does not inhibit TICT formation in polar solvents.
Subjects
間位二苯乙烯胺
分子內電荷轉移
扭轉分子內電荷轉移
3-aminostilbenes
ICT
TICT
3,4-N,N-dimethylaminostilbene
Type
thesis
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