کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5186392 1381103 2007 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Theoretical studies on the electronic structures and optical properties of the oligomers involving bipyridyl, thiophenyl and ethynyl groups
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Theoretical studies on the electronic structures and optical properties of the oligomers involving bipyridyl, thiophenyl and ethynyl groups
چکیده انگلیسی
Structural, electronic, and optical properties of a series of π-conjugated chain type oligomers composed of the bipyridyl, ethynyl and thiophenyl fragments are studied by advanced quantum chemical methods. The properties of the P-oligomers (P1-P4, with 1-4 repeating units, respectively) and the corresponding DP-oligomers (DP2-DP4, with 2-4 repeating units, respectively, but without the terminal thiophenyl fragments) are compared. The geometry optimization results at B3LYP/6-31G level show that all the fragments involved in both the P-oligomers and DP-oligomers in the ground state exhibit a zigzag chain within the molecular plane. The TD-DFT calculations reveal that the dipole-allowed lowest-lying X1A → A1B absorption band of each oligomer possesses the π → π∗ transition characters. The geometry structures of P1, P2 and DP2 in the excited state have been studied by the CIS method, the fluorescence of them revealed by TD-DFT method is originated from the 1[ππ∗] excited state. Upon increasing the number of the repeating unit, there is a progressive lowering in HOMO-LUMO gaps, being consistent with the red shifts in the lowest-lying absorptions and fluorescence. The ionization potentials (IPs) and electron affinities (EAs) of the polymer are obtained by the extrapolation method. The calculated IPs of DP-polymer are lower than those of P-polymer and the EAs of DP-polymer are higher than those of the P-polymer, which indicates that the DP-polymer is more suitable for electron transferring and hole creating material.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 48, Issue 2, 12 January 2007, Pages 502-511
نویسندگان
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