期刊
DYES AND PIGMENTS
卷 198, 期 -, 页码 -出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.dyepig.2021.109972
关键词
imidazo[4; b ]pyridines; Two-photon absorption; SOS model; Ultrafast transient absorption; Electron-withdrawing groups
资金
- Coordenacao de Aperfeicoamento de Pessoal de Nivel superior (CAPES) [001]
- CNPq
- Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [2018/11283-7]
This work investigates the influence of different electron-withdrawing groups on the two-photon absorption cross-section of imidazo[4,5-b]pyridine derivatives. The study provides insights into achieving high optical nonlinearities in these derivatives by linking electron-withdrawing groups to the core. The results show that when two electron-withdrawing groups are attached to the imidazo[4,5-b]pyridine core, high two-photon absorption cross-sections can be achieved.
This work investigates the influence of different electron-withdrawing groups (Cl, Br, fluorobenzonitrile), on the two-photon absorption cross-section of six imidazo[4,5-b]pyridine derivatives. The two-photon absorption crosssection spectra were obtained by ultra-fast Z-scan technique from 470 nm up to 700 nm. The Sum-Over-States approach was applied to model the two-photon absorption spectra, using a three-level energy system. Photophysical properties, such as transition dipole moment, the difference of permanent dipole moments, and anisotropy coefficient were determined through the analysis of one-photon absorption spectra, solvatochromism, and fluorescence anisotropy, respectively. Besides, the excited state absorption spectra were measured through ultra-fast transient absorption, allowing the excited state lifetime and spectral position determination. Twophoton absorption cross-sections of about 160 GM were observed when two electron-withdrawing groups are linked to the imidazo[4,5-b]pyridine core, elucidating a path to achieve high optical nonlinearities in imidazopyridine derivatives. Furthermore, a increase in the two-photon cross-section was observed when chloride is linked at the C-6 position (90 GM) instead of the C-5 position (50 GM), which is related to the proximity of a higher excited state.
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