Tuning the Direction of Intramolecular Charge Transfer and the Nature of the Fluorescent State in a T-Shaped Molecular Dyad
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- 作者：Abdellah Felouat ; Anthony D鈥橝l茅o ; Azzam Charaf-Eddin ; Denis Jacquemin ; Boris Le Guennic ; Eunsun Kim ; Kwang Jin Lee ; Jae Heun Woo ; Jean-Charles Ribierre ; Jeong Weon Wu ; Fr茅d茅ric Fages
- 刊名：Journal of Physical Chemistry A
- 出版年：2015
- 出版时间：June 18, 2015
- 年：2015
- 卷：119
- 期：24
- 页码：6283-6295
- 全文大小：551K
- ISSN：1520-5215
文摘
Controlling photoinduced intramolecular charge transfer at the molecular scale is key to the development of molecular devices for nanooptoelectronics. Here, we describe the design, synthesis, electronic characterization, and photophysical properties of two electron donor鈥揳cceptor molecular systems that consist of tolane and BF2-containing curcuminoid chromophoric subunits connected in a T-shaped arrangement. The two 蟺-conjugated segments intersect at the electron acceptor dioxaborine core. From steady-state electronic absorption and fluorescence emission, we find that the photophysics of the dialkylamino-substituted analogue is governed by the occurrence of two closely lying excited states. From DFT calculations, we show that excitation in either of these two states results in a distinct shift of the electron density, whether it occurs along the curcuminoid or tolane moiety. Femtosecond transient absorption spectroscopy confirmed these findings. As a consequence, the nature of the emitting state and the photophysical properties are strongly dependent on solvent polarity. Moreover, these characteristics can also be switched by protonation or complexation at the nitrogen atom of the amino group. These features set new approaches toward the construction of a three-terminal molecular system in which the lateral branch would transduce a change of electronic state and ultimately control charge transport in a molecular-scale device.