Gomez Eduardo, Hisaki Ichiro, Douhal Abderrazzak
Physical Chemistry Department, Faculty of Environmental Sciences and Biochemistry, and INAMOL, University of Castilla-La Mancha Departamento de Química Física, Facultad de Ciencias Ambientales y Bioquímica, and INAMOL, Universidad de Castilla-La Mancha, Avenida Carlos III, S.N., 45071 Toledo, Spain.
Division of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
Int J Mol Sci. 2021 Apr 30;22(9):4803. doi: 10.3390/ijms22094803.
Hydrogen-bonded organic frameworks (HOFs) are the focus of intense scientific research due their potential applications in science and technology. Here, we report on the synthesis, characterization, and photobehavior of a new HOF (T12F-1(124TCB)) based on a dehydrobenzoannulene derivative containing fluorine atoms (T12F-COOH). This HOF exhibits a 2D porous sheet, which is hexagonally networked via H-bonds between the carboxylic groups, and has an interlayers distance (4.3 Å) that is longer than that of a typical π-π interaction. The presence of the fluorine atoms in the DBA molecular units largely increases the emission quantum yield in DMF (0.33, T12F-COOH) when compared to the parent compound (0.02, T12-COOH). The time-resolved dynamics of T12F-COOH in DMF is governed by the emission from a locally excited state (S1, ~ 0.4 ns), a charge-transfer state (S1(CT), ~ 2 ns), and a room temperature emissive triplet state (T1, ~ 20 ns), in addition to a non-emissive triplet structure with a charge-transfer character (T1(CT), τ = 0.75 µs). We also report on the results using T12F-ester. Interestingly, FLIM experiments on single crystals unravel that the emission lifetimes of the crystalline HOF are almost twice those of the amorphous ones or the solid T12F-ester sample. This shows the relevance of the H-bonds in the photodynamics of the HOF and provides a strong basis for further development and study of HOFs based on DBAs for potential applications in photonics.
氢键有机框架（HOFs）因其在科学技术领域的潜在应用而成为密集科学研究的焦点。在此，我们报告了一种基于含氟原子的脱氢苯并环烯衍生物（T12F-COOH）的新型HOF（T12F-1(124TCB)）的合成、表征及光行为。该HOF呈现出二维多孔片层结构，通过羧基之间的氢键形成六边形网络，且层间距（4.3 Å）比典型的π-π相互作用的层间距更长。与母体化合物（0.02，T12-COOH）相比，DBA分子单元中氟原子的存在大大提高了其在N,N-二甲基甲酰胺（DMF）中的发射量子产率（0.33，T12F-COOH）。T12F-COOH在DMF中的时间分辨动力学由局域激发态（S1，~ 0.4 ns）、电荷转移态（S1(CT)，~ 2 ns）和室温发射三重态（T1，~ 20 ns）的发射以及具有电荷转移特征的非发射三重态结构（T1(CT)，τ = 0.75 µs）所决定。我们还报告了使用T12F-酯的结果。有趣的是，对单晶进行的荧光寿命成像（FLIM）实验表明，结晶态HOF的发射寿命几乎是无定形态或固体T12F-酯样品发射寿命的两倍。这表明了氢键在HOF光动力学中的重要性，并为基于脱氢苯并环烯的HOF在光子学潜在应用的进一步开发和研究提供了有力依据。
