Wildervanck Martijn J, Hecht Reinhard, Nowak-Król Agnieszka
Institut für Anorganische Chemie and Institute for Sustainable Chemistry & Catalysis with Boron, Universität Würzburg, 97074 Würzburg, Germany.
Institut für Organische Chemie and Center for Nanosystems Chemistry, Universität Würzburg, 97074 Würzburg, Germany.
Molecules. 2022 Aug 27;27(17):5510. doi: 10.3390/molecules27175510.
The solvatochromic behavior of two donor-π bridge-acceptor (D-π-A) compounds based on the 2-(3-boryl-2-thienyl)thiazole π-linker and indandione acceptor moiety are investigated. DFT/TD-DFT calculations were performed in combination with steady-state absorption and emission measurements, along with electrochemical studies, to elucidate the effect of two different strongly electron-donating hydrazonyl units on the solvatochromic and fluorescence behavior of these compounds. The Lippert-Mataga equation was used to estimate the change in dipole moments (Δ) between ground and excited states based on the measured spectroscopic properties in solvents of varying polarity with the data being supported by theoretical studies. The two asymmetrical D-π-A molecules feature strong solvatochromic shifts in fluorescence of up to ~4300 cm and a concomitant change of the emission color from yellow to red. These changes were accompanied by an increase in Stokes shift to reach values as large as ~5700-5800 cm. Quantum yields of ca. 0.75 could be observed for the ,-dimethylhydrazonyl derivative in nonpolar solvents, which gradually decreased along with increasing solvent polarity, as opposed to the consistently reduced values obtained for the ,-diphenylhydrazonyl derivative of up to ca. 0.20 in nonpolar solvents. These two push-pull molecules are contrasted with a structurally similar acceptor-π bridge-acceptor (A-π-A) compound.
研究了基于2-(3-硼基-2-噻吩基)噻唑π-连接体和茚二酮受体部分的两种供体-π-桥-受体（D-π-A）化合物的溶剂化显色行为。结合稳态吸收和发射测量以及电化学研究进行了DFT/TD-DFT计算，以阐明两种不同的强给电子肼基单元对这些化合物的溶剂化显色和荧光行为的影响。利用Lippert-Mataga方程，根据在不同极性溶剂中测得的光谱性质估算基态和激发态之间的偶极矩变化（Δ），理论研究支持这些数据。这两个不对称的D-π-A分子在荧光中表现出高达约4300 cm的强烈溶剂化显色位移，发射颜色随之从黄色变为红色。这些变化伴随着斯托克斯位移增加，达到高达约5700 - 5800 cm的值。对于N,N-二甲基肼基衍生物，在非极性溶剂中可观察到量子产率约为0.75，随着溶剂极性增加逐渐降低，相反，对于N,N-二苯基肼基衍生物，在非极性溶剂中量子产率持续降低，最高约为0.20。将这两个推挽分子与结构相似的受体-π-桥-受体（A-π-A）化合物进行了对比。
