Ultrafast Aggregation-Induced Tunable Emission Enhancement in a Benzothiadiazole-Based Fluorescent Metal–Organic Framework Linker

• DOI: 10.1021/acs.jpcb.1c08889
• Publication Date: 2021-11-30T16:32:08Z
• Authors: Luis Gutiérrez-Ar...; Issatay Nadinov; George Healing; Justyna Czaban-Jó...; Jiangtao Jia; Zhiyuan Huang; Yan Zhao; Osama Shekhah; Kirk S. Schanze; Mohamed Eddaoudi; Omar F. Mohammed
• Keywords: Photoexcitation

Aggregation-induced emission enhancement (AIEE) is a process recently exploited in solid-state materials and organic luminophores, it explained by tight-molecular packaging. However, solution-phase AIEE its formation mechanism have not been widely explored. This work investigated phenomena two donor–acceptor–donor-type benzodiazole-based molecules (the building block metal–organic frameworks) with an acetylene phenyl π-conjugated backbone tapered carboxylic acid group at either end. was done using time-resolved electronic vibrational spectroscopy conjunction time-dependent density functional theory (TD-DFT) calculations. Fluorescence up-conversion time-correlated single-photon counting conclusively showed intramolecular charge transfer-driven aggregate enhancement. shown red spectral shift of the spectra as well increase fluorescence lifetime from 746 ps 1.0 × 10–11 to 2.48 ns 2.0 10–3 M. The TD-DFT calculations that restricted rotation responsible for enhanced emission. femtosecond infrared (IR) transient absorption results directly revealed structural dynamics formation, evident evolution C≡C marker mode unit upon photoexcitation. Moreover, IR data clearly indicated aggregation occurred over time scale 10 ps, which consistent results. Interestingly, DFT demonstrated both bonds sulfur atom are key requirements achieve such controllable aggregation-induced finding only shows how slight changes chemical structure fluorescent chromophores could make tremendous change their optical behavior but also prompts surge research into profound understanding mechanistic origins this phenomenon. may lead discovery new strategies aim synthesize novel excellent properties light-harvesting applications.