Author
Zheng Haixia
Bio: Zheng Haixia is an academic researcher from China Three Gorges University. The author has contributed to research in topics: Excited state & Benzothiazole. The author has co-authored 1 publications.
Topics: Excited state, Benzothiazole, Intramolecular force
Papers
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TL;DR: In this article, the authors designed and synthesized HBT-fused aryl-imidazole derivatives HBTA, HBTB, HBTC and HBTD through π-expanded system, which have large absorption extinction coefficients, relatively high quantum yields, large Stokes shifts.
9 citations
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TL;DR: A review of the history, development, and future of imidazole dimers can be found in this article , where the authors also cover some heterocyclic structures derived from these compounds.
6 citations
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TL;DR: In this article , a new ESIPT-capable ligand called 1-hydroxy-5-methyl-4-(pyridin-2-yl)-2-(quinolin-2]-1H-imidazole (HLq) was proposed.
Abstract: The emission of ESIPT-fluorophores is known to be sensitive to various external and internal stimuli and can be fine-tuned through substitution in the proton-donating and proton-accepting groups. The incorporation of metal ions in the molecules of ESIPT fluorophores without their deprotonation is an emerging area of research in coordination chemistry which provides chemists with a new factor affecting the ESIPT reaction and ESIPT-coupled luminescence. In this paper we present 1-hydroxy-5-methyl-4-(pyridin-2-yl)-2-(quinolin-2-yl)-1H-imidazole (HLq) as a new ESIPT-capable ligand. Due to the spatial separation of metal binding and ESIPT sites this ligand can coordinate metal ions without being deprotonated. The reactions of ZnHal2 with HLq afford ESIPT-capable [Zn(HLq)Hal2] (Hal = Cl, Br, I) complexes. In the solid state HLq and [Zn(HLq)Hal2] luminesce in the orange region (λmax = 600-650 nm). The coordination of HLq by Zn2+ ions leads to the increase in the photoluminescence quantum yield due to the chelation-enhanced fluorescence effect. The ESIPT process is barrierless in the S1 state, leading to the only possible fluorescence channel in the tautomeric form (T), S1T → S0T. The emission of [Zn(HLq)Hal2] in the solid state is blue-shifted as compared with HLq due to the stabilization of the ground state and destabilization of the excited state. In CH2Cl2 solutions, the compounds demonstrate dual emission in the UV (λmax = 358 nm) and green (λmax = 530 nm) regions. This dual emission is associated with two radiative deactivation channels in the normal (N) and tautomeric (T) forms, S1N → S0N and S1T → S0T, originating from two minima on the excited state potential energy surfaces. High energy barriers for the GSIPT process allow the trapping of molecules in the minimum of the tautomeric form, S0T, resulting in the possibility of the S0T → S1T photoexcitation and extraordinarily small Stokes shifts in the solid state. Finally, the π-system of quinolin-2-yl group facilitates the delocalization of the positive charge in the proton-accepting part of the molecule and promotes the ESIPT reaction.
5 citations
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TL;DR: In this article , the authors combined experimental and theoretical studies of the proton transfer and proposed new types of ESIPT-capable molecules for understanding factors controlling the ESIPTs photoreaction.
Abstract: Search for new types of ESIPT-capable molecules is crucial for understanding factors controlling the ESIPT photoreaction. In this paper we present combined experimental and theoretical studies of the proton transfer...
2 citations
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TL;DR: In this article , the authors focus on phenanthro[9,10-d]imidazoles, which enable modification of their optical properties upon interaction with specific analytes, usually involving changes in the fluorescence intensity and/or color arising from processes like photoinduced electron transfer, intramolecular charge transfer, and Förster resonance energy transfer.
Abstract: Fluorescent and colorimetric sensors are important tools for investigating the chemical compositions of different matrices, including foods, environmental samples, and water. The high sensitivity, low interference, and low detection limits of these sensors have inspired scientists to investigate this class of sensing molecules for ion and molecule detection. Several examples of fluorescent and colorimetric sensors have been described in the literature; this Review focuses particularly on phenanthro[9,10-d]imidazoles. Different strategies have been developed for obtaining phenanthro[9,10-d]imidazoles, which enable modification of their optical properties upon interaction with specific analytes. These sensing responses usually involve changes in the fluorescence intensity and/or color arising from processes like photoinduced electron transfer, intramolecular charge transfer, intramolecular proton transfer in the excited state, and Förster resonance energy transfer. In this Review, we categorized these sensors into two different groups: those bearing formyl groups and their derivatives and those based on other molecular groups. The different optical responses of phenanthro[9,10-d]imidazole-based sensors upon interaction with specific analytes are discussed.
2 citations
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TL;DR: In this paper , the authors designed and synthesized six 6-substituted quinolines-fused α-cyanovinyl derivatives QM-1 ∼ 3 and QS-3 through π-expansion system with pull-push systems.
2 citations