- Stability of merocyanine-type photoacids in aqueous solutions
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Over the past years, protonated merocyanines (MEHs) have been used as photoacids to control various chemical, material, and biological processes using visible light. For the applications under aqueous conditions, stability of this type of photoacid has been a concern. While hydrolysis of merocyanines is well known, this work showed that deprotonation of MEH to form merocyanine is not necessary for the hydrolysis of MEH. The decomposition products were identified by ultraviolet-visible spectroscopy and liquid chromatography–mass spectrometry. Comparing the behaviors of different MEHs under different conditions indicates that the hydrolysis is catalyzed by OH? and thus MEHs are more stable at a lower pH. Modifying an MEH with an electron-donating group conjugated to the double bond significantly improved its stability. Photostability of an MEH was tested by conducting 100 irradiating/recovering cycles, and the photoacid showed good photostability.
- Abeyrathna, Nawodi,Liao, Yi
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- Light-controlled reversible self-assembly of nanorod suprastructures
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Nanorod suprastructures constructed by the coordination of zinc ions with the inclusion complex of 4,4′-dipyridine in β-cyclodextrin can dissociate and rebuild repeatedly via alternate visible light irradiation in the presence of photoacid merocyanine in
- Guo, Jie,Zhang, Heng-Yi,Zhou, Yan,Liu, Yu
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- Enhanced Photophosphorylation of a Chloroplast-Entrapping Long-Lived Photoacid
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Enhancing solar energy conversion efficiency is very important for developing renewable energy, protecting the environment, and producing agricultural products. Efficient enhancement of photophosphorylation is demonstrated by coupling artificial photoacid
- Xu, Youqian,Fei, Jinbo,Li, Guangle,Yuan, Tingting,Li, Yue,Wang, Chenlei,Li, Xianbao,Li, Junbai
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- Visible light mediated killing of multidrug-resistant bacteria using photoacids
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Increasing acidity is a promising method for bacterial inactivation by inhibiting the synthesis of intracellular proteins at low pH. However, conventional ways of pH control are not reversible, which can cause continuous changes in cellular and biological
- Luo, Yang,Wang, Chaoming,Peng, Ping,Hossain, Mainul,Jiang, Tianlun,Fu, Weiling,Liao, Yi,Su, Ming
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- Light-Responsive Dynamic DNA-Origami-Based Plasmonic Assemblies
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DNA nanotechnology offers a versatile toolbox for precise spatial and temporal manipulation of matter on the nanoscale. However, rendering DNA-based systems responsive to light has remained challenging. Herein, we describe the remote manipulation of native (non-photoresponsive) chiral plasmonic molecules (CPMs) using light. Our strategy is based on the use of a photoresponsive medium comprising a merocyanine-based photoacid. Upon exposure to visible light, the medium decreases its pH, inducing the formation of DNA triplex links, leading to a spatial reconfiguration of the CPMs. The process can be reversed simply by turning the light off and it can be repeated for multiple cycles. The degree of the overall chirality change in an ensemble of CPMs depends on the CPM fraction undergoing reconfiguration, which, remarkably, depends on and can be tuned by the intensity of incident light. Such a dynamic, remotely controlled system could aid in further advancing DNA-based devices and nanomaterials.
- Ryssy, Joonas,Natarajan, Ashwin K.,Wang, Jinhua,Lehtonen, Arttu J.,Nguyen, Minh-Kha,Klajn, Rafal,Kuzyk, Anton
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- Switching a pH indicator by a reversible photoacid: A quantitative analysis of a new two-component photochromic system
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A UV/visible and pH-metric quantitative analysis of the spiropyran reversible photoacid 1-MEH allowed us to determine the pKa's of the open and closed forms, the rate constants of relaxation, the quantum yield of decolouration and the UV/visible spectra of the protonated and deprotonated open and closed isomers. The coupling between 1-MEH and a selected pH-indicator acidochromic dye via proton exchange has also been analysed. The initial pH, stoichiometric ratio between the photoacid and the pH-indicator, light intensity and pKa range of the pH-indicator have been established to maximize the proton transfer from the photoacid donor to the pH-indicator acidochromic dye acceptor. When the pKa's are matched, the two-component system behaves like a single photochromic dye. The proposed model explains why 1-MEH photo-switches BromoCresol Green but not Methyl-Orange.
- Vallet,Micheau,Coudret
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- Long-lived photoacid based upon a photochromic reaction
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A visible-light activatable photoacid has been studied, which upon irradiation, changes from a weak acid, with a pKa of 7.8, to a strong acid, which achieves nearly complete proton dissociation. This process is reversible and the half-life of t
- Shi, Zheng,Peng, Ping,Strohecker, Daniel,Liao, Yi
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- Photoacid-Enabled Synthesis of Indanes via Formal [3 + 2] Cycloaddition of Benzyl Alcohols with Olefins
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An environmentally friendly and highly diastereoselective method for synthesizing indanes has been developed via a metastable-state photoacid system containing catalytic protonated merocyanine (MEH). Under visible-light irradiation, MEH yields a metastable spiro structure and liberated protons, which facilitates the formation of carbocations from benzyl alcohols, thus delivering diverse molecules in the presence of various nucleophiles. Mainly, a variety of indanes could be easily obtained from benzyl alcohols and olefins, and water is the only byproduct.
- Yang, Biao,Dong, Kui,Li, Xiang-Sheng,Wu, Li-Zhu,Liu, Qiang
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p. 2040 - 2044
(2022/03/17)
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- Effects of Substituents on Metastable-State Photoacids: Design, Synthesis, and Evaluation of their Photochemical Properties
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Recently, metastable-state photoacids have been widely used to control proton transfer in numerous chemical and biological processes as well as applications with visible light. Generally, substituents have a great influence on the photochemical properties of molecules, which will further affect their applications. Yet, the effects of substituents on metastable-state photoacids have not been studied systematically. In this work, 16 metastable-state photoacid derivatives were designed and synthesized on the basis of substituents having a large range of σ–π electron–donor–acceptor capabilities. The effects of substituents on the color display [or maximum absorption band(s)], solubility, pKa values, dark/photoacidity, photosensitivity, and relaxation kinetic(s) were investigated in detail. This study will be helpful for the targeted design and synthesis of promising photoacids and the application of their photocontrolled proton-release processes in functional materials/devices.
- Liu, Junning,Tang, Wenqi,Sheng, Lan,Du, Zhen,Zhang, Ting,Su, Xing,Zhang, Sean Xiao-An
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supporting information
p. 438 - 445
(2019/01/08)
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- A Photoinduced Reversible Phase Transition in a Dipeptide Supramolecular Assembly
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Tunable supramolecular assembly has found various applications in biomedicine, molecular catalysis, optoelectronics, and nanofabrication. Unlike traditional covalent conjugation, non-covalent introduction of a photoswitchable moiety enables reversible pho
- Li, Xianbao,Fei, Jinbo,Xu, Youqian,Li, Dongxiang,Yuan, Tingting,Li, Guangle,Wang, Chenlei,Li, Junbai
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supporting information
p. 1903 - 1907
(2018/01/27)
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- Waste management of chemically activated switches: Using a photoacid to eliminate accumulation of side products
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Molecular switches and machines that are powered by acid-base reactions are susceptible to low switching cycles because of the concomitant formation of waste products during their operation. Here, we demonstrate the fast, efficient, and reversible modulat
- Tatum, Luke A.,Foy, Justin T.,Aprahamian, Ivan
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supporting information
p. 17438 - 17441
(2015/02/19)
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