- Precise Design of Phosphorescent Molecular Butterflies with Tunable Photoinduced Structural Change and Dual Emission
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Photoinduced structural change (PSC) is a fundamental excited-state dynamic process in chemical and biological systems. However, precise control of PSC processes is very challenging, owing to the lack of guidelines for designing excited-state potential en
- Zhou, Chenkun,Tian, Yu,Yuan, Zhao,Han, Mingu,Wang, Jamie,Zhu, Lei,Tameh, Maliheh Shaban,Huang, Chen,Ma, Biwu
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- Anti-Markovnikov Hydroamination of Unactivated Alkenes with Primary Alkyl Amines
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We report here a photocatalytic method for the intermolecular anti-Markovnikov hydroamination of unactivated olefins with primary alkyl amines to selectively furnish secondary amine products. These reactions proceed through aminium radical cation (ARC) intermediates and occur at room temperature under visible light irradiation in the presence of an iridium photocatalyst and an aryl thiol hydrogen atom donor. Despite the presence of excess olefin, high selectivities are observed for secondary over tertiary amine products, even though the secondary amines are established substrates for ARC-based olefin amination under similar conditions.
- Miller, David C.,Ganley, Jacob M.,Musacchio, Andrew J.,Sherwood, Trevor C.,Ewing, William R.,Knowles, Robert R.
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supporting information
p. 16590 - 16594
(2019/11/03)
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- Highly Fluorinated Ir(III)-2,2′:6′,2″-Terpyridine-Phenylpyridine-X Complexes via Selective C-F Activation: Robust Photocatalysts for Solar Fuel Generation and Photoredox Catalysis
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A series of fluorinated Ir(III)-terpyridine-phenylpyridine-X (X = anionic monodentate ligand) complexes were synthesized by selective C-F activation, whereby perfluorinated phenylpyridines were readily complexed. The combination of fluorinated phenylpyridine ligands with an electron-rich tri-tert-butyl terpyridine ligand generates a "push-pull" force on the electrons upon excitation, imparting significant enhancements to the stability, electrochemical, and photophysical properties of the complexes. Application of the complexes as photosensitizers for photocatalytic generation of hydrogen from water and as redox photocatalysts for decarboxylative fluorination of several carboxylic acids showcases the performance of the complexes in highly coordinating solvents, in some cases exceeding that of the leading photosensitizers. Changes in the photophysical properties and the nature of the excited states are observed as the compounds increase in fluorination as well as upon exchange of the ancillary chloride ligand to a cyanide. These changes in the excited states have been corroborated using density functional theory modeling.
- Porras, Jonathan A.,Mills, Isaac N.,Transue, Wesley J.,Bernhard, Stefan
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supporting information
p. 9460 - 9472
(2016/08/12)
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- Discovery and high-throughput screening of heteroleptic iridium complexes for photoinduced hydrogen production
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The catalytic process of photoinduced hydrogen generation via the reduction of water has been investigated. The use of parallel synthetic techniques has facilitated the synthesis of a 32 member library of heteroleptic iridium complexes that was screened, using high-throughput photophysical techniques, to identify six potential photosensitizers for use in catalytic photoinduced hydrogen production. A Pd/Ni thin film hydrogen selective sensor allowed for rapid quantification of hydrogen produced via illumination of aqueous systems of the photosensitizer, tris(2,2′-dipyridyl)dichlorocobalt ([Co(bpy) 3]Cl2), and triethanolamine (a sacrificial reductant) with ultra-bright light emitting diodes (LEDs). The use of an 8-well parallel photoreactor expedited the investigation of the hydrogen evolution process and facilitated mechanistic studies. All six compounds investigated produced considerably more hydrogen than commonly utilized photosensitizers and had relative quantum efficiencies of hydrogen production up to 37 times greater than that of Ru(bpy)32+.
- Goldsmith, Jonas I.,Hudson, William R.,Lowry, Michael S.,Anderson, Timothy H.,Bernhard, Stefan
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p. 7502 - 7510
(2007/10/03)
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