An official website of the United States government
Molecular Ag(II) complexes are superoxidizing photoredox catalysts capable of generating radicals from redox-reticent substrates. In this work, we exploited the electrophilicity of Ag(II) centers in [Ag(bpy)2(TFA)][OTf] and Ag(bpy)(TFA)2(bpy, 2,2′-bipyridine; OTf, CF3SO3–) complexes to activate trifluoroacetate (TFA) by visible light–induced homolysis. The resulting trifluoromethyl radicals may react with a variety of arenes to forge C(sp2)–CF3bonds. This methodology is general and extends to other perfluoroalkyl carboxylates of higher chain length (RFCO2–; RF, CF2CF3or CF2CF2CF3). The photoredox reaction may be rendered electrophotocatalytic by regenerating the Ag(II) complexes electrochemically during irradiation. Electrophotocatalytic perfluoroalkylation of arenes at turnover numbers exceeding 20 was accomplished by photoexciting the Ag(II)–TFA ligand-to-metal charge transfer (LMCT) state, followed by electrochemical reoxidation of the Ag(I) photoproduct back to the Ag(II) photoreactant.
more »
« less
This content will become publicly available on July 8, 2026
Ligand‐to‐Metal Charge Transfer of Ag(II) CF 2 X Carboxylates: Quantum Yield and Electrophotocatalytic Arene Fluoroalkylation Tuned by X
Abstract Incorporation of CF2X groups beyond CF3into arene scaffolds is underdeveloped despite these groups’ utility as halogen‐bond donors and as precursors to bioisosteres. Herein, we report the synthesis, characterization, and comparative photochemistry of a suite of [Ag(II)(bpy)2O2CCF2X]+and Ag(II)(bpy)(O2CCF2X)2(bpy = 2,2´‐bipyridine, X = F, CF3, Cl, Br, H, CH3) carboxylate complexes. We find a dramatic effect of the X substituent on the efficiency of generating CF2X radicals by ligand‐to‐metal charge transfer (LMCT), with Ag(II) photoreduction rates varying by over an order of magnitude and quantum yields spanning over 20%. We provide insight into how electronic and structural perturbations of the Ag(II)–O2CCF2X core are manifested in the LMCT quantum efficiency. With this information in hand, Ag(II)‐mediated electrophotocatalytic CF2X functionalization is carried out on a range of (hetero)arenes. This work expands the nascent field of Ag(II)‐based photocatalysis by allowing for (hetero)aryl–CF2X functionalization directly from unactivated fluoroalkyl carboxylate precursors.
more »
« less
- Award ID(s):
- 2216066
- PAR ID:
- 10641795
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 64
- Issue:
- 37
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract With the astonishing advancement of present technology and increasing energy consumption, there is an ever‐increasing demand for energy‐efficient multifunctional sensors or transducers based on low‐cost, eco‐friendly material systems. In this context, self‐assembled vertically alignedβ‐Ga2−xWxO3nanocomposite (GWO‐VAN) architecture‐assisted self‐biased solar‐blind UV photodetection on a silicon platform, which is the heart of traditional electronics is presented. Utilizing precisely controlled growth parameters, the formation of W‐enriched verticalβ‐Ga2−xWxO3nanocolumns embedded into the W‐deficientβ‐Ga2−xWxO3matrix is reached. Detailed structural and morphological analyses evidently confirm the presence ofβ‐Ga2−xWxO3nanocomposite with a high structural and chemical quality. Furthermore, absorption and photoluminescence spectroscopy explains photo‐absorption dynamics and the recombination through possible donor–acceptor energy states. The proposed GWO‐VAN framework facilitates evenly dispersed nanoregions with asymmetric donor energy state distribution and thus forms build‐in potential at the verticalβ‐Ga2−xWxO3interfaces. As a result, the overall heterostructure evinces photovoltaic nature under the UV irradiation. A responsivity of ≈30 A/W is observed with an ultrafast response time (≈350 µs) under transient triggering conditions. Corresponding detectivity and external quantum efficiency are 7.9 × 1012Jones and 1.4 × 104%, respectively. It is believed that, while this is the first report exploiting GWO‐VAN architecture to manifest self‐biased solar‐blind UV photodetection, the implication of the approach is enormous in designing electronics for extreme environment functionality and has immense potential to demonstrate drastic improvement in low‐cost UV photodetector technology.more » « less
-
Abstract Visible‐light capture activates a thermodynamically inert CoIII−CF3bond for direct C−H trifluoromethylation of arenes and heteroarenes. New trifluoromethylcobalt(III) complexes supported by a redox‐active [OCO] pincer ligand were prepared. Coordinating solvents, such as MeCN, afford green, quasi‐octahedral [(SOCO)CoIII(CF3)(MeCN)2] (2), but in non‐coordinating solvents the complex is red, square pyramidal [(SOCO)CoIII(CF3)(MeCN)] (3). Both are thermally stable, and2is stable in light. But exposure of3to low‐energy light results in facile homolysis of the CoIII−CF3bond, releasing.CF3radical, which is efficiently trapped by TEMPO.or (hetero)arenes. The homolytic aromatic substitution reactions do not require a sacrificial or substrate‐derived oxidant because the CoIIby‐product of CoIII−CF3homolysis produces H2. The photophysical properties of2and3provide a rationale for the disparate light stability.more » « less
-
Abstract Synthesizing solids in molten fluxes enables the rapid diffusion of soluble species at temperatures lower than in solid‐state reactions, leading to crystal formation of kinetically stable compounds. In this study, we demonstrate the effectiveness of mixed hydroxide and halide fluxes in synthesizing complex Sr/Ag/Se in mixed LiOH/LiCl. We have accessed a series of two‐dimensional Sr(Ag1−xLix)2Se2layered phases. With increased LiOH/LiCl ratio or reaction temperature, Li partially substituted Ag to form solid solutions of Sr(Ag1−xLix)2Se2withxup to 0.45. In addition, a new type of intergrowth compound [Sr3Se2][(Ag1−xLix)2Se2] was synthesized upon further reaction of Sr(Ag1−xLix)2Se2with SrSe. Both Sr(Ag1−xLix)2Se2and [Sr3Se2][(Ag1−xLix)2Se2] exhibit a direct band gap, which increases with increasing Li substitution (x). Therefore, the band gap of Sr(Ag1−xLix)2Se2can be precisely tuned via fine‐tuningxthat is controlled by only the flux ratio and temperature.more » « less
-
null (Ed.)We report the hydrothermal syntheses and crystal structures of aquabis(2,2′-bipyridine-κ 2 N , N ′)copper(II) hexafluoridosilicate tetrahydrate, [Cu(bpy) 2 (H 2 O)][SiF 6 ]·4H 2 O (bpy is 2,2′-bipyridine, C 10 H 8 N 2 ), (I), bis(2,2′-bipyridine-3κ 2 N , N ′)-di-μ-fluorido-1:3κ 2 F : F ;2:3κ 2 F : F -decafluorido-1κ 5 F ,2κ 5 F -ditantalum(V)copper(II), [Cu(bpy) 2 (TaF 6 ) 2 ], (II), tris(2,2′-bipyridine-κ 2 N , N ′)copper(II) bis[hexafluoridotantalate(V)], [Cu(bpy) 3 ][TaF 6 ] 2 , (III), and catena -poly[[diaqua(2,2′-bipyridine-κ 2 N , N ′)copper(II)]-μ-fluorido-tetrafluoridotin-μ-fluorido], [Cu(bpy)(H 2 O) 2 SnF 6 ] n , (IV). Compounds (I), (II) and (III) contain locally chiral copper coordination complexes with C 2 , D 2 , and D 3 symmetry, respectively. The extended structures of (I) and (IV) are consolidated by O—H...F and O—H...O hydrogen bonds. The structure of (III) was found to be a merohedral (racemic) twin.more » « less
