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Photo‐Organocatalytic Enantioselective Radical Cascade Enabled by Single‐Electron Transfer Activation of Allenes
摘要： Allenes are commonly used in metal-mediated transformations, cycloaddition reactions, and radical processes. However, their activation by single-electron transfer (SET) is largely underexplored. Herein, we report a visible light-driven enantioselective organocatalytic process that uses the excited-state reactivity of chiral iminium ions to activate allenes by SET oxidation. The ensuing allene cation radicals participate in stereocontrolled cascade reactions to deliver bicyclic scaffolds with good enantioselectivity and exquisite diastereoselectivity. Density Functional Theory (DFT) calculations support a mechanism that combines the peculiar chemistry of allene radical cations with polar reactivity.
关键词： photochemistry,cascade process,allene,enantioselective organocatalysis,radical chemistry
更新于2025-09-19 17:13:59
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Effective utilization of NIR wavelengths for photo-controlled polymerization - penetration through thick barriers and parallel solar syntheses
摘要： This contribution details an efficient and controlled photopolymerization regulated by far-red (λ = 680 nm) and NIR (λ = 780 and 850 nm) light in the presence of aluminum phthalocyanine and aluminum naphthalocyanine. Initiating radicals are generated by photosensitization of peroxides affording an effective strategy that provides controlled polymerizations of a variety of monomers with excellent living characteristics. Critically, long wavelength irradiation provides penetration through thick barriers, affording unprecedented rates of controlled polymerization that can open new and exciting applications. Furthermore, a more optimized approach to performing solar syntheses is presented. By combining the narrow Q-bands of these PCs with others possessing complementary absorptions, layered, independent polymerizations and organic transformations may be performed in parallel under a single broadband emission source such as sunlight.
关键词： Reversible-deactivation radical polymerization,Photochemistry,Photopolymerization,Solar synthesis,NIR
更新于2025-09-12 10:27:22
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Matrix isolation infrared spectroscopic study of the photochemistry of bis(cyclopentadienyl)dicarbonyl titanium in solid nitrogen
摘要： Infrared spectra of the photochemical products of bis(cyclopentadienyl)dicarbonyl titanium, TiCp2(CO)2, isolated in an Ar matrix and a N2 matrix were measured. UV-irradiation of TiCp2(CO)2 produced TiCp2(CO) in the Ar matrix, and three types of nitrogen-containing compounds, TiCp2(CO)(N2), TiCp2(N2), and TiCp2(N2)2 were produced in the N2 matrix. The yields of the species changed with the duration of UV-irradiation. Annealing of the sample resulted in the disappearance of unstable TiCp2(N2) and an increase of TiCp2(N2)2. Isotope shifts of the IR spectra were measured using 15N2 to confirm the assignments. The structures of the species were estimated using a double hybrid density functional theory calculation (mPW2PLYP/cc-pVTZ), and the calculated infrared frequencies were in very good agreement with the experimentally measured spectra.
关键词： Photochemistry,Infrared spectroscopy,Nitrogen activation,Titanium complexes,Matrix isolation
更新于2025-09-12 10:27:22
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Reconfigurable Surfaces Based on Photocontrolled Dynamic Bonds
摘要： Photocontrolled surfaces have attracted increasing interest because of their potential applications in lithography, photopatterning, biointerfaces, and microfluidics. Light provides high spatiotemporal resolution to control functions of such surfaces without getting into direct contact. However, conventional photocontrolled surfaces can only be switched between two states (on and off). The development of photocontrolled reconfigurable surfaces that can be switched among multiple states is highly desirable because these surfaces can adapt to rapid environmental changes or different applications. Herein, recent developments of photocontrolled reconfigurable surfaces are reviewed. Specially, reconfigurable surfaces based on photocontrolled reversible reactions including thiol-quinone methide, disulfide exchange, thiol-disulfide interconversion, diselenide exchange, and photosubstitution of Ru complexes are highlighted. As a perspective, other photocontrolled dynamic bonds that can be used to construct reconfigurable surfaces are summarized. Remaining challenges in this field are discussed.
关键词： reconfigurable surfaces,photoswitches,photochemistry,dynamic bonds,photoresponsive
更新于2025-09-12 10:27:22
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Encapsulation‐controlled photoisomerization of a styryl derivative: stereoselective formation of the anti Z‐isomer in the cucurbit[7]uril cavity
摘要： The photochemical isomerization of a styrylpyridinium dye (SP) bearing an unsymmetrically attached benzo-15-crown-5 ether has been studied in aqueous solution in the absence and in the presence of cucurbit[7]uril (CB[7]). The detailed analysis of the UV/Vis and NMR spectra showed that the isomeric composition of the photostationary mixtures of SP can be modulated by the host–guest complexation with CB[7]. It was found that steric hindrance caused by encapsulation of SP in the host cavity induced the exclusive formation of the anti conformer of Z-SP in contrast with the mixture of both anti and syn conformers obtained during photoisomerization of dye without CB[7]. Remarkably, the displacement of anti Z-SP from the CB[7] did not lead to the transformation of the anti Z-isomer into the syn Z-isomer pointing out the conformational memory of the system. The obtained results provide an interesting example of the supramolecular stereorecognition by achiral CB[7] host.
关键词： cucurbituril,photochemistry,styryl dye,stereoisomers,self-assembly
更新于2025-09-12 10:27:22
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Shining Light on the Coiled-Flow Inverter—Continuous-Flow Photochemistry in a Static Mixer
摘要： We present the use of a coiled-flow inverter (CFI) for continuous-flow photochemistry at competitive photon efficiencies. The static mixer is placed inside a reaction chamber, while a dark adjacent chamber allows for orthogonal online reaction monitoring via fluorescence spectroscopy. The study of the aqueous visible-light induced degradation of fluorescein with ZnO-APTMS-Au photocatalyst showcases the challenge of uniformly irradiating photoreactors with non-planar surfaces. Fluorescence imaging is introduced as a simple method to visualize spatial gradients in the irradiance at the outer surface of such complex photoreactor geometries, allowing the analysis of photoreactor efficiency as a function of lighting configuration. We compared uniaxial and multiaxial lighting configurations and discuss the challenges associated with attaining uniform irradiance distribution of incident light on coiled-flow inverters, where chaotic advection combats light attenuation. A first calculation of the photochemical space-time yield (PSTY) for a “photo-CFI” is presented and contrasted with other photoreactor designs.
关键词： continuous-flow photochemistry,coiled-flow inverter,fluorescence imaging,ZnO-APTMS-Au photocatalyst,photochemical space-time yield
更新于2025-09-12 10:27:22
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Precisely Controlled Microsphere Design via Visible‐Light Cross‐Linking of Functional Prepolymers
摘要： A new strategy for particle synthesis is enabled by utilizing modern synthetic, polymer, and photochemical techniques to facilitate the synthesis of highly narrow–disperse multifunctional microspheres from visible-light induced crosslinking of prepolymers in both a single and dual polymer system. The approach requires no stabilizers, bases, or initiators, and proceeds at ambient temperature to yield microspheres with a tunable size range (0.25–5 μm) in less than 4 h, depending largely on solvent composition, but also polymer concentration (2–10 mg mL?1), ratio, and irradiation intensity (3–20 W). Critically, the visible-light induced dimerization reaction exploited herein enables simple functional particle syntheses via a single polymer system. Underpinned by an in-depth kinetic analysis of the particle formation as well as a detailed small molecule study, the mechanism for particle formation is also elucidated. Importantly, inherent advantages of the system are exploited for surface functionalization of residual acrylate and hydroxyl groups (generating inherently fluorescent particles).
关键词： polymer chemistry,photochemistry,materials chemistry,precipitation polymerization,particle synthesis
更新于2025-09-11 14:15:04
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Precise Synthesis of Ultra-High-Molecular-Weight Fluoropolymers Enabled by Chain-Transfer Agent Differentiation under Visible-Light Irradiation
摘要： A photo-mediated reversible-deactivation radical polymerization has been developed based on a novel chain-transfer agent (CTAs) differentiation mechanism, enabling the precise preparation of fluoropolymers with ultra-high molecular weights, narrow molecular weight distributions and excellent chain-end fidelity at complete conversions. Moreover, this synthetic approach is efficient, scalable, temporally controllable and compatible to a variety of monomers and CTAs.
关键词： block copolymers,photochemistry,polymerization,synthetic methods,fluorine
更新于2025-09-11 14:15:04
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It’s in the Fine Print: Erasable Three-Dimensional Laser-Printed Micro- and Nanostructures
摘要： 3D printing, on all scales, is currently a vibrant topic in scientific and industrial research as it has enormous potential to radically change manufacturing. Due to the inherent nature of the manufacturing process, 3D printed structures may require additional material to structurally support complex features. Such support material must be removed after printing – sometimes termed subtractive manufacturing – without adversely affecting the remaining structure. An elegant solution is the use of photoresists containing labile bonds that allow for controlled cleavage with specific triggers. Herein, we explore state-of-the-art cleavable photoresists for 3D direct laser writing, as well as their potential to combine additive and subtractive manufacturing in a hybrid technology. We discuss photoresist design, feature resolution, cleavage properties, and current limitations of selected examples. Furthermore, we share our perspective on possible labile bonds, and their corresponding cleavage trigger, which we believe will have critical impact on future applications and expand the toolbox of available cleavable photoresists.
关键词： direct laser writing,labile bonds,photochemistry,3D printing,degradable materials
更新于2025-09-11 14:15:04
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Properties of quantum dots coupled to plasmons and optical cavities
摘要： Quantum electrodynamics is rapidly finding a set of new applications in thresholdless lasing, photochemistry, and quantum entanglement due to the development of sophisticated patterning techniques to couple nanoscale photonic emitters with photonic and plasmonic cavities. Colloidal and epitaxial semiconductor nanocrystals or quantum dots (QDs) are promising candidates for emitters within these architectures but are dramatically less explored in this role than are molecular emitters. This perspective reviews the basic physics of emitter-cavity coupling in the weak-to-strong coupling regimes, describes common architectures for these systems, and lists possible applications (in particular, photochemistry), with a focus on the advantages and issues associated with using QDs as the emitters.
关键词： plasmonic cavities,photochemistry,quantum electrodynamics,quantum dots,photonic cavities
更新于2025-09-11 14:15:04