Photochemistry articles within Nature Chemistry

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  • Article |

    Moving beyond binary responses in photoswitches necessitates the introduction of new elements along their switching pathway. Now, a modified donor–acceptor Stenhouse adduct (DASA) capable of independently addressing multiple molecular states has been developed. This enables the transformation of a three-stage photoswitch to be controlled by regulating intermediates along the DASA reaction pathway.

    • Friedrich Stricker
    • , David M. Sanchez
    •  & Javier Read de Alaniz

  • Article |

    The acetylene contaminant present in ethylene feeds used to produce polymers is typically removed by thermal hydrogenation. Now, it has been shown that the conversion of acetylene to ethylene at room temperature can be achieved in a visible-light-driven process using an earth-abundant metal (cobalt) catalyst and a water proton source.

    • Francesca Arcudi
    • , Luka Ðorđević
    •  & Emily A. Weiss

  • In Your Element |

    The tris(2,2′-bipyridine)ruthenium(II) cation, or ‘rubipy’ to its friends, has had a significant influence on our understanding of the photophysics of transition metal complexes, and has also helped revolutionize organic photochemistry, explains Daniela M. Arias-Rotondo.

    • Daniela M. Arias-Rotondo

  • Article |

    Despite much research, the high-spin-state relaxation mechanism of Fe(II) spin-crossover complexes is unresolved. Using ultrafast circular dichroism spectroscopy it has now been revealed that the spin relaxation is driven by a torsional twisting mode, which breaks the chiral symmetry of a prototypical Fe(II) compound. Stereocontrolling the configuration of the complex can thus be used to slow down the spin relaxation.

    • Malte Oppermann
    • , Francesco Zinna
    •  & Majed Chergui

  • News & Views |

    Molecular photocatalysts for generating solar fuels such as hydrogen degrade over time, ceasing to function as intended. Now the mechanism by which a ruthenium–platinum-based hydrogen-evolving photocatalyst breaks down has been identified, leading to the development of a repair strategy that uses singlet oxygen to regenerate an inactivated bridging ligand.

    • Claudia Turro

  • Article |

    Molecular π-stacked chromophores are promising photonic materials, but much of our understanding is limited to covalent dimers. Now it has been shown that, in a slip-stacked perylenediimide trimer, coherent vibronic coupling to high-frequency modes facilitates ultrafast state mixing between the Frenkel exciton and charge-transfer states, which then collapses by solvent fluctuations and low-frequency vibronic coupling, resulting in ultrafast symmetry-breaking charge separation.

    • Chenjian Lin
    • , Taeyeon Kim
    •  & Michael R. Wasielewski

  • Article |

    In a similar fashion to its macroscopic counterpart, molecular gearing is a correlated motion of intermeshed molecular fragments against one another. Now it has been shown that photogearing can be used to actively fuel molecular gearing motions with light and concomitantly shift the axis of rotation.

    • Aaron Gerwien
    • , Frederik Gnannt
    •  & Henry Dube

  • Article |

    Ion pairing is ubiquitous in low-dielectric-constant solvents, but whether it influences the reactivity of common cationic photoredox catalysts has been unclear. However, it has now been shown that ion pairing is responsible for a 4-fold modulation in reactivity in a prototypical Ir(III) complex and is explained by excited-state ion-pair reorganization.

    • J. D. Earley
    • , A. Zieleniewska
    •  & G. Rumbles

  • Article |

    Most chemical glycosylation methods operate by acid-promoted, ionic activation of donors. Now, by exploiting the formation of a halogen-bond complex, the activation of glycosyl donors was achieved via a visible light-promoted radical cascade process, resulting in a general, simple and mild way to build challenging 1,2-cis-glycosidic bonds.

    • Chen Zhang
    • , Hao Zuo
    •  & Dawen Niu

  • Article |

    Rhodopsin activation is driven by an ultrafast double-bond isomerization, but questions remain about the origin of its sensitivity. Now, quantum–classical simulations show that, 15 fs after light absorption, a degeneracy between the reactive excited state and a neighbouring state causes the splitting of the rhodopsin population into subpopulations, which propagate with different velocities, leading to distinct contributions to the quantum efficiency.

    • Xuchun Yang
    • , Madushanka Manathunga
    •  & Massimo Olivucci

  • Article |

    Molecular catalysts for artificial photosynthesis can break down during operation and stop working, whereas biological photosynthesis uses an enzymatic repair strategy to maintain function. Now, the degradation pathway of a hydrogen-evolving RuPt photocatalyst has been identified, enabling the development of an active repair strategy involving the use of 1O2 to reoxidize the deactivated bridging ligand.

    • Michael G. Pfeffer
    • , Carolin Müller
    •  & Sven Rau

  • Article |

    Direct coupling methods, which do not require substrate prefunctionalization, are highly desirable for the construction of complex molecular scaffolds. Now, a photochemical method has been developed for the direct decarboxylative coupling of carboxylic acids with diverse nitrogen, oxygen and carbon nucleophiles, taking advantage of the photochemistry of copper(II) carboxylate complexes assembled in situ.

    • Qi Yukki Li
    • , Samuel N. Gockel
    •  & Tehshik P. Yoon

  • Article |

    A conjunctive olefination between aldehydes and carboxylic acids has been developed by merging photoredox catalysis with the Wittig reaction. The process uses a readily available phosphonium salt to join together complex molecular fragments with high functional group tolerance and minimal use of protecting groups, enabling access to coupling products with user-defined geometries.

    • Dario Filippini
    •  & Mattia Silvi

  • Article |

    Carbon dioxide is a substantial component of many planetary atmospheres, but reduction of carbon dioxide requires conditions and substrates that are rare on planetary surfaces. Now, the reduction of carbon dioxide to organic species with biological relevance has been photochemically coupled to the oxidation of sulfite, suggesting that prebiotic carbon fixation could take place on the surfaces of rocky planets.

    • Ziwei Liu
    • , Long-Fei Wu
    •  & John D. Sutherland

  • News & Views |

    Transition metal complexes with metal-to-ligand charge transfer (MLCT) luminescence and photoactivity typically rely on precious metals such as ruthenium or iridium. Now, two complexes of the Earth-abundant 3d manganese have displayed room-temperature MLCT luminescence in solution and a unique excited-state reactivity.

    • Katja Heinze

  • Article |

    Manganese(i) is isoelectronic to iron(ii) but has typically been overlooked as a cheap Earth-abundant metal for the development of 3d6 metal-to-ligand charge transfer (MLCT) emitters and photosensitizers. Now, using chelating isocyanide ligands, air-stable manganese(i) complexes have been obtained that exhibit MLCT luminescence, as well as energy- and electron-transfer photoreactivity.

    • Patrick Herr
    • , Christoph Kerzig
    •  & Oliver S. Wenger

  • Article |

    Prodrugs offer one route to treat cancer, but they require activation once they have been delivered to the tumour. Now, a simultaneous chemo-radiotherapy strategy has been demonstrated in mice that uses gamma or X-ray irradiation to locally activate an anticancer prodrug.

    • Jin Geng
    • , Yichuan Zhang
    •  & Mark Bradley

  • Article |

    Energy funnelling within multichromophoric assemblies is key to the conversion of solar energy by plants. Now, energy transport between phthalocyanine-based chromophores has been monitored at the submolecular level using scanning tunnelling microscopy, focusing on the role of ancillary, passive and blocking chromophores in promoting and directing energy transfer between distant donor and acceptor units.

    • Shuiyan Cao
    • , Anna Rosławska
    •  & Guillaume Schull

  • Article |

    A chiral (η3-allyl)iridium(iii) complex has previously been used to catalyse enantioselective allylic substitution reactions in the polar domain. Now, it has been shown that the visible-light excitation of this iridium complex unlocks an otherwise inaccessible radical-based pathway to achieve enantioselective alkyl–alkyl cross-coupling reactions between allylic alcohols and radical precursors.

    • Giacomo E. M. Crisenza
    • , Adriana Faraone
    •  & Paolo Melchiorre

  • Article |

    Voltage imaging is a powerful technique for studying electrical signalling in neurons. A palette of bright and sensitive voltage indicators has now been developed via enzyme-mediated ligation and Diels–Alder cycloaddition. Among these, a far-red indicator faithfully reports neuronal action potential dynamics with an excitation spectrum orthogonal to optogenetic actuators and green/red-emitting biosensors.

    • Shuzhang Liu
    • , Chang Lin
    •  & Peng Zou

  • Article |

    The assembly of a single configuration of an all-carbon quaternary centre within acyclic systems remains a challenge for synthetic chemists. Now, it has been shown that α-all-carbon quaternary centres can be installed in acyclic amides, with excellent levels of absolute stereocontrol, through a radical sulfinyl Truce–Smiles rearrangement.

    • Cédric Hervieu
    • , Mariia S. Kirillova
    •  & Cristina Nevado

  • Article |

    The overall efficiency of free-triplet generation from intramolecular singlet fission is limited by the efficiency of the dissociation of spatially adjacent triplet pairs. Now, using transient magneto-optical spectroscopy, it has been shown that this limitation can be overcome by promoting a pathway mediated by spatially separated triplet pairs in tetracene trimers and tetramers.

    • Zhiwei Wang
    • , Heyuan Liu
    •  & Min Xiao

  • News & Views |

    The formation of all-carbon quaternary centres is a challenging problem in organic chemistry, with far-reaching implications for functional molecule discovery. Now an inventive solution has been developed, using sulfinamides as traceless linkers for an asymmetric radical Truce–Smiles rearrangement.

    • David M. Whalley
    •  & Michael F. Greaney

  • Article |

    Solvent plays a critical role in electron-transfer reactions, but short-range solvation dynamics are challenging to observe. Now, femtosecond X-ray solution scattering has been used to directly monitor the reorganization of water upon ultrafast intramolecular electron transfer in a bimetallic complex. Coherent motions of the first-shell water molecules are observed, arising from changes in solute–solvent hydrogen bonding.

    • Elisa Biasin
    • , Zachary W. Fox
    •  & Munira Khalil

  • Article |

    Reactions at the interface between water and other phases play important roles in various chemical settings. Now, ultrafast phase-sensitive interface-selective vibrational spectroscopy has revealed that the photoionization of phenol can occur four orders of magnitude faster at the water surface than in the bulk aqueous phase.

    • Ryoji Kusaka
    • , Satoshi Nihonyanagi
    •  & Tahei Tahara

  • Article |

    Many biosynthetic cyclizations are catalysed by iron oxygenases and appear to involve long-lived radical species. Now, mimicking these biosynthetic transformations, the total synthesis of highly oxidized lignan natural products has been reported using redox-neutral photocatalysis to enable late-stage radical cyclizations that install challenging 5- and 11-membered rings.

    • Zheng Huang
    •  & Jean-Philip Lumb

  • Article |

    Cyanide-bridged CoFe coordination networks exhibit photomagnetism because of coupled charge-transfer and spin transition. Now, femtosecond X-ray and optical absorption spectroscopies have enabled the electronic and structural dynamics of this light-induced process to be disentangled and show that it is the spin transition on the cobalt atom, occurring within ~50 fs, that induces the Fe-to-Co charge-transfer within ~200 fs.

    • Marco Cammarata
    • , Serhane Zerdane
    •  & Eric Collet

  • Article |

    Nature successfully uses supramolecular assemblies for efficient and robust solar energy harvesting; however, mimicking such material systems for applications in optoelectronic devices has been hampered by stability issues such as the fragility of the supramolecular structures used and the delicate nature of Frenkel excitons. Now, enabled by tunable cage-like scaffolds, stable supramolecular light-harvesting nanotubes have been composed that are robust even under heat stress.

    • Kara Ng
    • , Megan Webster
    •  & Dorthe M. Eisele

  • News & Views |

    The [2+2] photocycloaddition of two double-bond moieties is arguably the most efficient way to form a four-membered ring, but this route is rarely used to construct azetidine rings. Now, the development of an isoxazoline carboxylate cycloaddition partner offers a general approach to synthesize diverse azetidine products.

    • Susannah Coote

  • Article |

    Although azetidines represent highly desirable building blocks in drug discovery, methods for their efficient and straightforward synthesis remain underdeveloped. Now, it has been shown that highly functionalized azetidines can be prepared via an intermolecular [2+2] photocycloaddition reaction between cyclic oximes and alkenes, in a process enabled by a visible-light-mediated triplet energy transfer.

    • Marc R. Becker
    • , Emily R. Wearing
    •  & Corinna S. Schindler

  • News & Views |

    Recent research has shown that vibronic coherences are one of the primary drivers for ultrafast light-induced processes. Now, ultrafast spectroscopy has been used to uncover vibronic coherences in the excited-state dynamics of an iron complex, leading to its redesign and the drastic prolonging of its excited-state lifetime.

    • Julia A. Weinstein

  • Article |

    Photoinduced isomerization reactions, including ring-opening reactions, lie at the heart of many chemical processes in nature. The pathway and dynamics of the ring opening of a model heterocycle have now been investigated by femtosecond photoelectron spectroscopy combined with ab initio theory, enabling the visualization of rich dynamics in both the ground and excited electronic states.

    • Shashank Pathak
    • , Lea M. Ibele
    •  & Daniel Rolles

  • News & Views |

    The potential applications of smart photoswitchable porous materials are currently limited by incomplete switching. Now, efficient bulk switching has been achieved by embedding a photoisomerizable overcrowded alkene in a highly porous aromatic framework, creating a material capable of photomodulated gas uptake.

    • Jet-Sing M. Lee
    •  & Hiroshi Sato

  • Article |

    Despite numerous potential applications, the development of light-responsive solid materials based on molecular photoswitches is impeded by the low efficiency of photoisomerization in the solid environment. Now a robust, solid porous material made from tetraphenylmethane and a photoswitchable overcrowded alkene exhibits nearly quantitative photoisomerization in the bulk and in photomodulation of gas uptake.

    • Fabio Castiglioni
    • , Wojciech Danowski
    •  & Ben L. Feringa

  • News & Views |

    Single-molecule magnets are able to store information through their magnetic anisotropy, making them very promising systems for memory applications. Now, femtosecond-laser-initiated molecular dynamics that modulate magnetic anisotropy have been observed, paving the way for operation on ultrafast timescales.

    • Eric Collet

  • Article |

    The photoinduced dimerization of a prochiral anthracenecarboxylic acid occurs in an enantioselective fashion when the molecules are adsorbed on helical metal nanostructures. This enantiopreference arises mostly from the helicity of the silver and copper substrates—prepared using shear forces during the deposition process—and may also be influenced by chiroplasmonic effects.

    • Xueqin Wei
    • , Junjun Liu
    •  & Zhifeng Huang

  • Article |

    Despite the importance of trifluoromethylated compounds, direct catalytic methods for the conversion of C(sp3)–H bonds into the corresponding C(sp3)–CF3 analogues have remained elusive. This transformation has now been achieved by the merger of copper catalysis with decatungstate photocatalysis, enabling the C(sp3)–H trifluoromethylation of abundant feedstocks, natural products and pharmaceuticals.

    • Patrick J. Sarver
    • , Vlad Bacauanu
    •  & David W. C. MacMillan

  • Article |

    Understanding the photophysical properties of transition-metal complexes is paramount to advances in photocatalysis, solar energy conversion and light-emitting diodes. Now, long-lived emission via thermally activated delayed fluorescence has been demonstrated from an air- and water-stable zirconium complex featuring excited states with significant ligand-to-metal charge transfer character.

    • Yu Zhang
    • , Tia S. Lee
    •  & Carsten Milsmann

  • Article |

    Generating high-energy triplet excitons from singlet fission without excess energy loss is a critical goal for potential applications. Now it is shown that molecular chromophores that are connected covalently can harbour multiple long-lived and high-energy triplets—created from one photon—only if more than two chromophoric units are present and they have sufficient flexibility to isolate the excitations upon torsional motion.

    • Nadezhda V. Korovina
    • , Christopher H. Chang
    •  & Justin C. Johnson

  • Article |

    Homogeneous photocatalysts for the conversion and storage of solar energy typically feature separate sensitizer–catalyst assemblies, whereas previous examples of single-chromophore single-molecule photocatalysts are inefficient and do not use significant portions of the visible spectrum. Now a dirhodium single-chromophore single-molecule catalyst has been developed that generates hydrogen using low-energy light through a previously unobserved mechanism.

    • T. J. Whittemore
    • , C. Xue
    •  & C. Turro

  • Article |

    Despite the potential of fluorinated compounds in pharmaceuticals and agrochemicals, the formation of C–F bonds remains challenging. It has now been shown that aryl sulfonium salts, which can be made by site-selective C–H functionalization, have advantageous photoredox reactivity compared to conventional (pseudo)halides and can be used for late-stage C–H fluorination.

    • Jiakun Li
    • , Junting Chen
    •  & Tobias Ritter

  • Article |

    Singlet fission produces two low-energy triplet excitons that are difficult to dissociate into free charges. Now, separate optima in charge yield have been observed as a function of driving force for singlet and triplet excitons in pentacene. At optimal driving forces, the triplet-exciton dissociation rate is at least five orders of magnitude smaller than the singlet-exciton dissociation rate.

    • Natalie A. Pace
    • , Nadezhda V. Korovina
    •  & Obadiah G. Reid

  • Article |

    Replacing rare elements in benchmark photosensitizers with iron would facilitate the large-scale implementation of solar energy conversion, but iron complexes generally do not exhibit sufficiently long-lived photoexcited states. Now, it has been shown that iron(ii) complexes with carefully designed ligands can absorb broadly across the visible light spectrum and have charge-transfer excited states with nanosecond lifetimes.

    • Jason D. Braun
    • , Issiah B. Lozada
    •  & David E. Herbert

  • News & Views |

    Although transporting a starship crewmember onto the surface of an alien planet is clearly science fiction, quantum state teleportation is not, and has been observed in various systems over the last few decades. Now, electron-spin teleportation has been observed in a carefully designed molecular system, paving the way for such behaviour to be tailored through molecular engineering.

    • Malcolm D. E. Forbes

  • Article |

    Tuning the selectivity for [2+2] photocycloadditions remains challenging. Now, triplet–triplet energy transfer from CdSe quantum dots enables the homo- and heterocouplings of 4-vinylbenzoic acid derivatives via [2+2] photocycloaddition. Preorganization of substrates on the quantum dots reverses intrinsic stereoelectronic preferences to yield cyclobutane products with unprecedented diastereo- and regioselectivity.

    • Yishu Jiang
    • , Chen Wang
    •  & Emily A. Weiss

  • Article |

    Quantum teleportation moves the quantum state of a system between physical locations without losing its coherence, an essential criterion for emerging quantum information applications. Now, electron-spin-state teleportation in covalent organic electron donor–acceptor–stable radical molecules is demonstrated using entangled electron spins produced by photo-induced electron transfer.

    • Brandon K. Rugg
    • , Matthew D. Krzyaniak
    •  & Michael R. Wasielewski

  • Article |

    Super-resolution microscopy has enabled optical imaging of individual biomolecules on the nanometre scale. Now, a new method has been developed that allows active manipulation of single-molecule targets on visualization in a sequential manner. This method, called ‘Action-PAINT’, combines real-time super-resolution microscopy (DNA-PAINT) and photoinducible crosslinking chemistry to deliver a single-molecule cargo with <30 nm selectivity.

    • Ninning Liu
    • , Mingjie Dai
    •  & Peng Yin

  • Article |

    Although they are synthetically tunable, organic molecules that undergo singlet fission (the generation of two excitons from one photon) have not demonstrated the excited-state properties necessary to improve optoelectronic devices. Now, a general ‘energy cleft’ molecular design scheme has been demonstrated that enables rapid generation and long lifetimes of multiple triplet excitons that are for device applications.

    • Andrew B. Pun
    • , Amir Asadpoordarvish
    •  & Matthew Y. Sfeir

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