Photochemistry articles within Nature Chemistry

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  • Article |

    Overcrowded alkene-derived molecular motors convert light and heat into chirality-directed unidirectional rotary motion, but the efficiency of their photochemical isomerization remains limited. Now formylation of the motor core has been shown to boost all aspects of motor photochemistry by improving photochemical efficiency, diminishing competing processes and redshifting absorption.

    • Jinyu Sheng
    • , Wojciech Danowski
    •  & Ben L. Feringa

  • Article
    | Open Access

    The spontaneous recombination of photogenerated radicals surrounded by solvent molecules is an important energy-wasting elementary step in photoredox reactions. Now the decisive role that cage escape plays in these reactions is shown in three benchmark photocatalytic reactions, with quantitative correlations observed between photoredox product formation rates and cage escape quantum yields.

    • Cui Wang
    • , Han Li
    •  & Oliver S. Wenger

  • Perspective |

    Although generally perceived as an old-fashioned and unselective tool to build molecules, the photochemistry community is now re-discovering the power of UV light and is using key mechanistic information to develop new catalytic processes driven by visible light. This Perspective discusses the progress and impact of UV light in organic synthesis.

    • Giulio Goti
    • , Kavyasree Manal
    •  & Luca Dell’Amico

  • Article |

    The design of highly oxidizing Earth-abundant transition metal complexes for photochemical applications is desirable, but progress in this area remains limited. Now a manganese(IV) diguanidylpyridine complex has been shown to photooxidize naphthalene, benzene and acetonitrile to their radical cations after excitation with near-infrared light. Experimental and theoretical studies indicate the presence of two distinct ligand-to-metal charge transfer excited states.

    • Nathan R. East
    • , Robert Naumann
    •  & Katja Heinze

  • Article
    | Open Access

    Light-induced ultrafast switching between the molecular isomers norbornadiene and quadricyclane can reversibly store and release a substantial amount of chemical energy. Two competing pathways have now been identified by which electronically excited quadricyclane molecules relax to the electronic ground state, facilitating interconversion between the two isomers on different timescales.

    • Kurtis D. Borne
    • , Joseph C. Cooper
    •  & Daniel Rolles

  • Research Briefing |

    Dinitrogen (N2) fixation to ammonia (NH3) is typically challenging under mild conditions. Now, lithium hydride (LiH) is shown to mediate photodriven N2 fixation under ambient conditions. Under ultraviolet illumination, LiH is photolysed to release H2, leaving electrons residing in surface hydrogen vacancies, which facilitate N2 activation and photocatalytic NH3 synthesis.

  • Article |

    While saturated N-heterocycles are widespread motifs in drug discovery, the seven-membered ring azepane is highly underrepresented. Now nitroarenes have been validated as competent substrates for azepane synthesis through conversion into singlet nitrenes for ring enlargement via N insertion and hydrogenolysis. This enables a highly versatile access towards polysubstituted azepanes in just two steps.

    • Rory Mykura
    • , Raquel Sánchez-Bento
    •  & Daniele Leonori

  • Article
    | Open Access

    Single-electron-mediated difunctionalizations of internal olefins allow the simultaneous formation of two contiguous Csp3-stereocentres. Here, we describe enantioenriched arylsulfinylamides as all-in-one reagents for the efficient asymmetric, intermolecular aminoarylation of alkenes. Mechanistic studies revealed an interesting dichotomy in the initiation of the reaction depending on the olefin redox potential.

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

  • Article |

    Single-step addition of an aryl ring and a protected amine across an alkene is a succinct route to valuable phenethylamine products, but existing methods suffer from limited scope. Now a family of compounds containing a sulfinamide functional group have been developed to react via electrophilic radicals to yield phenethylamines through an aryl migration with precise stereochemical control.

    • Efrey A. Noten
    • , Cody H. Ng
    •  & Corey R. J. Stephenson

  • Research Briefing |

    Trans–cis photoisomerization is a fundamental photochemical reaction that is thought to proceed through an intermediate with a perpendicular conformation. However, unambiguous identification of this state has proved challenging. The combination of state-of-the-art ultrafast spectroscopy and quantum chemical calculations now provides evidence for its structural observation in stilbene photoisomerization.

  • Perspective |

    The self-assembly of stimuli-responsive building blocks yields functional nano-systems and smart materials. This Perspective discusses how the integration of photoswitches into discrete coordination cages enables control over their assembly, guest binding and systems behaviour. Four scenarios are drawn to highlight the relationship between the photoswitching and dynamic assembly equilibria.

    • Elie Benchimol
    • , Jacopo Tessarolo
    •  & Guido H. Clever

  • Article |

    The prototypical trans–cis photoisomerization of stilbenes is thought to occur via a transient intermediate with a perpendicular conformation—often called ‘the phantom state’—but its unambiguous identification has thus far proved difficult. Now, using ultrafast ultraviolet Raman spectroscopy and ab initio molecular dynamics simulation, evidence for its existence and its perpendicular conformation has been obtained.

    • Hikaru Kuramochi
    • , Takuro Tsutsumi
    •  & Tahei Tahara

  • Article |

    Although exciplex-forming systems are widely used for fabricating organic light-emitting diodes (OLEDs), their structural and thermodynamic characterization is limited. Now donor/acceptor inclusion complexes that demonstrate thermally activated delayed fluorescence have been generated. Their cocrystal structures have been resolved and the thermodynamics of exciplex formation determined, which has enabled the fabrication of efficient OLEDs.

    • Chun-Yen Lin
    • , Chao-Hsien Hsu
    •  & Pi-Tai Chou

  • News & Views |

    Light is a major driver of the chemistry of the atmosphere and usually involves the photolytic fragmentation of molecules into radicals before their reaction. New results show that formaldehyde, excited by low-energy light, can react with oxygen, opening up alternative atmospheric oxidation pathways.

    • Paul W. Seakins

  • Article |

    Geometric phase interference has been predicted to appear around conical intersections but has been experimentally illusive owing to competing effects in molecular systems. Now, this effect has been demonstrated in chains of trapped ions using state-of-the-art quantum simulation and read-out techniques.

    • Jacob Whitlow
    • , Zhubing Jia
    •  & Kenneth R. Brown

  • Article
    | Open Access

    Radiation damage in biology is largely mediated by radicals and low-energy electrons formed by water ionization and extensive, localized water ionization can be caused by ultrafast processes following the core-level ionization of hydrated metal ions. Now it has been shown that, for Al3+ ions, relaxation occurs via sequential solute–solvent electron transfer-mediated decay.

    • G. Gopakumar
    • , I. Unger
    •  & O. Björneholm

  • News & Views |

    Although light-driven conversion of carbon dioxide receives widespread attention, it is also criticized due to the challenge of discerning true product formation from that of impurities. Now, significantly advanced guidelines for proper product identification have been developed, so we can better trust in what we see.

    • Jennifer Strunk

  • Article
    | Open Access

    Although noble metal coordination complexes typically show promising photophysical properties that enable applications in lighting, photocatalysis and solar energy conversion, first-row transition metal complexes rarely display properties as attractive. Now, two Cr(0) complexes are shown to afford excited-state lifetimes of ~50 ns and photophysical properties analogous to noble metal complexes, enabling efficient photoredox catalysis.

    • Narayan Sinha
    • , Christina Wegeberg
    •  & Oliver S. Wenger

  • Article
    | Open Access

    Pump–probe measurements conventionally achieve femtosecond time resolution for X-ray crystallography of reactive processes, but the measured structural dynamics are complex. Using coherent control techniques, we show that the ultrafast crystallographic differences of a fluorescent protein are dominated by ground-state vibrational processes that are unconnected to the photoisomerization reaction of the chromophore.

    • Christopher D. M. Hutchison
    • , James M. Baxter
    •  & Jasper J. van Thor

  • News & Views |

    Lactams and pyridines are privileged scaffolds, but strategies for combining these groups into one molecule are lacking. Now, N–N pyridinium ylides have been shown to form triplet state diradicals under photoinduced energy transfer, and subsequent [3+2] cycloaddition with the tethered alkene enables the synthesis of diverse ortho-pyridyl lactams.

    • Peng-Zi Wang
    •  & Jia-Rong Chen

  • Article |

    There is currently a lack of effective synthetic strategies for combining lactams and pyridines within a single molecular structure. Now, diastereoselective pyridyl lactamization has been developed using a photoinduced [3+2] cycloaddition of triplet diradical N–N pyridinium ylides with pendant alkenes. This method provides a useful synthon for preparing pyridyl γ- and δ-lactam scaffolds with syn-configuration.

    • Wooseok Lee
    • , Yejin Koo
    •  & Sungwoo Hong

  • Article |

    Acylhydrazones are often found in compounds across screening databases, and numerous bioactive acylhydrazones exist. This functional group can isomerize between E and Z in response to light or upon exposure to thiols. Now, E/Z isomerization is found to impact activities of bioactive acylhydrazones and should be routinely analysed.

    • Zhiwei Zhang
    • , Giang N. T. Le
    •  & G. Andrew Woolley

  • Article
    | Open Access

    The metallophilic interaction between cyclometalated palladium complexes can facilitate supramolecular nanostructure formation in living mice, providing a phototoxic prodrug with a long circulation time and high tumour-targeting efficiency. Upon green light irradiation, this palladium-based drug destroys solid tumours, leaving non-irradiated organs intact.

    • Xue-Quan Zhou
    • , Peiyuan Wang
    •  & Sylvestre Bonnet

  • Article
    | Open Access

    A simple and general enantioselective method for the synthesis of non-fused lower carbo[n]helicenes (n = 4–6) is reported. The helicene scaffold is constructed with high enantioselectivity by Pd0-catalysed C–H arylation with aryl bromides. A bifunctional ligand provides a precise chiral environment that allows fine control of the enantioselectivity.

    • Shu-Min Guo
    • , Soohee Huh
    •  & Olivier Baudoin

  • News & Views |

    Therapies that destroy senescent cells could be used to alleviate age-related disease, yet conventional drugs often suffer from low selectivity and unwanted side effects. Now, a photosensitive agent has been developed that is activated in situ in senescent cells, enabling their selective elimination.

    • Yunjie Xu
    • , Jong Seung Kim
    •  & Mingle Li

  • News & Views |

    Charge-transfer emission of any type is extremely rare for coordination complexes of iron. Now, an Fe(iii) complex has been devised that shows two-colour luminescence arising from dual metal-to-ligand and ligand-to-metal charge-transfer emission.

    • Robert J. Ortiz
    •  & David E. Herbert

  • Article
    | Open Access

    Noble metals dominate the field of photosensitizers and luminophores. Now, an approach incorporating cyclometalating and carbene functions into FeIII complexes has been shown to enable dual emission from the opposing ligand-to-metal and metal-to-ligand charge-transfer states. The latter shows an exceptionally long lifetime of 4.6 ns and is quenched by oxygen and other quenchers.

    • Jakob Steube
    • , Ayla Kruse
    •  & Matthias Bauer

  • Q&A |

    Amilra Prasanna (AP) de Silva talks to Nature Chemistry about his path in chemistry, from photochemistry to sodium sensors to logic gates, through connections between people and between two places that share more than it may seem, Sri Lanka and Northern Ireland.

    • Anne Pichon

  • Article
    | Open Access

    Neutral homoaromatic hydrocarbons—which possess an interrupted π-system yet display aromatic properties owing to through-space or through-bond interactions—have remained rare as they are typically unstable. Now a class of stable neutral homoaromatic homoannulenes has been synthesized, including one that acts as a photoswitch through a reversible [1, 11] sigmatropic rearrangement.

    • Trung Tran Ngoc
    • , Niklas Grabicki
    •  & Johannes F. Teichert

  • News & Views |

    Radical-mediated functionalization streamlines access to complex synthetic targets. Now, a sulfonium-based donor–acceptor pair enables photoinduced charge-transfer interactions to access electronically diverse aryl radicals. Reaction with enol ethers or isocyanide provides a metal-free method for arene functionalization.

    • Taylor N. Bednar
    •  & David A. Nagib

  • Article |

    Photoactivation of EDA complexes was previously limited to electronically biased partners to secure productive charge-transfer interactions. Now, the participation of triarylsulfonium salts—formed by selective C–H sulfenylation—in photoactive EDA complexes with catalytic triarylamine donors provides a site-selective and metal-free strategy for the generation of aryl radicals and the formal C–H functionalization of native arenes.

    • Abhishek Dewanji
    • , Leendert van Dalsen
    •  & David J. Procter

  • Review Article |

    The light-driven conversion of abundant resources such as CO2 and H2O into chemical fuels for energy storage is crucial to end our dependence on fossil fuels. This Review highlights how molecular catalysts and photosensitizers can be grafted onto metal–organic frameworks to combine the advantages of both classes of compounds. Different synthetic strategies are discussed, along with their advantages and limitations.

    • P. M. Stanley
    • , J. Haimerl
    •  & J. Warnan

  • Article
    | Open Access

    Iodic acid (HIO3) forms aerosols very efficiently, but its gas-phase formation mechanism is not well understood. Atmospheric simulation chamber experiments, quantum chemical calculations and kinetic modelling have now revealed that HIO3 forms as an early iodine oxidation product from hypoiodite. The mechanism explains field measurements and suggests a catalytic role for iodine in particle formation.

    • Henning Finkenzeller
    • , Siddharth Iyer
    •  & Rainer Volkamer

  • Article
    | Open Access

    The circadian rhythm generates out-of-equilibrium metabolite oscillations controlled by feedback loops under light/dark cycles. Now, it has been shown that these life-like properties can emerge from a non-equilibrium nanosystem comprising a binary population of enzyme-containing polymersomes capable of light-gated chemical communication, controllable feedback and coupling to macroscopic oscillations.

    • Omar Rifaie-Graham
    • , Jonathan Yeow
    •  & Molly M. Stevens

  • Article |

    Photoelectrochemical cells are hampered by electron–hole recombination. Now, supramolecular machinery has enabled the docking of macrocyclic electron-accepting redox mediators to a dye through pseudorotaxane formation. Upon electron transfer from the dye, the anionic redox-mediator rings are launched away from the surface, reducing charge recombination, establishing charge separation and improving the efficiency of the solar cells in which they feature.

    • T. Bouwens
    • , T. M. A. Bakker
    •  & J. N. H. Reek

  • Article |

    Room-temperature phosphorescence in organic solids is attractive for practical applications but remains rare. Now, highly phosphorescent boroxine-linked covalent organic frameworks have been prepared by covalent doping with halogen atoms through the use of halogenated precursors. The resulting porous COFs exhibited oxygen-sensing capabilities with millisecond response time over a wide range of partial oxygen pressures.

    • Ehsan Hamzehpoor
    • , Cory Ruchlin
    •  & Dmytro F. Perepichka

  • Article |

    Meso–meso linked porphyrin arrays have been described as rod-like photonic wires. Now it has been shown that they can be bent into rings using template-directed synthesis. These rings of porphyrins mimic the light-harvesting arrays of chlorophyll molecules responsible for photosynthesis.

    • Henrik Gotfredsen
    • , Jie-Ren Deng
    •  & Harry L. Anderson

  • Article |

    The principal mid-visible light-harvesting system in cyanobacteria is the phycobilisome. Now, using broadband multidimensional spectroscopy, delocalized vibronic excitations and sub-picosecond excitation transfer pathways have been observed in the rods of intact phycobilisomes. An observed kinetic bottleneck in the phycobilisome’s core arises from the intramolecular charge-transfer character of the bilin chromophores, enabling photoregulatory processes to operate on the >10-ps timescale.

    • Sourav Sil
    • , Ryan W. Tilluck
    •  & Warren F. Beck

  • Article |

    The majority of methods to prepare β-amino acid derivatives require metal-mediated multistep manipulations of pre-functionalized substrates. Now, a metal-free, energy-transfer enabled, highly regioselective aminocarboxylation reaction has been developed, for the single-step installation of both amine and ester functionalities into alkenes or (hetero)arenes. An oxime oxalate ester is used as a bifunctional reagent, supplying C-centred ester and N-centred iminyl radicals.

    • Guangying Tan
    • , Mowpriya Das
    •  & Frank Glorius

  • News & Views |

    N-heterocycles are valuable motifs in pharmaceuticals and materials, but divergent synthetic strategies are lacking. Now, bifunctional sulfilimines have been shown to form nitrogen-centred radicals under photocatalytic conditions, and subsequent coupling with olefins enables the synthesis of diverse N-heterocycles.

    • Prabagar Baskaran
    •  & Wei Li

  • Article
    | Open Access

    Intermolecular cyclization reactions using nitrogen-containing building blocks are scarce. Now, bifunctional sulfilimines have been shown to enable the modular construction of a diverse range of N-heterocycles by reacting with alkenes in a single photocatalysed step. Both sulfilimines and alkenes are easily accessible, providing access to a wide range of N-heterocycles with different ring types, ring sizes and substituents on the skeleton.

    • Qiang Cheng
    • , Zibo Bai
    •  & Tobias Ritter

  • Article
    | Open Access

    The design of photoactivatable fluorophores—which are required for some super-resolution fluorescence microscopy methods—usually relies on light-sensitive protecting groups imparting lipophilicity and generating reactive by-products. Now, it has been shown that by exploiting a unique intramolecular photocyclization, bright and highly photostable fluorophores can be rapidly generated in situ from appropriately substituted 1-alkenyl-3,6-diaminoxanthone precursors.

    • Richard Lincoln
    • , Mariano L. Bossi
    •  & Stefan W. Hell

  • Article |

    Methods to access bicyclo[1.1.1]pentane building blocks are limited, with current routes requiring multiple steps. Now, a diverse array of bicyclo[1.1.1]pentane boronates can be accessed via a multi-component reaction in a single step. Alkyl, aryl and alkenyl substructures can be installed onto bicyclo[1.1.1]pentane boronates by the use of carboxylic acids and organohalides.

    • Weizhe Dong
    • , Expédite Yen-Pon
    •  & Gary A. Molander

  • Article |

    A genetically encoded phototrigger based on a xanthone amino acid can expand the scope of time-resolved serial femtosecond crystallography beyond naturally photoactive proteins. This approach has been used to uncover metastable reaction intermediates that occur prior to C–H bond activation in a human liver fatty-acid-binding protein mutant.

    • Xiaohong Liu
    • , Pengcheng Liu
    •  & Jiangyun Wang

  • Article |

    Developing stimuli-responsive bioorthogonal tetrazine ligations remains highly challenging, but a versatile approach that uses photocaged dihydrotetrazines has now been developed. Photouncaging results in the spontaneous formation of reactive tetrazines that rapidly react with dienophiles such as trans-cyclooctenes. As a demonstration, the method was used for live-cell labelling with single-cell precision and light-triggered drug delivery.

    • Luping Liu
    • , Dongyang Zhang
    •  & Neal K. Devaraj

  • News & Views |

    Photoredox catalysts offer a promising approach to performing reactions with high energetic requirements, however, the influence of solvent and counter ions is not fully understood. Now, a microwave-based technique is shown to give direct insight into their effects on charge reorganization during catalysis.

    • Ferdinand C. Grozema

  • News & Views |

    This year marks the 50th anniversary of Baird’s rules of aromaticity — a set of perturbational molecular orbital theory analyses that has garnered considerable attention in the past ten years in light of its many real-world applications in photochemistry.

    • Lucas J. Karas
    •  & Judy I. Wu

  • News & Views |

    Over the past 25 years, the photo-induced spin-crossover behaviour of Fe(II) complexes has puzzled scientists. Now, a symmetry-breaking twisting mode has been observed during the relaxation of such a complex. Controlling its configuration using enantiopure counterions has also been shown to slow down the relaxation.

    • J. Olof Johansson

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