Optical spectroscopy articles within Nature Chemistry

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  • News & Views |

    Electron transfer is ubiquitous across both life and modern technologies, and thus being able to control it is an attractive goal. Now, targeted infrared excitation has been used to modulate the efficiency of electron transfer in a series of donor–bridge–acceptor molecules.

    • Igor V. Rubtsov

  • Article |

    The ultrafast and mode-specific infrared excitation of several donor–bridge–acceptor (DBA) assemblies in solution has been shown to modulate their light-induced electron transfer properties. New insights are afforded into the role of vibrational processes immediately following light absorption in charge-transfer molecules and a recipe for efficient ‘vibrational control’ of electron transfer is proposed.

    • Milan Delor
    • , Theo Keane
    •  & Julia A. Weinstein

  • Article |

    Fe(II) complexes display transitions between spin states that can be triggered externally. Now the light-induced ΔS = 2 transition upon excitation of the metal-to-ligand charge-transfer states of Fe(II)-polypyridine complexes has been investigated at high time-resolution in the visible and the ultraviolet range. It has been shown to occur in less than 50 fs — that is, on a sub-vibrational timescale.

    • Gerald Auböck
    •  & Majed Chergui

  • News & Views |

    The transfer of chirality is known to occur through chemical bonds. Now, chiral biomolecules have been observed to impart some of their optical properties to a spatially separated achiral dye — with the transfer mediated by plasmon resonance from an achiral metallic nanostructure.

    • Vladimiro Mujica

  • Article |

    Surface-enhanced resonant Raman optical activity (SERROA) reveals the through-space transfer of chirality from biomolecules to achiral benzotriazole dye-conjugated nanotags. The chiroptical responses generated by the stereoisomers of ribose and tryptophan establish this as the basis for a stereoselective nanosensor platform.

    • Saeideh Ostovar pour
    • , Louise Rocks
    •  & Ewan W. Blanch

  • News & Views |

    In 1972, Baird showed theoretically that the electron counting rule for aromaticity and antiaromaticity in the lowest ππ* triplet state is opposite to that in the electronic ground state. A pair of compounds that manifests this reversal in character has now been identified and characterized experimentally for the first time.

    • Henrik Ottosson
    •  & K. Eszter Borbas

  • Article |

    Photoswitching of phytochromes is based on the isomerization of the tetrapyrrole chromophore, and eventually leads to the (de)activation of an enzymatic output module. Now it has been shown that both the structural changes associated with photoswitching and the thermal decay of the light-activated state are coupled to proton translocations in the chromophore pocket.

    • Francisco Velazquez Escobar
    • , Patrick Piwowarski
    •  & Peter Hildebrandt

  • News & Views |

    The structure of liquid water is intensely studied, but it is not clear what happens to it when a surface is introduced. Now with the aid of X-ray spectroscopy it has been found that water molecules at the interface with a gold electrode have a different structure than in the bulk.

    • Bernd Winter

  • News & Views |

    Understanding the intrinsic properties of molecules that protect our skin from the harmful rays of the Sun is critical to developing more efficacious sunscreen products. Now, gas-phase spectroscopy and microsolvation studies of model ultraviolet-filter molecules have shown that they may provide a route to developing improved sunscreens.

    • Vasilios G. Stavros

  • Article |

    It is generally believed that, after being generated, an excess electron in water shrinks from a strongly delocalized to a localized state in about a picosecond. Now, these early stages in the behaviour of this electron have been observed using a combination of transient THz spectroscopy and ab initio molecular dynamics simulations.

    • Janne Savolainen
    • , Frank Uhlig
    •  & Pavel Jungwirth

  • Article |

    Tyrosine-kinase inhibitors (TKI) are amongst the best known examples of targeted cancer therapeutics. Now, using hyperspectral stimulated Raman scattering imaging, the label-free visualization and quantification of two TKI drugs inside living cells is reported. Significant trapping of TKI drugs in lysosomes was observed, which can be reversed by co-treatment with chloroquine through lysosome-mediated interactions.

    • Dan Fu
    • , Jing Zhou
    •  & X. Sunney Xie

  • Article |

    Singlet exciton fission produces two triplet excited states from one excited singlet through interchromophoric coupling, which is thought to require local order. Now, a triplet yield of 200% and diffusion-limited triplet formation are reported in solutions of TIPS pentacene. Kinetic studies revealed an excimer intermediate and enabled suggestions of design principles for the promotion of singlet fission.

    • Brian J. Walker
    • , Andrew J. Musser
    •  & Richard H. Friend

  • News & Views |

    The fate of newly created excited states in conjugated materials is not fully understood, with unanswered questions regarding where exactly excitons form and their subsequent behaviour. Now, single-molecule spectroscopy studies of large conjugated molecular wheels reveal that excitons localize at random positions around the wheel rims.

    • Ivan G. Scheblykin

  • Article |

    A deficiency in our molecular-level understanding of the electronic structure of conjugated polymers hinders their potential use in electronic applications. Shape-persistent highly ordered ring structures have been used to mimic conjugated polymers and have now been studied using single-molecule spectroscopy. The fundamentally non-deterministic nature of excitation energy localisation in π-conjugated macromolecules has been demonstrated.

    • A. Vikas Aggarwal
    • , Alexander Thiessen
    •  & John M. Lupton

  • News & Views |

    Covalently bonding groups to the walls of carbon nanotubes has been previously observed to quench their photoluminescence. Now, it has been shown that, if you get the chemistry just right, their photoluminescence can in fact be significantly brightened by introducing defects through functionalization.

    • Qing Hua Wang
    •  & Michael S. Strano

  • Article |

    Liquid water has the unique ability to mediate ultrafast energy transfer and relaxation in aqueous chemical reactions. Ultrafast broadband two-dimensional infrared spectroscopy that probes vibrations spanning the mid-infrared region with sub-70-femtosecond time resolution now provides evidence for highly intertwined intra- and intermolecular vibrations in water that act to efficiently dissipate vibrational energy.

    • Krupa Ramasesha
    • , Luigi De Marco
    •  & Andrei Tokmakoff

  • Article |

    Hydrophobe/water interfaces are crucial for many chemical processes, but to be fully understood, a better appreciation of the behaviour of non-hydrogen-bonded OH groups of water is required. It is now shown that such ‘dangling’ OH structures are entropically stabilized and form cooperatively, that is, the probability of their formation depends nonlinearly on hydrophobic surface area.

    • Joel G. Davis
    • , Blake M. Rankin
    •  & Dor Ben-Amotz

  • Article |

    The controlled functionalization of single-walled carbon nanotubes has been shown to brighten their photoluminescence up to 28 times, which challenges our current understanding of how chemical defects affect low-dimensional carbon materials. This significantly improved photon conversion efficiency promises to advance a broad range of optoelectronic and imaging applications based on carbon nanotubes.

    • Yanmei Piao
    • , Brendan Meany
    •  & YuHuang Wang

  • News & Views |

    Radiation of sufficient energy can knock out a tightly bound core-electron from the inner shell of a water molecule, leaving behind a short-lived, highly excited state. Now, through electron spectroscopy and theoretical simulations, these states have been observed to undergo previously unconsidered proton-mediated processes in solution.

    • Lars G. M. Pettersson

  • Article |

    Previously unobserved types of reactive species formed on the core ionization of liquid water have been identified using a combination of liquid microjet photoemission spectroscopy and ab initio calculations. The charge-separated di-cationic species are formed within a few femtoseconds, through proton-transfer-mediated processes followed by autoionization.

    • Stephan Thürmer
    • , Milan Ončák
    •  & Bernd Winter

  • Article |

    The average single-nanocrystal spectral linewidth within an ensemble of nanocrystal emitters in solution can be directly and quantitatively measured using photon-correlation Fourier spectroscopy (S-PCFS). Variations in single-nanocrystal linewidths between batches are found to be significant and synthetically tunable, introducing new avenues for the optimization of nanocrystals for optical applications.

    • Jian Cui
    • , Andrew P. Beyler
    •  & Moungi G. Bawendi

  • Article |

    The development of new reaction methodology is a core activity for organic chemists, but the process can be slow and can rely on serendipity. Here, a reaction discovery platform is described that relies on the labelling of a reaction component with a chemical tag that enables rapid mass spectrometric detection of the derived products in complex mixtures.

    • Jaime R. Cabrera-Pardo
    • , David I. Chai
    •  & Sergey A. Kozmin

  • News & Views |

    Combined spectroscopic measurements and theoretical calculations bring to light an ultrafast excited-state deactivation process in peptides that may contribute to the ultraviolet photostability of proteins.

    • Wolfgang Domcke
    •  & Andrzej L. Sobolewski

  • News & Views |

    Overcoming drug resistance requires drug–protein interactions that persist in spite of mutations, but such interactions are difficult to characterize. Two-dimensional infrared spectroscopy can reveal the dynamics of how key molecular groups interact, allowing new insights into how some drugs overcome resistance.

    • Christopher M. Cheatum

  • News & Views |

    Obtaining detailed structural information about the interactions between amyloid-forming proteins and inhibitors can be extremely difficult. Two-dimensional infrared spectroscopy has now risen to this challenge to show the mapping of protein–protein contact sites in real time.

    • Minhaeng Cho

  • Article |

    Despite recent progress, solving protein structures using solid-state NMR spectroscopy is not routine. Now, a method for the rapid determination of global protein fold is reported, based on measurements of 15N longitudinal paramagnetic relaxation enhancements in several protein variants modified with covalently attached cysteine–EDTA–Cu2+ tags.

    • Ishita Sengupta
    • , Philippe S. Nadaud
    •  & Christopher P. Jaroniec

  • Article |

    Molecular inhibitors of amyloid formation could help combat Alzheimer's disease, type 2 diabetes, and other major human diseases. Here, two-dimensional infrared spectroscopy and residue-specific isotope labelling are used to obtain detailed structural information on amyloid-inhibitor complexes. The unexpected behaviour observed helps to explain the moderate activity of the inhibitor studied.

    • Chris T. Middleton
    • , Peter Marek
    •  & Martin T. Zanni

  • News & Views |

    Ultrafast chemical physics follows in the explosive wake of technological innovation, using light and radiation sources to study phenomena at timescales where the boundaries between physics and chemistry dissolve. UCP 2011, the second meeting in a series, explored the current state of the art in ultrafast time-resolved spectroscopy.

    • Julia A. Weinstein
    •  & Neil T. Hunt

  • News & Views |

    Single-molecule spectroscopy allows fluctuations of conjugated polymer conformation to be monitored during solvent vapour annealing. Dramatic changes in fluorescence behaviour are observed and interpreted in terms of transformations between extended and collapsed polymer geometries.

    • Lewis Rothberg

  • News & Views |

    Controlled energy-transfer on a molecular scale is a goal in many areas of science, from artificial photosynthesis to molecular electronics. Now, DNA origami has been used to direct the transfer of energy from an excited input dye down one of two paths by precisely arranging a mediator dye.

    • Bo Albinsson

  • Research Highlights |

    Evidence for the involvement of conical intersections in the isomerization of retinal has been obtained using ultrafast spectrocopy.

    • Gavin Armstrong

  • Article |

    Although ultrasonic vibrations are known to be capable of aligning macromolecules in solution, the question of whether audible sound — which has much lower frequencies — can have such an effect is somewhat controversial. Now, however, it has been shown that supramolecular nanofibres can be preferentially aligned parallel to the propagation direction of audible sound.

    • Akihiko Tsuda
    • , Yuka Nagamine
    •  & Takuzo Aida

  • Article |

    The decomposition of ammonia is an important process if ammonia is to be used as a hydrogen storage medium. The most active catalyst for this is ruthenium, but its expense has provoked the search for alternatives. Now, using theory to guide the investigation, researchers have identified a bimetallic nickel–platinum surface as an active catalyst for this process.

    • Danielle A. Hansgen
    • , Dionisios G. Vlachos
    •  & Jingguang G. Chen

  • News & Views |

    The interactions of electrons and water molecules are not just of great fundamental interest but are also studied to understand the role electrons have in damaging biomolecules. Now using ultrafast photoelectron spectroscopy, key details about the energy and lifetime of the hydrated electron in bulk and at an interface have been determined.

    • Daniel M. Neumark

  • Article |

    The existence of solvated electrons bound at the liquid/water surface has not, until now, been proved experimentally. Here, using ultrafast photoelectron spectroscopy, the existence, vertical binding energies and lifetimes of solvated electrons bound at the water-surface/vacuum interface, and in bulk solution, have been revealed.

    • Katrin R. Siefermann
    • , Yaxing Liu
    •  & Bernd Abel

  • Article |

    Stepwise deuteration of protonated methane CH5+ — a fluxional structure that undergoes ‘hydrogen scrambling’ — leads to dramatic changes in the infrared spectra of the isotopologues. The spectra can be assigned using ab initio quantum simulations that account for the non-classical occupation — by H and D atoms — of topologically different sites within the molecule.

    • Sergei D. Ivanov
    • , Oskar Asvany
    •  & Stephan Schlemmer

  • Research Highlights |

    Details of how an ion's reactivity is affected by the size and shape of the water network surrounding it have been elucidated using infrared spectroscopy.

    • Gavin Armstrong

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