Article
Biochemistry & Molecular Biology
Johannes Knorr, Niklas Suelzner, Bastian Geissler, Christian Spies, Alexander Grandjean, Roger Jan Kutta, Gregor Jung, Patrick Nuernberger
Summary: This study reveals the phenomenon of photoacidity and its mechanisms in a new class of neutral super-photoacids. The experimental evidence shows that proton transfer can occur even under adverse conditions. The dynamics of solvation, rotational diffusion, and radiative relaxation processes are investigated, and the relevant steps and time scales of proton transfer are identified.
PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES
(2022)
Article
Chemistry, Multidisciplinary
Xiu-Wen Kang, Zijing Chen, Zhongneng Zhou, Yalin Zhou, Siwei Tang, Yifei Zhang, Tianyi Zhang, Bei Ding, Dongping Zhong
Summary: We present the direct observation of ultrafast proton rocking in the central motif of a BLUF domain protein scaffold. By mutant design, the proton-coupled electron transfer driving forces were modulated to remove the interference of a competing electron transfer pathway. Through femtosecond pump-probe spectroscopy and detailed kinetics analysis, we resolved an electron-transfer-coupled Grotthuss-type forward and reverse proton rocking along the FMN-Gln-Trp proton relay chain.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Gaoyuan Zhao, Juncheng Li, Ting Wang
Summary: The development of visible-light-induced photoacid catalyzed glycosylation using eosin Y and PhSSPh catalyst system was reported, demonstrating a broad substrate scope and mild reaction conditions.
CHEMICAL COMMUNICATIONS
(2021)
Article
Chemistry, Organic
Biao Yang, Kui Dong, Xiang-Sheng Li, Li-Zhu Wu, Qiang Liu
Summary: An environmentally friendly and highly diastereo-selective method for the synthesis of indanes has been developed using a metastable-state photoacid system containing catalytic protonated merocyanine (MEH). Under visible-light irradiation, MEH forms a metastable Spiro structure and releases protons, facilitating the formation of carbocations from benzyl alcohols. This method allows for the easy synthesis of diverse molecules, mainly indanes, in the presence of various nucleophiles, with water being the only byproduct.
Article
Chemistry, Multidisciplinary
Christopher D. M. Hutchison, James M. Baxter, Ann Fitzpatrick, Gabriel Dorlhiac, Alisia Fadini, Samuel Perrett, Karim Maghlaoui, Salome Bodet Lefevre, Violeta Cordon-Preciado, Josie L. Ferreira, Volha U. Chukhutsina, Douglas Garratt, Jonathan Barnard, Gediminas Galinis, Flo Glencross, Rhodri M. Morgan, Sian Stockton, Ben Taylor, Letong Yuan, Matthew G. Romei, Chi-Yun Lin, Jon P. Marangos, Marius Schmidt, Viktoria Chatrchyan, Tiago Buckup, Dmitry Morozov, Jaehyun Park, Sehan Park, Intae Eom, Minseok Kim, Dogeun Jang, Hyeongi Choi, HyoJung Hyun, Gisu Park, Eriko Nango, Rie Tanaka, Shigeki Owada, Kensuke Tono, Daniel P. DePonte, Sergio Carbajo, Matt Seaberg, Andrew Aquila, Sebastien Boutet, Anton Barty, So Iwata, Steven G. Boxer, Gerrit Groenhof, Jasper J. van Thor
Summary: The photoisomerization reaction of a fluorescent protein chromophore occurs on the ultrafast timescale. High-resolution pump-probe X-ray crystallography reveals complex sub-angstrom, ultrafast motions and hydrogen-bonding rearrangements in the active site of a fluorescent protein. The measured motions are not part of the photoisomerization reaction but instead arise from impulsively driven coherent vibrational processes in the electronic ground state.
Article
Chemistry, Physical
Myles C. Silfies, Arshad Mehmood, Grzegorz Kowzan, Edward G. Hohenstein, Benjamin G. Levine, Thomas K. Allison
Summary: In this study, transient absorption measurements and simulations were conducted on Salicylideneaniline (SA) under different conditions using cavity-enhanced transient absorption spectroscopy (CE-TAS). The results showed prompt excited-state intramolecular proton transfer (ESIPT) and the generation of a photochrome state in parallel with the fluorescent keto state. Increasing the internal energy led to an increase in the photochrome yield and a decrease in fluorescent yield and lifetime. In Ar clusters, the internal conversion of SA was hindered, but the photochrome yield remained unchanged.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Zilong Guo, Yulin Sha, Min Wang, Minjie Li, Yan Wan, Xiaonan Ma, Wensheng Yang
Summary: In this study, a robust humidity sensing strategy was demonstrated by loading photoacid HPTS into nanopores of hollow mesoporous organosilica capsules. The humidity sensors fabricated using this method exhibited rapid response and recovery, qualified reversibility, and selectivity, enabling continuous monitoring of human respiration. The sensitivity and response range of the sensor can be effectively tuned by fabricating capsules with properly sized nanopores, providing an opportunity for designing unique nanostructures for specific applications.
ACS APPLIED NANO MATERIALS
(2022)
Article
Chemistry, Physical
Niklas Suelzner, Bastian Geissler, Alexander Grandjean, Gregor Jung, Patrick Nuernberger
Summary: This study investigates the excited-state proton transfer (ESPT) of a neutral pyranine-derived super-photoacid in acetone-water mixtures using fluorescence spectroscopy. The addition of water promotes the formation of a hydrogen-bonded ground-state complex and accelerates the fluorescence dynamics of the emitting species. At least two water molecules are necessary for ESPT, and additional acidification inhibits the formation of the ground-state complex.
Article
Optics
Yonggang Yang, Qi Zhang, Yang Liu, Zhinan Jiang, Chaochao Qin, Kai Jiang, Yufang Liu
Summary: The dual fluorescence behaviors of 2-(2'-Hydroxyphenyl) benzothiazole (HBT) and 2-(2'-hydroxyphenyl) benzoxazole (HBO) molecules were studied using femtosecond transient absorption spectroscopy. The results showed that the proton transfer occurring in fs timescale is the main factor for the dual fluorescence of HBT.
JOURNAL OF LUMINESCENCE
(2022)
Article
Chemistry, Physical
Arivalagan Shabashini, Sumit Kumar Panja, Arnab Biswas, Sayantan Bera, Ganesh Chandra Nandi
Summary: This study recognizes 2-(3,4-Dihydroxybenzylidene)malononitrile (Hy34DC) as a photoacid and intramolecular charge transfer (ICT) probe for investigating the proton transfer process from solute to solvent. Microsolvation and intermolecular H-bonding interactions play a significant role in enhancing the proton transfer process. The study also reveals solvent-specific dual fluorescence properties of Hy34DC in solution.
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
(2022)
Article
Chemistry, Physical
Ye-Jin Choi, Hak-Won Nho, Ye-Jin Kim, Oh-Hoon Kwon
Summary: Time-resolved spectroscopy was used to quantify hydrogen (H)-bonded complexes with a photoacid. The new quantitative analysis method circumvents the limitations of the Benesi-Hildebrand plot and successfully measures an accurate H-bond formation constant when bulk solvent polarity is variable with the addition of a base in the solution.
Article
Chemistry, Multidisciplinary
Ho-Yin Tse, Chi Shun Yeung, Chun Yin Lau, Man Yee Cheung, Jianyu Guan, Md Khairul Islam, Paul T. Anastas, Shao-Yuan Leu
Summary: This study presents a green, simple, and efficient one-pot synthesis approach for a sustainable lignin nanoparticle biosensor. The biosensor showed superior harnessing abilities for excited state proton transfer photochemical dynamics and demonstrated outstanding selectivity for bisulfite ions, a key indicator of asthma and lung cancer. This study highlights the potential of valorizing lignin and plant extracts for molecular device development and applications.
Article
Chemistry, Physical
Ananta Dey, Nandan Ghorai, Amitava Das, Hirendra N. Ghosh
Summary: This study investigates the effects of H-bonding on PET and PCET processes. The results show that the presence of an intramolecular H-bond significantly increases the rate of electron transfer from Ru(II) to AQ. Additionally, the study demonstrates the ultrafast electron transfer and PCET dynamics in the presence of water and highlights the significant role of the bi-imidazole spacer and water molecules in both PET and PCET.
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
(2023)
Article
Chemistry, Physical
Micheline B. Soley, Pablo E. Videla, Erik T. J. Nibbering, Victor S. Batista
Summary: PCET is the underlying mechanism for important reactions in photosynthesis and hydrogen fuel cells. Proton and electron charge distribution motions can vary and occur on ultrafast time scales. Femtosecond soft-X-ray spectroscopy provides key insights into the PCET mechanism of photoinduced intramolecular tautomerization reactions.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Multidisciplinary Sciences
Bo Zhuang, Rivo Ramodiharilafy, Ursula Liebl, Alexey Aleksandrov, Marten H. Vos
Summary: This study revealed the photophysical properties of anionic semireduced flavin radicals and discovered their photoproducts in five different flavoprotein oxidases. It was found that photoexcitation leads to the oxidation of protein-bound anionic flavin radicals on a fast timescale, followed by decay of the generated photoproducts within a narrow time range. The active-site residues were proposed as the electron acceptors based on computational analysis.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Chemistry, Physical
Chahinez Abdellaoui, Volker Hermanns, Matiss Reinfelds, Maximilian Scheurer, Andreas Dreuw, Alexander Heckel, Josef Wachtveitl
Summary: This article investigates the photochemical reaction mechanism of fluorenols and finds that long-lived fluorenyl cations can affect the release of different leaving groups. It is discovered through various experimental methods that the stability of the cation is positively correlated with the release quantum yield. The research results of this article have important theoretical and practical significance for photochemical reactions.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Robin Klimek, Christoph Kaiser, Nina S. Murmann, Nina Kaltenschnee, Teresa Spano, Josef Wachtveitl, Erin M. Schuman, Alexander Heckel
Summary: Protein synthesis through ribosomes is a vital process in all living organisms. However, this process can be disrupted by the removal of a single nucleobase (depurination) at the sarcin/ricin loop of the ribosomal RNA. In this study, a fluorescent probe was developed to visualize depurination. Various RNA probes were designed and characterized, which fluoresce specifically in the presence of a depurinated sarcin/ricin-loop RNA. The main challenge was to achieve a high fluorescence signal when hybridized with an abasic RNA strand, while keeping the background fluorescence low. The new RNA probes enable efficient monitoring of depurinated RNA through fluorescence intensity and lifetime measurements.
CHEMISTRY-AN ASIAN JOURNAL
(2022)
Article
Biophysics
Clara Nassrin Kriebel, Marvin Asido, Jagdeep Kaur, Jennifer Orth, Philipp Braun, Johanna Becker-Baldus, Josef Wachtveitl, Clemens Glaubitz
Summary: This study presents an extensive chemical shift resonance assignment of Krokinobacter eikastus rhodopsin 2 (KR2) within lipid bilayers using solid-state NMR spectroscopy. The H180A mutation was found to silence the response of KR2 to oxidized sodium, while proton pumping was observed in the absence of sodium. The study reveals specific long-range effects of the mutation along the sodium transfer pathway.
BIOPHYSICAL JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Janik Kaufmann, Fabian Sinsel, Alexander Heckel
Summary: A system of two coumarin-based caging groups, one absorbing in the blue and the other in the green part of the visible spectrum, is described. They form a pair that allows selective photoactivation of either one in oligonucleotides. The article proposes a numerical characterization of chromatic selectivity and demonstrates how chromatically selective uncaging can be titrated in a kinetic reaction scheme.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Physical
Khushboo Yadav, Hariom Birla, Showkat H. Mir, Thomas Halbritter, Alexander Heckel, Jayant K. Singh, Thiruvancheril G. Gopakumar
Summary: In this article, we study the trans isomer of azobenzene (AB) and its derivatives and their switchability on surfaces. We find that the switching probability is very low due to the large activation barrier for switching from trans to cis. However, when switching is performed from a meta-stable initial condition, the switching probability is enhanced by several folds. The enhanced switching probability is a result of switching between two associated cis states with relatively low energy barriers.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Rebekka Weber, Kerby Chok, Stephan Junek, Clemens Glaubitz, Alexander Heckel
Summary: This study presents the synthesis and photophysical characterization of a two-photon sensitive uncaging dyad based on rhodamine 101 as donor fluorophore and a redshifted BODIPY as acceptor photocage. The liberation of p-nitroaniline (PNA) upon one-photon photolysis was confirmed by HPLC analysis. The considerable change of the fluorescence properties of the chromophores indicated the occurrence of the photoreaction. The possibility of fluorescent read-out enabled the detection of two-photon induced uncaging by confocal fluorescence microscopy.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Janik Kaufmann, Jonas Wolf, Alexander Heckel
Summary: The possibilities of dicyanocoumarin (DCCM)-modified oligonucleotides have expanded to include not only release and activation with green light (OFF?ON), but also fragmentation after exposure to green light (ON?OFF). The use of rigidified DCCM 5'-caps, such as those with ATTO 390 motif or julolidine core, has shown improved performance and compatibility with copper(I)-catalyzed alkyne-azide cycloadditions (CuAACs). These modifications allow for efficient caging through cyclization or other bioconjugation reactions, and their planarization even results in an additional red-shift, making them suitable for biological applications.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Rebekka Weber, Stephan Junek, Alexander Heckel
Summary: In this study, a blue light and NIR light activatable rhodamine fluorophore was developed for biological imaging. By immobilizing the fluorophore in a hydrogel, spatially resolved illumination patterns with excellent contrast could be written and read after both one-photon and two-photon excitation.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Physical
Marvin Asido, Josef Wachtveitl
Summary: The discovery of the light-driven sodium pump Krokinobacter eikastus rhodopsin 2 (KR2) in 2013 challenged the belief that ion transport in microbial rhodopsins is limited to proton translocation. The unique retinal binding pocket in KR2, with its tight interaction between the retinal Schiff base and counterion D116, also has interesting implications for the photochemical pathway of the chromophore.
JOURNAL OF PHYSICAL CHEMISTRY B
(2023)
Article
Multidisciplinary Sciences
Maximilian Wranik, Tobias Weinert, Chavdar Slavov, Tiziana Masini, Antonia Furrer, Natacha Gaillard, Dario Gioia, Marco Ferrarotti, Daniel James, Hannah Glover, Melissa Carrillo, Demet Kekilli, Robin Stipp, Petr Skopintsev, Steffen Brunle, Tobias Muhlethaler, John Beale, Dardan Gashi, Karol Nass, Dmitry Ozerov, Philip J. M. Johnson, Claudio Cirelli, Camila Bacellar, Markus Braun, Meitian Wang, Florian Dworkowski, Chris Milne, Andrea Cavalli, Josef Wachtveitl, Michel O. O. Steinmetz, Jorg Standfuss
Summary: Photopharmacology utilizes chemical triggers to change ligand affinities and biological activity by light, which is important for understanding ligand-protein binding and release processes.
NATURE COMMUNICATIONS
(2023)
Article
Biochemistry & Molecular Biology
Christoph Kaiser, Marc Vogel, Bettina Appel, Julia Weigand, Sabine Mueller, Beatrix Suess, Josef Wachtveitl
Summary: Engineering in vitro selected RNA aptamers into in vivo functional riboswitches is a challenge in molecular biology. Magnesium ions play a crucial role in the folding process.
JOURNAL OF MOLECULAR BIOLOGY
(2023)
Article
Chemistry, Physical
Hariom Birla, Showkat H. Mir, Khushboo Yadav, Thomas Halbritter, Alexander Heckel, Jayant K. Singh, Thiruvancheril G. Gopakumar
Summary: This study investigates the electronic structure, switching barrier, and electron/hole-induced switching of three different azobenzene derivatives on a graphite surface. It is found that molecules with strong inter-molecular interactions in the adlayer have a lower switching probability, and the molecule-surface interaction also affects the switching.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Multidisciplinary
Elena Buhl, Tom Resler, Rebecca Lam, Marvin Asido, Ernst Bamberg, Ramona Schlesinger, Christian Bamann, Joachim Heberle, Josef Wachtveitl
Summary: The study reveals the correlation between channel opening of CrChR2 and retinal isomerization, photocycle, and protein channel activity. The photocycle of the R120H variant is intact despite deficient channel activity. Analysis of the amide I mode shows impairment of the ultrafast protein response after retinal excitation.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Tobias Fischer, Jonas Leitner, Aaron Gerwien, Peter Mayer, Andreas Dreuw, Henry Dube, Josef Wachtveitl
Summary: The Hula-Twist (HT) photoreaction, which involves the motion of a double bond and an adjacent single bond, is a fundamental pathway for bond isomerizations. However, the fleeting nature of HT photoproducts has hindered direct experimental observation of this coupled motion. In this study, the Dube group designed a molecular framework using sterically crowded atropisomeric hemithioindigo (HTI) to stabilize the HT photoproducts and enable their direct observation. Furthermore, the researchers investigated the ultrafast excited state processes of the HT photoreaction, providing important insights into the mechanism of complex multibond rotations in the excited state.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Luuk J. G. W. van Wilderen, Daniela Kern-Michler, Carsten Neumann, Matiss Reinfelds, Jan von Cosel, Maximiliane Horz, Irene Burghardt, Alexander Heckel, Jens Bredenbeck
Summary: This work presents an experimental strategy that allows for the selective release of different leaving groups (LGs) using isotopologue photocage-LG mixtures combined with ultrafast VIbrationally Promoted Electronic Resonance (VIPER) excitation. This strategy enables the formation of multiple LGs on a short time scale and in any sequence, opening up possibilities for new complex uncaging applications.
