Review
Chemistry, Physical
Qianqi Lin
Summary: Electrochemistry has promising potential in studying interfacial electron transfers and redox reactions, but the lack of molecular structural information hinders understanding of complex systems. Complementary optical and spectroscopic techniques that provide electronic and structural identification of reactants and products are necessary for visualizing the electrochemical processes. Recent advancements in instrumentation and nanostructures allow for spatiotemporal resolution of molecules during complex reactions, enabling the optical revelation of intermediates, mechanisms, and rates, which are essential for fundamental and theoretical electrochemistry. This short review introduces the latest feasible optical and spectroscopic techniques, including dark-field, Raman, infrared, and ultraviolet-visible-near-infrared opto-and spectro-electrochemistry, for electrochemists to begin with.
CURRENT OPINION IN ELECTROCHEMISTRY
(2023)
Article
Chemistry, Inorganic & Nuclear
Mira T. Rupp, Thomas Auvray, Garry S. Hanan, Dirk G. Kurth
Summary: In this study, the impact of N-methylation on the electronic and photophysical properties of both homoleptic and heteroleptic Ru(II) bis-terpyridine complexes based on the ligand Bipytpy was investigated. The methylated complexes showed higher luminescence quantum yields and longer excited-state lifetimes, but were found to be inactive as photosensitizers under photocatalytic conditions.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2021)
Article
Chemistry, Inorganic & Nuclear
Zishun Lin, Ziteng Li, Wenbo Xiao, Lingqiao Kong, Jingwen Xu, Yonglin Xia, Xiaoming Zhu, Fuxing Zhang, Ya-Ping Ou
Summary: A series of asymmetrical terpyridine ruthenium-TAA complexes were prepared and characterized, and their bonding and electronic properties were studied by spectro-electrochemistry and theoretical calculations. The electrochemical results showed two successive single-electron redox processes, and the near-infrared spectroscopy revealed multiple absorption characteristics of the complexes. The electron coupling parameters obtained from the analysis of mixed-valence states decreased with bridge conjugate extension, consistent with the DFT calculation results.
JOURNAL OF ORGANOMETALLIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Jialong Peng, Qianqi Lin, Tamas Foldes, Hyeon-Ho Jeong, Yuling Xiong, Charalampos Pitsalidis, George G. Malliaras, Edina Rosta, Jeremy J. Baumberg
Summary: This article introduces an in-situ spectro-electrochemical technique for observing the redox dynamics of conductive polymers at the nanoscale to understand their doping mechanism. By encapsulating plasmonic nanoparticles with thin shells of different conductive polymers and tuning their refractive index, actively tunable scattering colors are achieved. Surface-enhanced Raman scattering combined with cyclic voltammetry enables detailed studies of the redox/doping processes of conductive polymers.
Article
Chemistry, Multidisciplinary
Yuanyuan Jiang, Zhenyu Ding, Meng Gao, Chuanxia Chen, Pengjuan Ni, Chenghui Zhang, Bo Wang, Guangbin Duan, Yizhong Lu
Summary: The study successfully developed a nanozyme method based on C3N4-Ru for detecting the generation of H2O2, with a wide linear range and low detection limit. Compared to the conventional modified titration method, it demonstrates higher selectivity for practical detection of H2O2 produced via the electrochemical oxygen reduction.
CHINESE JOURNAL OF CHEMISTRY
(2021)
Article
Crystallography
Valentina Sesti, Micol D'Antonio, Andrea Lucotti, Paola Moretti, Rossella Castagna, Chiara Bertarelli, Matteo Tommasini
Summary: In this study, we utilized UV-Vis and Raman spectroscopy to establish a correlation between the intensity of certain transitions and the occurrence of aggregation phenomena. Through TDDFT calculations, we provided a rational explanation for the formation of H-aggregates and their impact on the observed changes in the UV-Vis spectra. Both experimental observations and theoretical analysis support a correlation between Raman intensity and the molar absorption coefficient. Our methodology was further developed using Disperse Orange 3 (DO3), a well-known push-pull azobenzene dye with a strong optical absorption in the blue-green region, and a known tendency to form H-aggregates.
Article
Engineering, Multidisciplinary
F. Baniasadi, M. B. Fathi, M. M. Tehranchi, V Amani
Summary: The UV-Vis absorption spectra of discrete magnetic molecules were measured using density functional theory. The experimental data and theoretical computation showed that choosing 6-311++G** as the basis set improved computational results, especially in the visible region. The simulated results are important for simulating the light response of molecular magnets.
Article
Chemistry, Organic
Sonia Sonia, Sabyasachi Khatua, Siddhartha Samanta, Binitendra Naath Mongal
Summary: To study the effect of substituents on the terpyridine molecular system, a series of substituted 2,2':6',2''-terpyridines were synthesized and characterized. The substitutions ranged from electron-withdrawing groups (-F) to electron-donating groups (-OMe, -NMe2, triphenylamine) and heterocycles like furan and fused rings like anthracene. The synthesized terpyridines were characterized and analyzed using various techniques including UV-Vis absorption, luminescence, and potentiometry. The structure-activity relationship was determined based on experimental and theoretical calculations using density functional theory (DFT) methods.
POLYCYCLIC AROMATIC COMPOUNDS
(2023)
Article
Electrochemistry
Ludmila Simkova, Karol Luspai, Jiri Klima, Alan Liska, Miroslav Dudic, Josef Michl, Jiri Ludvik
Summary: The redox properties and UV-vis and EPR spectroelectrochemical behavior of cibalackrot and its six derivatives with two substituted phenyl rings were investigated. These dyes have potential applications in organic electronics and singlet fission for solar energy conversion. The compounds undergo two reversible one-electron reduction steps to form stable primary radical anions, and the first oxidation step produces a reversible radical cation. The presence of radical ions was confirmed using in situ UV-vis/EPR spectroelectrochemistry. The substituents have different effects on oxidation and reduction, as determined by the LFER approach and calculated frontier orbital energies.
ELECTROCHIMICA ACTA
(2023)
Article
Chemistry, Applied
Xu Zhao, Xiao-Ming He, Fen Liu, Chang-Qing Duan, Fei He
Summary: This study systematically elucidated the mechanism of intramolecular copigmentation in malvidin-3-O-(6-O-p-coumaryl)-glucoside, a type of acylated anthocyanin. The results showed that intramolecular copigmentation stabilized the anthocyanin and led to color changes. The conformational features and optical properties were analyzed using experimental and theoretical approaches.
Article
Chemistry, Physical
Fernando Steffler, Roberto L. A. Haiduke
Summary: Polyoxoniobates are polyoxometalates widely used in catalysis, water splitting, and organic reactions. Range-separated hybrids (RSHs) are successful in describing electronic excitations, with wavelength deviations usually smaller than 30 nm. There are slight variations in wavelengths among different compounds, with the largest electronic charge transfer occurring in [Nb6O19](8-).
JOURNAL OF MOLECULAR STRUCTURE
(2021)
Article
Chemistry, Multidisciplinary
Antoine Bohn, Juan Jose Moreno, Pierre Thuery, Marc Robert, Orestes Rivada-Wheelaghan
Summary: A pyrazole-based ligand with terpyridine groups at the 3 and 5 positions was synthesized to form the dinuclear cobalt complex 1, which electrocatalytically reduces CO2 to CO in the presence of Bronsted acids in DMF. Studies suggest pairwise reduction processes of complex 1 under inert atmosphere, and electroreduction of CO2 results in a reduced CO-containing dicobalt complex. Electrocatalytic studies with trifluoroethanol (TFE) revealed a single-site mechanism with high selectivity towards CO formation, but low faradaic efficiencies were attributed to the generation of CO-containing species inhibiting the reduction of CO2.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Materials Science, Ceramics
Shagun Monga, Neeraj Sharma, Navina Mehan, Yogendra Kumar Mishra, Arun Singh
Summary: This study compares the structural and optical properties of PZT materials prepared by different methods, showing significant differences in bandgap values between the two samples.
CERAMICS INTERNATIONAL
(2022)
Article
Chemistry, Inorganic & Nuclear
Tapas Ghorui, Amar Hens, Kausikisankar Pramanik
Summary: The mononuclear Zn(II) complexes with nitrogenous ligands showed superior complexing ability, significant color change, and fluorescence enhancement in the presence of Zn2+ ions, making them promising for naked eye detection. The ligands also exhibited sensing properties depending on the nature of the substituent. The fluorescent probes incorporating electron-excess and electron-deficient domains provided controlled ligand-centered fluorescence properties.
INORGANICA CHIMICA ACTA
(2021)
Article
Electrochemistry
Fariha Khan, Tim Kowalchik, Tanner Nelson, Aaron Atnip, Johnathan Johnson, Jeremiah Young, Connor Siri, Adam Dallon, Roseanne Warren
Summary: This article presents two easy-to-replicate, low-cost cell designs that can be incorporated with existing UV-vis systems, enabling high temperature, rapid heating spectroelectrochemical (SEC) experiments.
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
(2022)
Article
Chemistry, Physical
Ahmad Q. Daraosheh, Hassan Abul-Futouh, Natsuki Murakami, Karl Michael Ziems, Helmar Goerls, Stephan Kupfer, Stefanie Graefe, Akihiko Ishii, Malgorzata Celeda, Grzegorz Mloston, Wolfgang Weigand
Summary: The influence of substitution pattern in ferrocenyl alpha-thienyl thioketone as a proligand in complexation reactions with Fe-3(CO)(12) was investigated, resulting in the synthesis of two new sulfur-iron complexes. These complexes were found to catalyze the reduction of protons to molecular hydrogen, and the presence of the ferrocene moiety improved the stability of the reduced species.
Article
Chemistry, Physical
Patrick Herr, Alexander Schwab, Stephan Kupfer, Oliver S. Wenger
Summary: In octahedral complexes, molybdenum(0) with the same valence electron configuration as ruthenium(II) shows beneficial metal-to-ligand charge transfer excited states. The incorporation of thiophene units into the ligand backbones leads to red-shifted photoluminescence. This research is important for developing new luminescent compounds with potential applications in lighting and sensing.
Article
Chemistry, Physical
Georgina E. Shillito, Sven Rau, Stephan Kupfer
Summary: Quantum chemical methods were used to study the kinetics and thermodynamics of charge recombination in Ru-II based molecular photocatalysts. By selectively tuning the Ru-II coordination sphere, the charge transfer towards the bridging ligand during photoexcitation was promoted. This design method could potentially enhance the quantum efficiency of light-driven catalysis by promoting targeted electron transfer pathways and reducing deactivation pathways.
Editorial Material
Chemistry, Multidisciplinary
Clara Zens, Christian Friebe, Ulrich S. Schubert, Martin Richter, Stephan Kupfer
Summary: The development of organic batteries with stable radicals integrated within a conductive polymer backbone is crucial for sustainable energy storage devices. In this study, quantum chemical and quantum dynamical simulations were used to investigate the impact of substitution patterns, lengths, chemical linkers, and ratio of TEMPO and thiophene units on the thermodynamic properties and charge transfer kinetics. Two promising candidates with improved properties were synthesized and electrochemically characterized.
Article
Chemistry, Physical
Christian Friebe, Clara Zens, Stephan Kupfer, Ulrich S. Schubert
Summary: We propose an approach to overcome the low intrinsic electrical conductivity of established organic materials by directly electrochemically polymerizing suitable monomers onto the battery electrode. By linking a terthiophene to a TEMPO moiety, we not only achieve successful electropolymerization but also construct additive-free organic batteries. Cell tests demonstrate the system's high rate capabilities (20% capacity retention at 50C) and good long-term stability (0.03% capacity loss per cycle).
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Multidisciplinary
Jia-Wei Wang, Fan Ma, Tao Jin, Piao He, Zhi-Mei Luo, Stephan Kupfer, Michael Karnahl, Fengyi Zhao, Zihao Xu, Tao Jin, Tianquan Lian, Yong-Liang Huang, Long Jiang, Li-Zhi Fu, Gangfeng Ouyang, Xiao-Yi Yi
Summary: Exploiting noble-metal-free systems for efficient photocatalytic CO2 reduction remains challenging due to the difficulties in developing earth-abundant photosensitizers. This study focuses on a series of homoleptic Al(III) photosensitizers with 2-pyridylpyrrolide ligands for CO2 photoreduction using inexpensive aluminum metal. By introducing methyl groups at the pyrrolide rings, the visible-light absorption, reducing power, and durability of the Al(III) photosensitizers are greatly improved. The optimized system achieves a high quantum efficiency and CO2-to-CO conversion selectivity, making it a promising component in noble-metal-free systems for solar fuel conversion.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Review
Chemistry, Multidisciplinary
Martin Laemmle, Alexander K. K. Mengele, Georgina E. E. Shillito, Stephan Kupfer, Sven Rau
Summary: In recent decades, research on artificial photocatalysis aiming to mimic natural photosynthesis has focused on reducing fossil fuel consumption through efficient solar energy harvesting. However, the instability problems of catalysts during light-driven operation are major challenges for industrial-scale implementation. This review discusses the structure-catalyst-stability relationships of di- and oligonuclear photocatalysts with different bridging ligand architectures, as well as the effects of ligands on catalytic centers and their implications for catalytic activity in intermolecular systems, providing important insights for the future design of operationally stable catalysts.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Philipp Schueler, Simon Sengupta, Sven Krieck, Matthias Westerhausen
Summary: The alkaline-earth metals Mg and Ca are too inert for the direct metalation of primary and secondary amines. Activation prior to use or the use of Grignard reagents can be alternatives. However, the straightforward synthesis of alkylcalcium reagents has disadvantages due to various side reactions. Reactions of suspensions of magnesium or calcium with amine and ethyl bromide can lead to the formation of RAeX, which can undergo in situ Grignard metalation or addition reactions.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Multidisciplinary Sciences
Jia-Wei Wang, Zizi Li, Zhi-Mei Luo, Yanjun Huang, Fan Ma, Stephan Kupfer, Gangfeng Ouyang
Summary: The study designs a highly efficient CO2 photoreduction system based on earth-abundant elements by enhancing intermolecular electron transfer through suitable interactions between photosensitizer and catalyst. The dynamic z-z interaction between sensitizer and catalyst significantly accelerates the electron transfer rate, resulting in a notable quantum yield and near-unity selectivity.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Chemistry, Physical
Daniel Costabel, Ratnadip De, Franz Jacobi, Jonas Eichhorn, Konrad Hotzel, Afshin Nabiyan, Christof Neumann, Andrey Turchanin, Stephan Kupfer, Felix H. H. Schacher, Sven Rau, Benjamin Dietzek-Ivansic, Kalina Peneva
Summary: In this study, two organic-metal photocatalysts, P-L (PtCl2 and PdCl(2)), were proposed. X-ray photoelectron spectroscopy showed that their binding energies match precisely the binding energies of the respective M-(bpy)-Cl-2 complexes. Cyclic voltammetry measurements of the complexes displayed additional reduction potentials upon metal insertion. Light-driven catalysis demonstrated that both compounds are catalytically active, with P-Pt outcompeting P-Pd with a TON of 186 over 48 h in the presence of ascorbic acid (P-Pd: 50). Time-resolved spectroscopy on P-L and P-Pt yields insights into the light-induced intramolecular processes, and the role of different excitation states in the catalytic process.
Article
Chemistry, Physical
Keshav Kumar Jha, Amrutha Prabhakaran, Rengel Cane Sia, Ruben Arturo Arellano Reyes, Nirod Kumar Sarangi, Tingxiang Yang, Krishan Kumar, Stephan Kupfer, Julien Guthmuller, Tia E. Keyes, Benjamin Dietzek Ivansic
Summary: BODIPY-perylene dyads are efficient metal-free sensitizers for triplet-triplet annihilation upconversion. In this study, the behavior of established BODIPY-perylene dyads with non-orthogonal geometry is investigated. The addition of an iodine atom results in an increased rate of spin-orbit charge transfer intersystem crossing and a higher triplet yield.
Article
Chemistry, Physical
Guangjun Yang, Georgina E. Shillito, Clara Zens, Benjamin Dietzek-Ivansic, Stephan Kupfer
Summary: Excited states play a critical role in photocatalysis, and their excitation energy, accessibility, and lifetime are important parameters. Designing long-lived triplet states in molecular transition metal-based photosensitizers is challenging due to the low population associated with low spin-orbit coupling. The combination of a transition metal complex and an organic donor/acceptor group offers a promising approach to isolate the triplet excited state away from the metal.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Spectroscopy
Sebastian Seidenath, Phillip Seeber, Stephan Kupfer, Stefanie Graefe, Wolfgang Weigand, Grzegorz Mloston, Piotr Matczak
Summary: Quantum chemical calculations were used to elucidate the electronic structure and structure-property relationships of a series of ferrocenyl hetaryl ketones. Simulated NMR, IR and UV-vis spectra were employed. Density functional theory was employed to determine ground-state properties, and a broad range of theoretical methods were used to model excited-state properties.
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
(2023)
Article
Chemistry, Multidisciplinary
Fabian Seifert, Helmar Goerls, Stephan Kupfer, Robert Kretschmer
Summary: A tetranuclear magnesium hydride complex with a beta-oxo-delta-diiminate (BODDI) ligand was synthesized. The complex has three bridging mu(2)-hydride atoms and an unprecedented four-coordinate hydride with a nearly square-planar coordination environment in the solid state. Two different coordination polymers are observed depending on the bonding of the axial or equatorial oxygen lone pairs of 1,4-dioxane to magnesium.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Inorganic & Nuclear
Stefan Benndorf, Philipp Buday, Benedikt Callies, Helmar Goerls, Stephan Kupfer, Wolfgang Weigand
Summary: To improve the efficiency of synthesizing [FeFe] hydrogenase (H(2)ase) mimicking complexes, a new synthesis route using aprotic polar co-solvents like N-methyl-2-pyrrolidone (NMP) was introduced. This route reduced reaction temperatures and times while increasing yields. Kinetic monitoring and spectroscopic examination revealed the formation of byproducts and structural rearrangements when NMP was used.
DALTON TRANSACTIONS
(2023)
