TY - JOUR A1 - Kozlevcar, Bojan A1 - Golobic, Amalija A1 - Strauch, Peter T1 - Dynamic pseudo Jahn-Teller distortion in a compressed octahedral CuO6 complex JF - Polyhedron : the international journal of inorganic and organometallic chemistry N2 - The crystal structure of cis-[Cu(C8H7O3)(2)(H2O)(2)] (115 K data) reveals bidentate vanillinate ions coordinated via methoxy and deprotonated hydroxy oxygen atoms and water molecules in a distorted octahedral CuO6 chromophore. A cis orientation of the ligands enables two non-identical O(methoxy)-Cu-O(water) coordination axes (2.354(l) + 2.163(1); 2.151(1) + 2.020(1) angstrom), and the third shortest O(hydroxy)-Cu-O(hydroxy) axis (1.919(1) + 1.914(1) angstrom). This 115 K coordination sphere differs importantly to the one obtained from the 293 K data of the same compound, where two long 0(methoxy)-Cu-O(water) axes are of the same length, and only minor changes at the short 0(hydroxy)-Cu-O(hydroxy) axis are noticed. An axial symmetry of the complex with an inverse g(1.2)(g(perpendicular to)) > g(3)(g(parallel to)) pattern is observed in the temperature range from 298 to 180 K. A further decrease of temperature reveals gradual changes from axial to rhombic symmetry (g(1) > g(2) > g(3)) that is reversible. A mean-square displacement amplitude (MDSA) analysis reveals a disorder in the Cu-O(methoxy) bonds, but not in the other metal-ligand Cu-O(hydroxy) and Cu-O(water) bonds at 293 and 115 K. The disorder is significantly weaker in the 115 K structure. The MSDA analysis and the structural-EPR agreement show vibrational disorder in two coordination axes, due to the cis conformation of the complex with two 0(methoxy)-Cu-O(water) axes. KW - copper KW - vanillin KW - Jahn-Teller distortion KW - MSDA KW - cis KW - EPR Y1 - 2006 U6 - https://doi.org/10.1016/j.poly.2006.04.009 SN - 0277-5387 VL - 25 IS - 15 SP - 2824 EP - 2828 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Schwarze, Thomas A1 - Kelling, Alexandra A1 - Müller, Holger A1 - Trautmann, Michael A1 - Klamroth, Tillmann A1 - Baumann, Otto A1 - Strauch, Peter A1 - Holdt, Hans-Jürgen T1 - N-2-Pyridinylmethyl-N '-arylmethyl-diaminomaleonitriles: New Highly Selective Chromogenic Chemodosimeters for Copper(II) JF - Chemistry - a European journal KW - amides KW - chemodosimeter KW - colorimetric detection KW - copper KW - sensors KW - UV KW - Vis spectroscopy Y1 - 2012 U6 - https://doi.org/10.1002/chem.201201731 SN - 0947-6539 VL - 18 IS - 34 SP - 10506 EP - 10510 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Abbas, Ioana M. A1 - Vranic, Marija A1 - Hoffmann, Holger A1 - El-Khatib, Ahmed H. A1 - Montes-Bayón, María A1 - Möller, Heiko Michael A1 - Weller, Michael G. T1 - Investigations of the Copper Peptide Hepcidin-25 by LC-MS/MS and NMR⁺ JF - International Journal of Molecular Sciences N2 - Hepcidin-25 was identified as themain iron regulator in the human body, and it by binds to the sole iron-exporter ferroportin. Studies showed that the N-terminus of hepcidin is responsible for this interaction, the same N-terminus that encompasses a small copper(II) binding site known as the ATCUN (amino-terminal Cu(II)- and Ni(II)-binding) motif. Interestingly, this copper-binding property is largely ignored in most papers dealing with hepcidin-25. In this context, detailed investigations of the complex formed between hepcidin-25 and copper could reveal insight into its biological role. The present work focuses on metal-bound hepcidin-25 that can be considered the biologically active form. The first part is devoted to the reversed-phase chromatographic separation of copper-bound and copper-free hepcidin-25 achieved by applying basic mobile phases containing 0.1% ammonia. Further, mass spectrometry (tandemmass spectrometry (MS/MS), high-resolutionmass spectrometry (HRMS)) and nuclear magnetic resonance (NMR) spectroscopy were employed to characterize the copper-peptide. Lastly, a three-dimensional (3D)model of hepcidin-25with bound copper(II) is presented. The identification of metal complexes and potential isoforms and isomers, from which the latter usually are left undetected by mass spectrometry, led to the conclusion that complementary analytical methods are needed to characterize a peptide calibrant or referencematerial comprehensively. Quantitative nuclear magnetic resonance (qNMR), inductively-coupled plasma mass spectrometry (ICP-MS), ion-mobility spectrometry (IMS) and chiral amino acid analysis (AAA) should be considered among others. KW - hepcidin-25 KW - copper KW - nickel KW - copper complex KW - ATCUN motif KW - metal complex KW - MS KW - NMR structure KW - metal peptide KW - metalloprotein KW - metallopeptide KW - isomerization KW - racemization KW - purity KW - reference material Y1 - 2018 U6 - https://doi.org/10.3390/ijms19082271 SN - 1422-0067 SN - 1661-6596 VL - 19 IS - 8 PB - Molecular Diversity Preservation International CY - Basel ER - TY - JOUR A1 - Schwarz, Maria A1 - Lossow, Kristina A1 - Kopp, Johannes Florian A1 - Schwerdtle, Tanja A1 - Kipp, Anna Patricia T1 - Crosstalk of Nrf2 with the Trace Elements Selenium, Iron, Zinc, and Copper JF - Nutrients N2 - Trace elements, like Cu, Zn, Fe, or Se, are important for the proper functioning of antioxidant enzymes. However, in excessive amounts, they can also act as pro-oxidants. Accordingly, trace elements influence redox-modulated signaling pathways, such as the Nrf2 pathway. Vice versa, Nrf2 target genes belong to the group of transport and metal binding proteins. In order to investigate whether Nrf2 directly regulates the systemic trace element status, we used mice to study the effect of a constitutive, whole-body Nrf2 knockout on the systemic status of Cu, Zn, Fe, and Se. As the loss of selenoproteins under Se-deprived conditions has been described to further enhance Nrf2 activity, we additionally analyzed the combination of Nrf2 knockout with feeding diets that provide either suboptimal, adequate, or supplemented amounts of Se. Experiments revealed that the Nrf2 knockout partially affected the trace element concentrations of Cu, Zn, Fe, or Se in the intestine, liver, and/or plasma. However, aside from Fe, the other three trace elements were only marginally modulated in an Nrf2-dependent manner. Selenium deficiency mainly resulted in increased plasma Zn levels. One putative mediator could be the metal regulatory transcription factor 1, which was up-regulated with an increasing Se supply and downregulated in Se-supplemented Nrf2 knockout mice. KW - Nrf2 KW - selenium KW - iron KW - copper KW - zinc KW - homeostasis Y1 - 2019 U6 - https://doi.org/10.3390/nu11092112 SN - 2072-6643 VL - 11 IS - 9 PB - MDPI CY - Basel ER - TY - JOUR A1 - Witt, Barbara A1 - Schaumlöffel, Dirk A1 - Schwerdtle, Tanja T1 - Subcellular Localization of Copper BT - Cellular Bioimaging with Focus on Neurological Disorders JF - International Journal of Molecular Sciences N2 - As an essential trace element, copper plays a pivotal role in physiological body functions. In fact, dysregulated copper homeostasis has been clearly linked to neurological disorders including Wilson and Alzheimer’s disease. Such neurodegenerative diseases are associated with progressive loss of neurons and thus impaired brain functions. However, the underlying mechanisms are not fully understood. Characterization of the element species and their subcellular localization is of great importance to uncover cellular mechanisms. Recent research activities focus on the question of how copper contributes to the pathological findings. Cellular bioimaging of copper is an essential key to accomplish this objective. Besides information on the spatial distribution and chemical properties of copper, other essential trace elements can be localized in parallel. Highly sensitive and high spatial resolution techniques such as LA-ICP-MS, TEM-EDS, S-XRF and NanoSIMS are required for elemental mapping on subcellular level. This review summarizes state-of-the-art techniques in the field of bioimaging. Their strengths and limitations will be discussed with particular focus on potential applications for the elucidation of copper-related diseases. Based on such investigations, further information on cellular processes and mechanisms can be derived under physiological and pathological conditions. Bioimaging studies might enable the clarification of the role of copper in the context of neurodegenerative diseases and provide an important basis to develop therapeutic strategies for reduction or even prevention of copper-related disorders and their pathological consequences. KW - copper KW - cellular bioimaging KW - neurodegenerative diseases KW - copper-related disorders KW - SIMS techniques KW - TEM KW - S-XRF Y1 - 2020 U6 - https://doi.org/10.3390/ijms21072341 SN - 1422-0067 VL - 21 IS - 7 PB - Molecular Diversity Preservation International CY - Basel ER - TY - JOUR A1 - Hossain, Mohammad Delwar A1 - Chakraborty, Chanchal A1 - Rana, Utpal A1 - Mondal, Sanjoy A1 - Holdt, Hans-Jürgen A1 - Higuchi, Masayoshi T1 - Green-to-black electrochromic copper(I)-based metallo-supramolecular polymer with a perpendicularly twisted structure JF - ACS applied polymer materials N2 - A Cu(I)-based metallo-supramolecular polymer with a perpendicularly twisted structure was synthesized by a 1:1 complexation of tetrakis(acetonitrile)copper(I) triflate with the pi-conjugated dibenzoeilatin ligand. Stepwise complexation behavior of Cu(I) with the ligand was revealed by titrimetric ultraviolet- visible (UV-vis) spectroscopic analysis. Formation of a high-molecular-weight polymer (M-w = 1.21 x 10(5) Da) was confirmed by a size-exclusion chromatography-viscometry-right-angle laser light scattering study. A bundle structure of the polymer chains was observed by scanning electron microscopy. A cyclic voltammogram of the polymer film showed reversible redox waves at a negative potential. A device consisting of indium tin oxide (ITO) glass coated with a film of the polymer exhibited reversible green-to-black electrochromism upon alternate application of -3 and +1 V. KW - electrochromism KW - metallo-supramolecular polymers KW - stepwise complexation KW - metal-to-ligand charge transfer KW - copper KW - dibenzoeilatin Y1 - 2020 U6 - https://doi.org/10.1021/acsapm.0c00559 SN - 2637-6105 VL - 2 IS - 11 SP - 4449 EP - 4454 PB - American Chemical Society CY - Washington, DC ER - TY - JOUR A1 - Schwarze, Thomas A1 - Sperlich, Eric A1 - Müller, Thomas A1 - Kelling, Alexandra A1 - Holdt, Hans-Jürgen T1 - Synthesis efforts of acyclic bis(monoalkylamino)maleonitriles and macrocyclic bis(dialkylamino)maleonitriles as fluorescent probes for cations and a new colorimetric copper(II) chemodosimeter JF - Helvetica chimica acta N2 - In this article, we report on the synthesis of acyclic bis(monoalkylamino)maleonitriles and on the intended synthesis of macrocyclic bis(dialkylamino)maleonitriles to get fluorescent probes for cations. During our efforts to synthesize macrocyclic bis(dialkylamino)maleonitriles, we were only able to isolate macrocyclic bis(dialkylamino)-fumaronitriles. The synthesis of macrocyclic bis(dialkylamino)maleonitriles is challenging, due to the fact that bis-(dialkylamino)fumaronitriles are thermodynamically more stable than the corresponding bis(dialkylamino)-maleonitriles. Further, it turned out that the acyclic bis(monoalkylamino)maleonitriles and macrocyclic bis-(dialkylamino)fumaronitriles are no suitable tools to detect cations by a strong fluorescence enhancement. Further, only the bis(monoalkylamino)maleonitriles, which are bearing a 2-pyridyl unit as an additional complexing unit, are able to selectively recognize copper(II) by a color change from yellow to red. KW - copper KW - fumaronitrile KW - ligands KW - macrocycles KW - maleonitrile Y1 - 2021 U6 - https://doi.org/10.1002/hlca.202100028 SN - 1522-2675 VL - 104 IS - 6 SP - e2100028 PB - Wiley-VCH CY - Weinheim ER -