- Prof. at Inorganic Institute at KIT. Also have a research group at INT (North Campus) KIT. Major focus on "Coordinati... moreProf. at Inorganic Institute at KIT. Also have a research group at INT (North Campus) KIT. Major focus on "Coordination Clusters". Educated in the UK. Awarded PhD from the University of Manchester, 1985. Moved to Germany after 11 years in UK system in 1999. Many prize fellowships and visiting professorships. Extensive work on funding and reviewing panels, including, most recently, REF panel in UK. The group at KIT is very multicultural, hosting many AvH, CSI, DAAD scholars.edit
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ABSTRACT Reaction of manganese acetate and lanthanide nitrates in the presence of excess of PhCOOH affords highly asymmetric dodecanuclear mixed-metal [Mn(10)Ln(2)(OH)(O)(8)(PhCOOH)(PhCOO)(19)] (Ln = Pr-III (1), Nd-III (2)) clusters. The... more
ABSTRACT Reaction of manganese acetate and lanthanide nitrates in the presence of excess of PhCOOH affords highly asymmetric dodecanuclear mixed-metal [Mn(10)Ln(2)(OH)(O)(8)(PhCOOH)(PhCOO)(19)] (Ln = Pr-III (1), Nd-III (2)) clusters. The similar reaction, but with only 2 equiv. of PhCOOH resulted in the compounds with higher nuclearity [Mn11Eu4(O)(8)(OH)(8)(PhCOO)(18)(NO3)(2)(H2O)(6)]NO3 center dot 4CH(3)CN (3). Variable-temperature solid-state magnetic susceptibility of 1 and 2 in the temperature range 1.8-300 K were carried out, and for both complexes antiferromagnetic exchange interactions between the metal centers were observed, giving an estimated S = 17/2 ground state. AC magnetic susceptibility data have revealed out-of-phase signals, which suggest that these complexes exhibit a slow relaxation of magnetization as observed in single-molecule magnets.
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The level of cancer biomarkers in cells, tissues or body fluids can be used for the prediction of the presence of cancer or can even indicate the stage of the disease. Alpha-fetoprotein (AFP) is the most commonly used biomarker for early... more
The level of cancer biomarkers in cells, tissues or body fluids can be used for the prediction of the presence of cancer or can even indicate the stage of the disease. Alpha-fetoprotein (AFP) is the most commonly used biomarker for early screening and diagnosis of hepatocellular carcinoma (HCC). Here, a combination of three techniques (click chemistry, the biotin–streptavidin–biotin sandwich strategy and the use of antigen–antibody interactions) were combined to implement a sensitive fluorescent immunosensor for AFP detection. Three types of functionalized glasses (dibenzocyclooctyne- (DBCO-), thiol- and epoxy-terminated surfaces) were biotinylated by employing the respective adequate click chemistry counterparts (biotin–thiol or biotin–azide for the first class, biotin–maleimide or biotin–DBCO for the second class and biotin–amine or biotin–thiol for the third class). The anti-AFP antibody was immobilized on the surfaces via a biotin–streptavidin–biotin sandwich technique. To evalu...
Research Interests: Chemistry, Technology, Medicine, Click chemistry, Biotin, and 4 moreStreptavidin, XPS, DDC, and Biotinylation
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Dipyrromethene metal complexes are fascinating molecules that have applications as light‐harvesting systems, luminophores, and laser dyes. Recently, it has been shown that structurally rigid bis(dipyrrinato) zinc(II) complexes exhibit... more
Dipyrromethene metal complexes are fascinating molecules that have applications as light‐harvesting systems, luminophores, and laser dyes. Recently, it has been shown that structurally rigid bis(dipyrrinato) zinc(II) complexes exhibit high fluorescence with comparable quantum yields to those of boron dipyrromethenes or BODIPYs. Herein, eight new bis(dipyrrinato) ZnII complexes, obtained from symmetric and unsymmetrical functionalization of the dipyrromethene structure through a Knoevenagel reaction, are reported. It was possible not only to vary the maximum visible absorption from 490 to 630 nm, but also to enhance the emission quantum yield up to 66 %, which is extraordinarily high for homoleptic bis(dipyrrinato) zinc complexes. These results pave the way for designing highly luminescent bis(dipyrrinato) zinc complexes.
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An air stable, neutral Fe(ii) complex with four equatorial chlorido ligands has been stabilised through a serendipitous redox process and in situ ligand protonation. A three-dimensional non-covalent network composed of halogen bonding and... more
An air stable, neutral Fe(ii) complex with four equatorial chlorido ligands has been stabilised through a serendipitous redox process and in situ ligand protonation. A three-dimensional non-covalent network composed of halogen bonding and π-π stacking promotes magnetic exchange interactions though the lattice. The electronic structure has been investigated using DFT.
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Research Interests: Chemistry, Crystallography, Titanium, Medicine, Macromolecular X-Ray Crystallography, and 13 moreEDTA Chelation, CHEMICAL SCIENCES, Phenols, Monomer, Catechols, Molecular Conformation, Coordination number, Tris, Organometallic Compounds, Salicylic Acid, Molecular Structure, Salicylates, and The American
Research Interests: Chemistry, Inorganic Chemistry, Crystallography, Electrochemistry, Inorganic, and 13 moreMedicine, Macromolecular X-Ray Crystallography, Crystal structure, Copper, Animals, Naphthoquinones, Metal, Metals, Plasmodium falciparum, Antimalarials, Inorganic Biochemistry, Oxidation-Reduction, and Electron Paramagnetic Resonance
Reaction of PhP(CH2CH2SH)2 with 1,2-dichloroethane and Cs2CO3 under high dilution conditions affords 1-phenyl-1-phospha-4,7-dithiacyclononane (L) as an oil in 52% yield. The geometry of L has been probed by 1H NMR spectroscopy, which... more
Reaction of PhP(CH2CH2SH)2 with 1,2-dichloroethane and Cs2CO3 under high dilution conditions affords 1-phenyl-1-phospha-4,7-dithiacyclononane (L) as an oil in 52% yield. The geometry of L has been probed by 1H NMR spectroscopy, which indicates an equilibrium mixture containing gauche S–C–C–S and S–C–C–P segments, and molecular mechanics calculations which find a lowest energy endodentate conformation minimum and also energetically accessible exodentate minima.
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Research Interests: Chemical Engineering, Chemistry, Inorganic Chemistry, Crystallography, Electrochemistry, and 15 moreCarbon, Inorganic, Medicine, Macromolecular X-Ray Crystallography, Rhenium, Sulfur, Spectrum analysis, Radiopharmaceuticals, Alkanes, Ligands, QD, Molecular Structure, Nuclear Magnetic Resonance Spectroscopy, Sulfur Compounds, and thioether
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ABSTRACT A structural analogue of the previously reported record-high-spin (S = 83/2) mixed-valence [Mn19] coordination cluster [MnIII12MnII7(μ4-O)8(μ3-η1-N3)8(HLMe)12(MeCN)6]Cl2·10MeOH·MeCN (1) {H3LMe =... more
ABSTRACT A structural analogue of the previously reported record-high-spin (S = 83/2) mixed-valence [Mn19] coordination cluster [MnIII12MnII7(μ4-O)8(μ3-η1-N3)8(HLMe)12(MeCN)6]Cl2·10MeOH·MeCN (1) {H3LMe = 2,6-bis(hydroxymethyl)-4-methylphenol} was prepared in which the methyl group at the 4-position on the phenyl ring was replaced by a methoxy group to give the compound [Et3NH]2[MnIII12MnII7(μ4-O)8(μ3-η1-N3)7.4(μ3-Cl)0.6(HLOMe)12(MeOH)6]Cl4·14MeOH (2). Single-crystal X-ray diffraction analysis of 2 confirms that the molecular structure motif found for 1, comprising two supertetrahedral {MnIII6MnII4} units sharing a common MnII vertex, was retained. Magnetic susceptibility measurements on 2 show that the ferromagnetic spin structure, which results in the maximum ST = 83/2 spin ground state for 1, is largely robust with respect to the change in ligand substituent in 2. Molecules of compounds 1 and 2 were deposited onto highly oriented pyrolytic graphite (HOPG) substrates and were investigated by scanning tunneling microscopy (STM) andcurrent imaging tunneling spectroscopy (CITS). By usingextremely dilute solutions (10–9 mol L–1), one-dimensionalarrangements as well as isolated single molecules of [1]Cl2·10MeOH·MeCN were observed with STM topography, generally at the step edges or at defects of the HOPG surfaces, while small groups of molecules of 2 were observed. The size of the individual molecules was consistent with the X-ray crystallographic data. In the CITS images of the single molecules, a strong tunneling current contrast was observed at the positions of the metal ions.
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The synthesis and structures of the N‐[(2‐hydroxy‐3‐methyl‐5‐dodecylphenyl)methyl]‐N‐(carboxymethyl)glycine disodium salt (HL) ligand and its neutral mononuclear complex [FeIII(L)(EtOH)2] (1) are reported. Structural and electronic... more
The synthesis and structures of the N‐[(2‐hydroxy‐3‐methyl‐5‐dodecylphenyl)methyl]‐N‐(carboxymethyl)glycine disodium salt (HL) ligand and its neutral mononuclear complex [FeIII(L)(EtOH)2] (1) are reported. Structural and electronic properties of 1 were investigated by using scanning tunneling microscopy (STM) and current imaging tunneling spectroscopy (CITS) techniques. These studies reveal that molecules of 1 form well‐ordered self‐assemblies when deposited on a highly oriented pyrolytic graphite (HOPG) surface. At low concentrations, single or double chains (i.e., nanowires) of the complex were observed, whereas at high concentration the complex forms crystals and densely packed one‐dimensional structures. In STM topographies, the dimensions of assemblies of 1 found on the surface are consistent with dimensions obtained from X‐ray crystallography, which indicates the strong similarities between the crystal form and surface assembled states. Double chains are attributed to hydrogen...
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Research Interests: Computer Science, Physics, Condensed Matter Physics, Materials Science, Optics, and 15 moreThermodynamics, Chemistry, Organic Chemistry, Crystallography, Quantum Mechanics, Magnetic field, Hysteresis, Diffraction, Single Crystal, Magnetization, Magnet, Molecule, Triethanolamine, Antiferromagnetism, and Programming language
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Fully earth‐abundant and highly efficient systems for producing syngas CO/H2 through photocatalytic reduction from CO2 are essential to approach a sustainable way of closing the carbon cycle. Herein, the synthesis and characterization of... more
Fully earth‐abundant and highly efficient systems for producing syngas CO/H2 through photocatalytic reduction from CO2 are essential to approach a sustainable way of closing the carbon cycle. Herein, the synthesis and characterization of a new iron complex, FeIIL(NCS)2py, coordinated to an N,N,N‐pincer ligand 2,6‐bis(4’‐phenyl‐1’,2’,3’‐triazol‐1’‐yl‐methyl)pyridine (L), two isothiocyanate groups (NCS) and one pyridine is reported. Its catalytic activity in the photo‐driven reduction of carbon dioxide has been investigated and compared with its CoII analogue (CoL(NCS)2py) and their homoleptic complexes ML2. In this work, the catalysts are used in combination with the heteroleptic complex [CuI(dmp)(DPEphos)], where dmp is 2,9‐dimethyl‐1,10‐phenanthroline and DPEPhos is bis[(2‐diphenylphosphino)phenyl] ether, to reach entirely earth‐abundant systems. The new iron heteroleptic complex FeIIL(NCS)2py showed considerable activity with a TONCO of 576 obtained after 4 h (TOF=144 h−1) through visible light (λ=420 nm) and a quantum yield of 7.1 %.
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The new tetranuclear complexes [Fe3Ln (μ3-O) 2 (CCl3COO) 8 (H2O)(THF) 3]· THF (Ln= CeIII (1), PrIII (2), NdIII (3)) and [Fe3Ln (μ3-O) 2 (CCl3COO) 8 (H2O)(THF) 3]· THF· C7H16 (Ln= SmIII (4), EuIII (5), GdIII (6), TbIII (7), DyIII (8),... more
The new tetranuclear complexes [Fe3Ln (μ3-O) 2 (CCl3COO) 8 (H2O)(THF) 3]· THF (Ln= CeIII (1), PrIII (2), NdIII (3)) and [Fe3Ln (μ3-O) 2 (CCl3COO) 8 (H2O)(THF) 3]· THF· C7H16 (Ln= SmIII (4), EuIII (5), GdIII (6), TbIII (7), DyIII (8), HoIII (9), LuIII (10) and YIII (11)) have ...
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The tetranuclear aggregate... more
The tetranuclear aggregate (enH(2))[Fe(4)(mu(3)-O)(heidi)(4)(mu-O,O'-O(2)CNHC(2)H(4)NH(3))] x 4H(2)O contains a novel bidentate zwitterionic carbamic acid ligand. Magnetic studies indicate that the unsymmetrical Fe(4) core is ferrimagnetic with an S=4 ground state. Similar ligands have been obtained on rectangular tetranuclear aggregates [M(4)(mu-O)(mu-OH)(hpdta)(2)(mu-X)(2)](n-) (M[double bond]Fe, Al, Ga). The carbamic acid ligands are considered to result from the hydrolytic activation (fixation) of atmospheric CO(2) by the aggregate precursor to give a carbonato intermediate, which then reacts with the organic diamine used as base in the synthesis. Similar aggregates with acetate ligands result from hydrolytic activation of the DMA used as cosolvent. Closely related mechanisms for these two activation processes are proposed, which are also related to the accepted mechanisms for carbonic anhydrase and urease.
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Ligands of general formula N(CHRCH 2 OH)(CH 2 CO 2 H) 2 have been used to capture portions of the Fe(OH) 2 + lattice to give particles containing up to nineteen magnetically coupled iron(III) centres. If R = Me or Et, lattices containing... more
Ligands of general formula N(CHRCH 2 OH)(CH 2 CO 2 H) 2 have been used to capture portions of the Fe(OH) 2 + lattice to give particles containing up to nineteen magnetically coupled iron(III) centres. If R = Me or Et, lattices containing only Fe 19 clusters result and single ...
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We report evidences for long-range antiferromagnetic (AF) order in iron oxyhydroxides Fe19metheidi and (enH2)2Fe6 clusters that at low temperature behave like single molecule magnets with total spin S=33/2 and S=5, respectively. Anomalies... more
We report evidences for long-range antiferromagnetic (AF) order in iron oxyhydroxides Fe19metheidi and (enH2)2Fe6 clusters that at low temperature behave like single molecule magnets with total spin S=33/2 and S=5, respectively. Anomalies are clearly observed at 1.19 K in the heat capacity and in the low-field magnetization of Fe19metheidi while for (enH2)2Fe6 a broad λ-peak is found at 0.99 K
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Research Interests: Chemical Engineering, Biochemistry, Neuroscience, Biophysics, Chemistry, and 14 moreInorganic Chemistry, Molecular Biology, Biotechnology, Cell Biology, Lanthanide, Medicine, Chirality, Diamagnetism, Magnetization, Single crystals, Torque, Nicotinic acid, Magnetic Helicity, and Cantilever Torque Magnetometry
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ABSTRACT The tridecanuclear heterovalent mixed-metal (Mn11Gd2) complex [(Mn9Mn2Gd2III)-Mn-III-Gd-II(O)(8)(OH)(2)(O2CR)(17)(NO3)(2)(H2O)] has been obtained from the reaction of the hexanuclear compound... more
ABSTRACT The tridecanuclear heterovalent mixed-metal (Mn11Gd2) complex [(Mn9Mn2Gd2III)-Mn-III-Gd-II(O)(8)(OH)(2)(O2CR)(17)(NO3)(2)(H2O)] has been obtained from the reaction of the hexanuclear compound [Mn6O2(Piv)(10)(4-Me-py)(2.5)(PivH)(1.5)] with Gd(NO3)(3)center dot 6H(2)O in CH3CN. The complex presents an unusual "bell"-shaped core with a high-spin ground state and is a new member of the high-nuclearity 3d-4f single-molecule magnets family.
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We report two isostructural dinuclear transition metal complexes [M2(HL)2(N3)4], where M = Ni2+ (BS-1) or Mn2+ (BS-2) and HL is (2-methyl-2-((pyridin-2-ylmethyl)amino)propan-1-ol) and investigate them as molecular sensors towards... more
We report two isostructural dinuclear transition metal complexes [M2(HL)2(N3)4], where M = Ni2+ (BS-1) or Mn2+ (BS-2) and HL is (2-methyl-2-((pyridin-2-ylmethyl)amino)propan-1-ol) and investigate them as molecular sensors towards hazardous entities.
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Time‐domain synchrotron Mössbauer spectroscopy (SMS) based on the Mössbauer effect of 161Dy has been used to investigate the magnetic properties of a DyIII‐based single‐molecule magnet (SMM). The magnetic hyperfine field of... more
Time‐domain synchrotron Mössbauer spectroscopy (SMS) based on the Mössbauer effect of 161Dy has been used to investigate the magnetic properties of a DyIII‐based single‐molecule magnet (SMM). The magnetic hyperfine field of [Dy(Cy3PO)2(H2O)5]Br3⋅2 (Cy3PO)⋅2 H2O⋅2 EtOH is with B0=582.3(5) T significantly larger than that of the free‐ion DyIII with a 6H15/2 ground state. This difference is attributed to the influence of the coordinating ligands on the Fermi contact interaction between the s and 4f electrons of the DyIII ion. This study demonstrates that 161Dy SMS is an effective local probe of the influence of the coordinating ligands on the magnetic structure of Dy‐containing compounds.
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Artificial light-harvesting systems have until now not been able to self-assemble into structures with a large photon capture cross-section that upon a stimulus reversibly can switch into an inactive state. Here we describe a simple and... more
Artificial light-harvesting systems have until now not been able to self-assemble into structures with a large photon capture cross-section that upon a stimulus reversibly can switch into an inactive state. Here we describe a simple and robust FLFL-dipeptide construct to which a meso-tetraphenylporphyrin has been appended and which self-assembles to fibrils, platelets or nanospheres depending on the solvent composition. The fibrils, functioning as quenched antennas, give intense excitonic couplets in the electronic circular dichroism spectra which are mirror imaged if the unnatural FDFD-analogue is used. By slightly increasing the solvent polarity, these light-harvesting fibres disassemble to spherical structures with silent electronic circular dichroism spectra but which fluoresce. Upon further dilution with the nonpolar solvent, the intense Cotton effects are recovered, thus proving a reversible switching. A single crystal X-ray structure shows a head-to-head arrangement of porphy...
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Torque magnetometry and far-infrared spectroscopy elucidate electronic structure and magnetic properties of Dy3 single molecule magnet.
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The hepta-Ni(2+)-containing 30-tungsto-4-phosphate(v) [Ni7(OH)6(H2O)6(P2W15O56)2](16-) (1) has been synthesized in aqueous, slightly basic medium under conventional reaction conditions, and charactarized via different physical methods.... more
The hepta-Ni(2+)-containing 30-tungsto-4-phosphate(v) [Ni7(OH)6(H2O)6(P2W15O56)2](16-) (1) has been synthesized in aqueous, slightly basic medium under conventional reaction conditions, and charactarized via different physical methods. Single-crystal XRD showed that 1 consists of a corner-fused double-cubane {Ni7(OH)6(H2O)6}(8+) fragment sandwiched by two trilacunary [P2W15O56](12-) units. Polyanion 1 is solution-stable as shown by (31)P NMR. Ferromagnetic coupling interaction between the 7 paramagnetic centers of the double-cubane core in 1 with a S = 7 ground state was demonstrated. Electrochemical studies were also performed on 1.