Dieter Rehder

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Name: Dieter Rehder

Organization: University of Hamburg , Germany

Department: Department of Chemistry

Title: (PhD)

TOPICS

Inorganic Chemistry

Material Chemistry

Dye Sensitized Solar Cells

Organic Chemistry

Dye Sensitized Solar Cells

Chemicals
References

Implications of vanadium in technical applications and pharmaceutical issues

Co-reporter:Dieter Rehder

Inorganica Chimica Acta 2017 Volume 455(Part 2) pp:378-389

Publication Date(Web):30 January 2017

DOI:10.1016/j.ica.2016.06.021

•Vanadium compounds for industrial exploitation (catalysis, batteries, qubits, MOFs).•Naturally occurring vanadium compounds and implications for applications.•Potentiality of vanadium compounds in medicinal issues.This overview addresses technical, biological and medicinal aspects of vanadium chemistry with special emphasis directed towards recent developments in industrial areas and (potential) pharmacological applications, along with novel insight into vanadium compounds occurring in, or associated with, living organisms. This includes the model character and potentiality of some of these systems for application domains. Focal points are industrial processes such as oxidation and polymerisation catalysis, vanadium-based batteries, breathing metal-organic frame-works, and quantum information, along with environmental concern. Examples for the latter aspect are the detoxification of exhaust gases, and the (bacterial) detoxification of soils and water. With respect to pharmacological and thus health issues, diabetes and tropical diseases (sleeping sickness, Chagas disease, leishmaniasis and amoebiasis) are accentuated.Vanadium is a constituent of two types of enzymes (nitrogenase, peroxidase) and further accumulates unspecifically in a few organisms. Elemental vanadium is a constituent in steels; the use of vanadium compounds in technical applications includes catalysts, high-performance batteries, metal-organic frameworks and quantum information. Potential pharmaceutical issues are directed towards type 2 diabetes, infectious (viral, bacterial, protozoan and amoebic) diseases, tumours and cardio-vascular defects.

Oxidovanadium(IV/V) Complexes as New Redox Mediators in Dye-Sensitized Solar Cells: A Combined Experimental and Theoretical Study

Co-reporter:Andigoni Apostolopoulou, Manolis Vlasiou, Petros A. Tziouris, Constantinos Tsiafoulis, Athanassios C. Tsipis, Dieter Rehder, Themistoklis A. Kabanos, Anastasios D. Keramidas, and Elias Stathatos

Inorganic Chemistry 2015 Volume 54(Issue 8) pp:3979-3988

Publication Date(Web):April 6, 2015

DOI:10.1021/acs.inorgchem.5b00159

Corrosiveness is one of the main drawbacks of using the iodide/triiodide redox couple in dye-sensitized solar cells (DSSCs). Alternative redox couples including transition metal complexes have been investigated where surprisingly high efficiencies for the conversion of solar to electrical energy have been achieved. In this paper, we examined the development of a DSSC using an electrolyte based on square pyramidal oxidovanadium(IV/V) complexes. The oxidovanadium(IV) complex (Ph4P)2[VIVO(hybeb)] was combined with its oxidized analogue (Ph4P)[VVO(hybeb)] {where hybeb4– is the tetradentate diamidodiphenolate ligand [1-(2-hydroxybenzamido)-2-(2-pyridinecarboxamido)benzenato}and applied as a redox couple in the electrolyte of DSSCs. The complexes exhibit large electron exchange and transfer rates, which are evident from electron paramagnetic resonance spectroscopy and electrochemistry, rendering the oxidovanadium(IV/V) compounds suitable for redox mediators in DSSCs. The very large self-exchange rate constant offered an insight into the mechanism of the exchange reaction most likely mediated through an outer-sphere exchange mechanism. The [VIVO(hybeb)]2–/[VVO(hybeb)]− redox potential and the energy of highest occupied molecular orbital (HOMO) of the sensitizing dye N719 and the HOMO of [VIVO(hybeb)]2– were calculated by means of density functional theory electronic structure calculation methods. The complexes were applied as a new redox mediator in DSSCs, while the cell performance was studied in terms of the concentration of the reduced and oxidized form of the complexes. These studies were performed with the commercial Ru-based sensitizer N719 absorbed on a TiO2 semiconducting film in the DSSC. Maximum energy conversion efficiencies of 2% at simulated solar light (AM 1.5; 1000 W m–2) with an open circuit voltage of 660 mV, a short-circuit current of 5.2 mA cm–2, and a fill factor of 0.58 were recorded without the presence of any additives in the electrolyte.

Modelling the site of bromide binding in vanadate-dependent bromoperoxidases

Co-reporter:Verena Kraehmer and Dieter Rehder

Dalton Transactions 2012 vol. 41(Issue 17) pp:5225-5234

Publication Date(Web):14 Mar 2012

DOI:10.1039/C2DT12287A

Treatment of Boc-protected (S)-serine (Ser) methyl ester with triphenylphosphine bromide Ph3PBr (intermittently generated from PPh3 and N-bromosuccinimide) yields Boc-3-bromoalanine (R)-Boc–BrAlaMe and, after deprotection, bromoalanine methyl ester (R)-BrAlaMe in the form of its hydrobromide. Boc–BrAlaMe and BrAlaMe have been structurally characterised. The reaction between BrAlaMe, salicylaldehyde (sal) and VO2+ results in the formation of Schiff base complexes of composition [VO(sal–BrAlaMe)solv]+ (solv = CH3OH: 3, THF: 5) and [VO(sal–BrAla)THF] 4. DFT calculations of the structures of 3, 4 and 5, based on the B3LYP functional and employing the triple zeta basis set 6-311++g(d,p), provide distances Br⋯V = 4.0 ± 0.1 Å, if some distortion of the dihedral angle ∠N–C–C–Br is allowed (affording a maximum energy of ca. 45 kJ mol−1), and thus model Br⋯V distances detected by X-ray methods in bromoperoxidases from the marine algae Ascophyllum nodosum and Corallina pilulifera. The DFT calculations have been validated by comparing calculated and found structures, including the new complex [VVO(Amp–sal)OMe(MeOH)] (1, Amp is the aminophenol moiety) and the known complex [VO(L-Ser–van)H2O] (van = vanillin). Additional validation has been undertaken by checking experimental against calculated (BHandHLYP) EPR spectroscopic hyperfine coupling constants. Complexes containing bromine as a substituent at the phenyl moiety of a Schiff base ligand do not allow for an appropriate simulation of the Br⋯V distance in peroxidases. The closest agreement, d(Br⋯V) = 4.87 Å, is achieved with [VO(3Br–salSer)THF] (6), where 3Brsal–Ser is the dianionic Schiff base formed between 3-Br-5-NO2-salicylaldehyde and serine.

The redox interaction between the vanadyl cation and tris[6-(2-hydroxymethyl)pyridylmethyl]amine

Co-reporter:Jessica Nilsson, Stephen B. Colbran, Ulrich Behrens, Dieter Rehder, Ebbe Nordlander

Inorganica Chimica Acta 2012 Volume 392() pp:490-493

Publication Date(Web):30 September 2012

DOI:10.1016/j.ica.2012.04.041

Reaction of tris[6-(2-hydroxymethyl)pyridylmethyl]amine, tpa(OH)3, with VIVOSO4·5H2O resulted in an unexpected redox reaction producing [VIIILH][VIIILH2][PF6]3·1.5H2O (where H3L is bis(2-hydroxymethylpyridyl)(2-carboxypyridylmethyl)amine). This reaction is interesting in the light of the ability of ascidians to accumulate VIII by reduction of VV from sea water. It also provides additional proof to the susceptibility of pyridylmethylamines to oxidation by certain metal ions.Graphical abstractReaction of tpa(OH)3 with VIVOSO4·5H2O resulted in a redox reaction producing [VIIILH][VIIILH2][PF6]3·1.5H2O.Highlights► Reaction of the vanadyl cation, {VIVO}2+, with a polypyridyl ligand. ► A VIII complex containing an oxidized form of the ligand is formed. ► NMR spectroscopy indicates catalytic aerial oxidation of the ligand by VOSO4.

A possible role for extraterrestrial vanadium in the encounter of life

Co-reporter:Dieter Rehder

Coordination Chemistry Reviews 2011 Volume 255(19–20) pp:2227-2231

Publication Date(Web):October 2011

DOI:10.1016/j.ccr.2011.04.015

Extraterrestrial vanadium compounds typically contain vanadium in low oxidation states (VII, VIII), reflecting anoxic environments (low oxygen fugacities) during genesis. In meteorites, most of which are fragments from asteroids and thus represent samples from the very beginning of our solar system, are found the pyroxenes which are typical VII bearing minerals. In calcium- and aluminium-rich inclusions of dust particles collected from the coma of comet Wild 2, osbornite (TiN) with titanium replaced by up to 63% vanadium has been found. The atmospheres of “hot Jupiter” type exoplanets, as well as the atmospheres of early M type stars (red dwarfs) contain vanadium(II)oxide, which is also likely a constituent in interstellar clouds. The relevance of these vanadium occurrences for the generation of complex molecules out of simple ones under primordial conditions is briefly discussed in light of the catalytic potential of vanadium nitrides and -oxides. At higher oxygen fugacities, oxidic VIV and VV species are available. In this context, the ability of higher valent vanadium oxides to form nano-structured webs of protocells, and the potential of decavanadate and VO2+ to interfere with chemical processes in micellar structures and lipid vesicles is addressed.

Salicylamide and salicylglycine oxidovanadium complexes with insulin-mimetic properties

Co-reporter:Jessica Nilsson, Albert A. Shteinman, Eva Degerman, Eva A. Enyedy, Tamás Kiss, Ulrich Behrens, Dieter Rehder, Ebbe Nordlander

Journal of Inorganic Biochemistry 2011 Volume 105(Issue 12) pp:1795-1800

Publication Date(Web):December 2011

DOI:10.1016/j.jinorgbio.2011.09.022

Reaction of N-(2-hydroxybenzyl)-N-(2-picolyl) glycine (H2papy) with VOSO4 in water gives the oxidovanadium(V) oxido-bridged dimer [{(papy)(VO)}2 μ-O)] (1). Similarly, reaction of N-(2-hydroxybenzyl) glycine (H2glysal) with VOSO4 gives [(glysal)VO(H2O)] (2) and reaction of salicylamide (Hsalam) with VOSO4 in methanol gives [(salam)2VO] (3). The crystal structure of the oxido-bridged complex 1 is reported. The insulin-mimetic activity of all three complexes was evaluated with respect to their ability to phosphorylate protein kinase B (PKB). The speciations of complexes 1 and 2 were studied over the pH range 2–10. Complex 1 shows greater stability over the whole pH range but only 2 and 3 exhibit an insulin-mimetic effect.Vanadium oxido complexes of the ligands N-(2-hydroxybenzyl)-N-(2-picolyl) glycine, N-(2-hydroxybenzyl) glycine, and salicylamide (Hsalam) have been prepared and the ability of the vanadium complexes to effect phosphorylation of protein kinase B in rat adipocytes – an insulin-mimetic property – has been evaluated.

Bioanorganische Chemie des Vanadiums. Leben ohne Vanadium?

Co-reporter: Dr. Dieter Rehder

Chemie in unserer Zeit 2010 Volume 44( Issue 5) pp:322-331

Publication Date(Web):

DOI:10.1002/ciuz.201000517

Abstract

Vanadium wird von Mikroorganismen als Elektronenakzeptor in der Respiration sowie als essentielles Übergangsmetall in enzymatischen Reaktionen verwendet. Ein Beispiel für die Verwendung in respiratorischer Funktion, bei der Vanadat(V) zu Oxidovanadium(IV) reduziert wird, ist das Bodenbakterium Shewanella. Beispiele für enzymatische Reaktionen sind die Stickstofffixierung (durch das Proteobakterium Azotobacter und das Cyanobakterium Anabaena), sowie die Zweielektronen-Oxidation von Halogenid X^– zu einer Spezies {X⁺} durch marine Makroalgen, primitive Pilze und Flechten. In der Vanadiumnitrogenase ist Vanadium Bestandteil eines {Fe₇VS₉} Clusters, in den Vanadat-abhängigen Haloperoxidasen liegt H₂VO₄^– gebunden an einen Histidylrest aus der Proteinmatrix vor. Pilze der Gattung Amanita speichern Vanadium in Form von Amavadin mit “nacktem” Vanadium(IV); einige Seescheiden und Strudelwürmer reichern Vanadium aus dem Meerwasser an und speichern es als Aqua-Komplex des Vanadium(III). Maßgeschneiderte Vandiumkomplexe mit organischen Liganden haben sich in vivo und in vitro als Insulin-Mimetika erwiesen: Sie vermögen die Glucoseaufnahme durch die Zellen zu stimulieren und den Abbau von Fetten zu inhibieren. Diese Funktionen stehen in Beziehung zum Vanadat-Phosphat-Antagonismus.

Vanadium is used by microorganisms as an electron acceptor in respiration, and as an essential transition metal in enzymatic reactions. An example for the employment in respiratory function is the soil bacterium Shewanella, which reduces vanadate(V) to oxidovanadium(IV). Examples for enzymatic reactions are the nitrogen fixation (by the proteobacterium Azotobacter and the cyanobacterium Anabaena), and the two-electron oxidation of halide X^– to a species {X⁺} by marine macro-algae, fungi and lichen. In vanadium nitrogenase, vanadium is constituent of a {Fe₇VS₉} cluster, in vanadate-dependent haloperoxidases it is present in the form of H₂VO₄^– bound to a histidyl residue of the protein matrix. Mushrooms of the genus Amanita store vanadium in the form of amavadin, a “bare” (non-oxo) vanadium(IV) complex. Several sea squirts and fan worms accumulate vanadium from sea water and store it as an aqua complex of vanadium(III). “Tailored” vanadium complexes with organic ligands have been shown to be active as insulin-mimics in vivo and in vitro: They are able to stimulate the cellular uptake of glucose and to inhibit the degradation of lipids. These functions are related to the phosphate-vanadate antagonism.

Bis- and tris(pyridyl)amine-oxidovanadium complexes: Characteristics and insulin-mimetic potential

Co-reporter:Jessica Nilsson, Eva Degerman, Matti Haukka, George C. Lisensky, Eugenio Garribba, Yutaka Yoshikawa, Hiromu Sakurai, Eva A. Enyedy, Tamás Kiss, Hossein Esbak, Dieter Rehder and Ebbe Nordlander

Dalton Transactions 2009 (Issue 38) pp:7902-7911

Publication Date(Web):05 Aug 2009

DOI:10.1039/B903456K

Two novel vanadium complexes, [VIVO(bp-O)(HSO4)] (1) and [VIVO(bp-OH)Cl2]·CH3OH (2·CH3OH), where bp-OH is 2-{[bis(pyrid-2-yl)methyl]amine}methylphenol, were prepared and structurally characterised. EPR spectra of methanol solutions of 2 suggest exchange of Cl− for CH3OH and partial conversion to [VO(bp-OH)(CH3OH)3]2+. Speciation studies on the VO2+-bpOH system in a water/dmso mixture (4:1 v/v) revealed [VO(bp-O)(H2O)n]+ as the dominating species in the pH range 2–7. The insulin-mimetic properties of 1 and 2, [VIVO(SO4)tpa] (3), [VIVO(pic-trpMe)2] (5) and the new mixed-ligand complexes [VVO(pic-trpH)tpa]Cl2 (4Cl2) and [VVO(pic-OEt)tpa]Cl2 (6Cl2), tpa = tris(pyrid-2-yl)methylamine, picH-trpH = 2-carboxypyridine-5-(L-tryptophan)carboxamide (picH-trpMe is the respective tryptophanmethyl ester), pic-OEt = 5-carboethoxypyridine-2-carboxylic acid, were evaluated with rat adipocytes, employing two lipolysis assays (release of glycerol and free fatty acids (FFA)), respectively and a lipogenesis assay (incorporation of glucose into lipids). The IC50 values for the inhibition of lipolysis in the FFA assay vary between 0.41 (±0.03) (5) and 21.2 (±0.6) mM (2), as compared to 0.81 (±0.2) mM for VOSO4.

Aminoacid-derivatised picolinato-oxidovanadium(IV) complexes: Characterisation, speciation and ex vivo insulin-mimetic potential

Co-reporter:Hossein Esbak, Eva A. Enyedy, Tamás Kiss, Yutaka Yoshikawa, Hiromu Sakurai, Eugenio Garribba, Dieter Rehder

Journal of Inorganic Biochemistry 2009 Volume 103(Issue 4) pp:590-600

Publication Date(Web):April 2009

DOI:10.1016/j.jinorgbio.2008.11.001

The proligands PicMe-AaR (PicMe = methoxipicolyl-5-amide, where the amide substituent is an amino acid AaR = HisH, HisMe, IleH, IleMe, TrpH, TrpMe, HTyrEt, tBuTyrMe, HThrMe, tBuThrMe) and the complexes [VO(Pic-AaR)2] have been synthesised and characterised. A detailed EPR study of the VO2+/Pic-His systems in water revealed the predominance of the complex [VO(Pic-His)H2O] in the pH range 2–6, with tridentate coordination of Pic-His via the picolinate moiety and imidazole-Nδ. Speciation analyses of the binary systems VO2+/Pic-Aa (Aa = His, Ile, Trp) and the ternary systems VO2+/Pic-Aa/B (Aa = His, Ile; B = citrate (cit), lactate (lac), phosphate) showed a predominance of the ternary complexes [VO(Pic-Aa)(cit/lac)] and [VO(Pic-Aa)(cit/lac)OH]− in the physiological pH regime. If, in addition, human serum albumin (HAS) and apotransferrin (Tf) are present, with all of the low and high molecular mass constituents in their blood serum concentrations, about two thirds of VO2+ is bound to the protein, while there is still a sizable amount of ternary complex [VO(Pic-Aa)(cit/lac)] present (about 1/4 for Pic-His and 1/3 for Pic-Ile) when the vanadium(IV) concentration is relatively high; at lower concentrations Tf is the predominant binder. Insulin-mimetic studies for VO2+/Pic-Aa (Aa = His, Ile, Tyr and Trp), based on a lipolysis assay with rat adipocytes, provided IC50 values of 0.41(1) for VO2+/Pic-His and VO2+/Pic-Ile, which compares with 0.87(17) for VOSO4.

Is vanadium a more versatile target in the activity of primordial life forms than hitherto anticipated?

Co-reporter:Dieter Rehder

Organic & Biomolecular Chemistry 2008 vol. 6(Issue 6) pp:957-964

Publication Date(Web):16 Jan 2008

DOI:10.1039/B717565P

The two predominant forms of vanadium occurring in the geo-, aqua- and biosphere, soluble vanadate(V) and insoluble oxovanadium(IV) (vanadyl), are subject to bacterial activity and transformation. Bacteria belonging to genera such as Shewanella, Pseudomonas and Geobacter can use vanadate as a primary electron acceptor in dissimilation or respiration, an important issue in the context of biomineralisation and soil detoxification. Azotobacter, which can employ vanadium as an essential element in nitrogen fixation, secretes a vanadophore which enables the uptake of vanadium(V). Siderophores secreted by other bacteria competitively (to ferric iron) take up vanadyl and thus interfere with iron supply, resulting in bacteriostasis. The halo-alkaliphilic Thioalkalivibrio nitratireducens possibly uses vanadium as a constituent of an alternative, molybdopterin-free nitrate reductase. Marine macro-algae can generate a variety of halogenated organic compounds by use of vanadate-dependent haloperoxidases, and a molecular vanadium compound, amavadin, from Amanita mushrooms has turned out to be an efficient catalyst in oxidation reactions. The present account is a focused and critical review of the current knowledge of the interplay of bacteria and other primitive forms of life (cyanobacteria, algae, fungi and lichens) with vanadium, with the aim to provide perspectives for applications and further investigations.

Sulfoxygenation Catalysed by Oxidovanadium Complexes

Co-reporter:Pingsong Wu;Cem Çelik;Gabriella Santoni;Jérome Dallery

European Journal of Inorganic Chemistry 2008 Volume 2008( Issue 33) pp:5203-5213

Publication Date(Web):

DOI:10.1002/ejic.200800772

Abstract

Model complexes of vanadate-dependent peroxidases, viz. oxidovanadium(V) complexes of the general composition [VO(H_n–xL)], have been prepared and characterised. H_nL is an n-basic di- or trichiral aminodiethanol [HOCH(Ph)CH₂]₂NR, with R = N-methylimidazolyl (H₂L^A), tris(hydroxymethyl)methyl (H₅L^B, 2 isomers), 2,3-dihydroxypropyl (H₄L^C, 2 isomers) and 2-hydroxy-3-trityloxypropyl (H₃L^D). These ligands form the complexes [VO(OH)(L^A)], [VO(H₂L^B)], trigonal-bipyramidal [VO(HL^C)]_tbp and octahedral Λ-[VO(HL^C)]_oct. The ligands R,R,S-H₄L^C and R,R,R-H₃L^D, and the complexes Λ-[VO(R,R,S-HL^C)]_oct and [VO(R,R,S-HL^C)]_tbp have been characterised by X-ray structure analysis. The complexes [VO(H₂L^B)] and [VO(HL^C)] were immobilised on Merrifield and Barlos resin by anchoring through a free alcoholic group in the ligand side-chain R. {[VO(H₂O)L^E]}, an oxidovanadium(IV) complex tethered to Merrifield resin, was prepared by treating [VO(acac)₂] with {HL^E}, the immobilised Schiff base ligand obtained by condensation of salicylaldehyde with resin-anchored lysine. The complexes and in situ systems ([VO(OiPr)₃] + ligand) as well as the immobilised complexes were investigated for their catalytic activity in the oxygenation, by cumyl hydroperoxide, of thioanisol to its sulfoxide. All of the systems were active, with a selectivity (sulfoxide vs. sulfone) of 95–98 %. Satisfactory turnover rates and a chiral induction up to 37 % ee were observed.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Cellular cation transport studied by 6, 7Li and 23Na NMR in a porous Mo132 Keplerate type nano-capsule as model system

Co-reporter:Dieter Rehder;Erhard T. K. Haupt;Achim Müller

Magnetic Resonance in Chemistry 2008 Volume 46( Issue S1) pp:S24-S29

Publication Date(Web):

DOI:10.1002/mrc.2343

Abstract

Li⁺ ions can interplay with other cations intrinsically present in the intra- and extra-cellular space (i.e. Na⁺, K⁺, Mg²⁺ and Ca²⁺) and have therapeutic effects (e.g. in the treatment of bipolar disorder) or toxic effects (at higher doses), likely because Li⁺ interferes with the intra-/extra-cellular concentration gradients of the mentioned physiologically relevant cations. The cellular transmembrane transport can be modelled by molybdenum-oxide-based Keplerates, i.e. nano-sized porous capsules containing 132 Mo centres, monitored through ^6/7Li as well as ²³Na NMR spectroscopy. The effects on the transport of Li⁺ cations through the ‘ion channels’ of these model cells, caused by variations in water amount, temperature, and by the addition of organic cationic ‘plugs’ and the shift reagent [Dy(PPP)₂]⁷⁻ are reported. In the investigated solvent systems, water acts as a transport mediator for Li⁺. Likewise, the counter-transport (Li⁺/Na⁺, Li⁺/K⁺, Li⁺/Cs⁺ and Li⁺/Ca²⁺) has been investigated by ⁷Li NMR and, in the case of Li⁺/Na⁺ exchange, by ²³Na NMR, and it has been shown that most (in the case of Na⁺ and K⁺), all (Ca²⁺) or almost none (Cs⁺) of the Li cations is extruded from the internal sites of the artificial cell to the extra-cellular medium, while Na⁺, K⁺ and Ca²⁺ are partially incorporated. Copyright © 2008 John Wiley & Sons, Ltd.

Countercation Transport Modeled by Porous Spherical Molybdenum Oxide Based Nanocapsules

Co-reporter:Dieter Rehder Dr.;Erhard T. K. Haupt Dr.;Hartmut Bögge Dr.;Achim Müller Dr.

Chemistry – An Asian Journal 2006 Volume 1(Issue 1-2) pp:

Publication Date(Web):10 JUL 2006

DOI:10.1002/asia.200600035

Porous nanosized polyoxomolybdate capsule anions of composition [{Mo^VI(Mo^VI₅O₂₁)(H₂O)₆}₁₂(linker)₃₀]ⁿ⁻, where (linker)₃₀ is {Mo^V₂O₄(SO₄)}₃₀ (n=72) (1 a) or {Mo^V₂O₄(SO₄)}₂₄{Mo^V₂O₄(CH₃COO)}₆ (n=64) (2 a), model the (competitive) cellular transmembrane transport of Li⁺, Na⁺, K⁺, and Ca²⁺ ions along ion channels. According to X-ray crystallography and ⁷Li and ²³Na NMR spectroscopy, Li⁺ and Na⁺, the counterions for 1 a and 2 a, respectively, occupy internal sites of the capsule. This study of the counterion transport phenomenon shows that, while Li⁺ ions can be replaced to a large extent by Na⁺ and K⁺ ions and completely by Ca²⁺ ions added to a solution of 1 a, external Li⁺ ions do not replace the incorporated Na⁺ ions of 2 a in an analogous experiment. In this context, related properties of the capsules and especially of their flexible channels, in connection with the complex pathways of cation uptake, are discussed briefly. The relevance of these investigations for lithium-based therapies is also addressed.

Poröse, nano-skalige, anionische Polyoxomolybdat-Kapseln der Zusammensetzung [{Mo^VI(Mo^VI₅O₂₁)(H₂O)₆}₁₂(linker)₃₀]ⁿ⁻ – (linker)₃₀ entspricht {Mo^V₂O₄(SO₄)}₃₀ (n=72), 1 a, oder {Mo^V₂O₄(SO₄)}₂₄{Mo^V₂O₄(CH₃COO)}₆ (n=64), 2 a – modellieren den (kompetitiven) zellulären Transmembran-Transport von Li⁺, Na⁺, K⁺ und Ca²⁺ über Ionenkanäle. Gemäß Röntgenstrukturanalyse und ⁷Li- sowie ²³Na-NMR-spektroskopischen Untersuchungen besetzen die Gegenionen von 1 a und 2 a, Li⁺ und Na⁺, interne Positionen der Kapsel. Die hier vorliegende Studie zum Phänomen des Counter-Transportes der Ionen zeigt, dass bei externer Zugabe von Na⁺ und K⁺ zu Lösungen von 1 a das Li⁺ weitgehend, bei Zugabe von Ca²⁺ vollständig ausgetauscht wird. Andererseits zeigt das komplementäre Experiment – die externe Zufuhr von Li⁺ zu Lösungen von 2 a – dass inkorporiertes Na⁺ nicht verdrängt wird. Eigenschaften der Kapseln (und insbesondere ihrer Kanäle) werden im Kontext des komplexen Mechanismus’ der Aufnahme von Kationen kurz diskutiert. Die Relevanz dieser Untersuchungen für Therapien, die auf Lithium basieren, wird gleichfalls angesprochen.

Thio-Ligation to Vanadium: The NSSN and S′N′O Donor Sets (N = Pyridine, N′ = Enamine; S = Thioether, S′ = Thiolate)

Co-reporter:Mahin Farahbakhsh;Henning Nekola;Häke Schmidt

European Journal of Inorganic Chemistry 1997 Volume 130(Issue 8) pp:

Publication Date(Web):26 JAN 2006

DOI:10.1002/cber.19971300815

The tetradentate, neutral disulfide [bis(thioether)] ligand 1,6-bis(o-pyridyl)-2,4-dithiahexane, NSSN, reacts with [VCI₂(tmeda)₂] to form the octahedral (all-_cis; C_2v-symmetric) complex [VCl₂(_NSSN)] 1, the first low-valent vanadium complex in which the thio functions are exclusively organic sulfides. Treatment of (VOCl₂(thf)₂] with O-mercaptoaniline, followed by reaction with o-hydroxynaphthaldehyde yields the non-oxo V′” complex [V(S′N′O)₂] 2, derived from the Schiff base HS′N′OH, where 0 and S′ are phenolate and thiophenolate functions, respectively, and N′ is the Schiff base (enamine) nitrogen. Complex 2, with the ligands in a distorted trigonal-antiprismatic array, is a rare example of a structurally characterized complex where the Schiff base is preserved at the expense of its thiazoline tautomeric form.