Matthias Moll

Oxide nanotubes on Ti-Ru alloys: strongly enhanced and stable photoelectrochemical activity for water splitting.

The present work shows a significant enhancement of the photoelectrochemical water-splitting performance of anodic TiO(2) nanotube layers grown on low concentration (0.01-0.2 at% Ru) Ti-Ru alloys. Under optimized preparation conditions (0.05 at% Ru, 450 °C annealing) the water splitting rate of the oxide tubes could be 6-fold increased. Moreover, the beneficial effect is very stable with illumination time; this is in contrast to other typical doping approaches of TiO(2).

Ferritin-Mediated Iron Sequestration Stabilizes Hypoxia-Inducible Factor-1α upon LPS Activation in the Presence of Ample Oxygen

Both hypoxic and inflammatory conditions activate transcription factors such as hypoxia-inducible factor (HIF)-1α and nuclear factor (NF)-κB, which play a crucial role in adaptive responses to these challenges. In dendritic cells (DC), lipopolysaccharide (LPS)-induced HIF1α accumulation requires NF-κB signaling and promotes inflammatory DC function. The mechanisms that drive LPS-induced HIF1α accumulation under normoxia are unclear. Here, we demonstrate that LPS inhibits prolyl hydroxylase domain enzyme (PHD) activity and thereby blocks HIF1α degradation. Of note, LPS-induced PHD inhibition was neither due to cosubstrate depletion (oxygen or α-ketoglutarate) nor due to increased levels of reactive oxygen species, fumarate, and succinate. Instead, LPS inhibited PHD activity through NF-κB-mediated induction of the iron storage protein ferritin and subsequent decrease of intracellular available iron, a critical cofactor of PHD. Thus, hypoxia and LPS both induce HIF1α accumulation via PHD inhibition but deploy distinct molecular mechanisms (lack of cosubstrate oxygen versus deprivation of co-factor iron).

Zur kenntnis der chemie der metallcarbonyle und der cyanokomplexe in flüssigem ammoniak : XXXIII. Über die darstellung neuer carbamoylcarbonyl-komplexe aus bekannten und neuen kationischen carbonylverbindungen des mangans und rheniums

Abstract The covalent carbamoyl carbonyl compounds Re(CO) 5 COHN 2 , cis -M(CO) 4 (L)CONH 2 , M(CO) 3 (L) 2 CONH 2 and M(CO) 3 (D)CONH 2 (M = Mn, Re; L = PPh 3 , PEt 3 ; D = bipy, phen) are formed by reactions of the cationic complexes [Re(CO) 6 ] + , [M(CO) 5 L] + , [M(CO) 4 L 2 ] + and [M(CO) 4 D] + (M = Mn, Re; L = PPh 3 , PEt 3 ; D = bipy, phen) with liquid NH 3 with concomitant deprotonation: [M(CO) 6− n L n ] + + 2 NH 3 → M(CO) 5− n L n CONH 2 + NH 4 + ( n = 0, 1, 2) and [M(CO) 4 D] + + 2 NH 3 → M(CO) 3 (D)CONH 2 + NH 4 + The stability of the above-mentioned carbamoyl carbonyl complexes increases from the penta- to the tetra- to the tri-carbonyl derivatives. In all cases the rhenium compounds are much more stable than the corresponding manganese complexes. Whereas the carbamoyl compound Re(CO) 4 (PEt 3 )CONH 2 can be isolated by reaction of [Re(CO) 5 PEt 3 ] + with NH 3 , the corresponding manganese complex undergoes Hofmann degradation of amides even at −70°C to form HMn(CO) 4 PEt 3 and NH 4 NCO. The IR and some mass and 1 H NMR spectra of the new hexacoordinated carbamoyl carbonyl complexes are discussed and the reactions of these compounds with liquid NH 3 , HCl and CH 3 OH are described.

Chemie polyfunktioneller Moleküle: CXIII. Komplexe des Dicobaltoctacarbonyls mit den Liganden Bis(diphenylphosphino)amin und -amid

The yield of the earlier published Co2(μ-CO)2(CO)4(μ-dppa)·12 C6H6 (4·12 C6H6) [dppa = bis(diphenylphosphino)amin (1)] could now be increased from 30% to 80%. In the polar solvent tetrahydrofuran (THF) Co2CO)8 and dppa react to the ionic complex [Co(CO)(dppa)2][Co(CO)4] · 2 THF (5a · 2 THF). Metatheses of 5a · 2 THF with NaBPh4 in ethanol led to the formation of [Co(CO)(dppa)2]BPh4 (5b). Under UV irradiation 4 · 12 C6H6 and dppa gives the CO-bridging-free Co2(CO)4(μ-dppa)2 (7a). The course of the reaction was studied by infrared spectroscopy. After adding n-hexane to the THF solution of 7a the CO-bridged isomer Co2(μ-CO)2(CO)2(μ-dppa)2 (7b) precipitates. The structure of 7b was determined by X-ray crystallography. Co2+1(μ-CO) (CO)4((μ-PPh2-N-PPh2⊖)(μ-PPh2⊖) (9) was prepared from 4 · 12 C6H6, n-butyllithium and ClPPh2 in benzene. Suitable crystals for X-ray structural studies were obtained from a CH2Cl2/n-hexane mixture. The X-ray investigation showed that the Co-Co bond bridging anions [Ph2PXXXNXXXPPh2]⊖ and PPh2⊖ are in trans position to each other in 9· CH2Cl2. With the cobalt atoms they form five and three membered rings in the same plane. All compounds were characterized by 1H NMR, 13C{1H}NMR, 31P{1H} NMR and IR spectroscopy.

Transition metal complexes with sulfur ligands. XXXI. Six and seven coordinate CO, NO, PMe3 and phosphineiminato molybdenum complexes with [Mo{S4}] frameworks ({S4}=2, 3; 8, 9-dibenzo-1,4, 7,10-tetrathiadecane( 2 -))

Abstract In order to explain the high reactivity of [Mo- (NO)2(dttd)] towards phosphines the structures of [Mo(CO)2(PMe3)(dttd)] and [Mo(NO)(NPMePh2)- (dttd)] have been determined by X-ray structure analysis and compared with the structures of other [M(dttd)] complexes (dttd2-=2,3;8,9-dibenzo- 1,4,7,10-tetrathiadecane(2-)). In [Mo(CO)2(PMe3)- (dttd)] the seven coordinate Mo center is ligated by one P, two C and four sulfur atoms. [Mo(NO)(NP- MePh2)(dttd)] contains a six coordinate molybenum atom pseudooctahedrally surrounded by two N and four S atoms and possesses a bent [MNP] entity with an exceedingly small angle of 129.7(4)°; the pseudooctahedral [MS4] core in [M(dttd)] fragments is flexible enough to accommodate the coordination of two as well as three further coligands. The reaction between [Mo(NO)2(dttd)] and phosphines PR3 yielding the phosphineiminato complexes [Mo(NO)- (NPR3)(dttd)] is dominated by the nucleophilicity of PR3 as is shown by the fast reactions with PMe3 and PCy3 and the slow reactions with arylphosphines. [MNP] angles and νas(MNP) frequencies in [M- (phosphineiminato)] complexes correlate: small angles compare with low frequencies. 13C, 95Mo and 14N NMR data of the complexes are discussed and indicate the oxidation of Mo and the reduction of the nitrogen of one NO ligand, when [Mo(NO)2- (dttd)] is converted into [Mo(NO)(NPR3)(dttd)]; NPR3 ligands act as strong 4e- donors.

Phosphinsubstituierte chelatliganden: V. 1H- und 13C-NMR-spektroskopische untersuchungen an freien und koordinierten thiocarbamoylphosphinen, -phosphinoxiden und -phosphinsulfiden

Abstract In this paper, the first coherent report on 1 H and 13 C NMR spectra of heteroallylic thiocarbamoyl phosphine ligands and their manganese and rhenium carbonyl complexes is given. Temperature and field experiments verify the uniform molecular configurations, the secondary thioamides prefer the Z form and the N -silyl derivatives the E form. In the tetracarbonyl and tricarbonyl complexes, the anionic thioformimidate and the neutral thioformamide ligands occupy the sterically favourable Z form. In polar solvents (DMSO- d 6 , acetone- d 6 ) the tricarbonyl halide complexes show a distinct solvent interaction which causes temperature-variable 1 H NMR spectra. The 13 C NMR spectra show the expected dependence of the δ (CS) signal and the direct coupling constant 1 J (PC) from the bond degree, and anomalous vicinal PCNC coupling in all secondary thiocarbamoyl phosphines.

Chemistry of polyfunctional molecules—1231. Reactions of BiBr3, SbI3 and AsI3 with LiN(PPh2)2; X-ray structure of a cyclophosphazene salt containing arsenic(I)

Abstract BiBr3 or SbI3 react at 20°C with LiN(PPh2)2 (1) to give elementary Bi or Sb and the PP coupled phosphazene ligand Ph2PNPPh2PPh2NPPh2 (2). The reaction of AsI3 with 1 at room temperature formed yellow needles of the eight-membered heterocycle (3), whereas AsI3 interacted at 80°C with 1 in the molar ratio of 1:3 to give elementary arsenic and 2. Treatment of AsI3 and 1 at 20°C in a 1:2 stoichiometry yielded the seven-membered, cyclic arsenium(I) salt I·4THF (5·4THF), which was characterized by elemental analysis, conductivity, mass, IR and NMR spectroscopy and single-crystal X-ray structural analysis.

Übergangsmetallkomplexe mit Schwefelliganden: XXX. Struktur, stereoisomerie und reaktivität von eisen-, molybdän- und ruthenium-komplexen mit den fünfzähnigen thioether-thiolat-liganden dpttd2 = 2,3,11,12-dibenzo-1,4,7,10,13-pentathiatridecan(−2) und tbu4-dpttd2− = 14,16,18,20-tetra-t-butyl-2,3,11,12-dibenzo-1,4,7,10,13-pentathiatridecan(−2)

meso -[Fe(CO)(dpttd)] (dpttd 2− = 2,3,11,12-dibenzo-1,4,7,10,13-pentathiatridecane(−2)) can be isolated by fractional crystallization from a mixture of diastereomers of [Fe(CO)(dpttd)] and was characterized by X-ray structure analysis. The Fe center in meso -[Fe(CO)(dpttd)] is pseudo-octahedrally coordinated by one C and five S atoms and contains a mirror plane. The t-butyl derivative of dpttd-H 2 , the sterically demanding pentadentate thioether thiolate [ t bu 4 -dpttd] 2 − (= 14,16,18,20-tetra-t-butyl-2,3,11,12-dibenzo-1,4,7,10,13-pentathiatridecane(−2)) coordinates to Fe, Ru and Mo centers yielding mixtures of diastereomeric complexes. Thus FeCl 2 ·4H 2 O reacts with Na 2 [ t bu 4 -dpttd)] to give diastereomers of [Fe( t bu 4 -dpttd)], which coordinate CO to give three diastereomers of [Fe(CO)( t bu 4 -dpttd)], two of which could be separated. One of these was unambiguously identified by 1 H NMR spectroscopy to be meso -[Fe(CO)( t bu 4 -dpttd)]. meso -[Fe(CO)( t bu 4 -dpttd)] reacts with NO + retaining its configuration to yield meso -[Fe(NO)( t bu 4 -dpttd)] + ; a reaction mechanism via thionitrosylation of a thiolate S atom of the t bu 4 -dpttd 2− ligand is proposed. The reaction of [MoCl 4 (THF) 2 ] with t bu 4 -dpttd-H 2 and H 2 O yields a mixture of diastereomers of [MoO( t bu 4 -dpttd)], from which meso -[MoO( t bu 4 -dpttd)] is isolated by fractional crystallization. Reaction of RuCl 3 (NO)·χH 2 O and [RuCl 3 (PhSCH 3 ) 3 ] with t bu 4 -dpttd 2− yields mixtures of diastereomers of [Ru(NO)( t bu 4 -dpttd)] + and [Ru(Cl)(PhSCH 3 )( t bu 4 -dpttd)] 2 , respectively; the latter is reduced by Zn to give [Ru(PhSCH 3 )( t bu 4 -dpttd)].

Über die kristall- und molekülstruktur von 1,3-cyclohexadien-dicarbonyl-ethylisonitril-eisen(O) ☆

Zusammenfassung The X-ray structure of the monoclinic C 6 H 8 Fe(CO) 2 CNEt (space group P 2 1 / c ) has been determined. The iron atom is pentacoordinated by a square pyramide in which the isonitrile ligand CNEt, the CO group and two C atoms of the diene part of the C 6 H 8 -ring occupy the basal positions. The vibrational and p13 C NMR spectra indicate fluctional behaviour of this molecule in solution. The hydride abstraction from C 6 H 8 Fe(CO) 2 CNR (R = Me, Et) leads to the cation [C 6 H 7 Fe(CO) 2 CNR] + .

Chemie polyfunktioneller Molekäle, 130. Mitt. [1]: Rubidium- und Cäsium-bis(diphenylphosphanyl)amid – Synthesen, (18-Krone-6)-Komplexe, Spaltprodukte, Kristallstrukturen und Festkörper-NMR-Spektren

Summary. The metalation of bis(diphenylphosphanyl)amine, HN(PPh2)2 (5), with RbOtBu in the presence of N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDTA (3)) in toluene surprisingly affords the nearly PMDTA free RbN(PPh2)2 (6a). Recrystallization of 6a from tetrahydrofuran (THF) yields RbN(PPh2)2ċ0.5 THF (6b). Compounds 6a, b crystallize in thin needles; however, these are not suitable for X-ray structure analyses. The reactions of 5 with MOtBu (M=Rb, Cs) in the presence of 18-crown-6 in toluene yield the monomeric, pale yellow rubidium and caesium complexes [Rb(18-crown-6)(N(PPh2)2)] (7) and [Cs(18-crown-6)(N(PPh2)2)] (8), respectively. Allowing to stand a solution of 8 in THF for three months at 20°C results in a cleavage product of 8. This is identified as the dimeric yellow complex [(Cs(18-crown-6))2(μ-N*P(H)Ph2)2]ċTHF (9). The source of the hydrogen atom in the bridging phosphorane iminate anion [N*P(H)Ph2]− is uncertain. Compounds 7–9 are structurally characterized by X-ray analyses. These reveal that [N(PPh2)2]− acts as P-ligating chelate in 7, whereas it coordinates the Cs+ as N-donor as well as η2 C-donor with one phenyl group in 8. No phosphorus coordination is observed in 8. The two caesium cations in 9 are two-fold N-bridged by [N*P(H)Ph2]−. The coordination sphere of each caesium atom is completed by a 18-crown-6 ligand. The solid state 13C NMR spectrum of 8 reveals dynamic phenomena (rotation of the 18-crown-6 ligand). In the solid state 31P spectrum of 8, 31P, 31P–J-coupling is observed between the chemically non-equivalent phosphorus sites (J=390 Hz).