2-Methyl-2,4-pentanediol (MPD) boosts as detergent-substitute the performance of ß-barrel hybrid catalyst for phenylacetylene polymerization.

Covering hydrophobic regions with stabilization agents to solubilize purified transmembrane proteins is crucial for their application in aqueous media. The small molecule 2-methyl-2,4-pentanediol (MPD) was used to stabilize the transmembrane protein Ferric hydroxamate uptake protein component A (FhuA) utilized as host for the construction of a rhodium-based biohybrid catalyst. Unlike commonly used detergents such as sodium dodecyl sulfate or polyethylene polyethyleneglycol, MPD does not form micelles in solution. Molecular dynamics simulations revealed the effect and position of stabilizing MPD molecules. The advantage of the amphiphilic MPD over micelle-forming detergents is demonstrated in the polymerization of phenylacetylene, showing a ten-fold increase in yield and increased molecular weights.

Group 2 metal (Mg, Ca, Sr) silylamides supported by a cyclen-derived macrocyclic polyamine.

Heteroleptic bis(silyl)amides of magnesium and calcium [(L)M{N(SiMe3)2}] [M = Mg, Ca; LH = 1,4,7-trimethyl-1,4,7,10-tetraazacyclododecane; (Me3TACD)H] were previously synthesized from LH and [M{N(SiMe3)2}2]. Strontium bis(silyl)amides [Sr{N(SiMe3)2}2(thf)2] and [Sr{N(SiHMe2)2}2(thf)2/3] reacted with LH to give different types of products, depending on the presence of the ß-SiH function. While the former underwent protonolysis to give the amido-bridged dimer [(L)Sr{N(SiMe3)2}]2 (1), the latter gave the adduct [(LH)Sr{N(SiHMe2)2}2] (2) as a stable solid. 2 slowly underwent an intramolecular Si-H/H-N dehydrocoupling in solution to give [{(L)SiMe2N(SiHMe2)}Sr{N(SiHMe2)2}] (3) by liberating H2. The results of transamination of 1 with HN(SiHMe2)2 depended on the relative stoichiometric ratio. A 1 : 1 mixture in n-pentane gave [{(L)SiMe2N(SiHMe2)}Sr{N(SiMe3)2}] (4) and H2, while excess HN(SiHMe2)2 gave the adduct 2 under similar conditions. Compounds 2 and 3 exhibit Sr↼H-Si interactions according to X-ray crystallography, NMR, and IR spectroscopy. Lighter congeners of elusive [(L)Sr{N(SiHMe2)2}] were isolable for Mg (5) and Ca (6).

Supported Molybdenum Catalysts for the Deoxydehydration of 1,4-Anhydroerythritol into 2,5-Dihydrofuran.

Efficient deoxygenation strategies are crucial for the valorization of renewable feedstocks. Deoxydehydration (DODH) enables the direct transformation of two adjacent hydroxyl groups into a double bond. Supported molybdenum-based catalysts were utilized for the first time in DODH. MoOx /TiO2 showed superior catalytic activity compared to common molybdenum salts. The catalyst efficiently converted 1,4-anhydroerythritol into 2,5-dihydrofuran in the presence of 3-octanol as reducing agent, showing high reproducibility and stability.

Artificial Diels-Alderase based on the transmembrane protein FhuA.

Copper(I) and copper(II) complexes were covalently linked to an engineered variant of the transmembrane protein Ferric hydroxamate uptake protein component A (FhuA ΔCVF(tev)). Copper(I) was incorporated using an N-heterocyclic carbene (NHC) ligand equipped with a maleimide group on the side arm at the imidazole nitrogen. Copper(II) was attached by coordination to a terpyridyl ligand. The spacer length was varied in the back of the ligand framework. These biohybrid catalysts were shown to be active in the Diels-Alder reaction of a chalcone derivative with cyclopentadiene to preferentially give the endo product.

Discrete magnesium hydride aggregates: a cationic Mg13H18 cluster stabilized by NNNN-type macrocycles.

Large magnesium hydride aggregates [Mg13 (Me3 TACD)6 (µ2 -H12 )(µ3 -H6 )][A]2 ((Me3 TACD)H=1,4,7-trimethyl-1,4,7,10-tetraazacyclododecane; A=AlEt4 , AlnBu4 , B{3,5-(CF3 )2 C6 H3 }4 ) were synthesized stepwise from alkyl complexes [Mg2 (Me3 TACD)R3 ] (R=Et, nBu) and phenylsilane in the presence of additional Mg(II) ions. The central magnesium atom is octahedrally coordinated by six hydrides as in solid α-MgH2 of the rutile type. Further coordination to six magnesium atoms leads to a substructure of seven edge-sharing octahedra as found in the hexagonal layer of brucite (Mg(OH)2 ). Upon protonolysis in the presence of 1,2-dimethoxyethane (DME), this cluster was degraded into a tetranuclear dication [Mg2 (Me3 TACD)(µ-H)2 (DME)]2 [A]2 .

Layer-by-layer assembly of partially sulfonated isotactic polystyrene with poly(vinylamine).

The stereoregular synthetic polymer isotactic polystyrene bearing partially sulfonated groups (SiPS) was used as a layer-by-layer assembled thin film for the first time. When a low molecular weight compound was employed as the pair for the alternative layer-by-layer (LbL) assembly, the frequency shift was very small using quartz crystal microbalance (QCM) analysis, whereas poly(vinylamine) (PVAm) formed an effective pair for the construction of LbL films with SiPS. When it was neutralized, SiPS was not assembled, probably due to the loss of effective polymer-polymer interactions. The ionic strength conditions revealed a slight difference of the assembly behavior on the isotactic polymer as compared to the atactic one. The assembled LbL film showed the same peaks over the range from 1141 to 1227 cm(-1) and 700 cm(-1) in the FT-IR/ATR spectra as the bulk complex of SiPS/PVAm, and the thickness on one side was calculated at 76 nm by QCM analysis. The surface roughness of the film was also observed by AFM.

Discrimination of cryptochirality in chiral isotactic polystyrene by asymmetric autocatalysis.

Chiral isotactic polystyrenes induce the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde, affording the enantiomerically enriched pyrimidyl alkanol with the corresponding absolute configuration to that of cryptochiral polystyrenes in conjunction with asymmetric autocatalysis.

Enantiomerically pure titanium complexes containing an [OSSO]-type bis(phenolate) ligand: synthesis, structure, and formation of optically active oligostyrenes.

Chiral 1,2-trans-dithiocyclohexanediyl-bridged bis(phenols) of the type [2,2'-{HOC(6)H(2)-6-R(1)-4-R(2)}(2)S(2)C(6)H(10)] ([OSSO]H(2), R(1)=tBu, iPr, H; R(2)=tBu, iPr, Me) could be conveniently and selectively synthesized in three steps, starting from cyclohexene oxide and arene thiolate. The racemic bis(phenols) could be resolved using an enantiopure (S)-camphorsulfonic ester auxiliary or by (chiral) HPLC. Complexation of the racemic bis(phenols) to TiX(4) (X=Cl, OiPr) proceeds in a diastereoselective fashion to give only the Lambda,R,R and Delta,S,S enantiomers. Racemic [Ti{(OC(6)H(2)-6-tBu-4-Me)(2)S(2)C(6)H(10)}Cl(2)] reacts with benzyl magnesium bromide to afford the crystallographically characterized dibenzyl complex. The benzyl cation formed using B(C(6)F(5))(3) in C(6)D(5)Br slowly decomposes at temperatures above +10 degrees C. When treated with methylaluminoxane, the dichloro complexes [Ti{OSSO}Cl(2)] polymerize styrene with activities up to 146 kg (mol catalyst)(-1) [styrene (mol L(-1))](-1) h(-1); diisopropoxy complexes [Ti{OSSO}(OiPr)(2)] show mere trace activity. With 1-hexene as a chain-transfer agent, activated enantiopure titanium complexes give low-molecular-weight homochiral isotactic oligostyrenes, terminated by one to five 1-hexene units with M(n) values as low as 750 g mol(-1) for R=tBu and 1290 g mol(-1) for R=Me. Below M(n) approximately 5000 these oligostyrenes show optical activity.