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The encapsulation of a nanometer-sized octahedral anionic rhenium cluster complex with six terminal hydroxo ligands [Re6S8(OH)6]4− in maltose-decorated poly(propylene amine) dendrimers (POPAM, generation 4 and 5) has been investigated. Ultrafiltration experiments showed that maximal loading capacity of the dendrimers with the cluster complex is achieved after about ten hours in aqueous solution. To study the inclusion phenomena, three different methods have been applied: UV/Vis, time-resolved laser-induced fluorescence spectroscopy (TRLFS), and laser-induced liquid bead ion desorption mass spectrometry (LILBID-MS). From the results obtained, it could be concluded that: a) the hydrolytic stability of the rhenium cluster complex is significantly enhanced in the presence of dendritic hosts; b) the cluster anions are preferentially bound inside the dendrimers; c) the number of cluster complexes encapsulated in the dendrimers increases with rising dendrimer generation. On average, four to five cluster anions can preferentially be captured in the interior of sugar-coated dendritic carriers. An asymptotic progression of the release of cluster complexes from the loaded dendrimers was observed under physiologically relevant conditions (isotonic sodium chloride solution: approximately 93 % within 4 days for loaded POPAM-G4-maltose; approximately 86 % within 4 days for loaded POPAM-G5-maltose). These encapsulation and release properties of maltose-decorated nanocarriers imply the possibility for the development of the next generation of dendritic nanocarriers with specific targeting of destined tissue for therapeutic treatments.Die Einlagerung eines nanometergroßen, oktaedrischen Rheniumcluster-Anions mit sechs terminalen Hydroxo-Liganden, [Re6S8(OH)6]4−, in ‒ mit Maltose ummandelten ‒ Polypropylenamin-Dendrimeren (POPAM) der 4. und 5. Generation wurde untersucht. Ultrafiltrationsexperimente zeigten, dass die maximale Beladungskapazität der Dendrimere bezüglich des Cluster-Komplexes in wässriger Lösung nach ca. 10 Stunden erreicht wurde. Zur Untersuchung des Einschlussphänomens wurden folgende Methoden angewandt: UV/Vis-Spektroskopie, time-resolved laser-induced fluorescence spectroscopy (TRLFS), laser-induced liquid bead ion desorption mass spectrometry (LILBID-MS). Die Ergebnisse lassen folgende Schlussfolgerungen zu: a) Die hydrolytische Stabilität des Rheniumclusters wird in Gegenwart des Dendrimers deutlich erhöht. b) Die Cluster-Anionen werden bevorzugt innerhalb des Dendrimers gebunden, c) Die Anzahl der eingelagerten Cluster steigt mit zunehmender Dendrimer-Generation. Es werden durchschnittlich 4 bis 5 Cluster-Anionen im Inneren des dendritischen Trägers eingelagert. Unter physiologischen Bedingungen beobachtet man einen asymptotischen Verlauf der Abgabe des Clusters vom beladenen Dendrimer (isotonische NaCl-Lösung: ~93 % innerhalb von 4 Tagen für POPAM-G4-Maltose; ~86 % innerhalb von 4 Tage für POPAM-G5-Maltose). Ausgehend vom beobachteten Einlagerungs- und Abgabeverhalten der mit Maltose ummantelten Nanocarrier bietet sich die Möglichkeit, eine neue Generation targetspezifischer dentritischer Nanocarrier für therapeutische Behandlungen zu entwickeln.Catch and release! The encapsulation and release of nanometer-sized anionic rhenium cluster complexes in biocompatible maltose-decorated dendrimers have been studied in detail through the application of different physico-chemical methods. The determined properties suggest the possibility for the development of the next generation of dendritic nanocarriers with specific targeting of destined tissue for therapeutic treatments.

Substituted amines are a popular choice as molecules to selectively react with and separate CO2 from gas mixtures. Such separations are of particular interest, for example, for CO2 separations for carbon capture and sequestration. It is desirable to tune amine-CO2 reaction energies to suit a particular separation. Herein, we use DFT-B3LYP simulations to characterize the products and energetics of reactions of CO2 with a range of substituted amines, considering both 1:1 and 2:1 amine/CO2 reaction stoichiometries. The results show that by adjusting both the nature and the placement of functional groups, it is possible to tune reaction energies over a substantial range. Decomposition of the 2:1 reaction into separate carbamate and ammonium formation steps shows that the Brønsted basicity and Lewis basicity towards CO2 are largely uncorrelated and provide an independent means of tuning the overall reaction energies.

Lithium ion batteries (LIBs), which have the highest energy density among all currently available rechargeable batteries, have recently been considered for use in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and pure electric vehicles (PEV). A major challenge in this effort is to increase the energy density of LIBs to satisfy the industrial needs of HEVs, PHEVs, and PEVs. Recently, new types of lithium-air and lithium-copper batteries that employ hybrid electrolytes have attracted significant attention; these batteries are expected to succeed lithium ion batteries as next-generation power sources. Herein, we review the concept of hybrid electrolytes, as well as their advantages and disadvantages. In addition, we examine new battery types that use hybrid electrolytes.

Aqueous ethylenediamine (EDA) has been investigated as a solvent for CO2 capture from flue gas. EDA can be used at 12 M (mol kg-1 H2O) with an acceptable viscosity of 16 cP (1 cP=10-3 Pa s) with 0.48 mol CO2 per equivalent of EDA. Similar to monoethanolamine (MEA), EDA can be used up to 120 °C in a stripper without significant thermal degradation. Inhibitor A will effectively eliminate oxidative degradation. Above 120 °C, loaded EDA degrades with the production of its cyclic urea and other related compounds. Unlike piperazine, when exposed to oxidative degradation, EDA does not result in excessive foaming. Over much of the loading range, the CO2 absorption rate with 12 M EDA is comparable to 7 M MEA. However, at typical rich loading, 12 M EDA absorbs CO2 2 times slower than 7 M MEA. The capacity of 12 M EDA is 0.72 mol CO2/(kg H2O+EDA) (for PCO2=0.5 to 5 kPa at 40 °C), which is about double that of MEA. The apparent heat of CO2 desorption in EDA solution is 84 kJ mol-1 CO2; greater than most other amine systems.

The hydrolysis of [beta][bond]O[bond]4 bonds in two lignin model compounds was studied in an acidic ionic liquid, 1-H-3-methylimidazolium chloride. The [beta][bond]O[bond]4 bonds of both guaiacylglycerol-[beta]-guaiacyl ether and veratrylglycerol-[beta]-guaiacyl ether underwent catalytic hydrolysis to produce guaiacol as the primary product with more than 70 % yield at 150 °C. Up to 32 wt % substrate concentration could be treated in the system without a decrease in guaiacol production. The ionic liquid could be reused without loss of activity in guaiacol production from both guaiacylglycerol-[beta]-guaiacyl ether and veratrylglycerol-[beta]-guaiacyl ether. A possible mechanism accounting for the guaiacol production is presented.

Handy polymers: The lyotropic liquid crystalline phases of helically chiral polyguanidines are proposed as new chiral orienting media for organic compounds. The enantiomers of isopinocampheol (IPC) are oriented in an enantiodifferentiating manner (see figure). The difference in orientation induced for the two enantiomers seems to be larger than the one observed in poly-[gamma]-benzyl-L-glutamate (PBLG).

Enantiopure quaternary prolines have been prepared by stereoselective rearrangement of N-(arylsulfonyl)proline tert-butyl esters under basic conditions (see scheme), without any external source of stereochemical information. The sulfonamide aromatic ring must contain an electron-withdrawing group (EWG), which stabilizes an intermediate Meisenheimer complex. The overall process provides easy entry to a series of optically pure [alpha]-aromatic prolines.

En route to phosphinines: An efficient route to convert 1-phosphanorbornadienes into phosphinines is described (see scheme). This opens up the possibiltiy to use the broad and versatile phosphole chemistry as a starting point for an equally broad variety of phosphinines.

Various human diseases, including different types of cancer, are associated with a disturbed intracellular redox balance and oxidative stress (OS). The past decade has witnessed the emergence of redox-modulating compounds able to utilize such pre-existing disturbances in the redox state of sick cells for therapeutic advantage. Selenium- and tellurium-based agents turn the oxidizing redox environment present in certain cancer cells into a lethal cocktail of reactive species that push these cells over a critical redox threshold and ultimately kill them through apoptosis. This kind of toxicity is highly selective: normal, healthy cells remain largely unaffected, since changes to their naturally low levels of oxidizing species produce little effect. To further improve selectivity, multifunctional sensor/effector agents are now required that recognize the biochemical signature of OS in target cells. The synthesis of such compounds provides interesting challenges for chemistry in the future.

para-Phenylene-bridged spirobi(triarylamine) dimer 2, in which [pi] conjugation through four redox-active triarylamine subunits is partially segregated by the unique perpendicular conformation, was prepared and characterized by structural, electrochemical, and spectroscopic methods. Quantum chemical calculations (DFT and CASSCF) predicted that the frontier molecular orbitals of 2 are virtually fourfold degenerate, so that the oxidized states of 2 can give intriguing electronic and magnetic properties. In fact, the continuous-wave ESR spectroscopy of radical cation 2.+ showed that the unpaired electron was trapped in the inner two redox-active dianisylamine subunits, and moreover was fully delocalized over them. Magnetic susceptibility measurements and pulsed ESR spectroscopy of the isolated salts of 2, which can be prepared by treatment with SbCl5, revealed that the generated tetracation 24+ decomposed mainly into a mixture of 1) a decomposed tetra(radical cation) consisting of a tri(radical cation) moiety and a trianisylamine radical cation moiety ([ap]75 %) and 2) a diamagnetic quinoid dication in a tetraanisyl-p-phenylendiamine moiety and two trianisylamine radical cation moieties ([ap]25 %). Furthermore, the spin-quartet state of the tri(radical cation) moiety in the decomposed tetra(radical cation) was found to be in the ground state lying 30 cal mol-1 below the competing spin-doublet state.