Intermolecular exchange-induction energies without overlap expansion

An approach to evaluate the second-order exchange-induction energies of symmetry-adapted intermolecular perturbation theory (SAPT) for single-determinant ground-state monomer wavefunctions has been derived. This approach is correct to all orders of the intermonomer overlap, that is, it takes multiple electron exchange between the monomers into account. The resulting formulae can be written in a compact way and implemented efficiently. Here, the method is employed to investigate the performance of the S ²- or single-exchange approximation at the Hartree-Fock-SAPT level. The list of test systems comprises the prototypical van der Waals- and hydrogen-bridge complexes Ne₂, Ar–HF, and (H₂O)₂, but also the systems HeCl^?, NeNa⁺ and Li⁺F^? involving closed-shell ions. It was found that the errors introduced by the S ²-approximation are more pronounced for the second-order exchange-induction energy than for the first-order exchange energy. While these errors tend to be negligible throughout the well region of complexes such as the neon dimer, they start to be significant in the repulsive part of the well regions of systems such as the water dimer, and in particular for the ionic lithium fluoride molecule. The consequences of these findings for the Hartree-Fock level estimate of higher-order induction plus exchange-induction energies, which is frequently employed in SAPT are also discussed.     

Chinazolinone, 2. Mitt.: Synthese und einige Reaktionen von 2-Azidomethyl-3-aryl-4-chinazolinonen

Starting with the chloromethyl compounds7 the new 2-azidomethyl-3-aryl-4-quinazolinones8 a-h were prepared, some of which have been reduced so far to the corresponding amines9 a, b, e, g by H₂S in good yield. As a first example for the capability of the azides8 to undergo 1,3-dipolar cycloaddition the 2-quinazolinmethyl-1,2,3-triazol-4,5-dicarboxylicacid dimethylesters11 b, e, g were prepared by reacting8 with dimethylacetylenedicarboxylate (10).

1. Mitt.:Domanig R., Arch. Pharm., im Druck.     

Starke verdrillungen trotz schwacher sterischer hinderung

Considerable twisting of weakly hindered hydrazonyl radicals is explained on the basis of a low barrier to rotation due to compensation of the loss of π-π-delocalization on twisting by gain of π-σ-delocalization.     

Controlled synthesis of cell-laden microgels by radical-free gelation in droplet microfluidics

Micrometer-sized hydrogel particles that contain living cells can be fabricated with exquisite control through the use of droplet-based microfluidics and bioinert polymers such as polyethyleneglycol (PEG) and hyperbranched polyglycerol (hPG). However, in existing techniques, the microgel gelation is often achieved through harmful reactions with free radicals. This is detrimental for the viability of the encapsulated cells. To overcome this limitation, we present a technique that combines droplet microfluidic templating with bio-orthogonal thiol-ene click reactions to fabricate monodisperse, cell-laden microgel particles. The gelation of these microgels is achieved via the nucleophilic Michael addition of dithiolated PEG macro-cross-linkers to acrylated hPG building blocks and does not require any initiator. We systematically vary the microgel properties through the use of PEG linkers with different molecular weights along with different concentrations of macromonomers to investigate the influence of these parameters on the viability and proliferation of encapsulated yeast cells. We also demonstrate the encapsulation of mammalian cells including fibroblasts and lymphoblasts.     

Deoxygenation of coordinated oxaphosphiranes: a new route to pc double-bond systems

Phosphaalkenes: Deoxygenation of oxaphosphirane complexes 1 and 2 by using Ti(III) complexes gave mixtures of E/Z phosphaalkene complexes 3?a,?b and 4?a,?b. Theoretical calculations of deoxygenation pathways of 1 revealed that the final products are obtained via intermediate 5 providing the final products by reaction with a second [TiCpCl(2) ] unit and C?O bond cleavage.     

ÜBER EINIGE REAKTIONEN DER DIALKYLBENZYLPHOSPHINIMIDE

Abstract

Dialkylbenzylphosphine imides C₆H₅CH₂–PRR′[dbnd]N″ (R, R′ = CH₃, C₂H₅; R″ = H, CH₃, Si(CH₃)₃ react with aliphatic and aromatic aldehydes in benzene solution on heating to 80°C directly and in high yields according to a Horner-Wittig-reaction with formation of an olefine whereas ketones like benzophenone and acetophenone only perform an O/NR″ exchange (R″ = H).

Dialkylbenzylphosphinimide C₆H₅CH₂–PRR′[dbnd]N″ mit R, R′ = CH₃, C₂H₅ und R″ = H, CH₃, Si(CH₃)₃ reagieren mit aliphatischen und aromatischen Aldehyden in benzolischer Lösung beim Erwärmen auf 80°C direkt und mit hohen Ausbeuten im Sinne einer Horner-Wittig-Reaktion unter Olefinbildung, während sich mit Ketonen wie Benzophenon oder Acetophenon nur ein O/NR″-Austausch (R″ = H) vollzieht.