Introduction of permanently charged groups into PEGA resins leads to improved biotransformations on solid support

The application of biotransformations in solid phase synthesis is an attractive alternative to chemical methodologies. An important issue that needs to be addressed in this context is accessibility of functional groups within a porous polymer to the biocatalyst. This paper shows that such accessibility can be improved for penicillin G amidase by introducing permanent charges into the polymer. The effect appears to be due to better swelling of the polymer in buffer and to electrostatic interactions between polymer and enzyme.     

(o-Hydroxyphenyl)methylphosphonic acids: Synthesis and potentiometric determinations of their pKa Values

(o-Hydroxyphenyl)methylphosphonic acids are readily obtained from o-(bromomethyl)- or o-(hydroxymethyl)phenols and trialkyl phosphites. Subsequent hydrolysis leads to the corresponding phosphonic acids. For a series of such compounds, the pK_a values have been determined by potentiometry. Their dependence on additional substituents in the aromatic ring is discussed in terms of electronic and steric effects.     

Electrochemical deposition of copper phosphides

Summary Methods for preparation of copper phosphides at ambient temperatures by electrodeposition are presented. From P₄/PCl₃/Acetonitrile/TBA-BF₄/Cu⁺ (solvated) Cu₃P and Cu₃P₂ can be obtained at different deposition potentials.

---

Elektrochemische Abscheidung von Kupferphosphiden

Zusammenfassung Es werden Verfahren zur Herstellung von Kupferphosphiden bei ambienten Temperaturen beschrieben. Aus der Anordnung P₄/PCl₃/Acetonitril/TBA-BF₄/Cu⁺ (solvatisiert) können Cu₃P und Cu₃P₂ bei verschiedenen Abscheidungspotentialen erhalten werden.

     

One-step stereospecific synthesis of α,β-dehydroamino acids and dehydropeptides.

Dehydroamino acids and dehydropeptides were prepared by a one-pot reaction employing diethyl chloroposphate in the presence of sodium hydride. The reaction is stereospecific and proceeds without racemization.     

Induction of a nematic columnar phase in a discotic hexagonal ordered phase forming system

The induction of a nematic columnar phase in a discotic hexagonal ordered phase forming system is achieved by mixing hexakispentyloxytriphenylene 1 with a long chain derivative of trinitrofluorenone 3. The difference in chain length has a strong influence on the packing behaviour due to steric effects. The long hydrocarbon chains of the acceptor introduce a strong asymmetry into the electron donor acceptor complex. It could be shown by differential scanning calorimetry, optical microscopy and X-ray measurements that a nematic columnar phase is formed. In this mesophase the triphenylenes form columns but no hexagonal or orthorhombic lattice is built up. Each column behaves like a rod-like nematic mesogen. To prove that the long hexadecane alkyl chains of the acceptor are responsible for this induction, the acceptor 3 was mixed with the non-liquid-crystalline triphenylene derivative 2 containing six hexadecyloxy side groups. The long alkyl chains of the acceptor dissolve perfectly in the side chain region of the discs. No asymmetry is induced and the columns formed can be arranged on a hexagonal lattice resulting in a D_ho phase.