order in the mesophase is observed such that S, behavior in 2 leads to S, behavior in 3, and S, behavior in 2 leads to N behavior in 3. Thus, the only previously reportedc5' acac mononuclear complex containing an ortho-palladated phenyl-substituted pyrimidine ligand was monotropic (S,), whereas its parent binuclear complex displayed an enantiotropic (S,) mesophase.Moving from I-shaped "one-dimensional'' molecules 1 to highly symmetrical H-shaped "two-demensional" structures 2 greatly increases the range of mesogenic behavior, but at the expense of high transition temperatures and a scarcity of nematic phases. The new P-shaped "two-dimensional" symmetry-perturbed mononuclear species 3 are an excellent compromise, since they show mesophase ranges broader than the free ligands, melting temperatures even lower than the free ligands, and a less complex mesogenic behavior. The complete family of I-, H-, and P-shaped mesogens, which can be extended to many related complexes, offers a very promising horizon in the tailoring of mesogenic materials.
D‐Aminosäuren können durch Spaltung der korrespondierenden Hydantoine mit Agrobacterium‐radiobacter‐Biomasse in sehr guten Ausbeuten bei hoher Enantioselektivität chemoenzymatisch hergestellt werden. Hierbei werden auch Hydantoine mit hochfunktionalisierten Seitenketten akzeptiert. Das Synthesekonzept wird am Beispiel von D‐Citrullin 1 erläutert.
Liquid membrane reactors are well known for metal extraction. This technology may also be applied to the immobilization of enzymes in enzyme emulsions. The use of liquid membrane reactors for enzymatic bioconversions has several advantages in comparison to solid membrane reactors and conventional immobilization techniques: there is no membrane fouling, enzyme emulsions can be used in cell-free fermentation broths, in complex mixtures the membrane can preselect the desired substrate for enzymatic reaction, and substances that might decrease the enzyme activity can be excluded. The separation effect is not based on differences in molecular weight but on the chemical behavior of the substances to be separated. Thus, it is not necessary to use cofactors with increased molecular weight for enzymatic reactions, since the coenzyme cannot permeate the liquid membrane. The three systems presented here indicate that enzyme systems can be easily immobilized in liquid surfactant membrane emulsions and there is a broad field of application for enzyme emulsions.
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