Lyotropic Chiral Nematic Liquid Crystalline Aliphatic Conjugated Polymers Based on Disubstituted Polyacetylene Derivatives That Exhibit High Dissymmetry Factors in Circularly Polarized Luminescence
摘要:
We synthesized disubstituted liquid crystalline polyacetylene (diLCPA) derivatives bearing 4-nonyloxy phenyl groups with lyotropic and thermotropic LC behavior. The poly(diphenylacetylene) main chain structure of the diLCPAs and the chirality induced with either chiral moieties or chiral dopants allow the formation of a highly ordered lyotropic N*-LC phase. Circular dichroism (CD) spectra of the diLCPAs imply that one-handed intrachain helical structures are formed in solution, while interchain helical pi-stacking between the polymer main chains are formed in cast film and in the N*-LC state. Absorption dissymmetry factors (g(abs)) in the N*-LC state show values on the order of 10(-1). The N*-LC state facilitates the formation of helically pi-stacked structures with a high degree of helical ordering of the diLCPA and is indispensable for the generation of circularly polarized luminescence (CPL) with high emission dissymmetry factors (g(em)) on the order of 10(-1). To the best of our knowledge, this is the highest reported value of CPL achieved for aliphatic, conjugated polymers. As an alternative to the thermotropic N*-LC phase, we have found that the lyotropic N*-LC phase of diLCPA could be promising materials possessing CPL functionality for use in next-generation pi-conjugated organic optoelectronic devices, displays, and sensors.
Key residues were identified through combinatorial mutation of conserved residues with notably improved productivity in asymmetric reduction of α-chloroacetophenone.
gave ethyl (R)‐8‐chloro‐6‐hydroxyoctanoate, a key precursor for the synthesis of (R)‐α‐lipoic acid, in high space‐time yield (530 g L−1 d−1) and with excellent enantiomeric excess (>99%). This bioprocess was shown to be viable on a 10‐L scale. This method provides a greener and more cost‐effective method for the industrial production of (R)‐α‐lipoic acid.
从副产念珠菌中分离出了一种新型的还原酶(Cp AR2),该酶对ε-酮酯(8-氯-6-氧代辛酸乙酯)具有异常高的活性。共表达Cp AR2和葡萄糖脱氢酶基因的大肠杆菌细胞对8-氯-6-氧代辛酸乙酯的不对称还原产生了(R)-8-氯-6-羟基辛酸乙酯,这是合成(R)-α-的关键前体硫辛酸,时空产率高(530 g L -1 d -1),对映体过量极佳(> 99%)。该生物过程显示出在10 L规模上可行。这种方法为工业生产(R)-α-硫辛酸
Asymmetric reduction of ketones by Geotrichum candidum in the presence of AmberliteTM XAD, a solid organic solvent
作者:Kaoru Nakamura、Mikio Fujii、Yoshiteru Ida
DOI:10.1039/b005204n
日期:——
A hydrophobic polymer, Amberlite™ XAD, was used as material to control the stereochemical course of microbial reductions. In the presence of XAD, simple aliphatic and aromatic ketones were reduced to the corresponding (S)-alcohols in excellent enantiomeric excess (ee) while low enantioselectivities were observed in the absence of the polymer.
the corresponding ketone using 2-propanol as hydrogen donor or by enantioselectiveoxidationthrough kinetic resolution of the rac-alcohol using acetone as hydrogen acceptor employing whole lyophilized cells of Rhodococcus ruber DSM 44541. The microbialoxidation/reduction system exhibits not only excellent stereo- and enantioselectivity but also a broad substrate spectrum. Due to the exceptional tolerance
Asymmetric reduction of aliphatic ketones and acyl silanes using chiral anti-pentane-2,4-diol and a catalytic amount of 2,4-dinitrobenzenesulfonic acid
Aliphatic ketones were reduced to the corresponding secondaryalcohols by using anti-1,3-diol and a catalytic amount of 2,4-dinitrobenzenesulfonic acid (DNBSA) in benzene at reflux. Addition of 1-octanethiol in that media improved the efficiency of the reduction. Asymmetric reduction of aliphatic ketones was performed by using chiral anti-pentane-2,4-diol, and highly asymmetric induction (up to >99%