Stereoselective reduction of diarylmethanones via a ketoreductase@metal-organic framework.

Mainly owing to their well-defined pore structures and high surface areas, metal-organic frameworks (MOFs) have recently become a versatile class of materials for enzyme immobilization. Nevertheless, most previous studies were focused on model enzymes such as cytochrome c, catalase, and glucose oxidase, with the application of MOF-derived biocomposites for (asymmetric) organic synthesis being rare. In the present work, the immobilization of the ketoreductase KmCR2 onto the zeolitic imidazolate framework (ZIF), a prominent type of MOF, was pursued using the controlled co-precipitation strategy, with a low 2-methylimidazole (2-mIM)/Zn molar ratio of 8 : 1 being employed. Such fabricated biocomposites denoted as KmCR2@ZIF were found to exist mainly in an amorphous phase, as suggested by the scanning electron microscopy (SEM) and powder X-ray diffraction (PXRD) data. Improved thermal and storage stabilities were observed for KmCR2@ZIF compared with the free enzyme. Stereoselective reduction of nine diarylmethanones 1 catalyzed by KmCR2@ZIF was performed, and the corresponding enantioenriched diarylmethanols 2 were afforded in 40-92% conversions with good to excellent optical purities (up to >99% ee). Critically, the current work demonstrated that the unique characteristic of KmCR2, namely the substituent position-controlled stereospecificity (meta versus para or ortho), was not altered upon the enzyme immobilization onto the ZIF.

Recent Advances in Thermally Activated Delayed Fluorescent Polymer-Molecular Designing Strategies.

Thermally activated delayed fluorescent (TADF) materials, as the third generation of organic electroluminescent materials, have many advantages over other organic light-emitting diodes (OLEDs) materials, such as 100% internal quantum efficiency, no doping of heavy metals, and avoiding the shortages of ordinary fluorescent materials and phosphorescent materials. So it is considered to be the most competitive organic light-emitting materials, and has great application prospects in the field of OLEDs. So far, small-molecule TADF materials have achieved high quantum yield and full-color range of red, green, and blue. However, TADF polymers suitable for low-cost and easily scalable solution processing are less developed, which are confined by the preparation methods and polymers designing, and there are still challenges of increasing quantum efficiency and strengthening device performance. This review mainly summarizes different synthesis strategies of TADF polymers and the latest development in the field. Special attention is focused on illustrating the designing and structure-property relationship of TADF polymers, and finally, an outlook is given for the design and application prospect of TADF polymers in the future.

[Mechanism of lysosome-mediated eradication activity of macrophages on specific anti-Helicobacter pylori of patchouli alcohol].

The aim of this paper is to investigate the effect of patchouli alcohol in enhancing Helicobater pylori's action in eradicating macrophages and its mechanism. H. pylori was co-cultured with macrophages at a ratio of MOI=100 in different concentrations of patchouli alcohol. The effect of patchouli alcohol in eradicating macrophages was detected by agar dilution method. The effect of patchouli alcohol on NO and myeloperoxidase (MPO) levels in macrophages were measured by H. pylori by biochemical methods. Patchouli alcohol effect on H. pylori-induced pro-inflammatory gene expression and protein secretion in macrophages were detected by RT-qPCR and ELISA method. The eradication of H. pylori has significantly enhanced, and the destabilization of lysosomes has been reversed. Meanwhile, patchouli alcohol has an effect in inhibiting pro-inflammation and oxidation. The mechanism of patchouli alcohol in eradicating H. pylori and resisting oxidative stress may be associated to the blocking of bacteria escape lysosome combination procedures.

Crystal Structures and Vapor-Induced Crystalline Transformation of 7-Ethyl-10-Hydroxycamptothecin Pseudopolymorphs.

Solvent-induced 3 frameworks (the monohydrate, methanol solvate, and dimethyl formamide [DMF] solvate) of an anticancer drug, 7-ethyl-10-hydroxycamptothecin (SN38), were constructed. The crystal structures of the 3 pseudopolymorphs were characterized by single-crystal X-ray diffraction technique for the first time. Crystal structure analysis of all these polymorphs revealed that the monohydrate showed 3D frameworks linked by hydrogen bonds. In the methanol solvate, the 1D molecular chains were linked by the methanol molecules through intermolecular hydrogen bonds to form a 2D sheet. The DMF solvate exhibits the 1D hydrogen bonding-linked chains along b-axis. Vapor-induced transformation has been investigated for the monohydrate, the methanol solvate, and the DMF solvate. The conversion relationships among the 3 solid frameworks are illustrated. Insights regarding transformation mechanisms have been established from consideration of the crystal structures.