化学原理驱动的光生物不对称催化研究进展

手性选择性的调控一直是合成化学的重要研究主题。酶是绿色、高选择性的天然手性催化剂,但在绿色生物合成中的应用受限于进化形成的分子结构和催化机制,光催化通过捕获光子能量实现底物分子的化学键活化,是引发自由基反应的重要策略,融合光化学和酶的光生物催化正成为不对称催化合成的新兴合成工具。利用蛋白质改造、定向进化等先进分子生物学技术,基于光化学的化学原理挖掘辅酶的非天然催化功能,探索光催化剂与酶的协同耦合作用新模式,理性设计人为定义功能的人工光酶,能突破天然酶催化的底物谱和反应类型,有效弥补天然光酶的稀缺性,拓展生物催化的化学边界和合成空间。本文综述了化学原理驱动光生物催化不对称反应的最新研究进展,依据光和酶之间的耦合模式和催化机制,将文献分为外源光催化剂与天然酶耦合、电子供体-受体复合物激发驱动的光酶催化、辅酶直接光氧化还原和光酶能量转移催化四种不同类型,分别详细探讨其分子活化机制和立体化学调控的化学原理。此外,本文也对光生物不对称催化存在的辅酶类型单调、催化效率低等挑战进行了总结,并从天然酶库的深度挖掘、人工光酶类型的拓展、酶的从头设计和全细胞催化等角度展望了未来的发展方向,通过化学和生物融合实现高价值功能分子的绿色生物制造,推动合成化学的可持续发展。

A chemoenzymatic cascade for sustainable production of chiral N-arylated aspartic acids from furfural and waste

Both biomass valorization and waste upcycling are important routes to sustain the circular bioeconomy.In this work,we present a chemoenzymatic cascade for selective synthesis of chiral N-arylated aspartic acids from biomass-derived furfural and waste nitrophenols(NPs)by merging robust photo-and electrocatalysis with stereoselective biocatalysis.Concurrent photoelectrocatalytic oxidation of furfural into maleic acid(MA)and fumaric acid(FA)was significantly enhanced by combining catalyst and reaction engineering strategies including identification of a powerful photocatalyst meso-tetra(4-carboxyphenyl)porphyrin,continuous flow technique,enhancing dissolved O_(2) and paired electrosynthesis.The overall space-time yield(STY)approached 2.8 g L^(-1) h^(-1) in a fed-batch process,with the product titer of 28.3 g L^(-1) .Besides,photoelectrosynthesis of MA/FA was effectively fueled by sunlight,with the STY of up to 3.6 g L^(-1) h^(-1) .Both MA selectivity and yield could be facilely improved to around 89%by reducing the buffer concentrations.Paired electrosynthesis strategy not only resulted in greatly improved MA production at the anode,but also enabled NPs upcycling into value-added aminophenols(APs)at the cathode.The products formed in the two electrode chambers were converted into N-arylated(S)-aspartic acids by a bienzymatic cascade.This work presents a multicatalytic approach for integrating selective biomass valorization and waste upcycling towards sustainable manufacture.

光-酶催化偶联方式的研究进展

光-酶催化的偶联能够实时可逆、时空高效地调控酶的活性或拓展酶的功能,这一过程通常需要通过光响应结构将光能转化为酶所能利用的物理化学能,从而影响酶的活性和功能。目前研究的光-酶催化的偶联主要有4种方式:1.酶催化与能够在光照条件下发生异构体转换的小分子结构光开关偶联;2.酶催化与能够在光照条件下从保护基团离去的小分子结构光笼基团偶联;3.酶催化与能够在光照时发生构象改变的光感受器蛋白偶联;4.酶催化与光催化偶联,即光生物催化。应用这些光响应结构的偶联方法在酶的活性功能调控方面已经有比较成熟的技术,在体外催化体系中调控酶活性、拓宽酶的反应类型,以及体内调控生物过程、药物研发等领域都有广阔的前景。文章将主要介绍上述4种光-酶催化的偶联方式和应用,并探讨这些方法的未来发展方向。

Ⅰ-Ⅲ-Ⅵ chalcogenide semiconductor nanocrystals:Synthesis,properties,and applications

Colloidal semiconductor nanocrystals have been proven to be promising candidates for applications in low‐cost and high‐performance photovoltaics,bioimaging,and photocatalysis due to their novel size‐and shape‐dependent properties.Among the colloidal systems,I‐III‐VI semiconductor nanocrystals(NCs)have drawn much attention in the past few decades.Compared to binary NCs,ternary I‐III‐VI NCs not only exhibit low toxicity,but also a high performance similar to that of binary NCs.In this review,we mainly focus on the synthesis,properties,and applications of I‐III‐VI NCs.We summarize the major synthesis methods,analyze their photophysical and electronic properties,and highlight some of the latest applications of I‐III‐VI NCs in solar cells,light‐emitting diodes,bioimaging,and photocatalysis.Finally,based on the information reviewed,we highlight the existing problems and challenges.

Ferroelectric solid solution Li1-xTa1-xWxO3 as potential photocatalysts in microbial fuel cells:Effect of the W content

Microbial fuel cells(MFCs)are bio-electrochemical systems that can directly convert the chemical energy contained in an effluent into bioelectricity by the action of microorganisms.The performance of these devices is heavily impacted by the choice of the material that forms the cathode.This work focuses on the assessment of ferroelectric and photocatalytic materials as a new class of non-precious catalysts for MFC cathode construction.A series of cathodes based on mixed oxide solid solution of LiTaO_3with WO_3formulated as Li_(1-x)Ta_(1-x)W_xO_3(x=0,0.10,0.20 and0.25),were prepared and investigated in MFCs.The catalyst phases were synthesized,identified and characterized by DRX,PSD,MET and UV–Vis absorption spectroscopy.The cathodes were tested as photoelectrocatalysts in the presence and in the absence of visible light in devices fed with industrial wastewater.The results revealed that the catalytic activity of the cathodes strongly depends on the ratio of substitution of W^(6+)in the LiTaO_3matrix.The maximum power densities generated by the MFC working with this series of cathodes increased from60.45 mW·m^(-3)for x=0.00(LiTaO_3)to 107.2 mW·m^(-3)for x=0.10,showing that insertion of W^(6+)in the tantalate matrix can improve the photocatalytic activity of this material.Moreover,MFCs operating under optimal conditions were capable of reducing the load of chemical oxygen demand by 79%(COD_(initial)=1030 mg·L^(-1)).

Biocatalytic desymmetrization of 3-substituted glutaronitriles by nitrilases. A convenient chemoenzymatic access to optically active (S)-Pregabalin and (R)-Baclofen

Desymmetrization of prochiral 3-substituted glutaronitriles offers a new approach to access （S）-Pregabalin and （R）-Baclofen. A number of nitrilases from diverse sources were screened with 3-isobutylglutaronitriles （1a） or 3-（4＇-chlorophenyl）glutaronitriles （1b） as the substrate. Some nitrilases were found to catalyze the desymmetric hydrolysis of la and lb to form optically active 3-（cyanomethyl）-5-methylhexanoic acid （2a） and 3-（4＇-chlorophenyl）-4-cyanobutanoic acid （2b） with high enantiomeric excesse （ee）, respectively. This cannot be achieved using traditional chemical hydrolysis. Among them, AtNIT3 generated （R）-2b whereas BjNIT6402 and HsN1T produced the opposite （S）-enantiomer with high conversions and ee values. Not only the nitrilases showed different activities and stereoselectivities toward these 3-substituted glutaronitriles, the 3-substitueut of the substrates also exerted great effect on the enzyme activity and stereoselectivity. （S）-2a and （S）-2b were prepared with high yields and ee values using BjNIT6402 and HsNIT as the biocatalysts, respectively. A straightforward Curtius rearrangement of （S）-2a and （S）-2b, followed by the acidic hydrolysis, afforded （S）-Pregabalin and （R）-Baclofen. This offers a new platform methodology for the synthesis of optically active β-substituted T-amino acids of pharmaceutical importance.