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29. Light‐Regulated Nucleation for Growing Highly Uniform Single‐Crystalline Microrods.

Author

Sun, Lishan, Gong, Yanjun, Che, Yanxue, Ji, Hongwei, Liu, Bing, Che, Yanke, and Zhao, Jincai

Subjects
*NUCLEATION, *PHOTOINDUCED electron transfer, *DISCONTINUOUS precipitation, *LEWIS acids, *SUPERSATURATION, *ACYL chlorides
Abstract

We report a light‐irradiation method to control the synchronous nucleation of a donor‐acceptor (D‐A) fluorophore for growing highly uniform single‐crystalline microrods, which is in sharp contrast to the prevailing methods of restricting spontaneous nucleation and additionally adding seeds. The D‐A fluorophore was observed to undergo photoinduced electron transfer to CrCl3, leading to the generation of HCl and the subsequent protonation of the D‐A fluorophore. By intensifying photoirradiation or prolonging its duration, the concentration of protonated D‐A fluorophores can be rapidly increased to a high supersaturation level. This results in the formation of a controlled number of nuclei in a synchronous manner, which in turn kickstart the epitaxial growth of protonated D‐A fluorophores towards uniform single‐crystalline microrods of controlled sizes. The light‐regulated synchronous nucleation and uniform growth of microrods are a unique phenomenon that can only be achieved by specific Lewis acids, making it a novel probing method for sensitively detecting strong Lewis acids such as chromium chloride. [ABSTRACT FROM AUTHOR]

Published
2024
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30. Lipase‐Catalyzed Hydrolysis of α‐Phenylethyl Esters in a Hydrophobic Ionic Liquid‐Based Bicontinuous Microemulsion Stabilized by Zwitterionic Surfactant.

Author

Ma, Jun, Gong, Yanjun, and Huang, Xirong

Subjects
*LIPASES, *SURFACE active agents, *MICROEMULSIONS, *ESTERS, *HYDROLYSIS, *IONIC liquids, *STEREOSELECTIVE reactions
Abstract

In the present work, the biocompatible sulfobetaine‐type zwitterionic surfactant (SB‐n) was selected to construct hydrophobic ionic liquid (HIL)‐based bicontinuous microemulsion (BME). It is shown that the [C8mim][PF6] (1‐octyl‐3‐methylimidazolium hexafluorophosphate)‐based BME stabilized by mixed SB‐8/SB‐16 is more suitable for the expression of lipase activity than that stabilized by a single SB‐12. It is also demonstrated that the lipase activity in the present BME is higher than in the corresponding droplet‐type microemulsion. The lipase‐catalyzed hydrolysis of racemic α‐phenylethyl esters was used as a model reaction. It is found that the yield and the enantiomeric excess (ee) value of the product α‐phenylethanol depend on the lipase sources. In the SB‐8/SB‐16‐stabilized BME, Candida antarctica lipase (B) has the best hydrolysis activity and stereoselectivity toward α‐phenylethyl esters. It is also found that the surfactant content, buffer pH and substrate chain length affect the yield and the ee value of the product. Under optimized conditions, a yield of 41 % and an ee value of ~100 % were obtained. The present study is helpful for the development of an effective and environmentally benign medium for lipase‐based conversions. [ABSTRACT FROM AUTHOR]

Published
2024
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41. Microreactor for the characterization of zeolite hydrothermal synthesis by small angle X-ray scattering (SAXS).

Author

Xiao, Peng, Cao, Shiwei, Liu, Qi, Ge, Yafen, Chen, Zikang, Sun, Chengying, Gong, Yanjun, and Li, Zhihong

Subjects
SMALL-angle scattering, FRACTAL dimensions, ZEOLITES, SYNCHROTRON radiation, CRYSTAL growth, HYDROTHERMAL synthesis
Abstract

During zeolite synthesis, exploring the growth of nanoparticles is crucial for studying the crystallization mechanism. Synchrotron radiation small angle X-ray scattering (SAXS) is a powerful technique for the in-situ characterization of zeolite crystallization. Herein, a microreactor was developed for use at the Beijing Synchrotron Radiation Facility (BSRF) to achieve the in-situ SAXS characterization of the nucleation and growth of zeolite crystallization. The results show that the fractal structure convert from surface fractal during induction nucleation to mass fractal during crystal growth. The surface fractal dimension first fluctuated slightly and increased rapidly, while the mass fractal dimension gradually increased, reflecting the particle growth. This work provides important information for further exploring zeolite crystallization. [ABSTRACT FROM AUTHOR]

Published
2024
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42. Living Self‐Assembly of Metastable and Stable Two‐Dimensional Platelets from a Single Small Molecule.

Author

Liao, Chenglong, Gong, Yanjun, Che, Yanxue, Cui, Linfeng, Liu, Yangxin, Ji, Hongwei, Zhang, Yifan, Zang, Ling, Zhao, Jincai, and Che, Yanke

Subjects
*SINGLE molecules, *SMALL molecules, *BLOOD platelets, *SUPERSATURATED solutions, *DIMETHYL sulfide
Abstract

This study reports the design of a donor‐acceptor (D‐A) molecule with two fluorene units on each side of a benzothiadiazole moiety, which allows multiple intermolecular interactions to compete with one another so as to induce the evolution of the metastable 2D platelets to the stable 2D platelets during the self‐assembly of the D‐A molecule. Importantly, the living seeded self‐assembly of metastable and stable 2D structures with precisely controlled sizes can be conveniently achieved using an appropriate supersaturated level of a solution of the D‐A molecule as the seeded growth medium that can temporarily hold the almost‐proceeding spontaneous nucleation from competing with the seeded growth. The stable 2D platelets with smaller area sizes exhibit higher sensitivity to gaseous dimethyl sulfide, illustrating that the novel living self‐assembly method provides more available functional structures with controlled sizes for practical applications. The key finding of this study is that the new living methodology is separated into two independent processes: the elaborate molecular design for various crystalline structures as seeds and the application of a supersaturated solution with appropriate levels as the growth medium to grow the uniform structures with controlled sizes; this would make convenient and possible the living seeded self‐assembly of rich 1D, 2D, and 3D architectures. [ABSTRACT FROM AUTHOR]

Published
2023
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46. Comparison of NaY-Encapsulated and NaY-Embedded CuO Nanoparticle (Cu/NaY-En and Cu/NaY-Em) Catalysts for the Oxidation of Toluene.

Author

Ge, Yafen, Meng, Lingke, Xiao, Peng, Liu, Qi, Chen, Zikang, Sun, Chengying, Gong, Yanjun, and Zhang, Jing

Abstract

The transition Cu metal-loaded zeolite is a promising alternative oxidation catalyst for volatile organic compounds (VOCs) removal. Based on total toluene oxidation, NaY-encapsulated and NaY-embedded CuO nanoparticle catalysts were prepared by one-pot (OP) and initial impregnation (IWI) methods, respectively. Characterization results show that CuO nanoparticles in the Cu/NaY-En catalyst have higher dispersion and smaller particle size than the 10Cu/NaY-Em catalyst (2–4 nm), resulting in stronger interaction between CuO nanoparticles with zeolite. In addition, the relatively high crystallinity, low temperature reducibility, and high content of Cu+ and Lewis acid in the Cu/NaY-En catalyst are also key factors for promoting catalytic activity in this work. Therefore, the Cu/NaY-En catalyst has higher catalytic efficiency than Cu/NaY-Em with preparation optimization. Cu/NaY-En (5 wt % Cu) manifests super-reactivity with T90 (temperature for 90% conversion rate of toluene) of 251 °C, and the value of Cu/NaY-Em (10 wt % Cu) is 278 °C. Especially, Cu/NaY-En exhibits excellent water resistance during toluene reaction. This work is beneficial to the synthesis of catalysts with high catalytic activity for oxidation of VOCs. [ABSTRACT FROM AUTHOR]

Published
2023
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