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22. Predicting the Right Mechanism for Hypervalent Iodine Reagents by Applying Two Types of Hypervalent Twist Models: Apical Twist and Equatorial Twist

Author

Sun, Tian-Yu, Chen, Kai, You, Tingting, and Yina, Penggang

Subjects
Physics - Chemical Physics
Abstract

Since the hypervalent twist followed by reductive elimination is a general reaction pattern for hypervalent iodine reagents, mechanistic studies about the hypervalent twist step provide significant guidance for experiments. Our previous work showed there are two types of hypervalent twist models, i.e. apical twist and equatorial twist. We applied both hypervalent twist models to explain the isomerization mechanism of two important electrophilic trifluoromethylating reagents, Togni I and Togni II. To the best of our knowledge, there are less detailed studies about the different twist modes between both reagents, which are important to predict the right reaction mechanism and especially, understand well the differences of reactivity and stability. Here, we successfully identified Togni II's isomerization pathway via equatorial twist, and suggested different hypervalent twist models should be considered to predict the right mechanisms of reactions with hypervalent iodine reagents.

Published
2020
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23. Revisiting the Effect of f-Functions in Predicting the Right Reaction Mechanism for Hypervalent Iodine Reagents

Author

Sun, Tian-Yu, Chen, Kai, Zhou, Huakang, You, Tingting, Yin, Penggang, and Wang, Xiao

Subjects
Physics - Chemical Physics
Abstract

To understand the effect of f-functions in predicting the right reaction mechanism for hypervalent iodine reagents, we adopt the Ahlrichs basis set family def2-SVP and def2-TZVP to revisit the potential energy surfaces of IBX-mediated oxidation and Togni I's isomerisation. Our results further prove that f-functions (in either Pople, Dunning, or Ahlrichs basis set series) are indispensable to predict the correct rate-determining step of hypervalent iodine reagents. The f-functions have a significant impact on the predicted reaction barriers for processes involving the I-X (X = O, OH, CF$_3$, etc.) bond cleavage and formation, e.g. in the reductive elimination step or the hypervalent twist step. We furthermore explore two hypervalent twist modes that account for the different influences of f-functions for IBX and Togni I. Our findings may be helpful for theoretical chemists to appropriately study the reaction mechanism of hypervalent iodine reagents., Comment: 12 pages, 5 figures

Published
2020

38. Multifunctional TiN‐MXene‐Co@CNTs Networks as Sulfur/Lithium Host for High‐Areal‐Capacity Lithium‐Sulfur Batteries.

Author

Zuo, Xintao, Wang, Lufei, Zhen, Mengmeng, You, Tingting, Liu, Dapeng, and Zhang, Yu

Subjects
LITHIUM sulfur batteries, SULFUR, DENDRITIC crystals, CARBON nanotubes, SULFUR cycle, POLYSULFIDES
Abstract

The inevitable shuttling and slow redox kinetics of lithium polysulfides (LiPSs) as well as the uncontrolled growth of Li dendrites have strongly limited the practical applications of lithium‐sulfur batteries (LSBs). To address these issues, we have innovatively constructed the carbon nanotubes (CNTs) encapsulated Co nanoparticles in situ grown on TiN‐MXene nanosheets, denoted as TiN‐MXene‐Co@CNTs, which could serve simultaneously as both sulfur/Li host to kill "three birds with one stone" to (1) efficiently capture soluble LiPSs and expedite their redox conversion, (2) accelerate nucleation/decomposition of solid Li2S, and (3) induce homogeneous Li deposition. Benefiting from the synergistic effects, the TiN‐MXene‐Co@CNTs/S cathode with a sulfur loading of 2.5 mg cm−2 could show a high reversible specific capacity of 1129.1 mAh g−1 after 100 cycles at 0.1 C, and ultralong cycle life over 1000 cycles at 1.0 C. More importantly, it even achieves a high areal capacity of 6.3 mAh cm−2 after 50 cycles under a sulfur loading as high as 8.9 mg cm−2 and a low E/S ratio of 5.0 μL mg−1. Besides, TiN‐MXene‐Co@CNTs as Li host could deliver a stable Li plating/striping behavior over 1000 h. [ABSTRACT FROM AUTHOR]

Published
2024
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39. Sodium-Alginate-Doped Lignin Nanoparticles for PBAT Composite Films to Dually Enhance Tensile Strength and Elongation Performance with Functionality.

Author

Guo, Qiyue, He, Yuan, Wu, Jianyu, Ye, Haichuan, You, Tingting, and Xu, Feng

Subjects
VAPOR barriers, ZETA potential, TENSILE strength, WATER vapor, SODIUM alginate, LIGNINS
Abstract

It is a formidable challenge in thermoplastic/lignin composites to simultaneously boost tensile strength and elongation performance due to the rigidity of lignin. To address this issue, sodium-alginate-doped lignin nanoparticles (SLNPs) were prepared by combining solvent exchange and a coprecipitation method and used as an eco-friendly filler for poly(butylene adipate-co-terephthalate) (PBAT). The results indicated that the 1% polyanionic sodium alginate solution contributed to the formation of SLNP in lignin/THF solution. SLNP with a mean hydrodynamic diameter of ~500 nm and a Zeta potential value of −19.2 mV was obtained, indicating more hydrophobic lignin nanoparticles and a smaller number of agglomerates in SLNP suspension. Only 0.5 wt% SLNP addition improved the yield strength, tensile strength, and elongation at break by 32.4%, 31.8%, and 35.1% of the PBAT/SLNP composite films, respectively. The reinforcing effect resulted from the rigid aromatic structure of SLNP, whereas the enhanced elongation was attributed to the nanostructural feature of SLNP, which may promote boundary cracking. Additionally, the PBAT/SLNP composite films displayed excellent ultraviolet (UV) resistance with a UV shielding percentage near 100% for UVB and more than 75% for UVA, respectively. The addition of SLNP hindered water vapor, enhancing the moisture barrier properties. Overall, this study provides an effective strategy to eliminate the decrement in elongation performance for PBAT/lignin composites and suggest they are good candidates to be extensively utilized. [ABSTRACT FROM AUTHOR]

Published
2024
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46. Calculation and Analysis of Carbon Emissions from Road Maintenance Projects ——Taking the Tianjin Avenue Restoration and Maintenance Project as an Example

Author

Guo Liping, Zhu Xiaodong, You Tingting, Niu Kai, and Zhang Xingyu

Subjects
Environmental sciences, GE1-350
Abstract

In response to the phenomenon that road maintenance construction activities may have a certain impact on passing vehicles and generate additional carbon emissions, based on the Tianjin Avenue Restoration and Maintenance Project, a recommended list of carbon emission factors is proposed. A traffic impact carbon emission calculation model is used to calculate the traffic impact carbon emissions of the supporting project, analyze the characteristics of traffic impact carbon emissions composition, and explore the hot spots of traffic impact carbon emissions of maintenance projects, propose emission reduction strategies for road maintenance engineering traffic organization.

Published
2023
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48. Subtle Structural Differences Affect the Inhibitory Potency of RGD-Containing Cyclic Peptide Inhibitors Targeting SPSB Proteins.

Author

Li, Kefa, Luo, Yanhong, Hu, Weiwei, Yang, Jinjin, Zhang, Danting, Wei, Huan, You, Tingting, Lin, Hai-Shu, and Kuang, Zhihe

Subjects
PEPTIDES, CYCLIC peptides, SUPPRESSORS of cytokine signaling, NITRIC-oxide synthases, PROTEINS
Abstract

The SPRY domain-containing SOCS box proteins SPSB1, SPSB2, and SPSB4 utilize their SPRY/B30.2 domain to interact with a short region in the N-terminus of inducible nitric oxide synthase (iNOS), and recruit an E3 ubiquitin ligase complex to polyubiquitinate iNOS, resulting in the proteasomal degradation of iNOS. Inhibitors that can disrupt the endogenous SPSB-iNOS interactions could be used to augment cellular NO production, and may have antimicrobial and anticancer activities. We previously reported the rational design of a cyclic peptide inhibitor, cR8, cyclo(RGDINNNV), which bound to SPSB2 with moderate affinity. We, therefore, sought to develop SPSB inhibitors with higher affinity. Here, we show that cyclic peptides cR7, cyclo(RGDINNN), and cR9, cyclo(RGDINNNVE), have ~6.5-fold and ~2-fold, respectively, higher SPSB2-bindng affinities than cR8. We determined high-resolution crystal structures of the SPSB2-cR7 and SPSB2-cR9 complexes, which enabled a good understanding of the structure–activity relationships for these cyclic peptide inhibitors. Moreover, we show that these cyclic peptides displace full-length iNOS from SPSB2, SPSB1, and SPSB4, and that their inhibitory potencies correlate well with their SPSB2-binding affinities. The strongest inhibition was observed for cR7 against all three iNOS-binding SPSB proteins. [ABSTRACT FROM AUTHOR]

Published
2024
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