boronic ester
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2021 ◽  
Author(s):  
Antanas Karalius ◽  
Yunchuan Qi ◽  
Mubarak Ayinla ◽  
Zoltan Szabo ◽  
Olof Ramstrom

Complex dynamic systems displaying interdependency between nitroaldol and boronic ester reactions have been demonstrated. Nitroalkane-1,3-diols, generated by the nitroaldol reaction, were susceptible to ester formation with different boronic acids in aprotic solvents, whereas hydrolysis of the esters occurred in the presence of water. The boronic ester formation led to significant stabilization of the nitroaldol adducts under basic conditions. The use of bifunctional building blocks was furthermore established, allowing for main chain nitroaldol-boronate dynamers as well as complex network dynamers with distinct topologies. The shape and rigidity of the resulting dynamers showed an apparent dependency on the configuration of the boronic acids.


2021 ◽  
Author(s):  
Boyeong Kang ◽  
Julia Kalow

In dynamic materials, the reversible condensation between boronic acids and diols provides adaptability, self-healing ability, and responsiveness to small molecules and pH. Recent work has shown that the thermodynamics and kinetics of bond exchange determine the mechanical properties of dynamic polymer networks. However, prior studies have focused on how structural and environmental factors influence boronic acid–diol binding affinity, and design rules for tuning the kinetics of this dynamic bond are lacking. In this work, we investigate the effects of diol (or polyol) structure and salt additives on the rate of bond exchange, binding affinity, and the mechanical properties of the corresponding polymer networks. To better mimic the environment of polymer networks in our small-molecule model systems, we incorporated proximal amide groups, which are used to conjugate diols to polymers, and included salts commonly found in buffers. Using one-dimensional selective exchange spectroscopy (1D EXSY), we find that both proximal amides and buffering anions induce significant rate acceleration consistent with internal and external catalysis, respectively. This rate acceleration is reflected in the stress relaxation of gels formed using PEG modified with different alcohols, and in the presence of salts containing acetate or phosphate. These findings contribute to the fundamental understanding of the boronic ester dynamic bond and offer new molecular strategies to tune the macromolecular properties of dynamic materials.


2021 ◽  
Author(s):  
Xingjian Li ◽  
George Williams ◽  
Alex Quy ◽  
Yiming Zhao ◽  
Louise Male ◽  
...  

Four parthenolide derived prodrugs, containing different boronic ester moieties, were synthesised, their drug-like properties were calculated and their activity against chronic lymphocytic leukaemia (CLL) MEC1 cells measured. Differences in the clogP, the propensity towards oxidation by hydrogen peroxide, the affinity of the associated diols to a model boronic acid and the biological activity against MEC1 cells were contrasted, and it was found that the propensity for oxidation correlated to biological activity.


2021 ◽  
Author(s):  
Xingjian Li ◽  
George Williams ◽  
Alex Quy ◽  
Yiming Zhao ◽  
Louise Male ◽  
...  

Four parthenolide derived prodrugs, containing different boronic ester moieties, were synthesised, their drug-like properties were calculated and their activity against chronic lymphocytic leukaemia (CLL) MEC1 cells measured. Differences in the clogP, the propensity towards oxidation by hydrogen peroxide, the affinity of the associated diols to a model boronic acid and the biological activity against MEC1 cells were contrasted, and it was found that the propensity for oxidation correlated to biological activity.


Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3386
Author(s):  
Yanning Zeng ◽  
Jiawei Li ◽  
Shuxin Liu ◽  
Bin Yang

Rosin is an abundantly available natural product. In this paper, for the first time, a rosin derivative is employed as the main monomer for preparation of epoxy vitrimers to improve the mechanical properties of vitrimers. Novel epoxy vitrimer networks with dynamic reversible covalent boronic ester bonds are constructed by a reaction between thiols in 2,2′–(1,4–phenylene)–bis (4–mercaptan–1,3,2–dioxaborolane) (BDB) as a curing agent and epoxy groups in the rosin derivative. The rosin-based epoxy vitrimer networks are fully characterized by Fourier transform infrared spectroscopy (FTIR), an equilibrium swelling experiment, and dynamic mechanical analysis (DMA). The obtained rosin-based epoxy vitrimers possess superior thermostability and good mechanical properties. Due to transesterification of boronic ester bonds, rosin epoxy vitrimer network topologies can be altered, giving welding, recycle, self-healing, and shape memory abilities to the fabricated polymer. Besides, the effects of treating time and temperature on welding capability is investigated, and it is found that the welding efficiency of the 20% C-FPAE sample is >93% after treatment for 12 h at 160 °C. Moreover, through a hot press, the pulverized samples of 20% C-FPAE can be reshaped several times and most mechanical properties are restored after reprocessing at 200 °C for 60 min. Finally, chemical degradation is researched for the rosin-based epoxy vitrimers.


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