Polymers
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2019
·Vol. 11
·期 3
·399
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IF 3.164
Kan Zhang,Yuqi Liu,Zhikun Shang,Corey J. Evans,Shengfu Yang
A new type of atropisomerism has recently been discovered in 1,3-benzoxazines, where the intramolecular repulsion between negatively charged oxygen atoms on the imide and the oxazine ring hinders the rotation about the C–N bond. The imide group offers a high degree of flexibility for functionalization, allowing a variety of functional groups to be attached, and producing different types of end-caps. In this work, the effects of end-caps on the atropisomerism, thermally activated polymerization ofortho-imide functional benzoxazines, and the associated properties of polybenzoxazines have been systematically investigated. Several end-caps, with different electronic characteristics and rigidities, were designed.1H and13C nuclear magnetic resonance (NMR) spectroscopy and density functional theory (DFT) calculations were employed to obtain structural information, and differential scanning calorimetry (DSC) and in situ Fourier transform infrared (FT-IR) spectroscopy were also performed to study the thermally activated polymerization process of benzoxazine monomers. We demonstrated that the atropisomerization can be switched on/off by the manipulation of the steric structure of the end-caps, and polymerization behaviors can be well-controlled by the electronic properties of the end-caps. Moreover, a trade-off effect were found between the thermal properties and the rigidity of the end-caps in polybenzoxazines.Keywords:benzoxazine;ortho-imide;atropisomerization;thermal properties
研究领域:
高分子化学
·
材料科学
·
物理化学
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产品关联
DOI
PubMed
高影响因子
MICROCHEMICAL JOURNAL
·
2022
·
IF 5.304
Yiyi Liu,Fuxing Xu,Fangling Wu,Huanhuan Wang,Zhigang Liang,Chuan-Fan Ding
The distinction of enantiomers is increasingly critical in scientific research and chemical industries, because of their differences in the molecular structure and properties. R/S-Phenyl-1,2-ethanediol (PED), R,R/S,S-Hydrobenzoin (HB), and R/S-1,1,2-Triphenyl-1,2-ethanediol (TPED) are representative aromatic alcohol catalyst-class enantiomers, which directly affect the type and yield of reactants, that their chiral distinction and separation are important. In this work, the three groups of the enantiomers are recognized by measuring the ion mobility spectrometry (IMS) difference of their ternary complexes, which formed by simple non-covalent interaction with chiral selectors and metal ions. Their ion mobility was detected using trapped ion mobility spectrometry-mass spectrometry (TIMS-MS). Different chiral selectors include α-, β-, γ-Cyclodextrins (CDs), rifamycin (Rif), and natamycin (Nat) etc were investigated, and different metal ions were studied as ligands. Interestingly, the target enantiomers could not interact with the chiral selectors directly, but with the addition of metal ions, the ternary complexes of enantiomers-chiral selectors-metal ions can be formed. The mobility results reveal that the peak to peak resolution (R p-p ) was increased with the number of their benzene rings goes, which can up to 2.08. Simply, R/S-PED enantiomers can be successfully distinguished by measuring the IMS of the formed ternary complexes of [β-CD + PED + Cr-2H] + ; R,R/S,S-HB enantiomers can be distinguished by measuring the IMS of [Rif + HB + Ba-H] + and [Rif + HB + Ca-H] + ; And R/S-TPED enantiomers can be distinguished by measuring the IMS of [Nat + TPED + Mn-H] + , [Nat + TPED + Co-H] + , [Nat + TPED + Mg-H] + , [Nat + TPED + Ca-H] + , [Nat + TPED + Ba-H] + and [α-CD + TPED + Al-2H] + , respectively. Moreover, the tandem mass spectrometry experimental results showed that the binding stability of the R- and S-enantiomer ternary complexes has obvious difference and is related to different metal ion, indicating the ternary enantiomer complexes have different rigid structures. In addition, the relative quantification of R/S-enantiomer complexes were performed, good linear coefficient (R 2 ) greater than 0.99 was obtained. The method based on IMS analysis can represent an effective approach for the distinction of phenyl-Substituted ethanediol enantiomers, and the CDs, Rif, Nat can be promising chiral selectors for enantiomers distinction.
研究领域:
分析化学
·
药物化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）