Wang Fan, Wang Yuqing, Min Yixuan, Li Junqing, Zhang Lili, Zheng Ting, Shen Jun, Okamoto Yoshio
Polymer Materials Research Center, Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin, China.
Graduate School of Engineering, Nagoya University, Nagoya, Japan.
Chirality. 2022 May;34(5):701-710. doi: 10.1002/chir.23425. Epub 2022 Feb 16.
A novel cellulose derivative bearing bulky 4-(2-benzothienyl)phenylcarbamate substituents (Cel-1) was readily synthesized by carbamoylation followed by Suzuki-Miyaura coupling reaction. The corresponding coated-type chiral stationary phase (CSP) was prepared on basis of the derivative, and its chiral recognition ability was then evaluated by high-performance liquid chromatography (HPLC). The chiral recognition ability of the cellulose derivative was greatly influenced by introduction of the bulky benzothienyl pendants on the aromatic moieties of phenylcarbamates, compared with its analog with smaller groups. Many racemates, including the metal tris(acetylacetonate) complexes, chiral drug, and the analyte with axial chirality, were sufficiently separated with good enantioselectivities on Cel-1. Some of them were even higher than those on the commercially powerful Chiralcel OD, which is also a coated-type CSP derived from cellulose phenylcarbamate derivative containing smaller 3,5-dimethyl pendants. The H NMR and circular dichroism (CD) spectra of Cel-1 indicated that the obtained derivative possessed a regular higher order structure, and a strong cotton effect was observed within the absorption range of π-conjugated pendant at 350-500 nm. Impressively, the cellulose derivative bearing the bulky 4-(2-benzothienyl)phenylcarbamates exhibited good enantioselective fluorescence quenching behavior to the enantiomer pair of 1-phenylethylamine, probably suggesting its potential for the application as a chiral fluorescent sensor with high efficiency. The combination of the arrangement of bulky π-conjugated benzothienyl pendants on the phenylcarbamate moieties surrounding the helical backbone and the regular higher order structure of the polymer itself probably played a key role for this high chiral fluorescent recognition ability of Cel-1. The interaction sites of bulky 4-(2-benzothienyl)phenylcarbamate pendants in its excited state can exhibit higher enantioselective discrimination via fluorescent response to the chiral compound Q1, whereas the chiral recognition ability of Cel-1 to the same compound in the ground state had no clear improvement.
通过氨基甲酰化反应，随后进行铃木-宫浦偶联反应，很容易合成出一种带有庞大的4-(2-苯并噻吩基)苯基氨基甲酸酯取代基的新型纤维素衍生物（Cel-1）。基于该衍生物制备了相应的涂覆型手性固定相（CSP），然后通过高效液相色谱（HPLC）对其手性识别能力进行了评估。与带有较小基团的类似物相比，苯基氨基甲酸酯芳香部分引入庞大的苯并噻吩基侧链对纤维素衍生物的手性识别能力有很大影响。许多外消旋体，包括金属三（乙酰丙酮）配合物、手性药物和具有轴手性的分析物，在Cel-1上都能以良好的对映选择性得到充分分离。其中一些对映选择性甚至高于商业上强大的Chiralcel OD，后者也是一种源自含有较小的3,5-二甲基侧链的纤维素苯基氨基甲酸酯衍生物的涂覆型CSP。Cel-1的1H NMR和圆二色性（CD）光谱表明，所得到的衍生物具有规则的高阶结构，并在350 - 500nm的π共轭侧链吸收范围内观察到强烈的科顿效应。令人印象深刻的是，带有庞大的4-(2-苯并噻吩基)苯基氨基甲酸酯的纤维素衍生物对1-苯乙胺对映体对表现出良好的对映选择性荧光猝灭行为，这可能表明其具有作为高效手性荧光传感器的应用潜力。围绕螺旋主链的苯基氨基甲酸酯部分上庞大的π共轭苯并噻吩基侧链的排列与聚合物本身规则的高阶结构的结合，可能对Cel-1的这种高的手性荧光识别能力起到了关键作用。庞大的4-(2-苯并噻吩基)苯基氨基甲酸酯侧链在其激发态下的相互作用位点可以通过对手性化合物Q1的荧光响应表现出更高的对映选择性区分，而Cel-1在基态下对同一化合物的手性识别能力没有明显提高。
