Asymmetric Anionic Polymerization of 2,7-Bis(4-t-butylphenyl)fluoren-9-ylmethyl Methacrylate and Photo-induced Structural Transition of the Obtained Polymer
Asymmetric Anionic Polymerization of 2,7-Bis(4-t-butylphenyl)fluoren-9-ylmethyl Methacrylate and Photo-induced Structural Transition of the Obtained Polymer
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2,7-双(4-叔丁基苯基)芴-9-基甲基丙烯酸甲酯的不对称阴离子聚合及所得聚合物的光诱导结构转变
DOI：
10.1002/chir.20953
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发表时间：
2011
期刊：
影响因子：
2
通讯作者：
and T. Nakano (T. Nakano)
中科院分区：
文献类型：
--
作者：
K. Watanabe;T. Sakamoto;and T. Nakano (T. Nakano)
合成了甲基丙烯酸2，7-二（4-叔丁基苯基）芴-9-基甲酯（BBPFMMA）作为适用于不对称阴离子聚合（IUPAC命名法：不对称螺旋手性聚合）的大体积单体的新候选物，从而导致优选手性螺旋的光学活性聚合物。在-78 °C下，使用9-芴基锂和（S）-（+）-1-（2-吡咯烷基甲基）吡咯烷的络合物在甲苯中聚合新单体。与获得聚甲基丙烯酸酯的初衷相反，单体似乎经历结构转变（分解），得到2，7-双（4-叔丁基苯基）二苯并富烯，并且所获得的聚合物最有可能是BBPFMMA、2，7-双（4-叔丁基苯基）二苯并富烯和甲基丙烯酸的混合物。所得聚合物显示圆二色性（CD）光谱，表明在聚合过程中已引入到共聚物链的手性。在光照射下，聚合物经历了结构转变，包括通过尺寸排阻色谱法（SEC）测量的表观分子量显著降低和FT-IR光谱图的变化。然而，该聚合物的CD光谱没有明显的改变，通过照射，表明聚合物的手性不受光的影响。Chirality，2011.© 2011 Wiley Periodicals，Inc.
2,7‐Bis(4‐t‐butylphenyl)fluoren‐9‐ylmethyl methacrylate (BBPFMMA) was synthesized as a new candidate of a bulky monomer suitable for asymmetric anionic polymerization (IUPAC nomenclature: asymmetric helix‐chirogenic polymerization) leading to a preferred‐handed helical, optically active polymer. The new monomer was polymerized using the complex of 9‐fluorenyllithium and(S)‐(+)‐1‐(2‐pyrrolidinylmethyl)pyrrolidine in toluene at −78°C. As opposed to the original intention to obtain a polymethacrylate, the monomer seemed to undergo structural transition (decomposition) giving 2,7‐bis(4‐t‐butylphenyl)dibenzofulvene and the obtained polymer was most probably a terpolymer of BBPFMMA, 2,7‐bis(4‐t‐butylphenyl)dibenzofulvene, and methacrylic acid. The obtained polymer showed circular dichroism (CD) spectra, indicating that chirality had been introduced to the copolymer chain during the course of polymerization. On photo irradiation, the polymer underwent a structural transition involving a remarkable decrease in apparent molecular weight measured by size‐exclusion chromatography (SEC) and changes in FT‐IR spectral patterns. However, the CD spectrum of the polymer was not obviously altered by irradiation, indicating that polymer chirality is not affected by light. Chirality, 2011. © 2011 Wiley Periodicals, Inc.