Synthesis of cyclic polyenes by cycloaddition polymerization of 1,6-diynes and their properties

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K05172
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 35010:Polymer chemistry-related
• Research Institution: Kanagawa University
• Principal Investigator: Okamoto Sentaro 神奈川大学, 化学生命学部, 教授 (00201989)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 環化付加重合 / 環状ポリエン / ニッケル触媒 / 環状高分子

Outline of Final Research Achievements

Nickel complexes having a sterically demanding N,N- or N,N,N-type ligand are demonstrated to catalyse the cycloaddition oligomerisation of 1,6-heptadiynes to produce medium-size cyclic polyenes selectively with narrow molecular dispersity and minimum side reactions. The resulting cyclic polyenes exhibit non-conjugated behaviour on NMR and UV-Vis. absorption analyses. Meanwhile, regio-isomerised cyclic polyenes including trans-disubstituted alkenes, which are generated via thermal isomerisation of the cyclic polyenes at 200 °C, exhibit conjugated behaviour. The present oligomerisation reaction has wide functional group compatibility, enabling the production of medium-size cyclic polyenes bearing various functional groups. A plausible reaction mechanism that accounts for the narrow polydispersity is proposed.

Free Research Field

高分子化学　有機金属化学　触媒化学

Academic Significance and Societal Importance of the Research Achievements

いずれも多大な興味を惹く「環状高分子」と「共役ポリエン」を合わせ持つ「環状ポリエン高分子」の合成例は，極めて少なく，さらに1,6-ジインの非環状ポリエンヘの重合は，4つの形式が考えられ，その内二形式についてはメタセシス重合で合成可能であるが，本研究で明らかにしたtail-to-tail 型の重合は，前例が無いものである点で，本研究は興味深い未開拓領域を切り開くものである。モノマー構造に依存しない一定の狭い分子量分散でオリゴマーが再現性よく，また，官能基選択性高く得られる点で，今後，本手法の材料化学などへの応用が期待される。