Multifarious Polymorphism of a Multiblock Amphiphilic Macrocycle Bearing Thermally Responsive Polyether Segment,ACS Omega

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Multifarious Polymorphism of a Multiblock Amphiphilic Macrocycle Bearing Thermally Responsive Polyether Segment
ACS Omega ( IF 3.7 ) Pub Date : 2018-01-16 00:00:00 , DOI: 10.1021/acsomega.7b01737
Takahiro Muraoka ₁ , Tatsuya Shima ₂ , Kazushi Kinbara _{1,

2}

Affiliation

Formation of multiple crystalline phases of a multiblock amphiphilic macrocycle AT2B is demonstrated. AT2B forms a single crystal (Cr-α) by vapor diffusion and shows reversible single-crystal-to-single-crystal transition between two crystalline phases (Cr-α and Cr-β) by a temperature change, and crystalline AT2B (Cr-β) melts at 422 K, and the cooling rate from the melt influences the phase of the solid formed. By cooling at 1.0 K min^–1, AT2B forms crystalline phases (Cr-γ and Cr-δ), which are different from both Cr-α and Cr-β. On the other hand, cooling at 2.0 K min^–1 results in the formation of an amorphous phase, and a mechanical stress also triggers a crystal-to-amorphous solid transition. Interestingly, the amorphous solid crystallizes to give the fifth crystalline phase (Cr-γ) upon heating before melting. It is suggested that these multiple phase transitions are driven by thermal conformational changes at the tetraethylene glycol chains of AT2B.

中文翻译：

带有热响应性聚醚链段的多嵌段两亲性大环化合物的多态性

证明了多嵌段两亲性大环AT2B的多个结晶相的形成。AT2B通过蒸汽扩散形成单晶（Cr-α），并通过温度变化显示两个晶相（Cr-α和Cr-β）之间可逆的单晶至单晶转变，而AT2B（Cr- β）在422 K时熔化，来自熔化物的冷却速率会影响所形成固体的相。通过以1.0 K min ^–1冷却，AT2B形成结晶相（Cr-γ和Cr-δ），与Cr-α和Cr-β都不相同。另一方面，以2.0 K min ^–1冷却结果导致形成非晶相，机械应力也触发了晶体向非晶态的固相转变。有趣的是，非晶态固体在熔化之前加热后结晶，得到第五晶相（Cr-γ）。建议这些多相转变是由AT2B的四甘醇链的热构象变化驱动的。

更新日期：2018-01-16

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