以二苯脲弱鍵結系統建構氧化還原控制之分子開關

Abstract

第一部分：以二苯脲弱鍵結系統建構氧化還原控制之分子開關 在本研究中，我們以鈉陽離子做為模板，將BPX26C6引入與尿素辨識，並以兩個弱鍵結系統客體分子建構出能以氧化還原控制之車輪烷分子開關。利用NOBF4氧化三苯胺形成自由基陽離子，加強對BPX26C6之吸引力使其轉移位置至三苯胺旁的醯胺站上。加入鋅粉還原三苯胺使大環回歸至其原本的主要辨識站上。 第二部分：以內鎖雛菊鏈建立多維度分子肌肉 在本研究中，我們利用結構的剛硬性、金屬的配位化學以及苯環之間單鍵的扭轉張力，選擇性地合成出新型分子肌肉－[c3]與[c4]雛菊鏈。有別於傳統的線性伸縮肌肉分子，[c3]與[c4]雛菊鏈可藉由加入/移除鋅金屬離子控制二維平面或三維立體空間的舒張 (stretch) 與收縮 (contraction)，並可計算出其舒張後約伸展了23%與36%，與生物體中肌肉平均伸縮值 (27 %) 接近，由此類比分子肌肉進行運動之行為。

Part I：A Redox-Controllable Molecular Switch Based On Weak Recognition of BPX26C6 at a Diphenylurea Station. The Na+ ion-assisted recognition of urea derivatives by BPX26C6 has allowed the construction of a redox-controllable [2]rotaxane-type molecular switch based on two originally very weakly interacting host/guest systems. Using NOBF4 to oxidize the triarylamine terminus into a corresponding radical cation attracted the macrocyclic component toward its adjacent carbamate station; subsequent addition of Zn powder moved the macrocyclic component back to its urea station. Part II：Mechanically Interlocked Daisy Chain-Like Structures as Multidimensional Molecular Muscles We report artificial molecular muscles that—unlike one-dimensional biological muscles—contract and stretch in two or three dimensions. These systems have the structures of [c3]- and [c4]daisy chains (DCs) with subcomponents that operate as molecular switches, powered through the addition/removal of Zn2+ ions to impart the muscle–like behavior. We selectively assembled these [c3]- and [c4]DCs by exploiting structural rigidity, coordination geometries, and bond rotational barriers that disfavored the formation of smaller homologues. The switching phenomena of our [c3]- and [c4]DCs resulted in the contracted molecular muscles stretching by approximately 23 and 36%, respectively, comparable with the value (27%) for linear biological muscles.