金屬超分子衣烷之合成與自組裝及其分子動態特性

Abstract

藉由二苄基銨離子與二苯并-24-冠醚-8之間的分子間作用力，擁有三個冠醚結構的金屬配位超分子主體可以同時接受三個分支上各有一個銨離子修飾之客體分子穿過冠醚形成一個類衣烷。本研究中合成出末端帶有疊氮基團的客體分子，形成相同骨架的類衣烷後，藉由三種點擊化學對疊氮基團進行組裝後共價修飾，接上有立體阻礙的末端基團。經由施陶丁格反應、亞銅催化疊氮化物炔烴環加成反應、以及環張力促發疊氮化物炔烴環加成反應與主體分子產生機械性鍵結，產生新的衣烷。 形成衣烷結構後，主體超分子骨架上的三聯吡啶-金屬配位接合處仍處於動態平衡，可以對環境中的刺激響應，改變本來的籠狀結構。衣烷上包含了12個未修飾三聯吡啶，藉由我們團隊開發出的有自我辨識能力之6,6'修飾三聯吡啶，可以選擇性的與未修飾三聯吡啶產生雜配錯合物。在衣烷溶液中加入6,6'修飾三聯吡啶後，可與之形成1對12的雜配錯合物，同時分子的結構從原先的籠狀結構轉換成分岔的樹枝狀結構。對比之下，類衣烷在同樣的操作下會解離出獨立的三個樹枝狀超分子。這個從籠狀結構到樹枝狀結構的過程是可逆的，樹枝狀分子在環境中加入了未修飾三聯吡啶-鎘錯合物時，能夠與未修飾三聯吡啶進行配體交換，使外圍有修飾的末端基團改與未修飾三聯吡啶形成小分子的雜配化合物，進而釋放出上的衣烷骨架並重新組合出原先的籠狀衣烷。藉由合成帶有修飾三聯吡啶的輪烷與衣烷的自組裝，我們成功合成了帶有28個有機組份的II-B型樹狀物-[16]輪烷。

Supramolecular interactions between an azide-decorated trifunctional dibenzylammonium and multiple dibenzo‐24‐crown‐8‐ether moieties in a metal‐terpyridine coordination cage are utilized to achieve the formation of metallo-supramolecular pseudo-suitanes. Further derivation of the azide terminal groups allowed post-synthesis capping of pseudosuitane, which afforded interlocked metallo-supramolecular suitanes by Staudinger reaction, copper(I)-catalyzed or strain-promoted alkyne-azide cycloaddition. In the metallo‐supramolecular suitane, the terpyridine motifs remain dynamic where post-assembly modification of the cage structure could be achieved. Utilizing the complementary terpyridine ligand pair between 6,6'-substituted and non-substituted terpyridines developed by our group, we were able to transform the cage‐like suitane into a dendritic molecule with twelve terminal ends. The transformation between the suitane and the dendritic structure was reversible. When another non-substituted terpyridine ligand was introduced into the solution of the open dendritic structure, the added ligand was reacted with the substituted terpyridine to generate heterodimers and transform the dendritic scaffold into the original cage‐like suitane. This molecular transformation was further utilized to synthesize a type II-B [16]rotaxane dendrimer possessing 28 organic components with rotaxane-carrying terpyridine ligands.