I.不同主鏈結構之金屬應答型功能高分子材料─柔性/剛性碳氫鏈及醚鍵 II.金屬離子誘導機能性寡肽進行無規則線圈/螺旋構形轉變 III.吖啶鹽類氟離子及醋酸根離子發色螢光探針：以分子觀點探討陰離子選擇性的轉換

I.Metal Ion-Responsive Functional Polymers with Different Backbone Structures: Flexible/Rigid Hydrocarbon Chain and Ether Linkage II.Metal Ion-Induced Random Coil/Helix Conformation Transition of Functional Oligo-L-Lysine Based Octamers III.Acridinium Salt-Based Fluoride and Acetate Chromofluorescent Probes: Molecular Insights into Anion Selectivity Switching

林喻偵(Yu-Chen Lin)

指導教授 ： 陳昭岑 教授

國立臺灣大學/理學院/化學研究所/博士(2011年)

https://doi.org/10.6342/NTU.2011.00620

摘要

第一章節為發展側鏈上具有金屬感應單元的金屬應答型高分子材料，藉由改變高分子主鏈的組成進而影響其骨幹的柔軟性及剛硬性，以期用以發展金屬感測材料或是在金屬存在的導引下自組裝成高度有序的結構。由於冰片烯單體（norbornene）所特有的雙環束限結構，利用釕金屬觸媒進行開環複分解聚合反應（Ring-opening metathesis polymerization，ROMP）所建構的均聚冰片烯高分子可視為具有鋼性主鏈骨幹。主鏈剛性程度可以藉由與一適當的環烯烴共聚單體進行交替共聚反應來調控。在共聚單體的環張力與立體阻礙取得適當的平衡，有助於建構交替骨幹結構。因此，所引入的碳氫鏈或是醚基間隙物除了可以有效地隔開金屬螯合單元，進而避免自我驟熄的現象產生。亦可以藉由間隙物的特性用來改良高分子材料於有機溶液的溶解度。當使用7及14-員環雜環烯烴做為共聚單體時，由實驗結果得到低環張力的共聚單體無法與冰片烯單體進行有效地交叉增長反應，發現其幾乎無或是很低交錯聚合行為。
第二章為發展側鏈上帶有金屬離子螯合單元的寡賴氨酸八聚體PGLM8，其胜肽鍵的旋轉受限提供了一個剛性主鏈結構。位處於i, i + 4 間距的金屬離子螯合單元在四當量鍶離子的導引下，經由分子內金屬配位作用力形成三明治形態之金屬錯合物，使得PGLM8採以穩定的螺旋結構存在。當加入超過四當量的鍶離子時，所導引生成的螺旋結構會漸漸瓦解並伴隨著螢光增強的現象發生。由金屬離子選擇性的實驗結果得到，鹼土族金屬如鈣離子、鋇離子也可以促進螺旋結構的形成；而其他金屬離子如鈉、鉀、鉛離子則無法誘導PGLM8進行構形的轉變。由此可得知具有較高的電荷密度及幾何配位的鹼土族金屬適合做為側鏈交聯試劑。
第三章為發展一系列以吖啶鹽為主架構的顯色螢光陰離子探針用做偵測氟離子及醋酸根離子。藉由待測物的存在誘發受體進行高度選擇性且不可逆的化學反應，進而產生偵測訊號的改變(如:螢光放射、吸收…等)的原理設計發展針對特定標靶的顯色螢光探針。相較於吡啶或喹啉等結構類似物，親核性攻擊反應更容易、更快發生在吖啶鹽高度缺電子的9號位置。於是利用這個反應特性，發展一系列以吖啶鹽為主架構的顯色螢光陰離子探針ACD1-ACD4來有效地偵測陰離子。陰離子做為親核試劑進行親核攻擊反應後，破壞吖啶鹽結構生成對應的吖啶滿，進而造成紫外可見光吸收及螢光放射的改變。陰離子的選擇性可以藉由調控反應活性部位周圍的立體障礙及陰離子本身的大小不同而得到有效率地篩選。最重要的是，所發展的這一系列陰離子探針其辨識機制是一個可逆反應，可以用做達到重複使用的目的。

關鍵字

金屬應答型功能高分子 ； 柔性/剛性主鏈結構 ； 螺旋構形 ； 氟離子及醋酸根離子發色螢光探針

並列摘要

Chapter I describes the development of side-chain functionalized polymers containing metal ion-responsive units with flexible/rigid backbone structures that have potential in developing metal ions sensory materials or self-assembly into hierarchical ordered structures. Poly-norbornene based homopolymer derived from ring-opening metathesis polymerization (ROMP) is regarded as rigid backbones because of the bicyclic constraints of norbornene. Decrease of backbone rigidity can be achieved through the alternating copolymerization of an appropriate cyclic olefin comonomer. A balance of ring strain and steric hindrance of the comonomers plays a key role in constructing alternating backbone structures. Thus, the incorporation of hydrocarbon or ether spacers into copolymers efficiently keeps two metal ion-chelators away from each other to prevent self-quenching of the dye molecules and makes a difference in polymer solubility that copolymers with ether linkage in the backbone chain enhance solubility in organic solvents. The use of 7-membered and 14-membered heterocyclic olefin comonomers results in no and lower levels of alternation behavior suggesting that low ring strain comonomer could not undergo cross-propagation with norbornene monomer.
Chapter II describes that oligo-L-lysine based octamer PGLM8 containing metal ion-chelators in the side chains is of interest because the restricted rotation of peptide bonds provides a rigid backbone structure. PGLM8 adopts a stable helix conformation due to the formation of intramolecular sandwich-type complexes with four equivalents strontium ions through metal-coordination interaction at i, i + 4 spacing. The addition of more than four equivalents strontium ions results in the deformation of helix structure with a concomitant fluorescence enhancement. It is found that the presence of other alkaline earth metal ions such as Ca2+ and Ba2+ also promote the helix formation; other metal ions such as Na+, K+, and Pb2+ cannot induce the conformation transition, indicating that alkaline earth metals are suitable side chain cross-linking agents due to their higher charge density and coordination geometry.
Chapter III describes the development of acridinium salt-based chromofluorescent probes for the detection of anions – fluoride and acetate. Analytes that form covalent bonds with receptors to trigger highly selective reactions and induce changes in fluorescence emission or absorption are being used to design target-specific chromogenic/fluorogenic probes. A nucleophilic attack occurs at the highly electron- deficient C9 position of acridinium salts more readily than at the corresponding position in their pyridinium or quinolinium counterparts. Our strategy is using this reaction feature to develop acridinium-based chromogenic and fluorescent sensors ACD1–ACD4 for effective anion sensing and delineate the sensing mechanisms for F–, AcO– ions, and halides. Both of F– and AcO– ions act as nucleophiles to attack at the C9 position of acridinium moiety inducing pronounced changes in UV-vis absorption and fluorescence emission while halides only exert collision quenching of acridinium. Anion selectivity can be achieved through controlling the steric congestion around the reactive site. As a matter of fact, our designed fluorescent probes successfully differentiate fluoride and acetate and the sensing action of the probes is reversible, which is an important feature for fluorescent probes.

並列關鍵字

Metal Ion-Responsive Functional Polymers ； Flexible/Rigid Backbone Structures ； Helix Conformation ； Fluoride and Acetate Chromofluorescent Probes

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