博士 / 國立交通大學 / 應用化學研究所 / 98 / In recent years, a number of supramolecular interactions have been developed and explored for the formation of complex macromolecular architectures. A perfect example can be found in nature with the nucleobase pairs of DNA. It has attracted great attention recently because novel structural organizations can be formed through highly complementary nucleobase recognition. For example, self-assembly mediated by hydrogen bonding allows DNA-like polymer chains to rapidly form functionalizable materials exhibiting unique physical properties, such as high specificity, controlled affinity, and reversibility. Nevertheless, controlling the secondary (and higher) structures of synthetic polymers remains a challenging task. Indeed, the synthesis of well-defined polymer architectures is currently quite inefficient when compared to the level of control found in biomaterials, which efficiently program the formation of higher structures at the molecular level.
In this thesis, we synthesized three kinds of novel nucleobase-based supramolecular polymers and investigated their self-assembled arrays and nanostructures in sold-states:
(1) Biocomplementary Interaction Behavior in DNA-like and RNA-like Polymers
We synthesized poly[1-(4-vinylbenzyl)thymine] (PVBT) and 9-hexadecyladenine (A-C16) through atom transfer radical polymerization (ATRP) and alkylation, respectively. Bio-complementary PVBT/A-C16 hierarchical supramolecular complexes formed in dilute DMSO solution through nucleobase recognition—i.e., hydrogen bonding interactions between the thymine (T) groups of PVBT and the adenine (A) group of A-C16. In the bulk state, these complexes self-assemble into well-ordered lamellar structures; the changing d-spacing distance (ranging from 4.98 to 2.32 nm) at different A-C16 loadings reveals that the molecular structures of the PVBT/A-C16 complexes are readily tailored.
In addition, a series of nucleobased polymers and copolymers were synthesized through atom transfer radical polymerization (ATRP). Biocomplementary DNA-like and RNA-like supramolecular complexes are formed through nucleobase recognition. This study is of discussion on the difference in the hydrogen bond strength between T-A and U-A base pairs within polymer systems, indicating that the strength of hydrogen bonds in RNA U-A pairs is stronger than that in DNA T-A base pairs.
(2) Organic/Inorganic Supramolecular Materials
A new polyhedral oligimeric silsesquioxane macromer octakis[N-(6-aminopyridin-2- yl)undecanamide-10-dimethyl- siloxy]silsesquioxane (POSS-C11-Py), containing eight diaminopyridine arms, has been synthesized. This POSS-C11-Py macromer is able to self-assemble to form a physically crosslinked polymer-like structure with good mechanical properties (tensile strength= 46.1 MPa, tensile modulus= 0.58 GPa, elongation= 49.3%) through quadruple hydrogen bonding interactions between these diaminopyridine terminal groups. POSS-C11-Py is the first organic/inorganic supermolecule possessing enhanced film-forming and mechanical properties as a result of self-supporting interactions, providing a potential route toward design and fabrication of supramolecular materials.
(3) A New Supramolecular Material Containing Self-complementary Sextuple Hydrogen-bonding interaction
This study describes an exceptionally array formed through self-assembly of a new material containing self-complementary sextuple hydrogen-bonding interaction. The new (U-DPy) derivative, N-(6-(3-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)- propanamido)pyridin-2-yl)undec-10-enamide, was successfully synthesized through a three-step process with excellent yields. 1H NMR titration studies in CDCl3 showed that the self-complementary complexes formed rapidly on the NMR time scale with extremely high association constants (Kdimer >107 M-1). More surprisingly, the strength of hydrogen bonding formed through dimerization was over the fluorescence time scale. The U-DPy possessing extremely high association constant far exceeding those of existing systems provides a new strategy for designing and manipulating polymers with distinctive properties.
| Identifer | oai:union.ndltd.org:TW/098NCTU5500029 |
| Date | January 2010 |
| Creators | Cheng, Chih-Chia, 鄭智嘉 |
| Contributors | Chang, Feng-Chih, 張豐志 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | en_US |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 135 |
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