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Design and Synthesis of Terpyridine based Metallo-Supramolecular Architectures

Ludlow, James M, III
http://orcid.org/0000-0001-8064-5025
http://rave.ohiolink.edu/etdc/view?acc_num=akron1444989836

Abstract Details

2015, Doctor of Philosophy, University of Akron, Polymer Science.
In the field of metallo-supramolecular chemistry, the N-heteroaromatic ligand, [2,2’:6’,2”] terpyridine (tpy), has received considerable attention due in part to its ability to coordinate with a wide variety of transition metals; this has enabled a range of bonding strengths, properties, and molecular architectures. A variety of strategies have been employed with [tpy-M(II)-tpy] based architectures including the use of triangle-based frameworks, flexible ligands, and harnessing of additional non-covalent forces to enhance self-assembly. To achieve three-dimensional architectures, new strategies include use of meta-substitution, multi-planar vertices, flexible vertices, and by restricting the availability of planar conformations via precoordination or predesigned steric hindrance. There is also increasing focus on interconversions between supramolecular structures in response to reaction conditions and on their hierarchical self-assembly. Flexible, multitopic ligands can introduce new structural possibilities, allowing for intramolecular interactions and more adaptive systems to arise. When the semi-flexible 1,2-bis[4'-(4-ethynylphenyl)-2,2':6',2"-terpyridyl]-o-carborane is self-assembled under kinetic control, via formation of Fe(II) complexes, the main cyclic product is triangular (trimer). However, under thermodynamic control, using a labile transition metal, e.g. Zn(II), the cyclic trimer is in dynamic equilibrium with a cyclic dimer, and with adequate entropic driving force the cyclic dimer is obtained exclusively. The combination of flexible crown ethers possessing a trio of rigid, 60° ligands allows for the construction of a 3D structure (tetrahedron) under thermodynamic control. Formation of the tetrahedron is facilitated by intramolecular, pi-pi interactions. Structural confirmation utilized 1D and 2D NMR, and electrospray ionization mass spectrometry coupled with travelling wave ion mobility (ESI-TWIM-MS). 19F NMR experiments support presence of guest host interactions between anions and the supramolecular cavity. One step synthesis of the first homoleptic [tpy-Os(II)-tpy] metallomacrocycle was reported and characterized via NMR, ESI-MS, TWIM-MS, and UV-vis alongside its Fe(II) and Ru(II) analogues. Gradient tandem-MS was used to derive center-of-mass collision energies and revealed unexpectedly that the order of stability of the [tpy-M(II)-tpy] complexes was M(II) = Ru > Os > Fe. Toward hierarchical ordering of supramolecular materials, the effect of molecular geometry and amphiphilicity on the ability of self-assembled metallosupramolecular macrocycles to self-order was studied. Conversion of [tpy-M(II)-tpy] macrocycles into directional amphiphiles enhanced ordering characteristics, enabling the formation of nanoscale structures.
George Newkome, Dr (Advisor)
177 p.
Chemical Engineering; Chemistry; Materials Science; Polymer Chemistry; Polymers
supramolecular chemistry; self-assembly; terpyridine; carborane; osmium; metallosupramolecular; concentration dependence; crown ether; nanostructure

Recommended Citations

Citations

  • Ludlow, III, J. M. (2015). Design and Synthesis of Terpyridine based Metallo-Supramolecular Architectures [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1444989836

    APA Style (7th edition)

  • Ludlow, III, James. Design and Synthesis of Terpyridine based Metallo-Supramolecular Architectures . 2015. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1444989836.

    MLA Style (8th edition)

  • Ludlow, III, James. "Design and Synthesis of Terpyridine based Metallo-Supramolecular Architectures ." Doctoral dissertation, University of Akron, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1444989836

    Chicago Manual of Style (17th edition)

akron1444989836
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This open access ETD is published by University of Akron and OhioLINK.