Group 6 Metal Pentacarbonyl Complexes of Air-Stable Primary, Secondary, and Tertiary Ferrocenylethylphosphines

The synthesis and characterization of a series of Group 6 metal pentacarbonyl complexes of air stable primary, secondary, and tertiary phosphines containing ferrocenylethyl substituents are reported [M(CO)5L: M = Cr, Mo, W; L = PH2(CH2CH2Fc), PH(CH2CH2Fc)2, P(CH2CH2Fc)3]. The structure and composition of the complexes were confirmed by multinuclear NMR spectroscopy, IR and UV-Vis absorption spectroscopy, mass spectrometry, X-ray crystallography, and elemental analysis. The solid-state structural data reported revealed trends in M-C and M-P bond lengths that mirrored those of the atomic radii of the Group 6 metals involved. UV-Vis absorption spectroscopy and cyclic voltammetry highlighted characteristics consistent with electronically isolated ferrocene units including wavelengths of maximum absorption between 435 and 441 nm and reversible one-electron (per ferrocene unit) oxidation waves between 10 and -5 mV relative to the ferrocene/ferrocenium redox couple. IR spectroscopy confirmed that the σ donating ability of the phosphines increased as ferrocenylethyl substituents were introduced and that the tertiary phosphine ligand described is a stronger σ donor than PPh3 and a weaker σ donor than PEt3, respectively

Organic electronic materials for nanoscale systems: from luminescent bottlebrush copolymers to ultrastable fluorophores

Synthesis of multicomponent nanoscale structures with precisely addressable function is critical to discover new phenomena and new applications in nanotechnology. Though self-assembly offers a route such materials, these methods often require building blocks with particular structural motifs, limiting the scope of nanomaterials that can be prepared. Work described in the thesis uses a bottom-up approach based on covalent chemistry to synthesize a series of bottlebrush copolymers (BBCPs) – polymeric side chains attached covalently to a linear backbone – from organic semiconductors. Methods are also presented for the efficient synthesis of planar thermally activated delayed fluorescence (TADF) materials and stable organic fluorophores, incorporating them into nanoscale systems for biological imaging. A series of acrylic monomers was synthesized based on p-type organic semiconductor motifs found commonly in organic electronic devices. These monomers were polymerized by Cu(0)-reversible deactivation radical polymerization (RDRP), the kinetics of which are described in detail. By combining Cu(0)-RDRP and ring opening metathesis polymerization, narrowly dispersed multiblock bottlebrush fibers were prepared from monotelechelic dye-functionalized acrylate polymers with polymerizable norbornene end-functions (macromonomers). This strategy was used to construct nanofibers with the structure of phosphorescent organic light emitting diodes (OLEDs) on single macromolecules, such that the photophysical properties of each component of an OLED could be independently observed. Red, green, and blue (RGB) luminescent macromonomers were prepared using Cu(0)-RDRP, which were used to prepare multiblock organic nanofibers structurally analogous to nanoscale RGB pixels and multilayer white OLEDs. Changes in energy transfer efficiency and interchromophore distance were quantified using a Förster resonance energy transfer model. Additionally, donor-acceptor dyes were prepared using a novel acceptor based on N-phenylbenzimidazole constrained in a coplanar fashion with a methylene tether (IMAC). Emitters were designed with a twisted conformation between donor and acceptor resulting in effective spatial separation of the highest occupied molecular orbital and lowest unoccupied molecular orbital and small singlet-triplet energy gaps to give TADF. In fluorescent IMAC derivatives, locking these chromophores into planar configurations was demonstrated to improve their cross-section for two-photon excited fluorescence and reduce the rate of photobleaching. Proof-of concept studies incorporating these dyes into water-soluble polymer dots suitable for biological imaging was also demonstrated.Science, Faculty ofChemistry, Department ofGraduat