Functionalized organoboron polymers and supramolecular structures of pentafluorophenylcopper
Creators: name: Doshi, Ami P.
Publisher: name: No Publisher Supplied
Year: 2010

description: This thesis is divided into four different parts. The first three chapters discuss the development of synthetic routes to new boron containing polymers for their potential use as supported borane reagents (Ch. 1.) and photoluminescent materials (Ch. 2. and Ch. 3.). The last chapter (Ch. 4.) discusses the formation of supramolecular structures of pentafluorophenylcopper upon complexation with pyridine nucleophiles and electron rich aromatic π-systems. The individual research projects are briefly summarized in the following. Ch. 1. The functionalization of synthetic polymers with organoborane moieties has been extensively studied for applications as supported catalysts, sensors, stimuli responsive polymers, flame retardants, preceramic materials, and as intermediates for the preparation of other functional organic polymers. A polystyrene derivative in which the para-positions of the phenyl rings are selectively functionalized with BH2 moieties (PS-BH2) has been prepared from poly(4-trimethylsilyl styrene). The polymer was successfully isolated in the form of its polymeric acid-base complexes PS-BH2•D (D = tBuPy, PPh2Me). The selective and nearly quantitative placement of the BH2 functionalities was confirmed by multinuclear NMR spectroscopy and IR spectroscopy. Their thermal properties were studied by differential scanning calorimetry and thermogravimetric analysis.Ch. 2. Boron containing water soluble polymers could find a variety of applications as polyelectrolytes, for anion recognition in aqueous media and in various biological fields. We have previously shown that polystyrene based side chain functionalized triarylborane polymers can be employed as sensors for the recognition of cyanide and fluoride in organic media. Here we have persued the synthesis of polystyrene that bears Lewis acidic boron centers and dimethylamino-functionalized mesityl groups in the side chain. Attachment of these mesityl groups to the boron center has been realized by the use of boron-silicon exchange, followed by the replacement of the bromine on boron by suitable Grignard reagents. The polymers and model compounds show interesting photophysical properties and have the potential to be applied for anion sensing in aqueous media.Ch. 3. Main chain organoboron conjugated polymers have been established as an important class of materials due to their unusual optoelectronic properties. This behavior arises as a result of overlap between the empty p-orbital on boron and the conjugated π-system. The hydroboration polymerization and in situ Grignard synthesis have been employed for the preparation of such polymers. Here we have synthesized boron-functionalized distyryl monomers, which can be polymerized via ADMET polymerization. All monomers and ADMET products were characterized by multinuclear NMR spectroscopy. Moderate to high molecular weights in the range of 5,000-10,000 have been obtained. Photophysical data show that polymer emits in the blue-green region.Ch. 4. Treatment of organocopper species with strongly coordinating ligands is known to lead to break-down of the aggregated structures. One such example is the 1:1 complex of pentafluorophenylcopper with pyridine. The monomeric pyridine adduct shows an intriguing supramolecular structure governed by cuprophilic interactions. This complex was also found to display strong blue luminescence in the solid state at room temperature. To further examine the structural and photophysical properties of this new class of complexes, the pentafluorophenylcopper tetramer was treated with different substituted pyridine ligands. The coordination of these ligands to copper was confirmed by 1H, 19F, 13C NMR spectroscopy, x-ray crystallography and elemental analysis. Treatment of pentafluorophenylcopper with π-bases such as bithiophene, naphthalene anthracene or pyrene lead to novel luminescent supramolecular structures that feature the intact organocopper aggregate as the building block. Formation of bis-adducts with two equivalents of arenes was realized and the formation of sandwich-like structures of the intact tetramer and the corresponding arene was observed via single crystal x-ray analyses. Interestingly, the 1:1 complexes form extended binary stacks in the solid state, where the intact tetramer alternates with the arene.