The effects of chain conformation on the photo-oxidation and green emission of poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) are investigated at both single molecule and ensemble levels. Single molecule studies reveal the conformation of PFO chains to be more globular when cast from THF than from toluene. Intensity transients of single molecules show that the elongated molecules cast from toluene have more fluctuations due to a fewer number of emitting centers on the polymer. Photochemical degradation leads to intensity fluctuations for the elongated molecules, while the globular chains show monotonic decays. Emission spectra of the single molecules show that photochemical oxidation leads to reduction in the emission of the molecule with no change in the emission spectra. No green emission is detected for single molecules indicating that formation of emissive ketone defects occurs rarely. Ensemble studies show that molecule cast from THF develop some green emission upon photodegredation while those cast from toluene don't. The increase in green in the globular molecules suggests that interchain contacts are necessary for the photochemical formation of emissive ketone defects in the PFO. All emission spectra of the aggregated and nonaggregated PFO during photooxidation are also analyzed by using a modified FranckCondon progression model with an additional independent Gaussian component and fitting results from single PFO spectrum. While emission spectrum of single PFO molecule shows a good fitting result to the model, the other two bulk PFO films display needs to introduce an additional term for better fit. This additional independent Gaussian component implies that green emission comes from non-Franck-Condon process. Rotational dynamics of poly(methyl acrylate) is investigated by single molecule spectroscopy. Polarized fluorescence transients from single rhodamine 6G dye embedded in polymer matrix above glass transition are analyzed and the correlation function of reduced linear dichroism is fit by a stretched exponential function. The fitting results suggest that non-exponential decay of correlation function. However, more rigorous study is needed because of the intrinsic statistical error of limited experimental data and the effect of high numerical objective.

The olefin metathesis reaction has become one of the most powerful carbon-carbon bond forming reaction in synthetic chemistry. This work has expanded the utility of olefin metathesis in metal coordination spheres in three major directions (1) the synthesis and characterization of trans-spanning bis(pyridine)PtCl2 complexes, (2) the developme-adducts of polyacetylene (PA), and (3) the development of regioregular -adducts of poly(phenylene-vinylene) (PPV). Chapter I gives a brief overview of olefin metathesis and previous applications to organometallic substrates. Chapter II details the synthesis of pyridine ligands containing alkenyl substituents, 2-NC5H4(CH2O(CH2)nCH=CH2) (n = 1, 2), 3-NC5H4(CH2O(CH2)nCH=CH2) (n = 1-5, 8, 9), and 3,5-NC5H3(p-C6H4O(CH2)7CH=CH2)2. Metalation of the new ligands with PtCl2 affords the corresponding trans-bis(pyridine)dichloroplatinum complexes, trans-PtCl2(2-NC5H4(CH2O(CH2)nCH=CH2))2 (n = 1, 2), trans-PtCl2(3-NC5H4(CH2O(CH2)nCH=CH2))2 (n = 1-5, 8, 9), and trans-PtCl2(3,5-NC5H3(p-C6H4O(CH2)7CH=CH2))2. Ring-closing metathesefirst generation catalyst followed by hydrogenations with Pd/C afford the title complexes trans-PtCl2-(NC5H4(CH2O(CH2)2n+2OCH2)H4C5N)] (n = 1, 2), trans-PtCl2-(NC5H4(CH2O(CH2)2n+2OCH2)H4C5N)] (n = 4, 8, 9), and trans-PtCl2-(NC5H3(p-C6H4O(CH2)12O-p-C6H4)2H3C5N)]. Reactions with methylmagnesium bromide afford trans-PtCl(CH3)(3-NC5H4(CH2O(CH2)nCH=CH2))2 (n = 2, 8) and trans-PtCl(CH3-(NC5H4(CH2O(CH2)nOCH2)H4C5N)] (n = 10, 18), which feature dipolar rotators. Low temperature NMR spectra in the latter remained facile on the NMR time scale in CDFCl2 at -120 degrees Celsius. Chapter III focuses on the application of ROMP with organometallic monomers to form metal pi-adducts of polyacetylene. The new complex (n4-benzene)Cp*Ir has been synthesized, crystallographically characterized, and evaluated in the ROMP reaction. Monomers (n4-benzene)CpIr, [(n6-COT)CpRu][PF6], and (n4-COT)Fe(CO)3 were also evaluated in the ROMP reaction. ROMP of (?4-benzene)CpIr with Grubbs' first generation catalyst afforded the conductive regioregular polymer CpIr-PA. Chapter IV focuses on the synthesis of the divinyl benzene complexes [Cp*Ir(C6H4(CH=CH2)2)][BF4]2 and [Cp*Ru(C6H4(CH=CH2)2)][OTf] and their polymerization via ADMET to afford PPV systems. Treatment of divinyl benzene ed the conductive regioregular polymers [Cp*Ir-PPV][BF4]2n and [Cp*Ru-PPV][OTf]n. The photophysical properties of the new -metal adducts of PPV exhibit blue-shifts relative to typical PPVs and retain strong UV absorption.

Twelve porphyrin dyads linked by an ethene bridge were synthesised as model systems for conjugated polymers. The extent of interporphyrin interaction was investigated for meso-meso and meso-β linked homo- and heterobimetallo-porphyrin dyads. To complement these dyads, model monomers with alkenyl substituents were also studied. Once the synthesis of these compounds was achieved, the extent of interaction was studied using UV-visible and fluorescence spectroscopy and molecular modelling. In order to gain a true indication of the extent of interaction in a dyad, the effect of the bridge as a substituent must be accounted for. This was achieved by studying the series of monomers by UV-visible and fluorescence spectroscopy. The increased conjugation resulting from mono- and bis-alkenyl substituents results in a red shift of the origin of transition energies in the absorption spectrum which is accompanied by a broadened and less intense Soret band and an increase in the intensity of the Q bands. The emission of these compounds also displays an increase in Stokes shift and a loss of vibronic coupling due to the increased conjugation. The serendipitous synthesis of three asymmetric meso-β ethene-linked porphyrin dyads was achieved by the use of palladium-catalysed Heck coupling of mesoethenyl- with meso-bromoporphyrins. A possible mechanism for this meso to β rearrangement was proposed. A series of nine meso-meso ethene-linked dyads was synthesised by palladium-catalysed Suzuki coupling of meso-(2-iodoethenyl)- with meso-borolanylporphyrins. All of these dyads were characterised by 1D and 2D NMR as well as MS analysis. The absorption spectra of ethene-linked dyads exhibit a split Soret band and a red-shifted and intensified HOMO-LUMO band. In the meso-β dyads, the degree of splitting in the Soret band is sufficient only to generate a shoulder on the red edge, whereas in the meso-meso dyads two separate bands appear. The extent of splitting is believed to be an indication of the amount of porphyrin-porphyrin interaction. The fluorescence profiles of the dyads change dramatically depending upon the central substituents in the porphyrins and the wavelength used for irradiation, which suggests that different conformations of these compounds give rise to different parts of their absorption and emission profiles. The fluorescence profiles of the dyads also do not reflect their absorption profiles, and therefore the excitation of the dyad is believed to be accompanied also by a change in geometry. All ethene-linked dyads exhibited an anti-Stokes shift, and the excitation spectra of the different parts of the fluorescence envelope also support the possibility of different conformers contributing to the fluorescence spectra. Molecular mechanics and time-dependent quantum mechanical calculations were performed on seven ethene-linked porphyrin dyads. These calculations further support the proposal of different conformations contributing to the physical properties of ethene-linked dyads. Electronic structure calculations also show considerable electron density on the alkene for the meso-meso ethene-linked dyads, which highlights the important influence of this bridge upon the electronic nature of these conjugated diporphyrins.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references. Also available in print.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009. / Committee Chair: Dr. Uwe H.F. Bunz; Committee Member: Dr. Andrew Lyon; Committee Member: Dr. Laren Tolbert; Committee Member: Dr. Nicholas Hud; Committee Member: Dr. Sherry Michele Owen. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references. Also available in print.

Thesis (Ph.D.) - University of St Andrews, March 2008.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2007. / Tolbert, Laren, Committee Member ; Weck, Marcus, Committee Member ; Bunz, Uwe, Committee Chair ; Srinivasarao, Mohan, Committee Member.

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