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by Ka Lok Cheng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 115-122). / Abstracts in English and Chinese. / Abstract --- p.i / Abstract (in Chinese) --- p.ii / Acknowledgement --- p.iii / Table of Contents --- p.iv / List of Figures --- p.viii / List of Tables --- p.xi / Abbreviations --- p.xii / Chapter PART I --- SYNTHESIS OF FERROCENE-CONTAINING PUSH-PULL DIPHENYLPORPHYRINS --- p.1 / Chapter Chapter 1 --- Introduction --- p.2 / Chapter 1.1 --- Introduction to Nonlinear Optics --- p.2 / Chapter 1.1.1 --- Interactions of Light with Matters --- p.2 / Chapter 1.1.2 --- Structural Requirements of Second-Harmonic Generating Molecules --- p.4 / Chapter 1.2 --- Ferrocene as an Electron Donor in Second Harmonic Generating Molecules --- p.7 / Chapter 1.3 --- Porphyrin as a Platform of Second Harmonic Generating Molecules --- p.16 / Chapter 1.4 --- Target Molecules of this Project --- p.22 / Chapter Chapter 2 --- Result and Discussion --- p.23 / Chapter 2.1 --- Preparation of Alkynyl Fragments --- p.23 / Chapter 2.1.1 --- Preparation of 2-ferrocenylethyne (24) --- p.23 / Chapter 2.1.2 --- Preparation of 1 -ethynyl-4-nitrobenzene (26) --- p.24 / Chapter 2.1.3 --- "Preparation of l-ethynyl-4-(N,N-dimethylaminophenyl) benzene (28)" --- p.25 / Chapter 2.2 --- Preparation of Porphyrin Precursors --- p.26 / Chapter 2.3 --- "Synthesis and Characterizations of 5-(2'-Ferrocenylethynyl)-l5- formyl-10,20-diphenylporphyrinatonickel(II) (36)" --- p.29 / Chapter 2.4 --- "Synthesis and Characterizations of 5-(2',2'-Dicyanoethenyl)-l5- (2""-Ferrocenylethynyl)-10,20-diphenylporphyrinatonickel(II) (38)" --- p.33 / Chapter 2.5 --- "Synthesis and Characterizations of 5-Ferrocenylethynyl-l 5-(4""- nitrophenylethynyl)-10,20-diphenylporphyrinatonickel(II) (40)" --- p.37 / Chapter 2.6 --- "Synthesis and Characterizations of 5-Ferrocenylethynyl-l 5-(4'- (N,N-dimethylamino)phenyl)ethynyl)-10,20-diphenyl porphyrinatonickel(II) (47)" --- p.43 / Chapter 2.7 --- Conclusion for Part One --- p.47 / Chapter Chapter 3 --- Experimental Section --- p.48 / Chapter 3.1 --- General Information --- p.48 / Chapter 3.2 --- Physical Measurements --- p.48 / Chapter 3.3 --- Preparation of Alkynyl Fragments --- p.49 / Chapter 3.4 --- Preparation of Some Known Porphyrins --- p.54 / Chapter 3.5 --- "Synthesis of Ferrocenyl ""Push-pull"" Porphyrin" --- p.58 / Chapter PART II --- LIGHT-HARVESTING NAPHTHALENE-PHTHALOCYANINE SYSTEMS --- p.65 / Chapter Chapter 4 --- Introduction --- p.55 / Chapter 4.1 --- Porphyrin-based Light-harvesting systems --- p.66 / Chapter 4.1.1 --- Multiporphyrins --- p.57 / Chapter 4.1.2 --- Carotenoid-porphyrins --- p.74 / Chapter 4.1.3 --- Boron-dipyrrin porphyrins --- p.75 / Chapter 4.1.4 --- Anthracene-porphyrin systems --- p.73 / Chapter 4.1.5 --- Dendritic porphyrins --- p.79 / Chapter 4.2 --- Phthalocyanine-based Light-harvesting systems --- p.80 / Chapter 4.3 --- Objective of this project --- p.83 / Chapter Chapter 5 --- Result and Discussion --- p.84 / Chapter 5.1 --- Preparation of naphthalene-phthalocyanine systems --- p.84 / Chapter 5.1.1 --- Synthesis of zinc(II) tetra( 1 -naphthoxy)phthalocyanines --- p.84 / Chapter 5.1.2 --- Synthesis of tetra[2-(l´ة-naphthoxy)ethoxy] phthalocyaninatozinc(II) (83) --- p.85 / Chapter 5.1.3 --- "Synthesis of 2,3,9,10,16,17,23,24-octa( 1 -naphthoxy) phthalocyaninatozinc(II) (89)" --- p.86 / Chapter 5.2 --- Absorption spectra of naphthalene-phthalocyanine systems --- p.88 / Chapter 5.2.1 --- Absorption spectra at different concentrations --- p.89 / Chapter 5.2.2 --- Comparison of the absorption spectra of the naphthoxy phthalocyanine with the spectra of the mixture of corresponding 1-ethoxynaphthalene and alkoxyphthalocyanines --- p.92 / Chapter 5.3 --- Fluorescence Quantum yields of Naphthalene-Phthalocyanine Systems --- p.96 / Chapter 5.4 --- Singlet-singlet energy transfer efficiencies of Naphthalene- phthalocyanine Systems --- p.98 / Chapter 5.4.1 --- Methodology --- p.98 / Chapter 5.4.2 --- Determination of energy transfer quantum yields --- p.99 / Chapter 5.5 --- Conclusion for Part II --- p.103 / Chapter Chapter 6 --- Experimental Section --- p.104 / Chapter 6.1 --- General Information --- p.104 / Chapter 6.2 --- Synthesis of tetra( 1 -naphthoxy)phthalocyanines --- p.105 / Chapter 6.3 --- Synthesis of tetra(naphthoxyethoxy)phthalocyanine --- p.108 / Chapter 6.4 --- Synthesis of octa( 1 -naphthoxy)phthalocyanine --- p.111 / References --- p.115 / Appendix A: Spectra of new compounds not discussed in the main text --- p.123 / Appendix B: X-ray crystallographic data of compound40 --- p.133

The main goal of this thesis was to explore the role of H-bonding interactions in ferrocene peptide conjugates at the molecular and supramolecular level. With the help of detailed spectroscopic and crystallographic studies, the intermolecular association of a range of conjugates was studied and described here. It was shown that C-terminal modifications directed the supramolecular assembly. In the case of Fc[CO-Gly-Val-OH]2, the C-terminal carboxylate group directed intermolecular interactions, causing formation of a supramolecular architecture that was characterized by large solvent-filled hydrophobic channels. In the absence of this directional group, as was the case in Fc[CO-Leu-Val-OMe]2 extended β-sheets were formed. Hierarchical self-assembly of disubstituted ferrocene peptide conjugates possessing Gly-Val-Phe and Gly-Val-Phe-Phe peptide substituents gave rise to nano- and micro-sized assemblies. Spontaneous self-assembly of Fc-peptides through intra-and intermolecular hydrogen bonding interactions induced supramolecular building blocks, which further associated to fibers, large fibrous crystals, and twisted ropes. Next, intermolecular H-bonding interactions were studied using a surface-based approach. A fragment of the amyloid-beta (Aβ) peptide was bound to a gold surface through a C-terminal Cys. Various aspects of the peptide film were examined using different electrochemical and surface analytical techniques. The interaction of Congo red and of Lys-Leu-Val-Phe-Phe with the immobilized Aβ fragment was studied using electrochemical methods, showing responses that indicated intermolecular interactions. This surface approach was used to probe the interaction of a series of ferrocene peptides (Fc-CO-Leu-Val-Phe-Phe-OX and Fc-CO-Lys(Boc)-Leu-Val-Phe-Phe-OX with X=H and Me) with the surface-bound Aβ fragment. Biomolecular interactions between Fc-peptides and the Aβ-modified surface were studied by electrochemical methods. The current response of the Fc redox process was modulated by the interaction with the Aβ-modified surface.

Tau, a microtubule associated protein, has been implicated in the formation of neurofibrillary tangles, a hallmark of Alzheimer’s disease.1 Resulting from the hyperphosphorylation of tyrosine, serine and threonine residues, protein kinases play an intricate role in the pathway of NFT formation.2 While a number of serine/ threonine kinases such as Glycogen Synthase Kinase 3 beta, have been implicated in the hyperphosphorylation of tau, and it is now believed that tyrosine phosphorylation plays a role. It appears that the degree to which tau is phosphorylated, and region in which phosphorylation occurs play a critical role in aggregate formation. Here we present the use of Ferrocene bioconjugates to monitor tyrosine-mediated hyperphosphorylation and aggregation. Electrochemistry, electron microscopy, surface plasmon resonance, Time of Flight Secondary Ion Mass Spectrometry and X-Ray Photoelectron Spectroscopy were used to gain insight into the role of tyrosine phosphorylation on hyperphosphorylation.

Tau, a microtubule associated protein, has been implicated in the formation of neurofibrillary tangles, a hallmark of Alzheimer’s disease.1 Resulting from the hyperphosphorylation of tyrosine, serine and threonine residues, protein kinases play an intricate role in the pathway of NFT formation.2 While a number of serine/ threonine kinases such as Glycogen Synthase Kinase 3 beta, have been implicated in the hyperphosphorylation of tau, and it is now believed that tyrosine phosphorylation plays a role. It appears that the degree to which tau is phosphorylated, and region in which phosphorylation occurs play a critical role in aggregate formation. Here we present the use of Ferrocene bioconjugates to monitor tyrosine-mediated hyperphosphorylation and aggregation. Electrochemistry, electron microscopy, surface plasmon resonance, Time of Flight Secondary Ion Mass Spectrometry and X-Ray Photoelectron Spectroscopy were used to gain insight into the role of tyrosine phosphorylation on hyperphosphorylation.

Ferrocene-peptide conjugates represent a hybrid area between organometallic chemistry and biochemistry. In these bioconjugates, the ferrocene (Fc) moiety can serve as molecular scaffold, chromophore, sensitive probe, biological marker, redox active site, etc. Disubstituted Fc systems, in which both cyclopentadienyl rings are substituted, provide influence over the supramolecular structure of the assemblies, and serve as starting materials for the design of electronic biomaterials. Recently, 1'-amino-ferrocene-1-carboxylic acid (Fca) and 1,1'-diaminoferrocene Fc[NH2]2 were recognized as useful tools in bioorganometallic chemistry. This work sketches some novel preparative and structural aspects of Fc-peptide conjugates and explores their applications as biosensors and as polymeric materials. <p>First, I demonstrated that Fca invariably induces a turn-like structure, which is stable in solution and the solid state. The obtained results showed different behaviour for Fca peptides depending on the chirality and position of the attached amino acid. The axial chirality of the Fca is completely dependent on the chirality of the first amino acid attached to the amino terminal of the Fca group.<p>Second, I was able to develop a surface based sensor for the electrochemical detection of papain based on Fc-peptide conjugates. The idea was to place a surface-bound redox probe in close proximity to the electrode surface. In addition, the redox-active Fca label will be part of the recognition site but will not interfere with the recognition process. My sensor provides an attractive alternative for the electrochemical detection of non-labelled non-redox active proteins, which under current detection schemes remains a significant challenge.<p>This work represents a truly important proof of concept for establishing this novel bioorganometallic approach for the electrochemical detection of important biological targets.<p>Last, I was successful in developing a very convenient method to synthesize 1,1'-bis(tert-butoxycarbonylamino)ferrocene as a stable derivative of Fc[NH2]2. This new synthetic approach has circumvented the problems encountered with the explosive diazide usually used as a precursor in the conventional synthons of Fc[NH2]2. Building on this achievement, a series of novel peptide-like oligomeric and polymeric ferrocenyl-amides were synthesized and fully characterized. The electrochemical investigations on these polymers suggested unresolved or no electronic interaction between the ferrocene groups in all systems. These results may reveal the influence of the amide groups on suppressing the electronic interaction between the iron centers in my polymers. <p>Thus, my systematic work on Fc-peptide conjugates lays solid foundations in the fields of structural control, biosensors, and material science.

Ferrocene-peptide conjugates represent a hybrid area between organometallic chemistry and biochemistry. In these bioconjugates, the ferrocene (Fc) moiety can serve as molecular scaffold, chromophore, sensitive probe, biological marker, redox active site, etc. Disubstituted Fc systems, in which both cyclopentadienyl rings are substituted, provide influence over the supramolecular structure of the assemblies, and serve as starting materials for the design of electronic biomaterials. Recently, 1'-amino-ferrocene-1-carboxylic acid (Fca) and 1,1'-diaminoferrocene Fc[NH2]2 were recognized as useful tools in bioorganometallic chemistry. This work sketches some novel preparative and structural aspects of Fc-peptide conjugates and explores their applications as biosensors and as polymeric materials. <p>First, I demonstrated that Fca invariably induces a turn-like structure, which is stable in solution and the solid state. The obtained results showed different behaviour for Fca peptides depending on the chirality and position of the attached amino acid. The axial chirality of the Fca is completely dependent on the chirality of the first amino acid attached to the amino terminal of the Fca group.<p>Second, I was able to develop a surface based sensor for the electrochemical detection of papain based on Fc-peptide conjugates. The idea was to place a surface-bound redox probe in close proximity to the electrode surface. In addition, the redox-active Fca label will be part of the recognition site but will not interfere with the recognition process. My sensor provides an attractive alternative for the electrochemical detection of non-labelled non-redox active proteins, which under current detection schemes remains a significant challenge.<p>This work represents a truly important proof of concept for establishing this novel bioorganometallic approach for the electrochemical detection of important biological targets.<p>Last, I was successful in developing a very convenient method to synthesize 1,1'-bis(tert-butoxycarbonylamino)ferrocene as a stable derivative of Fc[NH2]2. This new synthetic approach has circumvented the problems encountered with the explosive diazide usually used as a precursor in the conventional synthons of Fc[NH2]2. Building on this achievement, a series of novel peptide-like oligomeric and polymeric ferrocenyl-amides were synthesized and fully characterized. The electrochemical investigations on these polymers suggested unresolved or no electronic interaction between the ferrocene groups in all systems. These results may reveal the influence of the amide groups on suppressing the electronic interaction between the iron centers in my polymers. <p>Thus, my systematic work on Fc-peptide conjugates lays solid foundations in the fields of structural control, biosensors, and material science.

Structural determinations and electrochemical properties in the series of multinuclear ferrocenyl¡Vethynyl complexes with formula [(£b5-C5H5)(P2)MII-C¡ÝC-(fc)n-C¡ÝC-MII(P2)(£b5-C5H5)] (fc = ferrocenyl; M = Fe(II), Os(II); P2 = Ph2PCH2CH2PPh2 (dppe)) are reported. These complexes undergo sequential reversible oxidation events from 0.0 to 1.0 V referred to the Ag/AgCl electrode in anhydrous CH2Cl2 solution and the low-potential waves have been assigned to the two end-capped metallic centers. The magnitude of the electronic coupling between the two terminal metallic centers in the series of complexes was estimated by the electrochemical technique. Based on the correlation between the ¡µE1/2 values and the second redox potentials of the end-capping metallic centers in the series of complexes, a qualitative explanation for the difference of the electronic coupling is given. Furthermore, we attempt to fabricate the SAMs of ferrocenyl-ethynyl molecules on gold surface and confirmed by XPS spectrum and the RAIR spectrum. CV and CA electrochemistry technique was employed in studied electron transfer rate (k).

The main goal of this thesis was to explore the role of H-bonding interactions in ferrocene peptide conjugates at the molecular and supramolecular level. With the help of detailed spectroscopic and crystallographic studies, the intermolecular association of a range of conjugates was studied and described here. It was shown that C-terminal modifications directed the supramolecular assembly. In the case of Fc[CO-Gly-Val-OH]2, the C-terminal carboxylate group directed intermolecular interactions, causing formation of a supramolecular architecture that was characterized by large solvent-filled hydrophobic channels. In the absence of this directional group, as was the case in Fc[CO-Leu-Val-OMe]2 extended β-sheets were formed. Hierarchical self-assembly of disubstituted ferrocene peptide conjugates possessing Gly-Val-Phe and Gly-Val-Phe-Phe peptide substituents gave rise to nano- and micro-sized assemblies. Spontaneous self-assembly of Fc-peptides through intra-and intermolecular hydrogen bonding interactions induced supramolecular building blocks, which further associated to fibers, large fibrous crystals, and twisted ropes. Next, intermolecular H-bonding interactions were studied using a surface-based approach. A fragment of the amyloid-beta (Aβ) peptide was bound to a gold surface through a C-terminal Cys. Various aspects of the peptide film were examined using different electrochemical and surface analytical techniques. The interaction of Congo red and of Lys-Leu-Val-Phe-Phe with the immobilized Aβ fragment was studied using electrochemical methods, showing responses that indicated intermolecular interactions. This surface approach was used to probe the interaction of a series of ferrocene peptides (Fc-CO-Leu-Val-Phe-Phe-OX and Fc-CO-Lys(Boc)-Leu-Val-Phe-Phe-OX with X=H and Me) with the surface-bound Aβ fragment. Biomolecular interactions between Fc-peptides and the Aβ-modified surface were studied by electrochemical methods. The current response of the Fc redox process was modulated by the interaction with the Aβ-modified surface.

Carbon nanotubes (CNTs) functionalized/embedded with ferromagnetic particles have several important advantages as materials for magnetic applications. The presence of ferromagnetic particles in a carbon matrix can substantially change the magnetic properties of CNT-based composites. For example, iron filled CNTs have been used as probes in magnetic force microscopy (MFM), and have potential in magnetic data storage applications. In addition, encapsulation in nanotubes provides iron nanoparticles with resistance to oxidation and mechanical damage. Chemical vapor deposition (CVD) is one of the most common single-step processes for the fabrication of high quality carbon nanotubes containing varying amounts of embedded ferromagnetic particles. This process results in the effective magnetic functionalization of CNTs and opens the door to numerous new applications. However, in order to optimize these materials for any application, their properties need to be understood. This study explores the ferromagnetic properties of carbon nanotubes containing nano-scaled iron particles which were derived from thermal decomposition of ferrocene. Both room temperature as well as low-temperature magnetic measurements will be presented and the results analyzed in the light of available theory.