本論文論述了一系列包含疏水性樹枝狀烷烴基團的兩親性分子的合成和表徵、在水溶液中的自組裝性質及其對小分子客體的增溶能力的研究。第一部分為第一至第三代兩親性“樹枝直鏈雜化物“[Gn]-OEG₈ 128-130, 該類雜化物含有的樹枝狀烷烴基團以醯胺鍵在其核心連接親水性八聚乙二醇基團。這些兩親性分子在水溶液中自組裝形成膠束結構。此外我們還製備了烷烴雙鏈[Dn]-OEG₈及烷烴單鏈[Ln]-OEG₈同分異構體，並研究其疏水基團的支化程度對自組裝性質的影響。第二部分,我們通過銅()催化-疊氮-端基炔的環加成反應（CuAAC）對第〇代至第二代樹枝狀烷烴聚合物OEG-[Gn]-dendrimer 171-173進行表面修飾，製備了具有親水性四聚乙二醇外殼的樹枝狀兩親性分子，並研究其疏水基團大小對自組裝性質及對小分子客體增溶能力的影響。 / 所有化合物的結構均通過核磁共振氫譜、碳譜、質譜和凝膠排阻色譜進行表徵。其自組裝性質如臨界膠束/聚集濃度（CMC/CAC）、微環境極性、粒子尺寸分佈和藥物承載能力的大小則通過熒光光譜、紫外可見光譜和光散射等方法進行研究。實驗結果表明：（一）臨界膠束/聚集濃度隨著疏水基團的增大而減小；（二）臨界膠束/聚集濃度隨著疏水基團的支化程度的提高而增加（即直鏈<雙鏈<樹枝狀）；（三）支化程度較高的兩親性分子會形成較為鬆散的膠束結構，其核心的極性也會相應提高；（四）膠束核心的極性隨著樹枝狀聚合物的代數增加而降低。這些結論均與疏水烷烴基團的尺寸（即長度或代數）及結構（即支化程度）相關聯，並與文獻中的計算擬合結果相符。 / 同時本工作也發現了一些與文獻的擬合結果不吻合的實驗結果：（一）由於長鏈烷烴的自卷現象，烷烴單鏈[L2]-OEG₈比其雙鏈[D2]-OEG₈異構體具有更高的臨界膠束濃度；（二）基於光散射實驗結果，具有“單分子膠束“結構的樹枝狀烷烴聚合物OEG-[Gn]-dendrimer 171-173能夠形成大型膠束聚集體；（三）這些樹枝狀烷烴聚合物的增溶能力與其疏水內核的大小並不相關。後兩個結果反映出由於大型兩親性分子具有多種自組裝方式，其膠束性質及增溶能力具有相當的複雜性和不確定性。 / 在此之前，相關研究工作主要集中在理論計算和電腦模擬部分，本論文首次以實驗手段研究具有不同支化程度的疏水樹枝狀烷烴基團的兩親性分子及其自組裝性質。我們的大部分結果證實了文獻報導的結論，並指出了一些模擬計算忽略的問題，為以後的相關工作提供重要的數據支援。 / This thesis described the synthesis, self-assembling and/or encapsulation properties of two different classes of amphiphilic dendritic compounds. The first set of amphiphilic dendrons [Gn]-OEG₈ 128-130 (n = 1-3) are dendritic-linear hybrid molecules that have a hydrophobic hydrocarbon (HC) dendron connected to a hydrophilic octa(ethylene glycol) chain. The effect of the branching architecture on their self-assembling properties was then compared to that of their doubly branched [Dn]-OEG₈ and linear [Ln]-OEG₈ analogs, which were also prepared in this study. The second set of compounds are a series of amphiphilic dendrimers OEG-[Gn]-dendrimer 171-173 (n = 0-2) decorated with surface tetra(ethylene glycol) chains on the periphery of a HC dendrimer. The size effect of the HC sector on their self-assembling and drug encapsulation properties with indomethacin was examined. / The structures of all compounds were characterized by ¹H and ¹³C NMR spectroscopy, mass spectrometry, and gel permeation chromatography. Their self-assembling and host-guest complexation properties, such as critical micellar/association concentrations (CMC/CAC), micro-environmental polarity, particle size distributions and drug loading capacity were investigated by various physical techniques such as UV and fluorescent spectroscopy, as well as static and dynamic laser light scattering. Based on our experimental findings, we were able to confirm the results obtained from earlier theoretical simulations. First, for both series of dendritic amphiphiles, their CMC/CAC values decreased with increasing size of the hydrophobic segment. Second, with the same molecular formula and hydrophobic/lipophilic balance (HLB), amphiphiles containing a hydrophobic segment of a higher branching degree possessed a higher CMC/CAC value. Third, the micellar core of amphiphiles with a dendritic hydrophobic sector was more polar than that of non-dendritic amphiphiles having the same molecular formula. Fourth, the micellar core of a dendritic amphiphile of a higher generation was more non-polar than that of the lower generation analogues. All the findings could be correlated to the size (i.e. length or generation) and the architecture (i.e. branching pattern) of the hydrophobic HC sector. / Three unusual findings that deviated from previous theoretical simulations were noted. First, the doubly branched [D2]-OEG₈ 132 was found to have a lower CMC value than the linear [L2]-OEG₈ 134. This anomaly could be rectified if backfolding of the linear HC chain is taken into consideration. Second, based on DLS study, it was noted that the ‘unimolecular’ OEG-[Gn]-dendrimers 171-173 were capable of forming ‘giant’ aggregates in aqueous solutions. Third, their drug loading capacity did not correlate to the size of the hydrophobic HC sector. The latter two findings revealed the complexity in dealing with the understanding of the self assembling and host-guest complexation processes of these large amphiphile dendrimers. Prior to our work, only theoretical calculations had been carried out. The work described in this thesis serves to provide solid experimental evidence in support of the theoretical simulations and offer additional insights that were previously neglected in this subject area. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Liang, Yuting. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 149-156). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Contents --- p.i / Acknowledgments --- p.vi / Abstract --- p.vii / Abbreviations --- p.xi / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- General --- p.1 / Chapter 1.2 --- Construction of Dendrimers --- p.2 / Chapter 1.2.1 --- The Divergent Approach --- p.2 / Chapter 1.2.2 --- Convergent Approach --- p.3 / Chapter 1.2.3 --- Modification --- p.4 / Chapter 1.2.3.1 --- Modification at the Focal Point --- p.5 / Chapter 1.2.3.2 --- Modification on the Periphery --- p.6 / Chapter 1.2.4 --- CuAAC ‘Click’ Reaction in Dendrimer Synthesis --- p.8 / Chapter 1.3 --- Physical Properties of Dendrimers --- p.13 / Chapter 1.3.1 --- Location of End Groups --- p.13 / Chapter 1.3.2 --- Comparison of Dendritic -- Linear Analogs --- p.15 / Chapter 1.3.3 --- Generation Dependence -- Dendritic Effect --- p.16 / Chapter 1.4 --- Dendritic Amphiphiles --- p.18 / Chapter 1.4.1 --- Amphiphiles and their aggregations --- p.18 / Chapter 1.4.2 --- Dendritic Amphiphiles --- p.20 / Chapter 1.4.2.1 --- Unimolecular Micelles --- p.20 / Chapter 1.4.2.2 --- Bolaamphiphiles --- p.22 / Chapter 1.4.2.3 --- Amphiphilic dendritic-linear polymer hybrids --- p.23 / Chapter 1.4.2.4 --- Facially amphiphilic dendrimers --- p.25 / Chapter 1.5 --- Applications of Dendritic Amphiphiles --- p.27 / Chapter 1.5.1 --- Drug Delivery --- p.27 / Chapter 1.5.1.1 --- Encapsulation via Non-Covalent Interactions --- p.27 / Chapter 1.5.1.2 --- Covalent Bonded Dendrimer -- Drug Conjugates --- p.29 / Chapter 1.5.2 --- Biomimetics --- p.30 / Chapter Chapter 2 --- Architecture and Generation Effects on the Self-Assembly of Amphiphilic Dendritic-Linear Polymer Hybrids --- p.33 / Chapter 2.1 --- Packing Parameters --- p.33 / Chapter 2.2 --- Computer Simulations --- p.35 / Chapter 2.3 --- Experimental studies --- p.38 / Chapter 2.4 --- Methods --- p.40 / Chapter 2.4.1 --- Fluorescence Studies --- p.41 / Chapter 2.4.2 --- Laser Light Scattering --- p.42 / Chapter 2.4.3 --- Electron Microscopy --- p.42 / Chapter 2.5 --- Research Objectives --- p.43 / Chapter Chapter 3 --- Design, Synthesis and Characterization of Novel Amphiphilic Dendritic-Linear Polymer Hybrids --- p.44 / Chapter 3.1 --- Design --- p.45 / Chapter 3.1.1 --- Dendritic-Linear Polymer Hybrids: Hydrocarbon Dendrons (Gn) and Their Linear (Ln) and Doubly Branched (Dn) Analogs --- p.45 / Chapter 3.1.2 --- Selection of Hydrophilic Block: Oligo(Ethylene Glycol) Chains --- p.47 / Chapter 3.2 --- Synthesis --- p.48 / Chapter 3.2.1 --- Preparation of Amino- and Azido- Functionalized Oligoethylene Glycols --- p.48 / Chapter 3.2.2 --- Preparation of [Gn]-COOH, [Dn]-COOH and [Ln]-COOH --- p.49 / Chapter 3.2.3 --- Preparation of [Gn]-OEG₈, [Dn]-OEG₈ and [Ln]-OEG₈ --- p.52 / Chapter 3.3 --- Characterization --- p.53 / Chapter 3.3.1 --- ¹H NMR Spectroscopy --- p.53 / Chapter 3.3.2 --- ¹³3C NMR spectroscopy --- p.55 / Chapter 3.3.3 --- Mass Spectrometry --- p.56 / Chapter 3.3.4 --- Gel Permeation Chromatography --- p.57 / Chapter 3.3.5 --- Physical Appearance and Melting Point --- p.59 / Chapter 3.4 --- Self-assembly Behavior of [Gn]-OEG₈, [Dn]-OEG₈ and [Ln]-OEG₈ in Water --- p.60 / Chapter 3.4.1 --- Critical Micellar Concentration (CMC) --- p.60 / Chapter 3.4.1.1 --- Effect of the size of hydrophobic sector --- p.63 / Chapter 3.4.1.2 --- Effect of Branching on Micelle Formation --- p.64 / Chapter 3.4.2 --- Microenvironment Polarity inside the Micelles --- p.67 / Chapter 3.4.3 --- Hydrodynamic Radius (R[subscript h]) --- p.71 / Chapter 3.5 --- Summary --- p.73 / Chapter Chapter 4 --- Amphiphilic Unimolecular Micelles: Multiple Surface Functionalized Hydrocarbon-Based Dendrimers --- p.75 / Chapter 4.1 --- Design --- p.75 / Chapter 4.1.1 --- The Surface Acetonide-Protected Hydrocarbon Dendrons --- p.76 / Chapter 4.1.2 --- Peripheral Post-Modification via CuAAC ‘click’ chemistry --- p.77 / Chapter 4.2 --- Synthesis --- p.78 / Chapter 4.2.1 --- Preparation of Amphiphilic HC Dendrimers with a Peripheral Acetylene Layer --- p.78 / Chapter 4.2.1.1 --- Preparation of Amphiphilic Dendrimers via CuAAC ‘click’ reaction --- p.83 / Chapter 4.3 --- Characterization --- p.85 / Chapter 4.3.1 --- ¹H NMR Spectroscopy --- p.85 / Chapter 4.3.1.1 --- Dendrons/Dendrimers with Acetonide-Protected or Polyol Surface --- p.86 / Chapter 4.3.1.2 --- Dendrons/Dendrimers with Multiple Acetylene Functionalized Surface --- p.87 / Chapter 4.3.1.3 --- Amphiphilic Dendrimers with Triazolo OEG Surface --- p.89 / Chapter 4.3.2 --- ¹³C NMR spectroscopy --- p.90 / Chapter 4.3.2.1 --- Dendrons/Dendrimers with Acetonide-Protected or Polyol Surface --- p.90 / Chapter 4.3.2.2 --- Dendrons/Dendrimers with Multiple Acetylene Surface --- p.91 / Chapter 4.3.2.3 --- Amphiphilic Dendrimers with Triazolo OEG Surface Groups --- p.93 / Chapter 4.3.3 --- Mass Spectrometry --- p.94 / Chapter 4.3.4 --- Gel Permeation Chromatography --- p.98 / Chapter 4.4 --- Micellar Properties of Amphiphilic OEG-[Gn]-Dendrimers 171-173 --- p.101 / Chapter 4.4.1 --- Critical Micellar Concentration (CMC) --- p.101 / Chapter 4.4.2 --- Particle Size Distribution and Aggregation Number --- p.105 / Chapter 4.5 --- Encapsulation with Hydrophobic Guest Molecule -- Indomethacin --- p.107 / Chapter 4.5.1 --- Hydrodynamic Radius of IMC Loaded Particles --- p.107 / Chapter 4.5.2 --- Loading Efficiency --- p.109 / Chapter 4.5.2.1 --- Effect of Amphiphile Concentration on Loading Efficiency --- p.109 / Chapter 4.5.3 --- Release Profile --- p.113 / Chapter 4.6 --- Summary --- p.113 / Chapter Chapter 5 --- Conclusions --- p.115 / Chapter Chapter 6 --- Experimental --- p.117 / Chapter 6.1 --- General Methods --- p.117 / Chapter 6.2 --- Synthesis --- p.118 / Chapter 6.3 --- Characterization of Micellar Properties --- p.143 / Chapter 6.3.1 --- Preparation of Micellar Solutions --- p.143 / Chapter 6.3.2 --- Preparation of Pyrene Loaded Samples --- p.143 / Chapter 6.3.3 --- Determination of CMCs from Fluorescence Probe Method --- p.143 / Chapter 6.3.4 --- Laser Light Scattering --- p.146 / Chapter 6.3.5 --- Transmission Electron Microscopy --- p.147 / Chapter 6.4 --- Drug Encapsulation and Release Study --- p.147 / Chapter 6.4.1 --- Preparation of Indomethacin (IMC) Loaded Samples --- p.147 / Chapter 6.4.2 --- Determination of IMC Loading Amount --- p.147 / Chapter 6.4.3 --- In vitro Drug Release Profile --- p.148 / Reference --- p.149 / Chapter Appendix --- List of Spectra --- p.Ai

Keung, Yiu Cheung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 58-59). / Abstracts in English and Chinese. / Contents --- p.i / Acknowledgement --- p.iii / Abstract --- p.iv / Abbreviations and Acronyms --- p.vi / Chapter Chapter 1 - --- Amphiphilic Dendrons and Gene Transfection / Chapter 1.1 --- Introduction to Dendrimers and Gene Transfection --- p.1 / Chapter 1.2 --- Overview of Gene Transfection Vectors in the Literature --- p.4 / Chapter 1.2.1 --- Viral Vectors --- p.5 / Chapter 1.2.2 --- Non-viral Vectors --- p.5 / Chapter 1.2.2.1 --- Cationic Lipids --- p.6 / Chapter 1.2.2.2 --- Cationic Polymers --- p.7 / Chapter 1.2.2.3 --- Cationic Dendrimers --- p.8 / Chapter Chapter 2 - --- En Route to Dendritic Amphiphilic Vectors / Chapter 2.1 --- Introduction to the Design of Dendritic Amphiphiles --- p.13 / Chapter 2.2 --- Barriers to Gene Transfection --- p.13 / Chapter 2.2.1 --- Cellular Barriers --- p.14 / Chapter 2.2.2 --- Extracellular Barriers --- p.16 / Chapter 2.2.3 --- Material Design Considerations --- p.17 / Chapter 2.3 --- Amphiphilic Vector Design Strategy --- p.18 / Chapter 2.4 --- Summary --- p.21 / Chapter Chapter 3 - --- "Design, Synthesis and Structural Characterization of New Amphiphilic Dendrons for Gene Transfection" / Chapter 3.1 --- Design of the New Amphiphilic Dendrons . --- p.23 / Chapter 3.1.1 --- Incorporation of Hydrocarbon Dendrons --- p.24 / Chapter 3.1.2 --- Synthesis Feasibility --- p.24 / Chapter 3.2 --- Synthesis of the New Amphiphilic Dendrons --- p.25 / Chapter 3.3 --- Characterization of the Intermediates and Targeted Amphiphilic Dendrons --- p.28 / Chapter 3.3.1 --- 1H NMR Spectroscopy --- p.28 / Chapter 3.3.2 --- I3C NMR Spectroscopy --- p.30 / Chapter 3.3.3 --- Mass Spectrometry --- p.33 / Chapter 3.3.4 --- Critical Micelle Concentration --- p.35 / Chapter 3.4 --- Conclusion --- p.38 / Chapter Chapter 4 - --- Determination of Transfection Efficiency and Cytotoxicity / Chapter 4.1 --- Preparation of the Amphiphilic Dendrons for Transfection --- p.39 / Chapter 4.2 --- Transfection Efficiencies of the Amphiphilic Dendrons 1-10 --- p.39 / Chapter 4.3 --- Cytotoxicity Assay --- p.42 / Chapter 4.4 --- Conclusions --- p.44 / Chapter Chapter 5 - --- Experimental Procedures / Chapter 5.1 --- General Information --- p.46 / Chapter 5.2 --- Experimental Procedures --- p.47 / References --- p.58 / Appendix / NMR Spectra --- p.60

"March 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (p. 116-126). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Chapter 1 gives a brief introduction about dendrimers, their synthesis, characterization methods and applications. Chapter 2 summarizes the current research progress on the various dendritic nanostructures, namely, dendronized polymers, dendrimer-linear polymer hybrids, poly(dendrimer)s and poly(dendrimer) networks. In Chapter 3, we reported the detailed synthesis of the two series of dendritic macromonomers (S-Gn and L-Gn, n = 1--3) with different branch lengths (C-O for S-Gn and C--C--C--O for L-Gn) and hence varying structural flexibilities. The structures of these dendritic compounds were characterized by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), mass spectrometry (MS) and elemental analysis. The polymerization reactions with trans -Pt-linker 65 was firstly conducted to obtain organoplatinum poly(dendrimer)s Pt-S/L-Gn 144-149. It was found that the structurally more rigid dendritic mamcromonomers (S-Gn series) have a higher degree of polymerization (DP) than the structurally more flexible one (L-Gn series) of the same generation. This was attributed to the formation of cyclic oligomers in the latter series. In Chapter 4, we investigated the polymerization behavior of the two series of dendritic macromonomers towards two other Pt-linkers of different geometry, namely, cis-Pt-linker 152 and long-trans-Pt-linker 156 to obtain poly(dendrimer)s cis-Pt-S/L-Gn 157-162 and long-trans-Pt-S/L-Gn 163-168 respectively. It was revealed that only oligomers and/or cyclic oligomers were formed in both S-Gn and L-Gn series in the former case. In contrast, poly(dendrimer)s long-trans-Pt-S/L-Gn 163-168 were obtained in high DP values and the formation of oligomers and/or cyclic oligomers was greatly suppressed. A model was proposed to account for the different polymerization outcomes based on the different steric and structural environment of the two reacting partners. A conclusion of this work and an outlook of the project were given in Chapter 5. / This thesis described the research work on the synthesis of poly(dendrimer)s using an outer-sphere--outer-sphere connection strategy. Two G1--G3 series of dendritic macromonomers having short branches ( 73-75) and long branches (76-78) containing two surfaces (functionalized acetylene surface groups) were prepared in high purity and copolymerized with three different type of platinum linkers 65, 152 and 156 to form organoplatinum poly(dendrimer)s. The structural effects of the dendritic macromonomers and platinum tinkers on the polymerization efficiency were investigated. / Cheung, Siu Yin. / "December 2009." / Adviser: Hak-Fun Chow. / Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 146-159). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Chapter 1. Bile acid derived adaptive dendrons Bile acids are naturally occurring rigid, chiral molecules with unique facial amphiphilicity making it an attractive build block for designing supramolecular systems. Synthesis of bile acid derived chiral dendrimers with acetates protecting the peripheral hydroxyl groups has already been reported by our group (Figure 1). These dendrons did not survive an attempted deprotection of the acetates, as the dendritic linkages were ester linkages. To keep the facial amphiphilicity of bile acid fragments intact, we have worked on two different synthetic strategies. Bile acid derived dendritic components having chloroacetate functional group were synthesized and the α-halo ketone was reacted with a bile acid carboxylate to generate a dendritic species with free hydroxyl group having a glyocolate spacer (Figure 2). At the same time we also were able to protect bile acid hydroxyl group as its corresponding benzyl ether and after dendron synthesis, benzyl groups were removed by hydrogenolysis to give bile acid derived dendritic components with free hydroxyl groups and simple ester linkages (Figure 2). Dye solubilization ability of these dendrons was tested. We observed that some of these structures had the ability to solubilize both a polar dye in a nonpolar solvent and/or a nonpolar dye in a polar solvent. We carried out different extraction techniques (liquid-liquid, solid-liquid) and transport experiments to establish that these dendrons can act as both as normal and inverse micellar mimics. Depending upon the polarity of the medium, this dendron (Figure 2, right) can adopt different conformation and hence this is described as an “adaptive dendron” (Figure 3). Chapter 2. Bile acid derived anion receptors We discovered that the self-condensation of 3α-chloroacetyloxy cholic acid produced a “cholaphane” with free hydroxyl groups in just two step from naturally occurring bile acid. This cyclic dimer (Figure 4) is an inside-out cyclodextrin analog having a polar interior and nonpolar outer surface. The structure of this molecule was confirmed by X-ray crystallography (Figure 5). This molecule showed a remarkable ability to bind two fluoride ions in its cavity (K1 = 1900 M-1 and K2 = 250 M-1 in CHCl3). The pair of doublets from the glycolate methylene hydrogen spacers were found to collapse to a singlet and they again reappear as a pair of doublets with increase in the concentration of fluoride. This anomalous behaviour of gylcolate methylene spacers were rationalized by MP2 calculation at the 6-31+G* level which showed that upon interaction with fluoride, electron density on C-H hydrogen decreased while that on the other geminal hydrogen increased. Detailed NMR study and interaction of fluoride with different acyclic compounds enabled us to determine the mode of fluoride binding. Based on the NMR data and calculation results, fluoride binding models were proposed involving O-H…F- and C-H…F- interactions. When the binding affinity of cyclic dimer was examined for other anions, this molecule showed weak affinity to chloride ions (K ~ 100 M-1) whereas for other bigger anion (HSO4-, H2PO4-) it showed no binding. Similar interactions were utilized to generate bile acid based tripodal geometry where those receptors were able to bind anions weakly (K ~ 100-200 M-1 for fluoride, chloride and bisulphate).

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Please refer to full text for abstract / AFRIKAANSE OPSOMMING: Sien volteks vir opsomming

Dendrimers are hyperbranched macromolecules, with branches-upon-branches architectures, precise constitutions and molecular weights of several kiloDaltons (Figure 1). The dendritic structure remains to be an influential feature in the developments of dendrimer chemistry at large. Organometallic catalysis forms an active area, wherein the dendrimers find a defined importance. A number of dendrimer types have been utilized to study organometallic catalysis that combine the dendritic architectural principles. Chapter 1 of the Thesis summarizes the advances in the dendrimer-mediated catalyses, apart from an overview of the methods adopted to synthesize dendrimers. Chapter 2 describes the synthesis of newer types of larger generation poly(propyl ether imine) (PETIM) dendrimers. The molecular structure of a sixth generation PETIM dendrimer is shown in Figure 2. The PETIM series of dendrimers are synthesized by iterative synthetic cycles of two reductions and two Michael addition reactions. Modifications of the synthetic methods were identified, so as to facilitate the synthesis and purification of the higher generation dendrimers. Formation of the PETIM dendrimers, possessing a tertiary amine as the branch juncture and ether as the linker component, is assessed systematically by routine analytical techniques. The peripheries of these dendrimers possess either alcohols or amines or carboxylic acids or esters or nitriles, thereby opening up possibilities for varied studies. Architecturally-driven effects are searched constantly while integrating dendrimers in wide ranging studies. With knowledge that un-functionalized PAMAM and PPI dendrimers show fluorescence properties, we tested the PETIM dendrimers for their luminescence property. The photophysical properties of PETIM dendrimers presenting esters, alcohols, acid salts, nitriles and amines at their peripheries were studied. The anomalous fluorescence arising from alcohol terminated PETIM dendrimers (Figure 3) was established through a series of experiments. Various experimental parameters including pH, viscosity of the solvents, aging, temperature and concentration were used to assess the photochemical properties of the PETIM dendrimers. It was observed that generations 1 to 5 absorbed in the region of 260-340 nm, in MeOH and in aqueous solutions. Excitation of the OH-terminated dendrimer solutions at 330 nm led to an emission at ~390 nm (Figure 4). Dendrimers presenting esters, acid salts and amines at their peripheries also exhibited a similar excitation and emission wavelengths. An increase in the fluorescence intensity was observed at low pH and with more viscous solvents. Lifetime measurements showed at least two species (~2.5 and ~7.0 ns) were responsible for the emission. The quenching of the fluorescence originating from the PETIM dendrimers by inorganic anions was also established in the present study. The periodate, persulfate, perchlorate and nitrite anions quenched the fluorescence efficiently among several anions tested. An ‘oxygen-interacted moiety’, in addition to altered hydrogen bonding properties of the dendrimers, was presumed contribute to the anomalous fluorescence behavior. Chapter 3 of the Thesis elaborates photophysical studies of several PETIM dendrimers. Incorporation of catalytically active moieties at the peripheries of dendrimers was identified as an important avenue, in order to explore the effect of the dendritic architectures on the catalytic activities of chosen catalytic moieties. In order to assess the effect of the dendritic scaffold, in relation to both numbers and locations of the catalytic units, an effort was undertaken to study the catalytic activities of catalytic units, that are present in varying numbers within one generation. Partial and full phosphine-metal complex substituted three generations of dendritic catalysts were synthesized, by using a selective alkylation as a key step. The number of the primary amine groups led to define the number of phosphine groups at the peripheries. The primary amine groups were, in turn, prepared by a Michael addition of acrylonitrile and hydroxyl groups, followed by a reduction of the nitrile moieties to the corresponding amines. The first and the second generation PETIM dendrimers utilized in this study present up to four and eight hydroxyl groups at their peripheries. A partial etherification was exercised in order to mask few hydroxyl groups, useful to prepare the partially substituted phosphine groups. Subsequent Michael addition of acrylonitrile with remaining hydroxyl groups, to afford the nitrile terminated dendrimers, and a metal-mediated reduction of the nitrile to amine led to the required number of amine functionalized dendrimers. Functionalization of the peripheries with alkyldiphenyl phosphine moieties was conducted through a Mannich reaction of the amines with formaldehyde and diphenyl phosphine. The subsequent metal complexation with Pd(COD)Cl2 afforded a series of phosphine-Pd(II) complexes, for the zero, first and second generation PETIM dendrimers. Figure 5 shows the molecular structures of a partially and a fully substituted second generation dendrimer. Catalytic activities of the dendrimer-Pd(II) complexes were assessed in both Heck and Suzuki coupling reactions. A C-C bond forming reactions were studied, with the series of dendritic-Pd(II) catalysts, using Cs2CO3 as a base and at 40 oC. In an overall observation, it was found that an individual catalytic site showed a considerable increase in the catalytic activity when it was present in multiple numbers than as a single unit within the same generation (Figure 6). Figure 6. Bar diagrams of (a) Heck reaction and (b) Suzuki reaction, employing the dendritic catalysts 1 - 11. The Heck coupling reaction involved tert-butyl acrylate and iodobenzene, and the Suzuki coupling reaction involved phenyl boronic acid and iodobenzene. The observations revealed that: (i) the higher generation dendritic catalysts exhibited higher catalytic activities per catalytic site and (ii) the dendritic scaffold has a role in enhancing the activities of the individual catalytic sites. The catalysis study identified the catalytic activities that occurred when a series of catalysts within a given dendrimer generation was used. Such a study is hitherto unknown and the observations of this study address some of the pertinent queries relating to the efficiencies of multivalent dendritic catalysts. Chapter 4 of the Thesis describes the synthesis and characterization of series of organometallic PETIM dendrimer and studies of their catalytic activities. Studies on solid-supported catalysis present a significant importance in heterogeneous organometallic catalysis. Silica is a prominently utilized heterogeneous metal catalyst support. Functionalization of the solid supports with suitable chelating ligands is emerging as a viable strategy to circumvent not only the pertinent metal catalyst deterioration and leaching limitations, but also to stabilize the metal particles and to adjust their catalytic efficiencies. In exploring heterogeneous organometallic catalysis, functionalization of silica with a first generation phosphinated dendritic amine was undertaken. The synthetic scheme adopted to synthesize dendrimer functionalized silica is shown in Scheme 1. The reaction of the chloropropylated silica 4 with amine 3 was conducted in CHCl3. Complexation of the functionalized silica 5 with Pd(COD)Cl2 led to isolation of Pd(II)- impregnated silica. Scheme 1. Preparation of Pd nanoparticles stabilized by functionalized silica. It was anticipated that the ratio of phosphine to Pd(II) would be 1:0.5, resulting from a bidendate binding of the phosphine ligand to Pd metal. The observed ICP-OES result indicated that all phosphine ligands did not chelate the metal. With the desire to obtain the metal nanoparticles, the metal complex was subjected to a reduction, which was performed by conditioning 5-Pd(II) complex in EtOH. The Pd metal nanoparticle thus formed was characterized by physical methods, and the spherical nanoparticles were found to have >85 % size distribution between 2-4 nm (Figure 7). Analyses of the Pd(0) impregnated in dendrimer functionalized silica were performed using NMR, XPS spectroscopies, elemental analysis and microscopies. Figure 7. Transmission electron micrograph and histogram of 6, obtained after treatment with EtOH. The Pd-nanoparticle stabilized silica was used in the hydrogenation of several α, β-unsaturated olefins. The catalyst recycling experiments were conducted more than 10 times, and no loss in the catalytic activities were observed. Chapter 5 describes the functionalization of the silica support with diphenylphosphinomethyl-derivatized dendritic amine, palladium nanoparticle formation and the catalysis studies. Overall, the Thesis establishes the synthesis of larger generation PETIM dendrimers, studies of their anomalous fluorescence behavior, organometallic catalysis in solution, as well as, in heterogeneous conditions, pertaining to the C-C bond forming reactions and hydrogenation reactions. (For figure, graph and structural formula pl see the pdf file)