Three synthetic methods have been explored for the preparation of several novel boron-substituted amidinates and guanidinates. The extension of heterocumulene insertion chemistries to boron-aryl, boron-metallocene and boron-transition metal moieties has also been achieved and the mechanism of such insertions is addressed via density functional theory modeling techniques. The reactivity of these complexes is also explored, mainly through halide abstraction methodologies to generate boron cations, which are potent Lewis Acids and may be useful in promoting organic transformations or in the polymerization of ethylene. The synthesis and characterization of the elusive monomeric low valent carbenoid boron(I), a compound with a formal lone pair located upon the boron center, has been lacking. The suitability of the guanidinate ligand system to support such a species is also discussed and a combined experimental and theoretical approach to this highly topical problem is also presented. Thirdly, the use of photovoltaics (devices which convert solar energy directly into electricity) as an alternative source of energy outwith fossil fuel technologies is a rapidly growing area of interest. Initial efforts to use a novel approach, which incorporates inorganic nanocrystals wired into a conducting polymer matrix, are also presented. Successful synthetic approaches to the gallium, aluminum and indium monomeric precursors suitable for electropolymerization were developed. These compounds proved to be effective starting points for the generation of conducting polymers with embedded III/VI (Ga₂S₃) nanocrystals with further studies currently underway as to their III/V (InP, GaAs) compatriots. Finally, a retrospective of projects that may best be described in terms of the moniker "Loose Ends and Future Directions" will be presented. The aim of which will be to serve as a useful guidepost for further studies in the fields and topics discussed. / text

Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 41-45). / v, 45 leaves, bound 29 cm

Thesis (M.S.)--Texas State University-San Marcos, 2007. / Vita. Includes bibliographical references (leaves 73-75).

Thesis (M.S.)--Texas State University-San Marcos, 2007. / Vita. Includes bibliographical references (leaves 73-75).

Thesis (M.S. in chemistry)--Washington State University, December 2007. / Includes bibliographical references (p. 46-47).

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (Ph. D.)-- State University of New York at Binghamton, Department of Chemistry, 2009.

Since Swiatoslaw Trofimenko first reported their synthesis in 1966, poly(pyrazolyl)borate ligands, [R”ₓB(pz，ᴿ⋅ᴿ’)₄₋ₓ], have found widespread utility in modern coordination chemistry, undoubtedly as a consequence of the numerous facets of the ligand scaffold that can be readily altered. Relative to the extensive efforts directed towards the incorporation of pyrazolyl moieties with different substituents and towards the installation of groups other than hydrogen on the bridgehead boron, comparatively few attempts have been dedicated to elucidating synthetic approaches to altering the identity of the bridgehead atom itself. Such manipulations have the potential to generate new compounds that exhibit both structural and electronic properties previously unobserved or inaccessible for the parent boron compound, and the research summarized herein is motivated both by the paucity of these derivatives and by this potential. Chapter 1 explores the use of aluminum and gallium as linker atoms to afford heavier congeners of traditional poly(azolyl)borates. This study has utilized LiEH₄ (E = Al, Ga) in place of LiBH₄, and significantly has afforded the first structurally characterized examples of tris(pyrazolyl)hydrogallates and of tris(pyrazolyl)methylgallates featuring substituted pyrazolyl groups. Moreover, the structures of {[R”ETpᴿ⋅ᴿ’]Li}₂ (E = Al, Ga) have been found to vary as a consequence of the identity of both the pyrazolyl substituents (R, R’) and the substituent on the linker atom (R”), and in some instances differ significantly from the structures of the corresponding boron derivatives. Additionally, the reactions of LiEH4 with tert-butylmercaptoimidazole, HmimBut, have afforded the first examples of tris(mercaptoimidazolyl) ligands to feature aluminum and gallium bridgeheads. The molecular structures of these derivatives similarly display interesting coordination modes which, in some cases, contrast greatly to those of the parent boron ligands. In Chapter 2, synthetic approaches for the preparation of novel dianionic tris(pyrazolyl) ligands, obtained via the use of magnesium and zinc as linker atoms, are summarized. Interestingly, the otherwise neutral {[MeMTpᴹᵉ²][Li₂]} fragment is found to associate with an additional Lipzᴹᵉ² molecule, thereby affording a series of [MeMTpᴹᵉ²][Li3(pzᴹᵉ²)Ln] compounds in which each lithium is coordinated to two pyrazolyl nitrogen atoms. Both chloride and iodide anions can also serve as capping ligands for the {[MeMTpᴹᵉ²][Li₃]}+ moieties, suggesting that the trilithio scaffold can be viewed as a trifold receptor for anions. Additionally, the tetrakis(pyrazolyl) derivatives, [(THF)2Li{μ-[M(pzᴹᵉ²)₄]}Li(THF)₂], have also been prepared and structurally characterized. Chapter 3 details the preparation, characterization, and reactivity of symmetric homodinuclear magnesium and zinc complexes, [MeM(pzᴹᵉ²)₃MMe]–, in which the two metal centers are bridged by three exo-bidentate pyrazolyl ligands. The bridging of two identical metal centers by more than two pyrazolyl groups is a rare structural motif, and so [MeM(pzᴹᵉ²)₃MMe]– represent important contributions to not only the chemistry of magnesium and zinc, but also to that of the pyrazolyl ligand. The reactivity of [MeZn(pzᴹᵉ²2)₃ZnMe]– towards protic reagents and trimethyltin halides has been investigated, and has most notably afforded a rare example of an anionic terminal zinc fluoride complex, [FZn(pzᴹᵉ²)₃ZnF]–. Additionally, the homodinuclear zinc hydride complex, [HZn(pzᴹᵉ²)₃ZnH]–, has been obtained and structurally characterized, and represents the first example of an anionic terminal zinc hydride compound. The spectroscopic characterization of both [HZn(pzMe2)₃ZnH]– and its isotopologue, [DZn(pzᴹᵉ²)₃ZnD]–, are summarized, as are the results of preliminary reactivity studies with CO2 and CS2, which suggest that insertion of these heterocumulenes into the Zn–H bonds is facile and affords, inter alia, zinc formate and zinc dithioformate species, respectively. Chapter 4 summarizes the exocyclic N-methylation of Nitron(S), a 1,2,4-triazole thione derived from Nitron. The molecular structures of both Nitron(S) and of the methylated derivative, Nitron(S)Me, are reported, and a comparison of metrical data indicates that (i) the structures of these thiones differ significantly from the dominant tautomer of Nitron and (ii) the structures of these thiones compare favorably with the NHC tautomer of Nitron. Analyses of these compounds using natural bond orbital (NBO) and natural resonance theory (NRT) methods are in accord with the experimental structures.

本論文報導了幾個系列的新型鋅酞菁配合物以及氟硼二吡咯染料的合成與表徵。 這些精心設計的化合物可作為高效的和選擇性的光敏劑應用於靶向性光動力療法和細菌的光動力失活。 / 第一章概述了光動力療法，包括歷史發展、光物理和生物機制及其臨床應用現狀。 重點介紹了用於靶向性光動力療法的第三代光敏劑，其中包括基於靶向性配體、納米載體的光敏劑以及可激活的光敏劑。 另外，本章還簡單介紹了用於抗菌光動力療法的光敏劑。 / 第二章報導了一種新型的由細胞核定位的短肽共軛修飾的鋅酞菁配合物的合成與表徵。 此短肽分子的氨基酸序列為：Gly-Gly-Pro-Lys-Lys-Lys-Arg-Lys-Val。 我們研究了該化合物的光物理性質、聚集行為以及離體光動力活性，同時與其非肽共軛修飾的化合物進行了詳細的比較。 利用HT29人結腸腺癌細胞，研究發現此多肽共軛修飾的酞菁展示了較高的細胞吸收、更高的細胞內活性氧的產生效率和光毒性。 同時活體實驗證明此化合物增加了酞菁在裸鼠腫瘤的停留時間。 這些結果在本章中均進行了詳細的報導。 / 第三章敘述了另一種多肽共軛修飾的鋅酞菁化合物的製備和光物理性質。 這個多肽包含了一個環狀的氨基酸序列，即 Arg-Gly-Asp-D-Phe-Lys，此多肽被認為能以腫瘤相關的血管新生時的高表達的跨膜受體（如 α[subscript v]β₃ 整合素）為靶向。 利用 α[subscript v]β₃ 整合素高表達的 U87-MG 人惡性膠質瘤細胞，我們研究了這個化合物的細胞吸收、細胞內活性氧的產生、離體光動力活性以及亞細胞定位。 同時，用 α[subscript v]β₃ 整合素低表達的 MCF-7 人乳腺癌細胞作為對照。 / 通常，腫瘤細胞外的pH值比正常細胞組織的低，因此，我們合成一個由酸敏感的縮醛鍵連接的酞菁二聚體。 此二聚體會發生自身淬滅且對pH有響應。 通過電子吸收和熒光光譜， 我們詳細地研究了這個化合物在不同酸性條件下的光物理性質和斷開動力學。 由於酞菁環具有強的二聚化趨勢，這個二聚體能自身淬滅，因而呈現“失活狀態。 通過降低檸檬酸緩衝液的pH值，這個化合物的乙縮醛鍵能優先斷開，並且斷開的速率隨pH值的降低而增加。 兩個酞菁環的分開增強了熒光強度和單態氧的產生。 這個二聚光敏劑還能在 HT29 細胞內被激活，從而產生較強的細胞內熒光。 相比之下，由乙二醇鏈連接的類似物基本上沒有熒光發射。 同時，這個可斷開的二聚物對HT29細胞光毒性也比不可斷開的類似物高（半致死量：IC₅₀ = 0.35 vs. 0.59 μM）。 第四章對這些結果進行了詳細的報導。 / 在第五章中，我們報導了兩種以腫瘤靶向配體葉酸共軛修飾的二（苯乙烯基）－氟硼二吡咯衍生物的合成、光譜表徵以及光物理性質。 在這兩個化合物中，葉酸和二（苯乙烯基）－氟硼二吡咯是通過不同長度的乙二醇鏈連接的。 我們研究了這兩個化合物的鏈長對KB人鼻咽癌細胞和MCF-7細胞的吸收和離體光動力活性的影響。 前者能高表達葉酸受體，而後者作為低葉酸受體表達的一個對照。 與MCF-7細胞相比，兩個化合物都展示了對KB細胞較高的吸收和光毒性（半致死量：IC₅₀ = 0.062 vs. 2.56 μM 和0.177 vs. 0.995 μM）。 此外，具有較長鏈的化合物優先定位在溶酶體中，而較短鏈的那個化合物則較多停留在細胞的內質網。 / 第六章重點開發了一系列多胺以及不同長度的聚賴氨酸（包括2、4、8個賴氨酸）共軛修飾的鋅酞菁配合物，并用於抗菌光動力療法。 我們報導了它們的合成、光物理性質以及對甲氧西林青霉素敏感的格蘭陽性金黄色釀膿葡萄球菌和格蘭陰性綠膿桿菌的光動力抗菌活性。 其中，三-N-甲基化的酞菁顯示了特別高的效果，在濃度為16 nM時，能降低大於5 log10 的金黄色釀膿葡萄球菌。 / 第七章闡述了前面幾章的實驗部份。 論文的最後附上所有新化合物的核磁共振氫譜和碳譜。 / This thesis describes the synthesis and characterization of several series of novel zinc(II) phthalocyanines and boron dipyrromethenes (BODIPYs), which are carefully designed as efficient and selective photosensitizers for targeted photodynamic therapy (PDT) and photodynamic inactivation of bacteria. / Chapter 1 presents an overview of PDT, including its historical development, photophysial and biological mechanisms, and current research directions. Emphasis is placed on the third-generation photosensitizers for targeted PDT, including targeting ligand-based photosensitizers, nanoparticle-based photosensitizers, and activatable photosensitizers. A brief review of photosensitizers that can be used for antimicrobial PDT is also given. / Chapter 2 reports the synthesis and characterization of a novel zinc(II) phthalocyanine conjugated with a short peptide with a nuclear localization sequence, namely Gly-Gly-Pro-Lys-Lys-Lys-Arg-Lys-Val. The photophysical properties, aggregation behavior, and in vitro photodynamic activity of this compound have been investigated and compared with its non-peptide-conjugated analogue. It has been found that the peptide-conjugated phthalocyanine shows an enhanced cellular uptake, higher efficiency in generating intracellular reactive oxygen species (ROS), higher photocytotoxicity against HT29 human colorectal adenocarcinoma cells, and enhanced tumor-retention property in tumor-bearing nude mice. The results are reported in detail in this chapter. / Chapter 3 describes the preparation and photophysical properties of another analogue conjugated with a peptide containing the cyclic Arg-Gly-Asp-D-Phe-Lys sequence, which is known to target the upregulated transmembrane protein receptors such as α[subscript v]β₃ integrin during angiogenesis. The cellular uptake, intracellular ROS generation, in vitro photodynamic activity, and subcellular localization of this conjugate have been investigated against U87-MG human glioblastoma cells, which have a high expression of α[subscript v]β₃ integrin. MCF-7 human breast adenocarcinoma cells, which have a low expression of α[subscript v]β₃ integrin, have been used as a negative control. / On the base that the extracellular pH in tumors is generally lower than that in normal tissues, we have developed a pH-responsive self-quenched phthalocyanine dimer connected with an acid-sensitive ketal linker. The basic photophysical properties of this compound and its cleavage kinetics upon exposure to different acidic conditions have been extensively studied by electronic absorption and fluorescence spectroscopy. Owing to the strong dimerization tendency of the phthalocyanine ring, this dimer is self-quenched and in the "OFF" state. By lowering the pH (< 6.5) in citrate buffer solutions, the linker is preferentially cleaved, and the rate of cleavage increases as the pH decreases. The separation of the phthalocyanine moieties leads to enhancement in fluorescence intensity and singlet oxygen production. This dimeric photosensitizer can also be activated inside HT29 cells causing strong intracellular fluorescence. By contrast, the fluorescence is hardly observed for the non-cleavable ethylene glycol-linked analogue. The photocytotoxicity of the cleavable dimer is also higher than that of the non-cleavable counterpart (IC₅₀ = 0.35 vs. 0.59 μM). The results are reported in detail in Chapter 4. / In Chapter 5, we describe the synthesis, characterization, and photophysical properties of two distyryl BODIPY derivatives conjugated with a folic acid as a tumor-targeting ligand via an ethylene glycol spacer with different chain length. The effects of the chain length on the cellular uptake and in vitro photodynamic activities of these compounds have been examined against KB human nasopharyngeal epidermal carcinoma cells and MCF-7 cells. The former are known to have a high expression of folate receptors, while the latter have been used as a negative control. Both compounds show enhanced cellular uptake and higher photocytotoxicity toward KB cells when compared with MCF-7 cells (IC₅₀ = 0.062 vs. 2.56 μM and 0.177 vs. 0.995 μM). The conjugate with a longer spacer shows preferential localization in the lysosomes, while the analogue with a shorter linker accumulates in the endoplasmic reticulum of the cells. / Chapter 6 focuses on the development of a series of zinc(II) phthalocyanines substituted with a polyamine moiety or a polylysine chain containing 2, 4, or 8 lysine units for antimicrobial PDT. Their synthesis, photophysical properties, and photodynamic antimicrobial activities against Gram (+) methicillin-sensitive Staphylococcus aureus and Gram (-) Pseudomonas aeruginosa are reported. The tri-N-methylated phthalocyanine is particularly potent showing a more than 5 log₁₀ reduction of the Staphylococcus aureus at 16 nM. / Chapter 7 gives the experimental details for the work described in the preceding chapters. ¹H and ¹³C{¹H} NMR of all the new compounds are given in the Appendix. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Ke, Meirong. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 159-176). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract --- p.i / Abstract (in Chinese) --- p.v / Acknowledgment --- p.viii / Table of Contents --- p.xi / List of Figures --- p.xvi / List of Schemes --- p.xxiv / List of Tables --- p.xxv / Abbreviations --- p.xxvi / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- General Introduction of Photodynamic Therapy --- p.1 / Chapter 1.2 --- Mechanisms of Photodynamic Therapy --- p.2 / Chapter 1.2.1 --- Photophysical Mechanisms --- p.2 / Chapter 1.2.2 --- Biological Mechanisms --- p.4 / Chapter 1.3 --- Clinical Status of Photodynamic Therapy --- p.5 / Chapter 1.4 --- Overview of Photosensitizers --- p.7 / Chapter 1.5 --- Targeted Photodynamic Therapy --- p.13 / Chapter 1.5.1 --- Targeting Ligand-Based Photosensitizers --- p.13 / Chapter 1.5.1.1 --- Synthetic Peptides --- p.13 / Chapter 1.5.1.2 --- Proteins --- p.16 / Chapter 1.5.1.3 --- Aptamers --- p.18 / Chapter 1.5.1.4 --- Folic acid --- p.19 / Chapter 1.5.1.5 --- Other Biological Ligands --- p.20 / Chapter 1.5.2 --- Nanoparticle-Based Photosensitizers --- p.20 / Chapter 1.5.2.1 --- Biodegradable Nanoparticle-Based Photosensitizers --- p.21 / Chapter 1.5.2.2 --- Non-Biodegradable Nanoparticle-Based Photosensitizers --- p.23 / Chapter 1.5.3 --- Activatable Photosensitizers --- p.25 / Chapter 1.5.3.1 --- Environment-Activated Photosensitizers --- p.26 / Chapter 1.5.3.2 --- Enzyme-Activated Photosensitizers --- p.27 / Chapter 1.5.3.3 --- Nucleic Acid-Activated Photosensitizers --- p.29 / Chapter 1.6 --- Antimicrobial Photodynamic Therapy --- p.32 / Chapter 1.6.1 --- General Introduction --- p.32 / Chapter 1.6.2 --- Photosensitizers for Antimicrobial Photodynamic Therapy --- p.34 / Chapter Chapter 2 --- A Phthalocyanine-Peptide Conjugate with High in vitro Photodynamic Activity and Enhanced in vivo Tumor-Retention Property --- p.36 / Chapter 2.1 --- Introduction --- p.36 / Chapter 2.2 --- Results and Discussion --- p.37 / Chapter 2.2.1 --- Molecular Design and Synthesis --- p.37 / Chapter 2.2.2 --- Electronic Absorption and Photophysical Properties --- p.42 / Chapter 2.2.3 --- In Vitro Photodynamic Activities --- p.44 / Chapter 2.2.4 --- In Vivo Studies --- p.50 / Chapter 2.3 --- Conclusion --- p.52 / Chapter Chapter 3 --- Synthesis, Characterization, and Photodynamic Activity of a cylic RGD-Conjugated Phthalocyanine --- p.53 / Chapter 3.1 --- Introduction --- p.53 / Chapter 3.2 --- Results and Discussion --- p.54 / Chapter 3.2.1 --- Molecular Design and Synthesis --- p.54 / Chapter 3.2.2 --- Electronic Absorption and Photophysical Properties --- p.57 / Chapter 3.2.3 --- In Vitro Photodynamic Activities --- p.59 / Chapter 3.3 --- Conclusion --- p.67 / Chapter Chapter 4 --- A pH-Responsive Fluorescent Probe and Photosensitizer Based on the Dimerization Property of Phthalocyanines --- p.69 / Chapter 4.1 --- Introduction --- p.69 / Chapter 4.2 --- Results and Discussion --- p.70 / Chapter 4.2.1 --- Synthesis and Characterization --- p.70 / Chapter 4.2.2 --- Electronic Absorption and Photophysical Properties --- p.74 / Chapter 4.2.3 --- In Vitro Studies --- p.80 / Chapter 4.3 --- Conclusion --- p.84 / Chapter Chapter 5 --- Synthesis, Characterization, and Photodynamic Activities of BODIPY-Folate Conjugates --- p.86 / Chapter 5.1 --- Introduction --- p.86 / Chapter 5.2 --- Results and Discussion --- p.87 / Chapter 5.2.1 --- Synthesis and Characterization --- p.87 / Chapter 5.2.2 --- Electronic Absorption and Photophysical Properties --- p.92 / Chapter 5.2.3 --- In Vitro Studies --- p.94 / Chapter 5.3 --- Conclusion --- p.100 / Chapter Chapter 6 --- Synthesis, Characterization, and Antimicrobial Photodynamic Activities of Cationic Phthalocyanines --- p.102 / Chapter 6.1 --- Introduction --- p.102 / Chapter 6.2 --- Results and Discussion --- p.103 / Chapter 6.2.1 --- Synthesis and Characterization --- p.103 / Chapter 6.2.2 --- Electronic Absorption and Photophysical Properties --- p.108 / Chapter 6.2.3 --- In Vitro Photodynamic Antimicrobial Activities --- p.112 / Chapter 6.3 --- Conclusion --- p.114 / Chapter Chapter 7 --- Experimental Section --- p.115 / Chapter 7.1 --- General --- p.115 / Chapter 7.2 --- Synthesis --- p.119 / Chapter 7.2.1 --- Synthesis for Chapter 2 --- p.119 / Chapter 7.2.2 --- Synthesis for Chapter 3 --- p.125 / Chapter 7.2.3 --- Synthesis for Chapter 4 --- p.128 / Chapter 7.2.4 --- Synthesis for Chapter 5 --- p.132 / Chapter 7.2.5 --- Synthesis for Chapter 6 --- p.138 / Chapter 7.3 --- pH-Response Properties of 4.6 and 4.7 in Citrate Buffer Solutions --- p.143 / Chapter 7.4 --- In Vitro Studies --- p.144 / Chapter 7.4.1 --- Cell Lines and Culture Conditions --- p.144 / Chapter 7.4.2 --- Photocytotoxicity Assay --- p.145 / Chapter 7.4.3 --- Photodynamic Antimicrobial Inactivatoin Studies --- p.147 / Chapter 7.4.4 --- Intracellular ROS Measurements --- p.148 / Chapter 7.4.5 --- Cellular Uptake (Determined by Extraction Method) --- p.149 / Chapter 7.4.6 --- Cellular Uptake (Determined by Confocal Microscopy) --- p.150 / Chapter 7.4.7 --- Cellular Uptake (Determined by Flow Cytometry) --- p.152 / Chapter 7.4.8 --- Fluorescence Microscopic Studies --- p.153 / Chapter 7.4.9 --- Subcellular Localization Studies --- p.153 / Chapter 7.4.10 --- pH-Dependent Intracellular Fluorescence Studies --- p.155 / Chapter 7.5 --- In Vivo Imaging and Ex Vivo Organ Biodistribution --- p.156 / Chapter Chapter 8 --- Conclusion and Outlook --- p.157 / References --- p.159 / Chapter Appendix --- NMR Spectra of New Compounds --- p.177

At the end of this thesis, the 1H and 13C {1H} NMR spectra of all the new compounds are listed in the Appendix. / Chapter 1 presents an overview of BODIPYs, including their general synthesis, properties, reactivities, and applications. The use of these compounds as photosensitizers for photodynamic therapy and fluorescent sensors for metal ions is highlighted. / Chapter 2 reports the synthesis, spectroscopic characterization, photophysical propreties, and in vitro photodynamic activities of a series of symmetrical distyryl BODIPYs substituted with one to five hydrophilic oligoethylene glycol monomethyl ether chain(s). In general, these compounds are essentially non-aggregated in DMF, resulting in a strong fluorescence emission and relatively high efficiency in generating singlet oxygen. Being formulated with 0.05% Tween 80, these compounds act as efficient photosensitizers. The compound which contains five triethylene glycol monomethyl ether chains exhibits the highest photocytotoxicity with an IC50 value as low as 7 nM toward HT29 human colorectal carcinoma cells. The high photodynamic activity of this compound can be attributed to its high efficiency in generating singlet oxygen, low aggregation tendency, and high cellular uptake. In addition, this compound also has a strong and selective affinity to the endoplasmic reticulum of the cells, causing cell death mainly through apoptosis. / Chapter 3 reports a related study on a series of unsymmetrical distyryl BODIPYs. These compounds possess three triethylene glycol monomethyl ether chains and another substituent at the other styryl group. The effects of this substituent on the photophysical properties, aggregation behavior, cellular uptake, and subcellular localization have been explored. Furthermore, their in vitro photodynamic activities have also been evaluated and compared with those of symmetrical analogues reported in Chapter 2. / Chapter 4 describes a novel ratiometric near-infrared fluorescent dye based on distyryl BODIPY with a 4-dimethylaminophenylethynyl group at the 2- and 6-positions. This compound exhibits a remarkable blue-shift in its absorption and fluorescence emission positions upon protonation with trifluoroacetic acid in organic solvents or HC1 in water in the presence of 0.05% Tween 80. These changes can be made reversible upon addition of a base. / Chapter 5 describes two monostyryl BODIPYs which contain two or four water-soluble amide chains as the metal chelators. The photophysical properties of these compounds and their spectral response to various metal ions have been investigated. The results show that the compound with two amide chains can detect Zn2+ ion in MeCN. They bind in a 1:1 stoichiometry with a binding constant of 2.2 x 104 M-1 . The fluorescence emission increases remarkably in intensity and shifts substantially to the blue from 620 to 572 nm due to the inhibition of the intramolecular charge transfer. The compound which contains four amide chains can detect Cd2+ ion with a high selectivity in phosphate buffered saline. / Chapter 6 reports the synthesis and spectral properties of a silicon(IV) phthalocyanine with two axial bis(2-picolyl)amine moieties which act as the binding sites for metal ions. The effects of various metal ions on its absorption and fluorescence spectra have been examined. The results indicate that this compound shows a relatively high sensitivity to Zn 2+ ion. Moreover, the proposed binding mode and the sensing mechanism are also discussed. / This thesis describes the synthesis and characterization of several series of functional boron dipyrromethenes (BODIPYs) and a silicon(IV) phthalocyanine. Their applications as efficient photosensitizers in photodynamic therapy and selective fluorescent sensors for metal ions are also reported herein. / He, Hui. / Adviser: Dennis Kee Pui Ng. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references. / 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, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.