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Thesis (M.Sc.). / Written for the Dept. of Chemistry. Title from title page of PDF (viewed 2009/06/29). Includes bibliographical references.

No description available.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2016. / In this PhD thesis, the synthesis, crystal chemistry and thermoresponsive behaviour of non-porous borophosphates [ABPO5 (A= Ca, Sr, Ba) and BPO4] and porous borophosphates [NH4Fe(III)[BP2O8(OH)] and MIxMIIz(H2O)2[BP2O8].zH2O (MI = Na, NH4 and MII = Mn, Co)] phases were investigated. Understanding the crystal structure dynamics as a function of temperature of the selected porous and non-porous borophosphates revealed the thermal stability of the studied compounds, while serving as a predictive measure of the effects of temperature on other materials properties and subsequent applications. The non-porous borophosphates were synthesized using the solid state method, whereas the porous borophosphates were synthesized using the hydrothermal method. The powder X-ray diffraction (PXRD) technique, along with the application of the Rietveld refinement method, was the principle characterisation technique employed for the non-destructive and non-invasive thermoresponsive characterisation of the studied borophosphate phases. This thesis consists of seven chapters, four of which are independent papers corresponding to four chapters. Chapter 1 reviews the relevant scientific literature, while chapter 2 describes the methods of characterisation used in this thesis. Concerning the highly thermally stable non-porous borophosphates, chapter 3 presents the thermal expansion behaviour of ABPO5 compounds, which have been determined from the sequential application of the Rietveld refinement method of variable temperature powder X-ray diffraction (VT-PXRD) data. For trigonal ABPO5 compounds, a near linear expansion of the unit cell axes was found for all structures as a function of temperature. The variation of the crystal structure with temperature of ABPO5 compounds was also established. With the general understanding that borophosphates display intriguing crystal structure architectures, chapter 4 describes the synthesis and characterisation of four metal borophosphate hydrates: NaMII(H2O)2[BP2O8](H2O); MII = Co (I), Mn (II) and (NH4)0.5MII1.25(H2O)2[BP2O8](H2O)0.5; MII = Co (III), Mn (IV). The structures refined at room temperature from PXRD data revealed that isostructural phases I and II have an ordered arrangement of water molecules in the voids, whereas isostructural phases III and IV have fractional and disordered distribution of water molecules in the voids. Scanning electron microscope (SEM), fourier transform infrared spectroscopy (FT-IR), variable temperature powder X-ray diffraction (VT-PXRD) and thermogravimetric analysis (TGA) for all compounds are also presented. Chapter 5 was an investigation into the synthesis, crystal structure and thermal properties of the porous iron borophosphate NH4Fe(III)[BP2O8(OH)]. Variable temperature PXRD and thermogravimetric analysis were used to investigate the compounds thermal stability and expansion behaviour. Thermal investigations indicated that the compound is stable up to 470 °C. Of great importance to the accurate and/or precise measurement of the crystal structures and lattice parameters of the phases investigated using powder diffraction was the correct application of the Rietveld refinement method to the measured diffraction data. Therefore, chapter 6 is an investigation into a number of different Rietveld refinement approaches, which were aimed at modelling the changes in the atomic coordinates of BPO4 as a function of temperature. Parametric Rietveld refinements and rigid body Rietveld refinements were among the refinement strategies employed. / LG2017

氟硼熒二吡咯染料是一類多功能的熒光材料，並得到了廣泛的應用。本論文的目標是探索此類染料以及它的氮雜類似物作為探測重金屬離子的熒光探針，非線性光學材料和構建人工光合作用模型的潛力。 本論文報導了一系列氟硼熒二吡咯染料和它的氮雜類似物的分子設計，合成，光學性質以及在相關領域的應用。 / 第一章簡單的概述了氟硼熒二吡咯染料的合成，光學性質和作為重金屬熒光探針和非線性光學材料的應用。然後詳細概述了氮雜氟硼熒二吡咯染料的發展，合成，光學性質，以及其在生物醫藥和材料科學領域的潛在應用。 / 第二章報導了一個對銅和汞二價離子具有高選擇性比色性識別的近紅外熒光探針。 這個探針以雙邊苯乙烯修飾的氟硼熒二吡咯染料為螢光團，並進一步修飾兩個二（三唑）胺的識別位點。在體積比為1 比1 的乙腈水溶液中，當加入銅和汞二價離子時，這個探針的吸收和熒光波長表現出不同程度的藍移，而且這個變化可以被肉眼觀察到。這是因為分子內的電荷傳遞過程被抑制的結果。另外，通過其熒光變化的工作曲線法，銅二價離子與此探針具有2 比1 的結合比例。進一步研究表明它們表現出較大的結合常數（(6.2 ± 0.6) × 10⁹ M⁻²），是汞二價離子的結合常數的六倍。 / 另外，除了分子內電荷傳遞的機理，光致電子轉移和熒光共振能量傳遞也是兩種常用的設計熒光探針的機理。第三章報導了兩個基於光致電子轉移和熒光共振能量傳遞的有高效選擇性的汞二價離子熒光探針。 我們使用電子吸收和熒光光譜的方法研究了他們之間的結合性能。其中一個探針在中間的位置連接了一個二（三唑）胺的結合位點，並對汞二價離子表現出很高的响應性。另一個探針進一步引入了兩個羅丹明熒光團到氟硼熒二吡咯染料上，於是當接觸到汞二價離子時，激發的氟硼熒二吡咯染料的能量將高效的傳遞到羅丹明上，從而表現出顯著的光譜的變化。 / 第四章描述了一系列含有兩個電子供體和推拉結構的氟硼熒以及氮雜氟硼熒二吡咯染料的設計，合成，以及作為非線性光學材料的潛力。通過薗頭偶合反應，兩個對位二苯胺基苯乙炔基或對位二甲氨基苯乙炔基被連接到了該染料的2 和6 位上。線性的吸收和熒光研究表明那些化合物表現出溶劑效應。 它們在甲苯中雙光子吸收的性能通過用雙光子激發熒光光譜的方法進行了研究。另外，對於推拉電子的一系類化合物，推電子的對位二甲氨基苯乙炔基和拉電子的對位硝基苯乙炔基分別連接到了該染料的2 和6 位上。這些化合物的光學和電化學性能得到了詳細的研究。在氯仿溶液中，它們的二價非線性光學性質通過電場誘導的二次諧波的方法進行了研究，其在1907 納米的標量積μ.β在94 ×10⁻⁴⁸ 到330 × 10⁻⁴⁸ esu 之間，並隨著3 和5 位取代基的不同而變化。 / 第五章報導了一個基於單邊苯乙烯氟硼熒二吡咯染料和富勒烯雙修飾的氮雜氟硼熒二吡咯染料的人工光合作用模型。這個三元體系的分子內光誘導的過程使用穩態的光學方法進行了研究。當激發單邊苯乙烯氟硼熒二吡咯染料部分時，這個被激發的部分會將能量傳遞給氮雜氟硼熒二吡咯染料，然後進一步的將電子傳遞給富勒烯。運用飛秒瞬態鐳射的方法，它們之間在苯睛中電子重排的速率是7.00 × 10⁸ s⁻¹，從而得到電荷分離態的壽命是1.47 納秒。 / 作為上一個工作的拓展，第六章報導了兩個或四個甲基化環糊精修飾的氮雜氟硼熒二吡咯染料與四磺酸基卟啉和其鋅卟啉，以及兩個帶正電的單邊苯乙烯修飾的氟硼熒二吡咯染料在水中的相互作用。使用各種光學方法，我們研究了它們的結合過程以及能量或者電子的傳遞過程。最後，四磺酸基卟啉， 環糊精修飾的氮雜氟硼熒二吡咯染料，以及單邊修飾的氟硼熒二吡咯染料在水溶液中進行了自組裝。當激發卟啉時，能量高效的傳遞到氮雜氟硼熒二吡咯染料上，接著電子從單邊修飾的氟硼熒染料傳遞到氮雜氟硼熒二吡咯染料上。因此，這個多重的超分子體系是一個很好的光合作用模型。 / 第七章和第八章分別闡述了前面幾章的實驗部分和引用文獻。 / 論文的最後一部分附上了所有新化合物的核磁共振氫譜和碳譜圖。 / Boron dipyrromethenes (BODIPYs) are versatile functional materials for a wide range of applications. This research work aims to explore the potential of these compounds and their aza analogues as fluorescent probes for heavy metal ions, nonlinear optical materials, and building blocks of artificial photosynthetic models. This thesis describes the molecular design, synthesis, spectroscopic characterization, and photophysical properties of several series of BODIPYs and aza-BODIPYs, as well as their potential applications in these areas. / Chapter 1 gives a brief overview of BODIPYs, focusing on their synthesis, spectroscopic properties, and applications as fluorescent probes for heavy metal ions and nonlinear optical materials. It then reviews the historical development, syntheses, and spectroscopic properties of their aza analogues. The potential applications of aza-BODIPYs in biomedicine and materials science are also discussed at the end of this chapter. / In Chapter 2, a highly selective colorimetric and near-infrared fluorescent probe for Cu²⁺ and Hg²⁺ ions is reported, which is based on a distyryl BODIPY with two bis(1,2,3-triazole)amino receptors. The compound selectively binds to Cu²⁺ and Hg²⁺ ions in CH₃CN/H₂O (1:1 v/v) giving remarkably blue-shifted electronic absorption and fluorescence bands as a result of inhibition of the intramolecular charge transfer (ICT) process upon binding. The color changes can be easily seen by the naked eye. The binding stoichiometry between this probe and Cu²⁺ ion has been determined to be 1:2 by a Job’s plot of the fluorescence data with a binding constant of (6.2 ± 0.6) × 10⁹ M⁻². The corresponding value for Hg²⁺ ion is about six-fold smaller. / In addition to the ICT mechanism, photoinduced electron transfer (PET) and fluorescence resonance energy transfer (FRET) are another two useful mechanisms for design of fluorescent probes. Chapter 3 reports two highly selective and sensitive BODIPY-based fluorescent probes for Hg²⁺ ion based on PET and FRET mechanisms. Their binding properties have been investigated by using electronic absorption and steady-state fluorescence spectroscopic methods. The probe with a bis(1,2,3-triazole)amino receptor at the meso position is highly responsive toward Hg²⁺ ion. By introducing two rhodamine B moieties to the BODIPY core, FRET occurs from the excited BODIPY to rhodamine B in a highly effective manner upon binding to Hg²⁺ ion, regarding to remarkable spectral changes. / Chapter 4 presents a series of BODIPY and aza-BODIPY derivatives bearing a donor-π-donor or push-pull structure as nonlinear optical materials. The donor-π-donor derivatives have been prepared by connecting 4-(diphenylamino)phenylethynyl or 4-(dimethylamino)phenylethynyl moieties to the 2- and 6-positions of the π systems through Sonogashira coupling reactions. The linear optical absorption and fluorescence properties of these compounds have been found to be solvent-dependent. Their two-photon absorption properties have also been measured in toluene by two-photon fluorescence excitation method. For the push-pull series, an electron-donating 4-(dimethylamino)phenylethynyl group and an electron-withdrawing 4-nitrophenylethynyl group have been added to the 2- and 6-positions of the BODIPY core. The spectroscopic and electrochemical properties of these compounds have been studied. Their second-order nonlinear optical properties have also been examined by electric-field-induced second-harmonic generation method in CHCl₃. The values of the dot product μ.β are in the range from 94 × 10⁻⁴⁸ to 330 × 10⁻⁴⁸ esu at 1907 nm, depending on the substituents at the 3- and 5-positions. / Chapter 5 describes the synthesis and characterization of an artificial photosynthetic model in which an aza-BODIPY core is covalently linked to a monostyryl BODIPY component and a fullerene (C₆₀) unit. The photoinduced intramolecular processes of this triad and the model compounds have been studied in detail by steady-state and time-resolved spectroscopic methods. Upon excitation at the monostyryl BODIPY moiety, excitation energy transfer occurs to the aza-BODIPY core, which is followed by an electron transfer to the C₆₀ unit. From the femtosecond transient absorption studies, the rate constant of charge recombination has been determined to be 7.00 × 10⁸ s⁻¹ in benzonitrile, giving a lifetime of 1.47 ns for the charge-separated state. / As an extension, Chapter 6 presents related supramolecular systems in which an aza-BODIPY derivative bearing two or four permethylated β-cyclodextrin moieties binds to metal-free and zinc(II) tetrasulfonated porphyrins, as well as two cationic monostyryl BODIPYs in water. The complexation of these components has been studied by various spectroscopic methods. The resulting host-guest complexes exhibit efficient energy and/or electron transfer depending on the nature of the guests. A novel mixed array of metal-free porphyrin, aza-BODIPY, and monostyryl BODIPY has also been assembled. Upon excitation at the porphyrin unit, singlet-singlet energy transfer occurs to the aza-BODIPY core, which then obtains an electron from the monostyryl BODIPY moieties. This supramolecular hetero-array thus also serves as an artificial photosynthetic model. / Chaper 7 gives the experimental details for the work described in the preceedingchapters. All the references cited herein are given in Chapter 8. / ¹H and ¹³C{¹H} NMR spectra 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. / Detailed summary in vernacular field only. / Shi, Wenjing. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 204-220). / Abstracts also in Chinese. / Table of Contents --- p.I / Acknowledgment --- p.VII / Abstract --- p.IX / Abstract (in Chinese) --- p.XIII / Abbreviations --- p.XV / List of Figures --- p.XXI / List of Tables --- p.XXXII / List of Schemes --- p.XXXIV / Publication Related to This Thesis --- p.XXXVI / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- General --- p.1 / Chapter 1.2 --- Synthesis, Reactivity, and Spectroscopic Properties of BODIPYs --- p.2 / Chapter 1.2.1 --- Synthesis of BODIPYs --- p.2 / Chapter 1.2.2 --- Reactivity of BODIPYs --- p.5 / Chapter 1.2.3 --- Spectroscopic Properties of Selected BODIPYs --- p.6 / Chapter 1.3 --- Applications of BODIPYs --- p.9 / Chapter 1.3.1 --- BODIPYs as Fluorescent Probes for Heavy Metal Ions --- p.9 / Chapter 1.3.2 --- BODIPYs as Two-Photon Absorbing Materials --- p.14 / Chapter 1.3.2.1 --- General for Two-Photon Absorption --- p.14 / Chapter 1.3.2.2 --- Selected Examples of TPA Materials --- p.15 / Chapter 1.4 --- Aza-BODIPYs: Aza Analogues of BODIPYs --- p.18 / Chapter 1.4.1 --- General --- p.18 / Chapter 1.4.2 --- Synthesis and Reactivity of Aza-BODIPYs --- p.18 / Chapter 1.4.3 --- Spectroscopic Properties of Aza-BODIPYs --- p.21 / Chapter 1.4.4 --- Applications of Aza-BODIPYs --- p.29 / Chapter 1.4.4.1 --- Aza-BODIPYs as Artificial Photosynthetic Models --- p.29 / Chapter 1.4.4.2 --- Aza-BODIPYs as Fluorescent Probes --- p.33 / Chapter 1.4.4.3 --- Aza-BODIPYs as Photosensitizers and Imaging Probes --- p.37 / Chapter 1.4.4.4 --- Other Applications --- p.39 / Chapter 1.5 --- Objectives of this Study --- p.41 / Chapter Chapter 2 --- A Highly Selective Colorimetric and Fluorescent Probe for Cu²⁺ and Hg²⁺ Ions Based on a Distyryl BODIPY with Two Bis(1,2,3-triazole)amino Receptors / Chapter 2.1 --- Introduction --- p.42 / Chapter 2.2 --- Results and Discussion --- p.43 / Chapter 2.2.1 --- Synthesis and Characterization --- p.43 / Chapter 2.2.2 --- Metal Sensing Properties --- p.46 / Chapter 2.2.3 --- Binding Properties --- p.48 / Chapter 2.2.3.1 --- Binding Properties of 2.10 with Cu²⁺ Ion --- p.48 / Chapter 2.2.3.2 --- Binding Properties of 2.10 with Hg²⁺ Ion --- p.52 / Chapter 2.3 --- Conclusion --- p.55 / Chapter Chapter 3 --- Detection of Hg²⁺ Ion with BODIPY-Based Fluorescent Probes Substituted with a Bis(1,2,3-triazole)amino Receptor / Chapter 3.1 --- Introduction --- p.56 / Chapter 3.2 --- Results and Discussion --- p.57 / Chapter 3.2.1 --- Molecular Design, Synthesis, and Characterization --- p.58 / Chapter 3.2.2 --- Metal Binding Properties of 3.6 --- p.61 / Chapter 3.2.3 --- Metal Binding Properties of 3.7 --- p.66 / Chapter 3.2.4 --- Fluorescence Resonance Energy Transfer in 3.7 --- p.72 / Chapter 3.3 --- Conclusion --- p.73 / Chapter Chapter 4 --- Synthesis and Nonlinear Optical Properties of BODIPY and Aza-BODIPY Derivatives / Chapter 4.1 --- Introduction --- p.74 / Chapter 4.2 --- Results and Discussion --- p.75 / Chapter 4.2.1 --- Synthesis of D-π-D BODIPY and Aza-BODIPY Derivatives --- p.75 / Chapter 4.2.2 --- Synthesis of Push-Pull BODIPY Derivatives --- p.81 / Chapter 4.2.3 --- Linear Electronic Absorption and Fluorescence Properties of D-π-D BODIPY and Aza-BODIPY Derivatives --- p.84 / Chapter 4.2.4 --- Electrochemical Properties of D-π-D BODIPY Derivatives --- p.88 / Chapter 4.2.5 --- Two-Photon Absorption Properties of D-π-D BODIPY and Aza-BODIPY Derivatives --- p.90 / Chapter 4.2.6 --- Linear Electronic Absorption and Fluorescence Properties of Push-Pull BODIPY Derivatives --- p.93 / Chapter 4.2.7 --- Electrochemical Properties of Push-Pull BODIPY Derivatives --- p.96 / Chapter 4.2.8 --- Second-Order Nonlinear Optical Properties of Push-Pull BODIPY Derivatives --- p.97 / Chapter 4.3 --- Conclusion --- p.99 / Chapter Chapter 5 --- Photosynthetic Antenna-Reaction Center Mimicry with a Covalently Linked Monostyryl Boron Dipyrromethene-Aza Boron Dipyrromethene-C₆₀ Triad / Chapter 5.1 --- Introduction --- p.101 / Chapter 5.2 --- Results and Discussion --- p.103 / Chapter 5.2.1 --- Synthesis --- p.103 / Chapter 5.2.2 --- Steady-State Electronic Absorption and Fluorescence Properties --- p.105 / Chapter 5.2.3 --- Electrochemical Properties and Energy Levels --- p.109 / Chapter 5.2.4 --- Transient Absorption Studies --- p.112 / Chapter 5.2.4.1 --- Femtosecond Transient Absorption Studies --- p.112 / Chapter 5.2.4.2 --- Nanosecond Transient Absorption Studies --- p.117 / Chapter 5.2.5 --- Energy-Level Diagrams --- p.119 / Chapter 5.3 --- Conclusion --- p.121 / Chapter Chapter 6 --- Formation and Photoinduced Processes of the Host-Guest Complexes of β-Cyclodextrin-Conjugated Aza-BODIPYs with Tetrasulfonated Porphyrins and Monostyryl BODIPYs / Chapter 6.1 --- Introduction --- p.122 / Chapter 6.2 --- Results and Discussion --- p.123 / Chapter 6.2.1 --- Synthesis and Characterization --- p.123 / Chapter 6.2.2 --- Host-Guest Complexes of 6.3 with Tetrasulfonated Porphyrins --- p.131 / Chapter 6.2.3 --- Host-Guest Complexes of 6.7 with Tetrasulfonated Porphyrins --- p.141 / Chapter 6.2.4 --- Host-Guest Complexes of 6.7 with Monostyryl BODIPYs --- p.146 / Chapter 6.2.5 --- Host-Guest Complexes of 6.7 with Tetrasulfonated Porphyrins and Monostyryl BODIPYs --- p.154 / Chapter 6.3 --- Conclusion --- p.159 / Chapter Chapter 7 --- Experimental Section / Chapter 7.1 --- General --- p.160 / Chapter 7.2 --- Experiments in Chapter 2 --- p.162 / Chapter 7.2.1 --- Synthesis --- p.162 / Chapter 7.2.2 --- Absorption and Fluorescence Studies --- p.164 / Chapter 7.2.3 --- Determination of Binding Constants (K) --- p.165 / Chapter 7.3 --- Experiments in Chapter 3 --- p.165 / Chapter 7.3.1 --- Synthesis --- p.165 / Chapter 7.3.2 --- Absorption and Fluorescence Studies --- p.169 / Chapter 7.3.3 --- Determination of Binding Constants (K) --- p.169 / Chapter 7.4 --- Experiments in Chapter 4 --- p.170 / Chapter 7.4.1 --- Synthesis --- p.170 / Chapter 7.4.2 --- Electrochemical Measurements --- p.188 / Chapter 7.4.3 --- NLO Measurements --- p.188 / Chapter 7.5 --- Experiments in Chapter 5 --- p.190 / Chapter 7.5.1 --- Synthesis --- p.190 / Chapter 7.5.2 --- Electrochemical Measurements --- p.196 / Chapter 7.5.3 --- Time-Resolved Transient Absorption Measurements --- p.196 / Chapter 7.6 --- Experiments in Chapter 6 --- p.198 / Chapter 7.6.1 --- Synthesis --- p.198 / Chapter 7.6.2 --- Determination of Binding Constants (K) --- p.201 / Chapter 7.6.3 --- Molecular Dynamic Simulation --- p.202 / Chapter 7.6.4 --- Electrochemical Measurements --- p.203 / Chapter Chapter 8 --- References --- p.204 / Appendix --- p.221

Wang, Yang. / "October 2011." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 87-92). / Abstracts in English and Chinese. / Acknowledgement --- p.I / Abstract (in English) --- p.III / Abstract (in Chinese) --- p.IV / Abbreviation --- p.V / List of Compounds --- p.VI / List of Figures --- p.IX / Contents --- p.X / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Synthesis and Structure of Half-Sandwich Group 4 Metallocarboranes Containing the Dicarbollyl Ligand --- p.2 / Chapter 1.2 --- Half-Sandwich Group 4 Metallacarboranes Catalyzed Reactions --- p.20 / Chapter 1.2.1 --- Polymerization of Olefins --- p.20 / Chapter 1.2.2 --- Catalytic Dimerization and Hydrogenation of Alkynes --- p.22 / Chapter 1.2.3 --- Catalytic Addition of Amines to Carbodiimides --- p.23 / Chapter 1.2.4 --- Catalytic Transamination of Guanidines --- p.24 / Chapter 1.2.5 --- Catalytic Synthesis of A^-Heterocycles --- p.25 / Chapter 1.3 --- Research Objectives of This Thesis --- p.26 / Chapter Chapter 2 --- Half-Sandwich Group 4 Metallacarborane Monoamindes --- p.27 / Chapter 2.1 --- Introduction --- p.27 / Chapter 2.2 --- Synthesis of Dicarbollyl Ligands Bearing Functional Side Arms --- p.27 / Chapter 2.3 --- Synthesis and Characterization of Half-Sandwich Group 4 Metallacarborane Monoamindes --- p.33 / Chapter 2.4 --- Summary --- p.43 / Chapter Chapter 3 --- Synthesis of 2-Aminoimidazoles Catalyzed by Half-Sandwich Titanacarborane Monoamide --- p.44 / Chapter 3.1 --- Introduction --- p.45 / Chapter 3.2 --- Known Methods for the Synthesis of 2-Aminoimidazole --- p.44 / Chapter 3.2.1 --- Condensations Methods --- p.44 / Chapter 3.2.2 --- Direct Introduction of N at C2 Position --- p.46 / Chapter 3.2.3 --- Heterocyclic Exchange Reactions --- p.47 / Chapter 3.2.4 --- Transition Metal Catalyzed Reactions --- p.48 / Chapter 3.3 --- Results and Discussion --- p.49 / Chapter 3.3.1 --- Synthesis of Propargy 1 Amines --- p.49 / Chapter 3.3.2 --- Synthesis and Characterization of 2-Aminoimidazoles --- p.50 / Chapter 3.3.3 --- Proposed Reaction Mechanism --- p.55 / Chapter 3.4 --- Summary --- p.57 / Chapter Chapter 4 --- Conclusion --- p.59 / Chapter Chapter 5 --- Experimental Section --- p.61 / References --- p.87 / Appendix / Chapter I. --- Publication Based on the Research Findings --- p.93 / Chapter II. --- Crystal Data and Summary of Data Collection and Refinement --- p.94 / Chapter III. --- X-ray crystallographic data in CIF (electronic form)

A series of boron suboxide films with hardness higher than 40 GPa was prepared and characterized. The correlation between OB ratio and mechanical properties, both hardness and elastic modulus were analyzed. Our studies on beta r-B, B2O3, surface oxidation of betar-B, and B6O illustrate that an XPS peak shift can be caused by a change in chemical state and bonding configuration. The shifts of B 1s peaks provide some good evidence to substantiate this conventional wisdom of XPS. We have applied this concept to enrich our XPS studies of boron and BxO y, and indeed found an intriguing variety of surface and interfacial physical conditions of those samples. / In our study, three boron nitride (BN) samples, the c-BN, h-BN and a-BN were prepared to serve as the standard specimens. And also, a series of thick BN films with different cubic phase content were prepared using a dual-ion beam assisted deposition (DIBAD) system. A quantitative method to measure the various phases content in BN film by the deconvolution of the energy loss features of N 1s signal was established. The feasibility of this method was proved by comparing the results with the results from FT-IR. To our understanding, this method has never been reported. / Many mechanical applications constantly demand superhard materials. Commonly a material is qualified as "superhard" when its microhardness exceeds 40 GPa. Therefore, great efforts have been made to search for other materials with high hardness in the past several decades. In the design of superhard materials, boron is a peculiar element/constituent. c-BN that possesses the zinc-blende structure shows numerous highly desirable mechanical properties, especially the high hardness and chemical inertness. Boron often exhibits three-center two-electron bonds in addition to the common two-center two-electron bonds. This overall bonding configuration must be very effective as shown by the high hardness of solid boron at 35 GPa. When impurities with more valence electrons than boron are added to pure boron, the overall mechanical strength can be further enhanced. By incorporation of oxygen, a family of hard boron suboxide compounds is thereby formed such as B6O. / Zheng Bin. / "August 2005." / Adviser: Chan Man Chor. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6427. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

A series of photochromic dithienylethene-containing triarylboranes has been synthesized and characterized. The X-ray crystal structure of (4,5-bis(2,5-dimethylthiophen-3-yl)-thiophen-2-yl)dimesitylborane has been determined. An intense electronic absorption band was observed in all the triarylborane-containing compounds, corresponding to the intramolecular charge-transfer transition from the π-conjugated thiophene / fused thiophene / bithiophene to the vacant pπorbital of boron. This class of compounds was also found to bind fluoride ion such that the trigonal planar geometry of the boron center would be changed to tetrahedral, leading to a significant perturbation in the photophysical properties. Upon photo-excitation into the transition band, (4,5-bis(2,5-dimethylthiophen-3-yl)-thiophen-2-yl)dimesityl- borane and (4,5-bis-(2,5-dimethylthiophen-3-yl)-thieno[3,2-b]thiophen-2-yl)- dimesitylborane displayed multi-addressable photochromic reactivities upon addition of fluoride, in which a green solution was found in the closed form of the unbound compounds, while they changed to a purple color upon fluoride binding. Interestingly, both (4',5'-bis(2,5-dimethyl-thiophen-3-yl)-2,2'- bithiophen-5-yl)dimesitylborane and (4',5'-bis(2,5-dimethyl-thiophen-3-yl)-2,2'- bithiophen-3-yl)dimesitylborane displayed gated photochromic reactivities upon addition of fluoride, while only typical photochromic reactivity was observed in (4',5'-bis(2,5-dimethyl-thiophen-3-yl)-2,2'-bithiophen-4-yl)- dimesitylborane, indicative of a strong influence of the substituent effect on the photochromic reactivity upon incorporation of the -BMes2 group. A series of photochromic dithienylethene-containing β-diketones and the corresponding boron(III) compounds, appended with -BF2, -B(C6F5)2 and -BPh2, have been designed and synthesized. Upon photo-excitation into the transition band, typical photochromism was observed in all the dithienylethene- containing β-diketone ligands with the color changed from pale yellow to green in degassed benzene solution. Upon incorporation of the -BF2 and -B(C6F5)2 groups, near-infrared responsive photochromic behavior was observed, in which the absorption of the closed form was found to be at ca. 758-863 nm, suggesting that a pronounced perturbation of the dithienylethene was achieved by coordination of the boron(III) center. Moreover, a significant reduction in luminescence intensity of over 90 % was observed upon photocyclization, indicative of their potential application as photoswitchable luminescence materials. The thermal stability of the closed form and the activation energy for the thermal cycloreversion have also been studied on the representative compounds, 1-(4,5-bis(2,5-dimethylthiophen-3-yl)thiophen-2- yl)-butane-1,3-dione and difluoroboryl(1-(4,5-bis(2,5-dimethylthiophen-3-yl)- thiophen-2-yl)butane-1,3-dionate). A series of photochromic dithienylethene-containing BODIPY has been successfully prepared and characterized. The electronic absorption properties have been studied. These compounds showed an intense visible absorption band, corresponding to the 0-0 band of a strong S0→S1 transition of the BODIPY core, with a weak and broad absorption band at higher energy, corresponding to the S0→ S2 transition of the BODIPY core. An absorption band in the UV region was also observed in 2,3-bis(2,5-dimethyl- thiophen-3-yl)thiophene-containing derivatives, corresponding to the π→π* transitions of the dithienylethene moiety. The photochromic reactivities have also been studied such that the photostationary state was found to be reached upon irradiation in the UV region for over eight hours, while no observable changes would be obtained upon photo-excitation in the visible region. The slow conversion rate has been suggested to be attributed to the fact that a rapid excitation energy transfer could occur from the excited Th-DTE to the BODIPY moiety, rendering the suppression of the photocyclization. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

The first example of an N,N'-chelated [beta]-diketiminato phosphenium salt has been isolated by careful tuning of both the ligand architecture and the electronic characteristics of the phosphorus containing moiety. Using a two-electron reduction approach, the first example of a phosphinidene valence isomer has been isolated and structurally characterized. The mechanism of formation of this valence isomer was elucidated via Density Functional Theory (DFT) calculations. These calculations revealed that the formation of this valence isomer involves the intermediacy of a triplet diradical. In turn, the triplet diradical decays by two further steps to generate the observed product. A cationic phosphinous acid has been prepared via the hydrolysis of a cationic phosphenium complex in basic solution. DFT calculations reveals that the introduction of a positive charge stabilizes the phosphinous acid form. Two N,C-bonded phosphenium cation salts have also been obtained, the crystal structures of which reveal that the formation of these compounds involves C-H activation of a methyl group on the [beta]-diketiminate ligand. Three synthetic methods, namely halide abstraction, aluminum/boron halide exchange process and salt metathesis, have been explored for the preparation of boron cations supported by [beta]-diketiminate ligands. The first structurally characterized boron cation supported by a [beta]-diketiminate ligand has been isolated as its [Al₂Cl₇]⁻ salt. A Ga-Fe organometallic complex supported by a [beta]-diketiminate ligand has also been synthesized via salt metathesis reaction and fully characterized. Finally, several bisamidinate supported boron complexes have been synthesized and structurally characterized. Such complexes may have applications as bifunctional catalysts or as building blocks for novel polymers.

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