Dissertations / Theses on the topic 'Acid-base propertie'

The design of chiral synthetic polymers capable of self-assembling into stable secondary structures represents an attracting approach with important biological applications, such as selective subcellular localization, protein surface mimicry and recognition. Chirality in polymers may be expressed based on the location of the stereogenic centers: i) main-chain chirality; ii) side-chain chirality and iii) self-assembled structures. Synthetic polymers as polyacetylenes, polyolefines and polymethacrylamides showing side-chain chirality may be synthesized by radical polymerization processes starting from modified α-amino acids. In previous work, a new family of biomimetic polymers showing side-chain chirality, named polyamidoamino acids (PAACs), were introduced. The first polymer of this family was named L-ARGO7, derived by the step-wise polyaddition of L-arginine with N,N’-methylenebisacrylamide (MBA). The reaction was carried out in water, at 50°C and pH > 9 for 6 days, yielding a polymer with Mw ≈8000 and PDI 1.4. L-ARGO7 turned to be highly cytocompatible (IC50 ≥ 8 mg mL-1) and easily internalized in mouse embryo fibroblasts balb/3T3 clone A31 cell line proving, in this respects, to share some of the unique biological properties of polyarginine cell-permeating peptides. The objectives of this work were multiple: to obtain a library of PAACs from the reaction of N,N’-methylenebisacrylamide with various natural α-amino acids following the same general procedure adopted for the synthesis of L-ARGO7, thus demonstrating the versatility of the synthetic process devised; to study the solution properties of PAACs, namely as acid-base behavior, ionization state, size and viscosity; to elucidate their conformational properties and ability to fold in aqueous media into compact and stable secondary structures; to study the responsiveness of these conformations to external stimuli; to study the fluorescent properties of PAACs from L-tryptophan; most important, to assess the PAAC ability to exhibit chirality-dependent interactions with biomolecules. The PAACs synthesized in this work can be classified based on the structural features of the α-amino acid residue: i) cationic arginine derived PAACs obtained from D-, L- and D,L-arginine; these polymers are moderately basic, since the guanidine group is internally neutralized by the carboxylate. Basicity is mainly due to the presence of the tert-amine; ii) hydrophobic alkyl-substituted PAACs derived from L-alanine (M-L-Ala), L-valine (M-L-Val) and L-leucine (M-L-Leu); these polymers are obtained by reacting slightly hydrophobic α-amino acids bearing lateral substituents of increased steric hindrance; iii) polar glutamine-derived PAAC obtained from L-glutamine (M-L-Gln); glutamine was chosen for its ability to form hydrogen bonds as protons donor or acceptor; iv) amphipathic homo- and copolymeric L-tryptophan-based PAACs synthesized from, respectively, L-tryptophan (M-L-Trp) and L-tryptophan/glycine mixtures (M-G-L-Trp); tryptophan was chosen for its fluorescence properties, used to characterized conformational and structural features of homo- and copolymers. EXPERIMENTAL PART: PAACs SYNTHESIS The synthetic procedure of the investigated PAACs is reported in Scheme 1. L-, D- and D,L-PAACs were obtained in variable yield (60-70 %) carrying out the polymerization in aqueous solutions at 50 °C and pH > 9 for 6 days. In no case, traces of hydrolytic degradation or formation of aggregates were seen. After 6 days, solutions were acidified to pH 4, purified by ultrafiltering through membranes with 100 and 5 kDa nominal molecular weight cut-off. The intermediated fractions were freeze-dried and structurally analysed by means of 1H and 13C NMR in D2O, at pH 4.5. Molecular weights (Mw and Mn) was measured by means of size exclusion chromatrographic (SEC) analysis, carried out in 0.1 M TRIS buffer pH 8.00 ± 0.05, with 0.2 M NaCl. RESULTS i) ARGO7 and Alkyl-substituted PAACs Circular dichroism (CD) measurements were recorded between 200 – 280 nm in the 3-12 pH interval. Spectra were consistent with the presence of pH-dependent ordered secondary structures, whose changes with pH were rapidly achieved and fully reversible. In addition, conformations resulted thermodynamically stable and reversible in the 3-70°C range. CD spectra were collected at ionic strength up to 2 M NaCl and in presence of denaturating agents, as urea and guanidinium chloride. Conformation of ARGO7 isomers resulted unaffected by ionic strength and presence of denaturants, whereas M-L-Ala, M-L-Val and M-L-Leu conformations changed with the introduction of guanidinium chloride. Molecular dynamics (MD) simulations were performed at Politecnico di Milano (prof. G. Raffaini and F. Ganazzoli) and revealed that ARGO7 and alkyl-substituted PAACs had a compact, coiled structure (Rgs 0.8-1.11 nm). MD showed that PAACs’ main chains were organized into a transoid arrangement characteristics of hairpin-like conformations. Structuring and size were mainly dictated by intramolecular interactions of electrostatic nature in the polymer main chain, with minor dependence from the amino acids side chain. Hydrodynamic radius (Rh) was determined by DLS as a function of pH, time, ionic strength and presence of denaturating agents (urea and guanidinium chloride). Results revealed that these PAACs had monomodal volumetric distributions of 1.5 ± 0.3 nm average radius, stable at 25 °C for at least 1 month and unaffected by pH, ionic strength and presence of denaturants. In addition, nanoparticles’ dimensions did not change by increasing the PAACs concentration in the 0.5 – 20 mg mL-1 range, suggesting these polymers may intramolecularly self-assembled into stable single chain nanoparticles. ii) glutamine-derived PAACs Differently from the other PAACs, M-L-Gln Mw and Mn values were more than two times higher than the others. This was tentatively ascribed to the presence of intra- and intermolecular hydrogen bonding, further studied with CD and NMR spectroscopy. CD spectra resulted sensitive to the presence of urea, a protein denaturant known to form H-bonding, with time dependent spectral variations. DOSY, variable-temperature NMR (VT-NMR) and NOESY were used to obtain the structural and conformational features of M-L-Gln. DOSY showed only one diffusion coefficient, from which a Rh of 3.53 nm was calculated. VT-NMR was carried out at pH 4.5 and revealed that side-chain amide groups were involved in the formation of H-bonding, whereas only a small percentage of amides of the MBA backbone did the same. In addition, NOESY experiments measured two NOEs, both involving CH2 next to the tert-amine and CH2 in β and γ position of the glutamine side chain, respectively. Thus, M-L-Gln showed a coiled structure in which glutamine side chain moved closer to the main chain. iii) tryptophan-based PAACs Polymers bearing tryptophan as side substituent were synthesized by Michael-type polyaddition of MBA with L-tryptophan, its isomer, and different molar ratio of L-tryptophan/glycine mixtures. Differently from the other PAACs, these reactions were carried out under nitrogen flux and by portion wise addition of the base to avoid indole oxidation. UV–Vis absorption and scattering of polarized IR beam tests showed all of them to have composition- and pH-dependent solubility. CD studies and DLS measurements were comparable with the other PAACs. CD were consistent with the formation of pH dependent self-assembled structures, whose conformation was dictated by the polymer main chain and its average ionization degree. Rhs resulted stable for at least 1 month, unaffected by pH but, to some extent, sensitive to concentration in the range 1–30 mg·mL−1. Photoluminescence analyses, quantum yields, steady state and time-resolved fluorescence were measurements at different pH, polymers concentration and tryptophan content. Results indicated that the photoluminescence properties of tryptophan derived polymers were governed solely by tryptophan. All polymers exhibited pH-dependent quantum yields, lifetimes and emission maximum. Interestingly, fluorescence studies conducted on oxygen-free solution gave comparable results, indicating compact conformations where L-tryptophan moieties were not accessible to the quencher. Also, intermolecular quenching by approaching chains was studied and observed in M-L-Trp and M-G-L-Trp10. iv) L- and D-ARGO7 chiral recognition To assess ARGO7 chiral recognition ability, sodium deoxycholate (NaDC), one of the components of bile salts, was chosen as a chiral model surface. Through a stepwise mechanism, NaDC can form chiral micelles, whose self-assembly behaviour is mainly affected by pH. In particular, NaDC showed three main pH dependent behaviour: homogenous solution (pH > 8), gel phase (pH 7 – 7.5), flocculation and aggregation (pH < 7). Pulsed-gradient spin echo NMR (PGSE-NMR), surface tension, circular dichroism (CD), dynamic light scattering (DLS), zeta potential (ZP) and small-angle neutron scattering (SANS) experiments were carried out on NaDC/L- and NaDC/D-ARGO7 mixtures, to assess chirality-dependent interactions. Surface tension, DLS, zeta potential and PGSE NMR measurements were recorded to characterize NaDC behaviour in solutions (CMC and self-assembly) as a function of pH and concentration and will not be considered in this report. CD measurements were carried out on 5 mg mL-1 of NaDC mixed with 0.5 mg mL-1 of either L-, D- or D,L-ARGO7 solutions, in the 190 – 300 nm range in a 1 mm cell. Prior to the analysis, solutions were corrected to pD (pH of D2O solutions) 9.06, and 7.50. At pD 9.06, the addition of NaDC did not result in any significant modification of the polymers’ spectra, in either L- or D- form of the polymers. Thus, no chiral discrimination could be found at this pH. At pD 7.30, CD spectra of NaDC gel phase showed different pattern upon addition of L- and D-ARGO7, whereas no changes were seen with D,L-ARGO7. Thus, the self-reorganization of NaDC into an ordered gel, was likely due to the chiral recognition of the different isomers. Small-angle neutron scattering (SANS) measurements were carried out at the ISIS Neutron and Muon Source facility (Rutherford Appleton Laboratory in Oxfordshire, UK, under the supervision of Prof. Peter Griffiths) to study chiral recognition, by looking at the conformational modifications of NaDC micelles upon introduction of the different isomeric forms of the polymer, at different pHs and concentrations. SANS collected at pD 8.5 - 8.8 for various NaDC concentrations were consistent with the presence of micelles, described by prolate ellipsoids with polar radius of 22 – 28 Å and equatorial radius of 7 – 10 Å. By decreasing pH, NaDC micelles’ structure changed from a prolate ellipsoid (pD 8.80) to an elongated rod (pD 7.30) described by elliptical cylinders of 487.6 ± 21.2 Å length and 2.88 ± 0.19 axis ratio (Figure. 1a, black curve). NaDC/ARGO7 mixtures were prepared adding 5 mg mL-1 of NaDC to 0.5 mg mL-1 solution of D-, L-, D,L-ARGO7 and an equimolar mixture obtained by mixing L- and D-isomer of the polymer (D-/L-ARGO7). All NaDC/ARGO7 mixtures showed superimposable curves. They were fitted with the same model used for NaDC solutions, that is micelles with prolate ellipsoidal morphology (Figure 1a). Only small changes in the total charge and in the semi-minor and semi-major axis were seen. This confirmed the modest effect of the electrostatic interactions between the two components, ARGO7 and NaDC, and the absence of chiral discrimination. Chiral recognition was then assessed collecting SANS data for 5 mg mL-1 NaDC gels (pD 7.3 – 7.5) with 0.5 mg mL-1 of D-, L-, D,L-ARGO7 or an equimolar mixture composed of 0.5 mg mL-1 D-ARGO7 and 0.5 mg mL-1 L-ARGO7. They showed that NaDC structure was differently affected by the chirality of the polymer (Figure 1b), confirming results obtained from CD spectra. In particular, D-, D,L-ARGO7 and the equimolar mixture changed SANS pattern in the same way. They retained the same rod-like structure of NaDC micelles, albeit with a lower axis ratio (1.51 ± 0.41). Different was the case of the NaDC/L-ARGO7 solutions, where L-ARGO7 appeared to trigger the formation of NaDC ellipsoidal clusters. In conclusion, PAACs represent singular examples of synthetic bioinspired chiral polymers that showed potential for biotechnological applications on account of their i) stimuli-responsiveness, ii) self-assembly ability and iii) selective interactions with chiral structures, including biological structures.

Estudaram-se as propriedades ácido base e de complexação com íons Cu(II) dos ácidos húmico (AH) e fúlvico (AF) extraídos de vermicomposto. O isolamento e a purificação foram realizados de acordo com o método descrito pela Sociedade Internacional de Substâncias Húmicas (IHSS). Estudaram-se as propriedades ácido-base por titulação potenciométrica em meio de KNO3 0,10 mol L-1 utilizando-se funções de Gran modificadas. Caracterizaram-se cinco classes de grupos ionizáveis, constatando-se predominância de grupos carboxílicos sobre grupos fenólicos e amínicos, especialmente para o AF, cuja acidez total foi maior do que a do AH. Estudaram-se as propriedades complexantes com íons Cu(II) nos pH 4, 5 e 6 por titulação potenciométrica com um eletrodo íon-seletivo para Cu(II), adotando-se os métodos de Scatchard e de regressão não linear com a equação de Langmuir para tratamento de dados. Em pH 5 e 6 caracterizaram-se duas classes de sítios de complexação, enquanto em pH 4, apenas uma classe foi caracterizada. De maneira geral, a estabilidade e a capacidade de complexação aumentaram com o pH, indicando a competição de prótons pelos sítios de complexação. Os resultados indicam maior estabilidade e capacidade para a complexação com AH em relação ao AF. Esta tendência foi verificada por funções diferenciais de equilíbrio diferenciais aplicadas em baixos graus de ocupação de sítios.
Acid base and complexation with Cu(II) ions were studied for humic (AH) and fulvic (AF) acids extracted from vermicompost. The isolation and purification was performed according the procedure described by the International Humic Substances Society (IHSS). The acid base properties were studied by potentiometric titration in 0,10 mol L-1 KNO3 using modified Gran functions. Five classes of ionizable sites were characterized, showing a predominance of carboxylic over phenolic and aminic groups, especially for AF, which has total acidity larger than the one determined for AH. Complexing properties with Cu(II) ions were studied by potentiometric titration at pH 4, 5 and 6 using Cu(II) ion-selective electrode. Data treatment was performed using the Scatchard method, as well as non-linear regression with the Langmuir equation. At pH 5 and 6, two classes of binding sites were characterized, but at pH 4 only a single complexing site was characterized. Stability and capacity increased with pH, suggesting competition of protons by the binding sites. The results indicate larger stability and capacity for complexation with AH in comparison with AF. This trend was also verified by differential equilibrium functions at low degree of site occupation.

The release of toxic metal species is of concern due to their detrimental effects on the environment and human health. Industrial effluents are a major source of mobilised metal species. Suitable technologies are needed to sequester toxic metal species at the point of source. Biosorption, which is based on the passive adsorption of contaminants onto biological materials, promises to offer an effective alternative or complementary step to existing treatment methods. However, to date there has been no widespread commercialisation of the technique. This is partly due to an insufficient understanding of the complex underlying mechanisms which makes it difficult to select suitable biomass for specific remediation problems and to predict process performance. This study characterised two gram-positive, thermophilic bacteria, Anoxybacillus flavithermus (BF) and Geobacillus stearothermophilus (BS), harvested at two different growth times, with regard to their acid-base and Cd�⁺ adsorption behaviour. The aim was to investigate the metal cation adsorption properties of thermophilic bacteria which has not been studied previously, and to gain a better understanding of the interactions responsible for bacterial metal cation adsorption. Experimental techniques employed in this study included microscopy to establish cell and cell wall morphology, batch acid-base and Cd�⁺ adsorption experiments to quantify proton active surface functional groups and Cd�⁺ adsorption, electrophoretic mobility measurements to assess the overall surface charge of the bacteria and in situ attenuated total reflection infrared (ATR-IR) spectroscopy to reveal the chemical identities of functional groups. Chemical equilibrium models based on batch acid-base titration and electrophoretic mobility data were developed to quantitatively describe proton active surface functional groups. These groups can also interact with metal cations. It was found that growth time was an important factor in all experiments with the differences between growth times often being more pronounced than the differences between the two bacterial strains. Microscopy revealed a gram-positive cell wall structure with different widths and staining behaviour for exponential phase cells of BF and BS. Stationary / death phase cells showed disintegrating cell walls. Acid-base titrations indicated that all cells possessed buffering capacity over the whole investigated pH range (pH 2 - 10). From electrophoretic mobility measurements, isoelectric points of ~ 3.2 for BF and < 1.8 and ~ 4.2 for exponential and stationary / death phase cells of BS respectively were estimated. Chemical equilibrium models including a Donnan electrostatic model were derived which described both the batch acid-base titration data and the electrophoretic mobility data reasonably well, although a comparison with IR data suggested room for further improvement. In situ ATR-IR spectroscopy of hydrated bacterial cells at various pH values revealed amide and carboxyl groups and a contribution from phosphate / polysaccharide moieties. Group specific interactions with Cd�⁺ were not detected, however, a partially reversible absorbance increase of all peaks suggested conformational changes in the presence of Cd�⁺. BF and BS adsorbed ~ 70 [mu]mol Cd�⁺ (g dry bacterial)⁻� at pH 5 in 0.01 M NaNO₃. Release of major cations occurred concomitantly with Cd�⁺ adsorption. The buffering and Cd�⁺-binding capacities of BF and BS were found to be comparable to those of mesophilic bacteria and ion exchange was identified as an important adsorption mechanism.

[Truncated abstract] The influence of environmental conditions and properties of pyritic shale in the mining waste from Mt. Whaleback in Western Australia, in particular the inclusions and encapsulation of pyrite on the oxidation of pyritic shale and its subsequent acid mine drainage, was studied by employing an isothermal batch reactor system and QEMSCAN technique. The experimental technique was validated by comparing the experimental results obtained in this study with the literature data. It was found that the presence of water significantly accelerates the rate of shale oxidation. Weathering of the shale samples was found to influence the O2 consumption rate. It was also found that shale properties have a major effect on the oxidation rate and thereby affect the acid generation. Static test methods (Sobek and Lawrence) were employed to test the Neutralisation Potential (NP) of more than 100 actual and composite samples including pyritic shale samples, rock samples, mineral samples, various pyrite-mineral, pyrite-shale, and pseudo-shale blends. The influence of sample properties (bulk elemental composition, and mineralogy), test technique (Sobek and Lawrence) and associated variables (acid strength and volume) on the acid neutralisation potential of the samples was studied. It was found that the Sobek method produced consistently higher NP results under comparable acid conditions to those obtained with the Lawrence method. The theoretical NP values of individual minerals were calculated based on the mineral composition combined with the acid neutralising equations and ideal chemical formula. ... To experimentally model the major mineral phases, 11 minerals were used to produce pyrite-mineral blends and pseudo-shales, whose compositions mimic those of the actual shales studied. Mineral blends were employed to evaluate and contrast their individual acid generation or neutralisation behaviour with binary and higher order interactions. Blends of pyrite with some selected shales were also employed in this study. It was found that interactions can occur between the multiple mineral components which can enhance the rate of acid generation beyond that of the individual behaviour. It was found that the products from the pre-oxidation of shales, the properties and morphology of a sample such as the surface area, encapsulation, the mineralogy and pH all play a significant role in the acid generation and neutralisation rates. However, the absolute rate of acid generation appears to be most sensitive to the components such as Fe3+, which contribute to its reaction mechanisms. This investigation has provided a scientific insight into the acid generation and neutralisation behaviour of pyritic shale in relation to its mineralogy. It was found that the relative instantaneous rates of acid generation and consumption for individual minerals can be significantly different to that of their total potentials for acid generation and neutralisation. The significantly different behaviour of the actual and pseudo shales suggests that at low pH, there may be other mechanisms underlying the net capacity and rates of shales to generate or consume acid than bulk mineralogy. These findings have significant implications to the mining industry operating in reactive grounds.

This dissertation covers the studies of two major topics: the photochemistry of mononuclear and multinuclear gold(I) complexes and synthetic approaches to tailor photophysical properties of cyclic trinuclear d10 complexes. First a detailed photochemical examination into the photoreactivity of neutral mononuclear and multinuclear gold(I) complexes is discussed, with the aim of gold nanoparticle size and shape control for biomedical and catalysis applications. Next is a comprehensive systematic synthetic approach to tailor the photophysical properties of cyclic trinuclear d10 complexes. This synthetic approach includes an investigation of structure-luminescence relationships between cyclic trinuclear complexes, an examination into their π-acid/π-base reactivity with heavy metal cations and an exploration into the photophysical properties of new heterobimetallic cyclic trinuclear complexes. These photophysical properties inspections are used to screen materials for their employment in molecular electronic devices such as organic light-emitting diodes (OLEDs) and thin film transistors (OTFTs).

Acid/base and metal ion adsorption properties have been investigated for a range of chemically modified bleached Kraft fibre materials (pulps). The studies were performed via potentiometric titrations, Flame Atomic Absorbtion (and Emission) Spectroscopy, Inductively Coupled Plasma Optical Emission Spectroscopy and Extended X-ray Absorbtion Fine Structure measurements. As a result of a chemical modification procedure, the total concentration of acidic carboxylate groups in the fibre materials ranged between 43 and 590 μmol/g. The preferable surface potential model for modelling the ionic strength dependent acid/base properties of fibre materials with low charge densities, i.e. unmodified fully bleached Kraft fibre materials, was found to be the Basic Stern Model. For fibre materials with high total charge, ≳100 μmol/g, this model resulted in poor fits to data, and for such materials a number of Constant Capacitance Models, one at each ionic strength, must be recommended. With respect to metal ion adsorption, the results have indicated that the unspecific Donnan theory could correctly model the simultaneous adsorption of several metal ions, i.e. K+, Na+, Mg2+, Ca2+ and Cu2+, provided that the salt concentration in the fibre suspension is low. In suspensions of high salt concentration it was, however, found that this very same model strongly underestimated the adsorption of Ca2+ and Cu2+. Here, the Donnan model had to be complemented by specific ion exchange equilibria. These results were corroborated by spectroscopic evidence of specific interactions between Cu2+-ions and fibres. The spectroscopic indication of a complex formed between two fibre surface carboxylate groups and one Cu2+-ion, agree with the specific ion exchange model. It was therefore concluded that specific metal ionfibre interactions cannot be neglected, especially at high salt concentrations. The interactions occurring between the polycation GaO4Al12(OH)24(H2O)127+ and fibre materials were studied by both adsorption and spectroscopic measurements. These indicate that GaO4Al12(OH)24(H2O)127+ is surprisingly stable in fibre suspensions and that intact GaO4Al12(OH)24(H2O)127+- ions are strongly adsorbed onto the fibres. Also for this ion, specific interactions has to be considered, since the strong adsorption registered was too strong to be explained by Donnan equilibria. In the thesis, the stochiometric composition and an equilibrium constant characterising these interactions is presented.

Glycerol and fructose are molecules that are readily available in substantial quantities fromthe biomass. In this work dehydration routes for valorization of these compounds wereinvestigated. Therefore, zirconia and titania based catalysts, and calcium phosphate materialswere prepared and evaluated in the glycerol dehydration in gas phase. Niobia-ceria mixedoxides and mesoporous Nb2O5-MeO2 (M = Ce, Zr, Ti) mixed oxides were prepared andtested in fructose dehydration reaction in aqueous phase. The surface acid-base properties ofthe studied catalysts were correlated to their catalytic performance.

Le comportement en corrosion d'alliages chromine (Cr2O3) et alumine (Al2O3) formeurs dans des verres sodo-calciques à haute température a été étudié en utilisant des techniques électrochimiques. Les mécanismes réactionnels de la corrosion par ce type de milieu ont ainsi pu être abordés, de même que les aspects cinétiques. Les résultats ont montré que l'alumine n'est pas capable de protéger les alliages, étant donnée sa très forte solubilité dans le verre. Cependant, les alliages chromine formeurs ont montré une meilleure résistance à la corrosion, et ce s'ils ont subi un traitement de pré-oxydation. Une compétition entre la croissance de la couche de chromine et sa dissolution régit la durée de vie de la couche protectrice. Ainsi la physico-chimie de la chromine en milieu verre fondu a été étudiée. Sa solubilité a été mesurée afin de comprendre l'influence des paramètres température (T), fugacité en oxygène (fO2) et composition du verre. Une étude cinétique a mis en évidence l'influence de ces paramètres sur les mécanismes et le temps de mise à l'équilibre. D'un point de vue thermodynamique, l'influence des paramètres T et fO2 sur la solubilité du chrome dans des verres ternaires Na2O-CaO-xSiO2 est cohérente avec celle déjà observée sur des verres binaires Na2O-xSiO2, la solubilité de la chromine étant bien plus faible dans les verres ternaires. L'influence de la basicité a été étudiée en prenant en compte la basicité optique théorique (^th) et l'activité en oxyde de sodium (aNa2O). Les rapports redox (CrII/CrIII et (CrVI/CrIII) ont été déterminés suite à un affinement mathématique. Les grandes différences observées par rapport aux résultats théoriques (vérifiés dans les verres binaires) dans le cas où la spéciation du chrome intervient laissent penser que l'oxyde de calcium CaO influe sur les réactions impliquant le couple O2/O2-
The corrosion behaviour of chromia (Cr2O3) and alumina (Al2O3) forming alloys in soda-lime silicate melts was studied by using electrochemical measurements. The general aspects of the corrosion by molten glass as well as the redox reactions and the kinetics ruling the corrosion process were determined. The results revealed that Al2O3 is not able to provide protection against corrosion since it has a high dissolution in the melt. However Cr2O3 forming alloy could resist against corrosion if the alloy was subjected to a preoxidation treatment. A competition between the oxide growth and its dissolution in the melt rules the durability of the protective Cr2O3 layer. Thus, the physicochemistry of Cr2O3 in molten glass was then studied in order to understand the influence of temperatures (T), oxygen fugacities (fO2) and glass composition on the limit of solubility of Cr2O3. A preliminary kinetics study revealed that the time to reach equilibrium varies with these parameters. A thermodynamic study showed that the influence of T and fO2 on the Cr2O3 solubility in ternary soda-lime silicate melts (Na2O-CaO-xSiO2) is in coherence with results previously obtained in binary melts (Na2O-xSiO2). Nevertheless, the Cr2O3 solubility in ternary melts is lower than in binary melts. The influence of basicity was studied in both melts by taking into account the theoretical optical basicity (^th) and the activity of Na2O (aNa2O). The redox ratios (CrII/CrIII and CrVI/CrIII) were determined through a mathematical refinement. The comparison with the results obtained in binary melts and the deviation from the theoretical values expected when speciation of Cr is involved, induced assumptions on the role played by CaO in influencing the reactions involving species from O2-/O2 couple

Aquest treball d’investigació aplica una aproximació racional per a la millora de les propietats del catalitzador emprat en la transesterificació de la urea amb etilenglicol (EG), per a la producció de carbonat d'etilè (EC) sobre òxids metàl•lics; i un enfocament estadístic per maximitzar la formació del producte desitjat. Per a l’aproximació racional, òxids metàl•lics singulars i mixtes amb combinacions elementals (Zn, Mg, Al, Fe), i amb una àmplia varietat de propietats àcid-base, han estat sintetitzats i avaluats per a la reacció de transesterificació. El rol de l’acidesa i la basicitat en les rutes de reacció identificades han estat clarificats en base a la selectivitat dels productes, i als paràmetres cinètics obtinguts a partir dels perfils de concentració dels reactius i dels productes per a cada ruta de reacció, mitjançant monitorització IR in situ i els subseqüents anàlisis multivariable. Les rutes de formació del EC són catalitzades favorablement mitjançant centres de reacció àcids, mentre que els centres bàsics catalitzen totes les rutes de reacció cap a productes indesitjats. No obstant això, els centres superficials estan obstruïts quan l’acidesa es massa elevada i, per tant, existeix un valor òptim per a la relació del total de centres àcids i bàsics, el qual permetrà obtenir un catalitzador eficient per a la reacció desitjada. L’òxid metàl•lic mixt basat en Zn i Fe amb una relació atòmica 3:1 ha estat identificat com el catalitzador òptim ja que posseeix propietats àcid-base equilibrades adequadament. Els estudis mecanístics han mostrat la formació d’espècies sobre la superfície del catalitzador - isocianats i cianats – indicant diferents mecanismes per a l’activació dels reactius. Els isocianats han estat observats, majoritàriament, sobre òxids basats en Mg, mentre que els òxids acídics així com els basats en Zn promouen la formació de cianat. A més a més, l’aproximació al disseny d’experiments (DoE) ha estat utilitzada per a identificar, d’una forma estadística, els paràmetres crítics de reacció i per a optimitzar dits paràmetres per als millors catalitzadors basats en Zn i Fe. Aquestes aproximacions han permès, de forma exitosa, l’obtenció de coneixements sobre els factors materials determinants en la reacció objectiu i assolir una selectivitat excel•lent per al EC i amb un rendiment elevat
En este trabajo se presenta: (i) un enfoque racional, con el objetivo de mejorar las propiedades de materiales como catalizadores para la transesterificación de urea mediante la conversión de etilenglicol (EG) a carbonato de etileno (EC) sobre óxidos metálicos y, (ii) un enfoque estadístico para maximizar el producto deseado. Para el enfoque racional se han sintetizado y evaluado diversas combinaciones elementales de óxidos metálicos individuales y mixtos (Zn, Mg, Al, Fe) con una variedad de propiedades ácido-base. Los roles de la acidez y la basicidad en el camino de la reacción se han clarificado en base a la selectividad de los productos y, a los parámetros cinéticos extraídos de los perfiles de concentración de los reactivos y de los productos en cada camino de la reacción, por medio de in situ IR monitoring y el posterior análisis multivariable. El camino hacia EC es catalizado favorablemente por sitios ácidos, mientras que los sitios básicos, catalizan todos los caminos hacia los productos no deseados. Sin embargo, los sitios superficiales son bloqueados cuando la acidez es demasiado alta. Existe un valor óptimo para la proporción de sitios ácidos y básicos, para que el catalizador sea eficiente en una reacción específica. La mezcla de óxidos metálicos consistente en Zn y Fe con una proporción atómica de 3:1 ha sido identificada como el catalizador óptimo con unas propiedades ácido-base equilibradas. Estudios mecanísticos, muestran la formación de diferentes especies sobre el catalizador - cianatos e isocianatos - indicando así, diferentes mecanismos para la activación de los reactivos. Los isocianatos se observan principalmente sobre óxidos básicos que contienen Mg. En cambio, la formación de cianatos, se observa en óxidos ácidos que contienen Zn. Además, un enfoque de diseño de experimentos (DoE) se ha utilizado para identificar estadísticamente los parámetros críticos de la reacción, así como, para optimizarlos con el propósito de encontrar el mejor catalizador compuesto por Zn y Fe. Estos enfoques, nos han permitido determinar con éxito, conocimientos acerca de los factores materiales determinantes para dicha reacción, además de obtener una excelente selectividad para EC (hasta un 99.6%) con un alto rendimiento.
This work employs (i) a rational approach to improve material properties as catalyst for urea transesterification with ethylene glycol (EG) to ethylene carbonate (EC) over metal oxides and (ii) a statistical approach to maximize the desired product. For the rational approach, single and mixed metal oxides with different elemental combinations (Zn, Mg, Al, Fe) with a variety of acid-base properties were synthesized and evaluated for the reaction. The roles of acidity and basicity in the identified reaction paths were clarified based on product selectivities and kinetic parameters extracted from the concentration profiles of reactants and products in every reaction path by means of in situ IR monitoring and subsequent multivariate analysis. The paths towards EC are favorably catalyzed by acidic sites, while basic sites catalyze all paths towards undesired products. However, surface sites are blocked when acidity is too high and there exists an optimum value for the ratio of total acidic and basic sites to be an efficient catalyst in the targeted reaction. Mixed metal oxide consisting of Zn and Fe at 3:1 atomic ratio was found to be the optimum catalyst with a well-balanced acid-base property. Mechanistic study showed formation of species over catalyst surface – isocyanates and cyanates– indicating different mechanism of reagent activation. Isocyanates were mostly observed over basic Mg-containing oxides, whereas acidic and Zn-containing oxides promote cyanate formation.Furthermore, design of experiments (DoE) approach was used to statistically identify critical reaction parameters and optimize them for the best Zn- and Fe- containing catalyst. These approaches successfully gained insights into the determining material factors for the reaction and afforded excellent EC selectivity (up to 99.6%) with high yield.

Ce travail de thèse se focalise sur l'impact des propriétés acido-basiques des catalyseurs (quantité et force des sites) dans la production d’acroléine par couplage oxydant d’alcools en phase gazeuse. L'influence du rapport entre site acides et sites basiques des catalyseurs a été étudiée dans la condensation aldolique de l'acétaldéhyde et du formaldéhyde en acroléine, réalisée en conditions oxydantes. Les données et corrélations obtenues ont donné des informations indispensables à l’identification des paramètres qui doivent être modifiés afin d'améliorer la sélectivité en acroléine. La première réaction du procédé implique l'oxydation du méthanol et de l'éthanol respectivement en formaldéhyde et acétaldéhyde sur un catalyseur rédox de type FeMoOx.Ensuite, l'aldolisation croisée des deux aldéhydes et la déshydratation en acroléine sont effectuées sur des catalyseurs acido-basiques.Les alcools impliqués dans ce procédé pouvant dériver de la biomasse, cette nouvelle voie de production d'acroléine présente un intérêt élevé puisqu'elle peut remplacer la production actuelle d'acroléine basée sur des ressources fossiles (aujourd'hui l’acroléine est produite industriellement par oxydation du propylène).Le catalyseur optimal doit présenter des caractéristiques amphotères avec une quantité similaire de sites basiques et acides. Une présence modérée et équilibrée de sites acides et basiques améliore le rendement en acroléine et déplace à plus haute température la production des oxydes de carbone. Parmi tous les catalyseurs étudiés, et grâce à ses propriétés acido-basiques spécifiques, MgO supporté sur silice a été identifié comme étant le meilleur catalyseur pour la condensation aldolique des aldéhydes en acroléine en conditions oxydantes
The present work focuses on the impact of the amount and strength of acidic and/or basic sites on the yield of acrolein produced by alcohols oxidative coupling in gas phase. The influence of acid/base ratio of catalytic sites has been studied in the aldol condensation of acetaldehyde and formaldehyde to acrolein performed in oxidizing conditions. The obtained data and correlations supplied valuable information to understand which parameters have to be modified to improve the acrolein selectivity. The first reaction of the process implies methanol and ethanol oxidation respectively to formaldehyde and acetaldehyde on a FeMoOx redox catalyst. Then the cross-aldolization of the two aldehydes and the dehydration to acrolein is performed on acid/base catalysts. Because the alcohols involved in this process can be bio-sourced, this new route to produce acrolein presents a very high interest, since it can replace the current fossil-based acrolein production (nowadays industrially produced by oxidation of propylene). The optimal catalyst should present amphoteric features with a similar amount of both basic and acidic sites. A moderate and balanced presence of acidic and basic sites improves the acrolein yield and the production of carbon oxides is significantly increased only at high temperature. Among all studied catalysts, MgO supported on silica has been identified as the best catalyst for aldol-condensation of aldehydes to acrolein in oxidizing conditions thanks to a given ratio of basic to acidic sites

The chemistry of mineral surfaces is of great importance in many different areas including natural processes occurring in oceans, rivers, lakes and soils. Manganese (hydr)oxides are one important group to these natural processes, and the thermodynamically most stable trivalent manganese (hydr)oxide, manganit (γ-MnOOH), is studied in this thesis. This thesis summarises six papers in which the surface chemistry of synthetic manganite has been investigated with respect to surface acid-base properties, dissolution, and adsorption of Cd(II) and the herbicide N-(phosphonomethyl)glycine (glyphosate, PMG). In these papers, a wide range of analysis techniques were used, including X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS) spectroscopy, Fourier transform infra-red (FTIR) spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), potentiometry, electrophoretic mobility measurements and wet chemical techniques, in order to obtain a more complete understanding of the different processes occurring at the manganite-water interface. From the combined use of these techniques, a 1-pKa acid-base model was established that is valid at pH>6. The model includes a Na+ interaction with the surface: =MnOH2+½ --> =MnOH-½ + H+ log β0 (intr.) = -8.20 = -pHiep =MnOH2+½ + Na+ --> =MnOHNa+½ + H+ log β0 (intr.) = -9.64 At pH<6 the manganite crystals dissolve and disproportionate into pyrolusite (β-MnO2) and Mn(II)-ions in solution according to: 2 γ-MnOOH + 2H+ --> β-MnO2 + Mn2+ + 2H2O log K0 = 7.61 ± 0.10 The adsorption and co-adsorption of Cd(II) and glyphosate at the manganite surface was studied at pH>6. Cd(II) adsorption displays an adsorption edge at pH~8.5. Glyphosate adsorbs over the entire pH range, but the adsorption decreases with increasing pH. When the two substances are co-adsorbed, the adsorption of Cd(II) is increased at low pH but decreased at high pH. The adsorption of glyphosate is increased in the entire pH range in the presence of Cd(II). From XPS, FTIR and EXAFS it was found that glyphosate and Cd(II) form inner sphere complexes. The binary Cd(II)-surface complex is bonded by edge sharing of Mn and Cd octahedra on the (010) plane of manganite. Glyphosate forms inner-sphere complexes through an interaction between the phosphonate group and the manganite surface. The largest fraction of this binary glyphosate complex is protonated throughout the pH range. A ternary surface complex is also present, and its structure is explained as type B ternary surface complex (surface-glyphosate-Cd(II)). The chelating rings between the Cd(II) and glyphosate, found in aqueous complexes, are maintained at the surface, and the ternary complex is bound to the surface through the phosphonate group of the ligand.

Ce travail est en relation avec la thématique "Chimie Verte" en particulier, le rôle de la catalyse,l'utilisation des matières premières renouvelables et l'élimination des produits nocifs.- Quatre échantillons commerciaux de zircone tungstatée de Mel-Chemicals.- deux séries de zircone tungstatée préparées par deux méthodes différentes avec une teneuren WO3 de 1 à 20 % en masse.- des oxydes binaires tels que WO3-ZrO2, B2O3-ZrO2, Al2O3-ZrO2, Ga2O3-ZrO2 et In2O3-ZrO2.- des oxydes binaires tels que WO3-Me2O3 (Me = B, Al, Ga et In) et finalement des oxydesternaires WO3/(Me2O3-ZrO2) (Me = B, Al, Ga et In) ont été étudiés et préparés lors de cettethèse.La performance catalytique de ces catalyseurs a été évaluée dans l'hydrolyse de la cellobiose, ladéshydratation du fructose et la réduction catalytique sélective des NOx. Les propriétés acides etredox de surface ont été corrélées aux performances catalytiques. En général, la conversion totale est liée à l'acidité des catalyseurs. Les catalyseurs les plus sélectifs pour la déshydratation du fructose et en deNOx sont ceux présentant une acidité modérée.

Les carbones poreux ont été largement utilisés et étudiés ces dernières années. Ce travail de recherche porte sur la préparation de matériaux carbonés mésoporeux modifiés ou non par de l'azote. Tout d'abord, un carbone mésoporeux pur a été synthétisé. Puis des atomes d'azote ont été introduits dans ce carbone mésoporeux par deux méthodes de dopage ("in situ" et "post-synthèse" respectivement). La comparaison des propriétés acido-basiques dans des conditions différentes pour les trois types de matériaux mésoporeux carbonés, avec ou sans diazote, a été faite grâce à des techniques calorimétriques. Ces carbones mésoporeux ont aussi été utilisés dans l'adsorption de polluants, le stockage de l'hydrogène et en tant que supports pour les métaux précieux et l'oxyde de fer en catalyse. Les différentes performances dans ces applications ont été mises en relation avec les différentes propriétés structurelles et surfaciques causées par le dopage au diazote
Porous carbon materials are widely used and studied in recent years. In this work, three kinds of mesoporous carbon materials were prepared. Firstly, cost-effective pure mesoporous carbon was synthesized. Then nitrogen atoms were introduced into the mesoporous carbon by “in situ” and “post” doping methods respectively. The comparisons of the acid-base properties in different conditions of the three kinds of mesoporous carbon materials with or without nitrogen were studied and revealed by different calorimetric techniques. The three kinds of mesoporous carbons were also applied in pollutants adsorption, hydrogen storage and as supports of precious metals and iron oxide in catalysis. The different performances in applications were related to the different structural and surface properties caused by the N-doping

Dans cette étude, l’amélioration des propriétés physiques et de sa durabilité aux agents de dégradation biologique du hêtre européen (Fagus sylvatica) a été réalisée au moyen de différents traitements. Les premiers types de traitements sont basés sur l'imprégnation de dérivés vinyliques de glycérol ou de polyglycérol en tant qu'additif suivi d’une étape de modification thermique réalisée dans un réacteur ouvert (OHT) ou fermé (HPS). Le deuxième type de traitement repose sur la poly-estérification in situ du sorbitol et de l'acide citrique à différentes concentrations et températures de durcissement en système ouvert. Diverses propriétés de durabilité physique, chimique, mécanique et biologique des bois modifiés ont été évaluées. Les résultats montrent que certains traitements peuvent améliorer de manière significative les propriétés de durabilité physique et biologique du bois contre les agents de pourriture blanche, brune et molle et surtout vis-à-vis de l’attaque des termites comparativement au bois non traité ou modifié thermiquement uniquement
In this study, improvement of physical and biological durability properties of European beech (Fagus sylvatica) has been performed through different bulking impregnation treatments. The first modification was based on the impregnation of vinylic derivatives of glycerol or polyglycerol as additive followed with different thermal modification conditions in the opened system (OHT) or in the closed system (HPS). The second modification was based on the in-situ polyesterification of sorbitol and citric acid at different concentrations and curing temperatures in the opened system. Various physical, chemical, mechanical, and biological durability properties of the modified woods were evaluated, including certain properties during modification. The results have disclosed that certain treatments can improve significantly physical and biological durability properties of wood against decay (white rot, brown rot, and soft rot fungi) and termites attacks in comparison to untreated wood or thermally modified woods

碩士
國立中央大學
化學研究所
95
ABPBI is synthesized successfully in this research. After synthesized , ABPBI mix with three different acid polymers PVSA, PVPA, and PAA to form acid-base polyelectrolyte membranes. FT-IR and XRD data show that the compatibility between acid and base polymers is high because of the acid-base interaction, Besides, after adding small amount of acid polymer in ABPBI, the regular arrangement of ABPBI is destroyed because of the acid-base interaction. The interaction between ABPBI and PVSA is the strongest of all the membranes, even the 50ABPBI-50PVSA is similar to the formation of salt. All the membranes have high thermal stability up to 200℃, it means that the membranes can be used safely in high temperature fuel cells. If acid and base polymers mix well to form an ordered structure, the decomposition temperature of functional groups is increasing, and the thermal stability is higher. Variable temperature conductivity for dry membranes follows the Arrhenius law. With the increase of temperature, the proton conductivity is increasing. In ABPBI-PVPA system, 50：50 ratio shows the lowest proton conductivity. High resolution solid state NMR shows that ABPBI and PVPA form a compact complex when the ratio is 50：50. This result suggests that the proton is more easily to transport in this membrane. In the wet condition, proton conductivity increase with increasing temperature before water loss temperature. When water starts to vaporize, proton conductivity drops quickly, it means water is the major medium to transport proton in membranes. According to the data above, the hopping and vehicle mechanism to transport proton both exist in membranes, and ABPBI-PVPA system shows the highest proton conductivity in dry and wet conditions. It means the interaction between imidazole and phosphonic acid is suitable for proton transport.

碩士
國立交通大學
電子物理系所
107
In this thesis, we reported the property of GaN nanowires grown in HVPE, and we learned if the property changed even in extreme situation and their durability. First, we cleaned the Si substrates and steeped them into HF to remove native oxide. Then we used electron beam evaporation to deposit Ni onto Si substrates as catalyst. Finally, we used hydride vapor phase epitaxy (HVPE) to grow GaN nanowires. Nowadays, nanowires had been greatly applied in sensor area since their large surface area. However, compared with other material, GaN could be used in harder environment because of better thermal conductivity and chemical stability. Through annealing GaN nanowires in different temperature, we observed that GaN nanowires could still remain the emission property and even get better in red-light-band in 600 ∘ C by photoluminescence (PL). We could be sure that the structure of GaN nanowires were still complete via X-Ray diffraction (XRD). Besides, we found the limitation of GaN nanowires in etching liquid was 85% phosphoric acid in 60∘C. Finally, we used PL to know the emission property of GaN nanowires in various acid/base liquid, which were all reversible. These are important if we’re going to apply GaN nanowires in extreme environment in the future.

Reactions leading to cyclization on methylene bridges in PCPCP structure motif were investigated. It was found, that these reactions result in number of various isomers. Some of these isomers were characterized by NMR and MS spectroscopy, but none was isolated. Further, acid-base properties of bis(methylenephosphonato)phosphineic acid were investigated. Formation of complexes was studied with lithium(I), calcium(II), copper(II) and zinc(II) cations. Furthermore, interaction between bis(methylenephosphonato)phosphinic acid and ethylenediamine was investigated by NMR and potentiometric titration. The results show formation of H-bond-based adducts.

Direct methanol fuel cells (DMFC) are being investigated for use as low-power electrochemical energy conversion devices. These types of fuel cells can be useful for portable electronics. The polymer electrolyte membrane plays a critical role in the overall performance of DMFC. The commercially available membrane, Nafion, suffers from high methanol permeability and a resulting methanol crossover from the anode to the cathode; it is also expensive. Accordingly, alternative membrane materials, such as sulfonated hydrocarbons, are intensively pursued for DMFC. For example, sulfonated poly (ether ether ketone) (SPEEK) and sulfonated polysulfone (SPsf) are two such candidates. This thesis focuses first on a simple synthesis method for a cross-linked sulfonated polysulfone membrane. Sulfonated polysulfone (Psf) membranes, with high IEC (1.4 - 2.2 meq/g), were characterized by nuclear magnetic resonance spectroscopy (NMR), proton conductivity, and water uptake. The degree of sulfonation was calculated by NMR and verified by acid-base titration analysis. Although the membranes showed good proton conductivity, they suffered from excessive swelling at high temperatures. Furthermore, the post-sulfonation of a carboxyl-substituted polysulfone (Psf-COOH) was carried out with trimethylsilyl chlorosulfonate, and solubility issues of the Psf-COOH in chlorinated solvents led to difficulty in controlling the degree of sulfonation (DS) and in purification. Accordingly, this approach to cross-linking sulfonated polysulfone was rejected as a viable method. This thesis then focused on the investigation of the mechanical properties of acid-base blend membranes based on SPEEK and heterocycle-tethered Psf and cross-linked membranes based on SPEEK that were previously reported by our group; these membranes were known to exhibit good performance in DMFC. However, the assessment of the mechanical stability of any new membranes developed is critical for their practical viability in DMFC. Accordingly, the mechanical strength and ductility of these membranes were investigated and compared for various membrane compositions. The acid-base blend membranes investigated consisted of SPEEK (acidic polymer) and a heterocycle-tethered Psf (basic polymer); for example, blends consisting of SPEEK and amino-benzimidazole-tethered Psf (SPEEK/Psf-ABIm) and SPEEK and benzotriazole tethered Psf (SPEEK/Psf-Btraz) were investigated. The cross-linked SPEEK was made by Friedel-Craft acylation with Psf-COOH (DS = 1 or 2). The two blend membranes showed superior mechanical properties compared to Nafion 115 and comparable to plain SPEEK. The crosslinked membranes showed good mechanical properties and better strength than Nafion 115, but they were more brittle than both Nafion 115 and plain SPEEK. Further optimization of cross-linking conditions is necessary to produce the best performing membrane.
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碩士
國立中正大學
化學暨生物化學研究所
106
The experiment studies an oxide catalyst derived from Mg-Al-Si under co-precipitation through the process of ethanol to C4 product transformation. Consequential reactions followed by ethanol-C4 product transformation include dehydration, dehydrogenation and aldol condensation. The experiment had two different series of catalysts: series 1: From the initial reaction, the hydrotalcite mix with different ratios of silica shows its selectivity of C4 product was up to 90%, therein 77% selectivity for 1-butanol and 55% for 1,3-butadiene. The amount of acid/base found on the surface of the catalyst under CO2/NH3-TPD and In-situ CO2 FT-IR can be altered by changing the ratio of silica which can influence the selectivity of 1-butanol and 1,3-butadiene. Series 2: magnesium aluminium silicate forms mesoporous material without surfactant as a catalyst, allowing the study of catalytic pore formation mechanism and ethanol transformation. Due to the low amount of basicity and weak strength of the above catalyst, the impact on aldol condensation consequently causes a decrease of C4 product selectivity to 30% and 1,3-butadiene as primary product. The study further investigates the reactive mechanisms and stability of two different series of catalysts by simultaneously feeding the intermediates, acetaldehyde and ethanol which later concludes that the catalysts determine the pathways of reaction. In the first series of catalyst, ethanol dehydrogenation transforming into acetaldehyde was the rate-determining step. Meanwhile aldol condensation dictates the rate-determining step for the second series of catalyst. The acid-base sites affecting the dehydrogenation mechanism in the reaction was investigated by the following two experiments: The dehydrogenation and dehydration tendency of the catalyst was observed by isopropanol reaction, and the surface silianol group interaction was investigated by the adsorption surface of ethanol. Lastly, using high conversion ethanol reaction contrasted the stability and products’ selectivity difference of the two series catalysts. The study from various analysis angles hopes to explore more properties and extended their applications.

Title: Comlpexes of aminoalkylphosphineoxides Author: Bence Mészáros Department: Department of Inorganic Chemistry, Faculty of Science UK Supervisor: doc. RNDr. Vojt ch Kubí ek, Ph.D. Supervisor's e-mail address: kubicek@natur.cuni.cz Three selected aminoalkylphosphine oxides were synthesized: Aminomethyl(diphenyl)phosphine oxide, N-piperidylmethyl(diphenyl)phosphine oxide, N,N-diethylaminomethylbis(hydroxomethyl)phosphine oxide. All prepared substances were characterized by NMR spectroscopy and mass spectrometry. The aminomethyl(diphenyl)phosphine oxide and N-piperidylmethyl(diphenyl)phosphine oxide were obtained in the solid state as single crystals and their structure was determined by X-ray analysis. Acid-base and complexing properties of the studied compounds were studied by potentiometric titration and NMR titration. Protonation constants of all three compounds were obtained, stability constants were not determined because of the low solubility of the complexes in water or low stability of the complexes. The structure of the aminomethyl(diphenyl)phosphine oxide complex with Cu2+ was determined by X-ray analysis. Keywords: complexes, organophosphorus synthesis, phosphine oxides, acid-base and complexation properties

博士
國立暨南國際大學
應用化學系
102
This thesis involves three parts: In part 1, a series of pyridine- and pyrazine-containing rod-like molecules was synthesized. In solution, rod-like molecules can be complexed with dibenzo[24]crown-8 (DB24C8) to form [2]pseudorotaxane by intermolecular hydrogen bonding and π-π interactions. We also can control the association and dissocation of the [2]pseudorotaxane complex by adding acid/base, changing temperature, and adjusting solvent polarity of the solvent system. In part 2, two noval tripodal semi-rigid ligands, o-H3tpat and m-H3tpat, consisting of triazine central core and three pyridine donating functions attached to flexible -NHCH2- arms have been designed and synthesized. Self-assembly of o-H3tpat and m-H3tpat with Cu2+ and Co2+ ions form a series of coordination complexes, including 1-D polymer chain structures ((1), (2) and (6)), discrete M8L4 cage structures ((3) and (4)) and metallacyclophane structure (5). Magnetic studies reveal that in (1) every two Cu centers are antiferromagnetically coupled via the chloride bridges. For (2), very weak antiferromagnetic interactions are observed between the Cu centers. In part 3, the goal of this part is to develop a self-assembly strategy for preparation of coordination polymers using flexible N-donor ligands (bpzpip, mm-dpma, pp-dpma) and polycarboxylate O-donor ligands (D-H2Cam, H2BDC, H2NDC, H3BTC). Chiral complexes (7) and (8) are isostructural and both display a (4,6)-connected net in topology hiding a pts-net of square-planar and tetrahedral nodes. Complexes (9) and (11) both adopt a 2-D brickwall structure, which expands into a 3-D supramolecular net through the connection of hydrogen bonds. Complex (10) adopts a 3-D structure, which has a (412‧63)-pcu topology. Complexes (12), (13) and (14) all exbibit a 1-D polymer chain structure. The adsorption properties of complexes (9), (10), (11), exhibit that all of them are capable of adsorbing H2O, but only (9) and (10) show the adsorption behavior to pyridine molecules. On the other hand, desolvated complex (13) is capable of adsorbing CH2Cl2 or CHCl3.

The goal of this study was to characterize the binding sites on the surface of wheat roots, Triticum turgidum, involved in the adsorption of protons and metals, and quantify the thermodynamic constants needed for a surface complexation model to predict metal binding. The adsorption of protons, Cd(II), Cu(II), and Ni(II) to the root surface as a function of pH and ionic strength in single metal exposure scenarios was quantitatively described using potentiometric titrations, batch metal adsorption experiments, and the least squares fitting program FITEQL. Model predictions from single metal exposures were compared to measured metal adsorption concentrations when roots were exposed to binary and ternary combinations of the metals. Proton dissociation was a function of three discrete monoprotic acid sites on the root surface with log proton dissociation constants of -4.50, -6.23, and -7.37 respectively, upon which varied ionic strength had no effect. The total proton binding capacities for the three sites were 2.58 x 10-4, 1.29 x 10-4, and 2.58 x 10-4 M, respectively. Metal complexation was best described by a two-site model having conditional stability constant log values of 3.04 and 3.30 for Cd(II), 3.21 and 3.25 for Cu(II), and 2.83 and 2.84 for Ni(II) at ionic strength 0.01M. At ionic strength 0.1 M the conditional stability constants log values were 2.37 and 3.36 for Cd(II), 3.11 and 2.56 for Cu(II), and 2.18 and 3.00 for Ni(II). When roots were exposed to binary or ternary mixtures of the metals, the two monoprotic acid single metal model did not provide ideal fits to the data indicating that adsorption in a metal mixture scenario cannot be considered additive and is dependent on the combination of metals present in the exposure environment. The experimentally determined proton dissociation constants and metal stability constants could be used in commercial geochemical speciation programs such as Visual MINTEQ to predict metal adsorption to plants.
Natural Sciences and Engineering Research Council of Canada, The Mining Association of Canada, Ontario Power Generation, Environment Canada.

Poly(1,4-diethynylbenzene) ( -conjugated polymer) was prepared as an insoluble polymer network via chain coordination polymerization of 1,4-diethynylbezene catalyzed with [Rh(NBD)acac] complex. Thermodynamic properties and acid-base characteristics of the prepared poly(1,4-diethynylbenzene) were studied by means of Inverse Gas Chromatography (IGC) in the temperature range 80-100 řC. Retention data of selected testing substances were used to determine the Gibbs energy of sorption, the sorption enthalpy and their acid-base and disperse parts as well as the disperse contribution to the surface energy and parameters of KA, KD, ANHPS and DNHPS quantifying the acid-base character of the studied polymer. The results showed that poly(1,4-diethynylbenzene) interacted more efficiently with Lewis bases than with Lewis acids. The values of experimental sorption enthalpy were used for the determination of the parameters KA and KD. Values of these parameters classify poly(1,4-diethynylbenzene) as the material with a slightly acid character. This conclusion is further supported by the results of H. P. Schreiber method based on the application of ANHPS and DNHPS parameters for the evaluation of the acid-base properties of the material. The infrared spectroscopy proved that poly(1,4-diethynylbenzene) contained...