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This thesis concerns the thermodynamics of macrocycles and their metal cation complexes in non-aqueous media and these are discussed under two main headings, i) Thermodynamics of Alkali-Metal Cations and Macrocycles in Solution and in the Solid State. Thermodynamic parameters of complexation for alkali-metal cations and macrocycles (18-crown-6 and ethyl p-tert-butylcalix(6)arene hexanoate) in benzo-nitrile at 298.15 K are first reported. These data are compared with those previously reported for cryptand 222 and these cations in this solvent. A 'peak' selectivity for potassium is observed for the complexation of the calix(6)arene ester with alkali metal cations. The process is enthalpy controlled with an exothermic maximum for the potassium cation. Thermodynamic data of complexation are characterised by a lower enthalpic stability and a more favourable entropy (except for K+) than corresponding data involving cryptand 222 or indeed 18-crown-6. Standard enthalpies of solution, DeltasH0, of macrocycles and their sodium and potassium salts in benzonitrile measured calorimetrically are discussed in relation to (i) data for the uncomplexed salts and (ii) previously reported data for sodium and potassium cryptate salts in various solvents. Enthalpies of coordination, DeltacoordH0, for eighteen systems involving sodium and potassium coronates, cryptates and calix(6)arenates are derived and whenever possible these are discussed on the basis of (i) available X-ray crystallographic data and (ii) the anion effect on the coordination process. ii) Thermodynamics of Lower Rim Calix(4)arene Derivatives with the Silver Cation in Different Media at 298.15 K. The DeltasH0 values of p-tert-butyl(bis-diethylamine-bis-methysulphanyl) calix(4)arene (EATCalix4) in various solvents at 298.15 K are reported. Transfer parameters from acetonitrile to other solvents are calculated. The interaction of EATCalix4 and the silver cation was investigated by 1H NMR in deuterated acetonitrile at 298 K showing that the ligand hosts the metal cation through interaction with the different donor atoms (O, N, S). Conductimetric titrations indicate that the stoichiometry of the complex is 1:1. The thermodynamics of complexation of EATCalix4 and silver in six solvents at 298.15 K is reported. The DeltasH0 values of the free and the complex silver perchlorate salts have been also measured in various solvents and these have been combined with DeltacH0 data to derive the DeltacoordH0 of this system. A few representative examples about the use of coordination data are given. The medium effect on the complexation process is assessed in terms of DeltatG0, DeltatH0 and DeltatS0 of the reactants and the product from acetonitrile to the appropriate solvent. The relevance of analysing the solvation changes that these species undergo upon complexation is emphasised.

Studies of gas-phase ionic clusters have become an integral component in understanding microsolvation and catalysis by transition metal cations. Further interest in this field is due to the possibility of bridging the gap between the condensed and gas phases by developing our understanding of clusters and the possibility that small clusters can have unique chemical and catalytic properties. Most gas phase studies have focused on singly charged ions. Electrospray allows for the production of multiply charged ions solvated by a few solvent molecules. Understanding smaller reactive species such as metal centered clusters with well-defined, gas phase conditions also allows for detailed comparison between theory and experiments. In these studies the main focus is to understand bond activation by transition metal cations and solvation of transition metal dications. The gas phase ions of interest are studied using an electrospray-ionization or laser-ablation dual time-of-flight mass spectrometer and are characterized using photofragment spectroscopy in the visible and ultraviolet regions of the spectrum. Photofragment spectroscopy is a powerful method that can be used in gas phase studies to gather a wealth of information on the ions' bond strengths, spectroscopic constants, and dissociation kinetics and dynamics. The study of TiO + (CO 2 ) spectroscopy (Chapter 3) was a result of study of CO 2 bond activation by Ti + that went on to provide a wealth of information on the spectroscopy and dissociation kinetics of this molecule. An electronic transition of the TiO + chromophore was observed, 2 Π[arrow left] 2 Δ, revealing new information about the excited state and the effect of TiO + electronic state on the metal- CO 2 ligand interaction. The photodissociation spectrum of this molecule is well resolved and shows progressions in the covalent Ti-O stretch and metal-ligand stretch and rock. The lifetime of electronically excited TiO + (CO 2 ) was measured, and depends strongly on vibrational energy. Calculations on TiO + and TiO + (CO 2 ) were combined with experimental results on TiO + (CO 2 ) to predict spectroscopic transitions of TiO + , an astrophysically interesting molecule. The photodissociation dynamics of M 2+ (CH 3 CN)n(H 2 O)m where M = Co and Ni, (Chapter 4) is important in understanding the gas phase microsolvation of metal dications. The coordination number and type of solvent affect the dissociation pathways. M 2+ (CH 3 CN)n (n>2) primarily lose a solvent molecule. Electron transfer is a minor channel for n=3 and is the only channel observed for n=2. Mixed clusters M 2+ (CH 3 CN)n(H 2 O)m preferentially lose water. Loss of acetonitrile is a minor channel, as is proton transfer. Water is the proton donor. Replacing acetonitrile with water increases the proton transfer channel. Nickel and cobalt complexes show similar dissociation dynamics, with proton transfer more likely for nickel complexes. Methane activation by transition metal catalysts is industrially important as it can be used to produce gasoline from natural gas. We studied the products and intermediates of the reaction of laser-ablated platinum atoms with methane (Chapter 5). Photoionization efficiency curves were measured for PtCH 2 and the [H-Pt-CH 3 ] insertion intermediate using tunable vacuum ultraviolet light. The resulting ionization energies were combined with bond strengths for the cations to derive bond strengths for the neutrals. These were used to construct a potential energy surface for methane activation by platinum atoms.

The objective of this work is development of a new adsorbent on the base of an organoclay with a chelating ligand covalently attached to the clay mineral surface. The presence of a chelating ligand in the clay structure significantly improves its ability to immobilize heavy metal ions from contaminated sludge of wastewater. Montmorillonite and kaolinite were chosen as typical examples of expandable and non-expandable clay minerals. A two-step modification procedure comprised of sequential modification with oxides and grafting of a chelating agent to the modified clay minerals was used. Modifications with silica and ferric oxide were conducted by reacting the dispersed raw clay minerals with tetraethoxysilane and ferric nitrate solution. A chelating ligand, N-[3-(trimethoxysilyl)propyl]ethylenediamine triacetic acid trisodium salt, was introduced into interlayer space of raw and modified clay minerals in aqueous solutions. Laboratory tests of the organoclay efficiency for purification of wastewater were conducted with the most promising sample, i.e., organoclay with the highest specific loading of chelating agent. Experiments were conducted with model wastewater containing either individual or mixed heavy metal ions. The modified organoclay displayed high adsorption capacity for heavy metal cations even in acidic media. The method of modification presented in this work can be used for synthesis of efficient adsorbents for applications in contaminated areas.

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Made available in DSpace on 2015-05-14T13:21:21Z (GMT). No. of bitstreams: 1 ArquivoTotal.pdf: 2474612 bytes, checksum: c81546edfad45aee18046ef7339ed083 (MD5) Previous issue date: 2013-06-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Clay minerals have been used for adsorption of pollutant substances. In this work, sodium palygorskite (pali) was applied for adsorption of the RN blue, RB red and yellow reactive dyes from aqueous solutions and the modified forms with silanes 3-aminepropyltrimethoxysilane (N) and 3-propylethylenediaminetrimethoxissilane (NN) were obtained. The sample pali-N were utilized for removing Cu2+, Co2+ and Ni2+ cations and the same dyes. The experimental factors as time of contact, pH and initial concentration of the adsorbates were investigated. The solids were characterized using composition chemical analysis, X-ray diffraction, 27Al and 29Si nuclear magnetic resonance, infrared spectroscopy, nitrogen adsorption-desorption measurements, thermogravimetry, scanning electronic microscopy and C, H, N elemental analysis. The results showed that the precursor pali was pure clay mineral containing traces of quartzo. The sample was a dioctaedrical type with surface area of 118 m2 g-1 constituted of aggregates of fibers. The modified solids showed an immobilization degree of 0.92 and 0.67 mmol g-1 for pali-N and pali-NN, respectively. The results of dye adsorption on pure sample showed the maximum retention of 55 mg g-1 for reactive blue RN and red RB and 45 mg g-1 for reactive yellow GR. For sample pali-N, the maximum adsorption capacities were 120, 110 and 100 mg g-1 for red RB, blue RN and yellow GR, respectively, which all processes were described by pseudo- second-order kinetic and the equilibrium data were fitted to Langmuir model. In the adsorption of metal cation on pali-N, the maximum adsorbed quantities were 0.73, 0.62 and 0.58 mmol g-1 for Cu2+, Co2+ and Ni2+, respectively. The data were fitted to pseudo-second-order kinetic and the equilibrium data were fitted to Langmuir model. / Os argilominerais têm sido largamente utilizados na retenção de diversos poluentes. Neste trabalho, a paligorsquita sódica (pali) foi aplicada na remoção dos corantes reativos azul RN, vermelho RB e amarelo GR em soluções aquosas e as formas modificadas com o agente sililante 3-aminopropiltrimetoxissilano (Pali-N) e 3-propiletilenodiaminotrimetoxissilano (Pali-NN) foram obtidas. A amostra pali-N foi utilizada na remoção dos íons metálicos Cu2+, Co2+ e Ni2+ e dos mesmos corantes. Os fatores como tempo de contato, pH e concentração inicial dos adsorvatos foram investigados. Os diversos sólidos foram caracterizados por análise de composição, difratometria de raios X, ressonância magnética nuclear de 27Al e 29Si, espectroscopia de absorção na região do infravermelho, medidas de sorção-dessorção de nitrogênio, análise termogravimétrica, microscopia eletrônica de varredura e análise elementar de carbono, hidrogênio e nitrogênio. Os resultados mostraram que a pali apresentou-se como um argilomineral de elevada pureza, sendo do tipo dioctaédrica com área superficial de 118 m2 g-1 e constituída por feixes de fibras formando agregados. As amostras modificadas obtiveram graus de imobilização de 0,92 e 0,67 mmol g-1 para a pali-N e pali-NN, respectivamente. Os resultados da sorção na amostra pura para os corantes reativos azul RN e vermelho RB mostraram retenções máximas de 55 mg g-1 e de 45 mg g-1 para o corante reativo amarelo GR. Na amostra pali-N, as capacidades máximas de sorção foram de 120, 110 e 100 mg g-1, para o vermelho reativo RB, azul reativo RN e amarelo reativo GR, respectivamente, sendo que todos esses processos seguiram uma cinética de pseudo 2ª ordem e foram descritos pelo modelo de Langmuir. Nos ensaios de retirada dos íons metálicos Cu2+, Co2+ e Ni2+ em pali-N, as quantidades máximas adsorvidas foram de 0,73, 0,62 e 0,58 mmol g-1, respectivamente. Os dados seguiram o modelo cinético de pseudo 2ª ordem e para os estudos de equilíbrio houve ajuste ao modelo de Langmuir.

Les chromènes photochromiques sont largement utilisés dans les technologies modernes en raison de leur capacité à changer les propriétés sous irradiation UV. Les chromènes présentés dans ce travail possèdent en outre des fragments pouvant participer à la coordination avec des cations métalliques, acides aminés, ou de l'ADN. Pour ce type de molécule, l'interdépendance éventuelle entre les propriétés photochromiques et complexantes permet d'envisager soit le photo-contrôle de la complexation, soit la modulation du photochromisme par le biais de coordination.Ce travail est divisé en deux parties : la première est consacrée à la préparation des molécules cibles et la seconde à l'étude de la complexation. Les approches synthétiques élaborées ont permis d'obtenir une série de nouveaux chromènes annelés par des éthers couronnes de taille et de composition hétéroatomique différentes. Le processus de complexation de certains dérivés a été étudié en détail par spectroscopie RMN et absorptionUV-Visible. Il a été établi que la nature des cations métalliques détermine la stoechiométrie du complexe formé ainsi que la structure spatiale. Pour tous les composés étudiés, la complexation affecte les paramètres photochromiques notamment la vitesse de décoloration. En ce qui concerne la complexation des chromènes synthétisés avec les acides aminés protonés, il a été établi qu'en fonction de la longueur de chaine de ces acides, la formation de complexe mono- ou ditopique est favorisée.De plus, l'interaction d'un nouveau chromène cationique avec l'ADN a été étudiée. Il a été constaté que contrairement à la forme initiale, la forme colorée de ce composé générée sous irradiation UV permet l'intercalation au sein de l'ADN / Photochromic chromenes are widely used in modern technologies due to their abilityto change their properties upon UV irradiation. The chromenes presented in this work alsopossess fragments able to participate to the coordination with metal cations, amino acids, orDNA. These properties may sustain mutual influence on each other resulting in either photocontrolof complexing ability or photochromism tunable by complex formation.This work is divided in two parts, one devoted to the synthesis of the targetcompounds and the second to study on the complexing ability of the substances,respectively. Thus, the synthetic approaches to photochromic benzo- and naphthopyrans,annelated to the crown ether moieties of different size and heteroatomic composition, weredeveloped. The complex formation of several chromenes with metal cations wasinvestigated by means of UV-Vis absorption and NMR spectroscopies. The metal cationnature was found to determine the stoichiometry of the complexes as well as their spatialstructure. The complex formation was found to affect the photochromic properties of thecompounds, especially the bleaching rate. Investiga.on of complexation of the chromeneswith protonated amino acids revealed that, depending on the length of the carbon chain ofthe acid used, mono- or ditopic complexes may be formed.The interaction of the new chromene, possessing a positively charged group, with DNAwas also studied. In contrast to the initial form, the photo-induced colored form was foundto intercalate with DNA.

This study is divided into three parts. Part I deals with the mechanism of the self-initiated polymerization (or thermal polymerization) of styrene in the gas phase. In this work, we present the first direct evidence for the thermally self-initiated polymerization of styrene in the gas phase. Our approach is based on on-line analysis of the gas phase Oligomers by mass-selected ion mobility. The mobility measurements provide structural information on the ionized oligomers based on their collision cross-sections (Ω) which depend on the geometric shapes of the ions. Theoretical calculations of possible structural candidates of the Oligomers ions are then used to compute angle averaged Ω for comparison with the measured ones. The agreement between the measured and calculated Ω of the candidate structures provides reliable assignments to the structures of the oligomers. Furthermore, collisional-induced dissociations of the mass-selected oligomer ions provide further support for the structures obtained from the mobility measurements. Our results indicate that the gas phase polymerization of styrene proceeds via essentially the same initiation mechanism (the Mayo mechanism) as in condensed phase polymerization. The structural evidence, the mechanism of formation and the observed fragmentation pathway of the growing dimers and trimers in the gas phase are presentedIn Part II the solvation of a variety of metal cations by benzene clusters have been studied using laser vaporization, cluster beam and time-of-flight mass spectrometry techniques. In this work strong magic numbers were observed for clusters containing 10, 13 and 14 benzene molecules depending on the nature of the metal cation involved. The metal cations exhibiting preference solvation by 14 benzene molecules show a strong tendency to form sandwich structures with two benzene molecules. The interpretation of these results in view of the proposed structures and the growth patterns of the clusters are presented. In Part III, the work is focused on the investigation of the intracluster ion molecule reactions following the generation of Mg+ within the polar clusters (water, methanol, ether and acetonitrile).

Positive-ion electrospray ionisation Fourier transform ion cyclotron resonance and ion trap mass spectrometry have been used to investigate the reactions of the flavonoids 3-hydroxyflavone, 5-hydroxyflavone, 5-methoxyflavoe, quercetin, quercitrin and rutin with monovalent Li+, Na+, K+ and Cs+, divalent Cu2+, Zn2+ and Pb2+ and trivalent La3+ and Eu3+ metal cations. The effect of capillary-skimmer potential difference and the ion residence time in the hexapole ion trap of the Fourier transform ion cyclotron resonance mass spectrometer are systematically investigated for the flavonoid-alkali and divalent metal ion experiment. It is observed that these variables impact significantly on the type of ions observed in the ESI experiments and hence the mass spectra. The binding selectivity of alkali metal ions towards 3-hydroxyflavone, 5-hydroxyflavone and 5-methoxyflavone are determined using the results from FTICR mass spectrometry experiments. The selectivity order follows the order Li+>Na+>K+ for individual flavonoids. Collision-induced dissociation experiments are carried out by Fourier transform ion cyclotron resonance and ion trap mass spectrometry to compare the fragmentation behaviour of metal-flavonoid complexes. Low energy collision-induced dissociation experiments of the [2L+M]+ for 3-hydroxyflavone, 5-hydroxyflavone and 5-methoxyflavone alkali metal complexes show the loss of ligand only. When the energy is increased only the lithiated dimer [2L+Li]+ for 5-methoxyflavone shows the loss of methyl radical along with the ligand. For quercitrin the predominant dissociation pathways are the loss of rhamnose for Li+, Na+ and K+ complexes although aglycone loss is also observed for the K+ complex. The favourable dissociation pathways for rutin are the loss of disaccharide, aglycone and rhamnose for the Na+ complex and the loss of disaccharide for the K+ complex. Collision-induced dissociation data are also used to determine the threshold dissociation energies for displacement of one flavonoid ligand from alkali metal flavonoid complexes. The threshold dissociation energies for loss of one ligand from [2L+M]+ of 5-methoxyflavone and quercitrin follow the order Li+ > Na+ > K+, rutin follows the order Na+ > K+ > Li+ , and 3-hydroxyflavone and 5-hydroxyflavone follow the order Li+ > Na+. For the same metal cation experiment, 5-methoxyflavone system has the highest dissociation energy compared to the 3-hydroxyflavone and 5-hydroxyflavone experiment. Preliminary DFT calculations show that the calculated dissociation energies follow the same trend as the experimental dissociation energies for the simple flavonoid alkali metal cation experiments. For 5-methoxyflavone-divalent metal cation (Zn2+, Cu2+ and Pb2+) complexes loss of methyl radical is the common process. CO loss is also observed for the Zn2+ complex whereas CHO and H2O losses are observed for Cu2+. For 3-hydroxyflavone and 5-hydroxyflavone divalent metal cation experiments loss of ligand is the dominant process. Zn2+ and Cu2+ complexes also show CO loss. La3+ and Er3+ with the same flavonoids show the ligand as the dominant product. For quercetin-divalent metal cation experiment, ligand loss is the dominant process. For quercitrin and rutin various dissociation products are observed where the dissociation occurs via the loss of the rhamnose and/or the disaccharide moieties. Similar dissociation patterns are also observed for La3+ and Er3+ complexes for quercitrin and rutin.