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Progettazione e sintesi di nuovi derivati azetidinonici biologicamente attiviVentrici, Caterina <1982> 04 June 2010 (has links)
In this PhD-thesis new synthetic approaches towards new azetidinone derivatives are described. In particular, 4-alkyliden-β-lactams were used as starting materials for the preparation of new biologically active compounds.
The carbapenem Thienamycin has got a broad spectrum of activity as antibiotic. It has got 3 stereocenters and apart of one epimer, all isomers have been synthesized. Using the 4-alkyliden-β-lactam benzilyc ester as precursor, we developed a synthesis for this missing epimer, which is described in chapter II. Biological tests in order to establish its biological activity are under way.
The Hunsdiecker-Borodine reaction was extensively studied for the preparation of the mono halogenated and – surprisingly – the dihalogenated derivative from the 4-alkyliden-azetidinone carboxylic acid. The herein described synthetic procedures allowed the preparation of chloro-, bromo- and iodo derivatives in good to excellent yield. Furthermore, the reaction mechanism was investigated by NMR-experiments and is described in detail in chapter III.
In chapter IV, synthetic approaches towards new β-lactam derivatives for inhibition of the histone deacetylase enzymes (HDACs) are reported. In collaboration with the company Sigma-Tau (Rome), 14 new β-lactams were synthesized. The new β-lactams were evaluated for the activity showing a promising activityparticulary, 10 of the β-lactams synthesized were evaluated for the in vitro inhibitory activity against the 11 human HDACs isoforms and they showed a selective inhibition of HDAC6 or HDAC8 in micromolar range.
Finally, preliminary studies were conducted for the employment of 4-alkyliden-β-lactams as precursors for the synthesis of chiral β-amino acids by an opening of the β-lactam ring. In chapter V is described the ring opening reaction catalyzed by the enzyme lipase Cal-B. Preliminary results have shown that the enzyme not only catalyzes the ring opening of the β-lactam precursor, moreover, it leads to the formation of a cyclic dimer by the reaction of two molecules of β-amino acid obtained.
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Materiali Politiofenici Otticamente AttiviBrazzi, Alice <1982> 29 March 2010 (has links)
Much effort has been devoted in the recent years to the investigation of optically active polythiophenes characterized by the presence of a chiral moiety linked to the 3-position of the aromatic ring. In addition to their potential technological applications as materials for enantioselective electrodes and membranes, chiral poly(thiophene)s offer the possibility of studying the structural changes accompanying the transition from the disordered state by following the variation of their chiroptical properties by circular dichroism (CD). In solution of a good solvent, that kind of polythiophenes doesn’t display any optical activity arising from the presence of dissymmetric conformation of the backbone, as shown by circular dichroism (CD) spectra. When the macromolecules begin to aggregate, as it occurs e.g. by addition of a poor solvent, or lowering the solution temperature, or when the macromolecules are assembled in the solid state as thin films obtained by solution casting or spin coating, significant CD bands are observed in the spectral region related to the electronic absorptions of the aromatic polythiophene chromophore. These CD bands are indicative of a chiral macromolecule arrangement of one prevailing chirality.
The synthesis of -substituted polythiophenes can be carried out starting from the corresponding -substituted mono- or oligomeric thiophenic monomers under regioselective or regiospecific conditions in order to minimize or avoid the formation of head-to-head dyads unfavourably affecting the presence of coplanar conformations of thiophene rings as a consequence of steric interactions between the side-chain substituents, both in solution and in the solid state. To this regard, non-symmetrically substituted monomers require therefore to perform the polymerization in the presence of highly demanding catalysts and reaction condition, whereas with symmetrically substituted oligothiophenic monomers containing the -substituents located far apart from the reacting sites, it is instead possible to obtain regioregular macromolecules by adopting more simple and economic polymerization methods, such as, e. g., the chemical oxidative polymerization with iron (III) trichloride.
In order to verify how the polymer structure affects its optical activity, further poly-3-alkylthiophenes, substituted by an enantiomerically pure chiral alkyl group, namely poli[3,3”-di[2((S)-(+)-2-methylbutoxy)ethyl]-2,2’:5’,2”-terthiophene] (PDMBOETT), poli[3,3’di[2((S)-(+)-2-methylbutoxy)ethyl]-2,2’-bitiofene] (PDMBOEBT), poli[3,3””-didodecyl-4’,3”’-di(S)-(+)-2-methylbutyl-2,2’:5’,2”:5”,2”’:5”’,2””-quinquethiophene (PDDDMBQT) have been synthesized and characterized by instrumental techniques.
The spectroscopic behaviour of thin films of poly(DDDMBQT) has been investigated in the solid state under different sample preparation procedures. It was also compared with the behaviour of polymers previously made. The experimental results are interpreted in terms of influence of the side-chain substituents on the extent of planarity of the polymeric chains and the formation of optically active chiral aggregates.
In recent years conjugated block copolymers have received considerable attention.
It is well known that conjugated block copolymers composed of two electronically different blocks can have morphologic and optical properties, that differ from those of their homopolymers.
A recent study has also shown that the electronic properties and the supramolecular organization of one conjugated block can also be influenced by the other block.
In order to study better this behavior, a new conjugated block copolymers, composed of a regioregular hydrophylic block and a regioregular hydrophobic block namely poli[3[2-(2-metossietossi)etossi]metiltiofene]-co- poli[3(1-octilossi)tiofene], has been synthesized and characterized.
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Derivati polimerici organometallici ancorati su matrice inorganica per applicazioni in chimica fineUgolini, Sara <1982> 29 March 2010 (has links)
Organotin compounds have found in the last few decades a wide variety of applications. Indeed, they are used successfully as antifouling paints, PVC stabilizers and ion carriers, as well as homogeneous catalysts. In this context, it has been proved that the Lewis acidity of the metal centre allows these compounds to promote the reaction between alcohol and ester. However their use is now limited by their well-known toxicity, moreover they are hardly removable from the reaction mixture.
This problem can be overcome by grafting the organotin derivative onto a polymeric cross-linked support. In this way the obtained heterogeneous catalyst can be easily filtered off from the reaction mixture, thus creating the so-called "clean organotin reagents", avoiding the presence of toxic organotin residues in solution and the tin release in the environment.
In the last few years several insoluble polystyrene resins containing triorganotin carboxylate moieties have been synthesized with the aim of improving their catalytic activity: in particular we have investigated and opportunely modified their chemical structure in order to optimize the accessibility to the metal centre and its Lewis acidity.
Recently, we replaced the polymeric matrix with an inorganic one, in order to dispose of a relatively cheaper and easily available support. For this purpose an ordered mesoporous silica, characterized by 2D-hexagonal pores, named MCM-41, and an amorphous silica have been selected.
In the present work two kinds of MCM-41 silica containing the triorganotin carboxylate moiety have been synthesized starting from a commercial Cab-O-Sil M5 silica. These catalysts have two different spacers between the core and the tin-carboxylate moiety, namely a polyaliphatic chain (compound FT29) or a poliethereal one (compound FT6), with the aim to improve the interaction between catalyst and reacting ester.
Three catalysts supported onto an amorphous silica have been also synthesized: the structure is the same as silica FT29, i.e. a compound having a polialiphatic chain, and they have different percentage of organotin derivative grafted on the silica surface (10, 30, 50% respectively for silica MB9, SU27 and SU28).
The performances of the above silica as heterogeneous catalysts in transesterification reactions have been tested in a model reaction between ethyl acetate and 1-octanol, a primary alcohol sensitive to the reaction conditions. The alcohol conversion was assessed by gas-chromatography, determining the relative amount of transesterified product and starting alcohol after established time intervals.
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Active bis-ferrocene molecules as unit for molecular computationZoli, Luca <1982> 04 June 2010 (has links)
Traditional logic gates are rapidly reaching the limits of miniaturization. Overheating of these components is no longer negligible. A new physical approach to the machine was proposed by Prof. C S. Lent “Molecular Quantum cellular automata”. Indeed the quantum-dot cellular automata (QCA) approach offers an attractive alternative to diode or transistor devices. Th units encode binary information by two polarizations without corrent flow. The units for QCA theory are called QCA cells and can be realized in several way. Molecules can act as QCA cells at room temperature. In collaboration with STMicroelectronic, the group of Electrochemistry of Prof. Paolucci and the Nananotecnology laboratory from Lecce, we synthesized and studied with many techniques surface-active chiral bis-ferrocenes, conveniently designed in order to act as prototypical units for molecular computing devices. The chemistry of ferrocene has been studied thoroughly and found the opportunity to promote substitution reaction of a ferrocenyl alcohols with various nucleophiles without the aid of Lewis acid as catalysts. The only interaction between water and the two reagents is involve in the formation of a carbocation specie which is the true reactive species. We have generalized this concept to other benzyl alcohols which generating stabilized carbocations. Carbocation describe in Mayr’s scale were fondametal for our research. Finally, we used these alcohols to alkylate in enantioselective way aldehydes via organocatalysis.
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Elettrodi modificati per lo sviluppo di sensori elettrochimiciGuadagnini, Lorella <1982> 03 June 2010 (has links)
No description available.
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Sistemi liquido cristallini complessi: simulazioni al calcolatore e studi ESRMiglioli, Isabella <1982> 04 June 2010 (has links)
The aim of this PhD thesis was to study at a microscopic level different liquid crystal (LC) systems, in
order to determine their physical properties, resorting to two distinct methodologies, one involving computer
simulations, and the other spectroscopic techniques, in particular electron spin resonance (ESR) spectroscopy.
By means of the computer simulation approach we tried to demonstrate this tool effectiveness for calculating anisotropic static properties of a LC material, as well as for predicting its behaviour and features. This
required the development and adoption of suitable molecular models based on a convenient intermolecular
potentials reflecting the essential molecular features of the investigated system.
In particular, concerning the simulation approach, we have set up models for discotic liquid crystal dimers and
we have studied, by means of Monte Carlo simulations, their phase behaviour and self-assembling properties,
with respect to the simple monomer case. Each discotic dimer is described by two oblate GayBerne ellipsoids
connected by a flexible spacer, modelled by a harmonic "spring" of three different lengths. In particular we
investigated the effects of dimerization on the transition temperatures, as well as on the characteristics of
molecular aggregation displayed and the relative orientational order.
Moving to the experimental results, among the many experimental techniques that are typically employed
to evaluate LC system distinctive features, ESR has proved to be a powerful tool in microscopic scale
investigation of the properties, structure, order and dynamics of these materials. We have taken advantage
of the high sensitivity of the ESR spin probe technique to investigate increasingly complex LC systems
ranging from devices constituted by a polymer matrix in which LC molecules are confined in shape of nano-
droplets, as well as biaxial liquid crystalline elastomers, and dimers whose monomeric units or lateral groups
are constituted by rod-like mesogens (11BCB).
Reflection-mode holographic-polymer dispersed liquid crystals (H-PDLCs) are devices in which LCs are
confined into nanosized (50-300 nm) droplets, arranged in layers which alternate with polymer layers, forming
a diffraction grating. We have determined the configuration of the LC local director and we have derived
a model of the nanodroplet organization inside the layers. Resorting also to additional information on the
nanodroplet size and shape distribution provided by SEM images of the H-PDLC cross-section, the observed
director configuration has been modeled as a bidimensional distribution of elongated nanodroplets whose
long axis is, on the average, parallel to the layers and whose internal director configuration is a uniaxial quasi-
monodomain aligned along the nanodroplet long axis. The results suggest that the molecular organization is
dictated mainly by the confinement, explaining, at least in part, the need for switching voltages significantly
higher and the observed faster turn-off times in H-PDLCs compared to standard PDLC devices.
Liquid crystal elastomers consist in cross-linked polymers, in which mesogens represent the monomers
constituting the main chain or the laterally attached side groups. They bring together three important aspects: orientational order in amorphous soft materials, responsive molecular shape and quenched topological constraints.
In biaxial nematic liquid crystalline elastomers (BLCEs), two orthogonal directions, rather than the one of
normal uniaxial nematic, can be controlled, greatly enhancing their potential value for applications as novel
actuators. Two versions of a side-chain BLCEs were characterized: side-on and end-on. Many tests have
been carried out on both types of LCE, the main features detected being the lack of a significant dynamical
behaviour, together with a strong permanent alignment along the principal director, and the confirmation of
the transition temperatures already determined by DSC measurements. The end-on sample demonstrates a
less hindered rotation of the side group mesogenic units and a greater freedom of alignment to the magnetic
field, as already shown by previous NMR studies. Biaxial nematic ESR static spectra were also obtained
on the basis of Molecular Dynamics generated biaxial configurations, to be compared to the experimentally
determined ones, as a mean to establish a possible relation between biaxiality and the spectral features.
This provides a concrete example of the advantages of combining the computer simulation and spectroscopic
approaches.
Finally, the dimer α,ω-bis(4'-cyanobiphenyl-4-yl)undecane (11BCB), synthesized in the "quest" for the
biaxial nematic phase has been analysed. Its importance lies in the dimer significance as building blocks
in the development of new materials to be employed in innovative technological applications, such as faster
switching displays, resorting to the easier aligning ability of the secondary director in biaxial phases. A
preliminary series of tests were performed revealing the population of mesogenic molecules as divided into
two groups: one of elongated straightened conformers sharing a common director, and one of bent molecules,
which display no order, being equally distributed in the three dimensions. Employing this model, the
calculated values show a consistent trend, confirming at the same time the transition temperatures indicated
by the DSC measurements, together with rotational diffusion tensor values that follow closely those of the
constituting monomer 5CB.
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Cluster-derived Gold/Iron catalysts for environmental applicationsBonelli, Rosa <1982> 29 March 2010 (has links)
During the last years we assisted to an exponential growth of scientific discoveries for catalysis by gold and many applications have been found for Au-based catalysts.
In the literature there are several studies concerning the use of gold-based catalysts for environmental applications and good results are reported for the catalytic combustion of different volatile organic compounds (VOCs).
Recently it has also been established that gold-based catalysts are potentially capable of being effectively employed in fuel cells in order to remove CO traces by preferential CO oxidation in H2-rich streams.
Bi-metallic catalysts have attracted increasing attention because of their markedly different properties from either of the costituent metals, and above all their enhanced catalytic activity, selectivity and stability.
In the literature there are several studies demostrating the beneficial effect due to the addition of an iron component to gold supported catalysts in terms of enhanced activity, selectivity, resistence to deactivation and prolonged lifetime of the catalyst.
In this work we tried to develop a methodology for the preparation of iron stabilized gold nanoparticles with controlled size and composition, particularly in terms of obtaining an intimate contact between different phases, since it is well known that the catalytic behaviour of multi-component supported catalysts is strongly influenced by the size of the metal particles and by their reciprocal interaction.
Ligand stabilized metal clusters, with nanometric dimensions, are possible precursors for the preparation of catalytically active nanoparticles with controlled dimensions and compositions. Among these, metal carbonyl clusters are quite attractive, since they can be prepared with several different sizes and compositions and, moreover, they are decomposed under very mild conditions.
A novel preparation method was developed during this thesis for the preparation of iron and gold/iron supported catalysts using bi-metallic carbonyl clusters as precursors of highly dispersed nanoparticles over TiO2 and CeO2, which are widely considered two of the most suitable supports for gold nanoparticles.
Au/FeOx catalysts were prepared by employing the bi-metallic carbonyl cluster salts [NEt4]4[Au4Fe4(CO)16] (Fe/Au=1) and [NEt4][AuFe4(CO)16] (Fe/Au=4), and for comparison FeOx samples were prepared by employing the homometallic [NEt4][HFe3(CO)11] cluster. These clusters were prepared by Prof. Longoni research group (Department of Physical and Inorganic Chemistry- University of Bologna).
Particular attention was dedicated to the optimization of a suitable thermal treatment in order to achieve, apart from a good Au and Fe metal dispersion, also the formation of appropriate species with good catalytic properties.
A deep IR study was carried out in order to understand the physical interaction between clusters and different supports and detect the occurrence of chemical reactions between them at any stage of the preparation. The characterization by BET, XRD, TEM, H2-TPR, ICP-AES and XPS was performed in order to investigate the catalysts properties, whit particular attention to the interaction between Au and Fe and its influence on the catalytic activity.
This novel preparation method resulted in small gold metallic nanoparticles surrounded by highly dispersed iron oxide species, essentially in an amorphous phase, on both TiO2 and CeO2. The results presented in this thesis confirmed that FeOx species can stabilize small Au particles, since keeping costant the gold content but introducing a higher iron amount a higher metal dispersion was achieved.
Partial encapsulation of gold atoms by iron species was observed since the Au/Fe surface ratio was found much lower than bulk ratio and a strong interaction between gold and oxide species, both of iron oxide and supports, was achieved.
The prepared catalysts were tested in the total oxidation of VOCs, using toluene and methanol as probe molecules for aromatics and alchols, respectively, and in the PROX reaction.
Different performances were observed on titania and ceria catalysts, on both toluene and methanol combustion.
Toluene combustion on titania catalyst was found to be enhanced increasing iron loading while a moderate effect on FeOx-Ti activity was achieved by Au addition. In this case toluene combustion was improved due to a higher oxygen mobility depending on enhanced oxygen activation by FeOx and Au/FeOx dispersed on titania.
On the contrary ceria activity was strongly decreased in the presence of FeOx, while the introduction of gold was found to moderate the detrimental effect of iron species. In fact, excellent ceria performances are due to its ability to adsorb toluene and O2. Since toluene activation is the determining factor for its oxidation, the partial coverage of ceria sites, responsible of toluene adsorption, by FeOx species finely dispersed on the surface resulted in worse efficiency in toluene combustion.
Better results were obtained for both ceria and titania catalysts on methanol total oxidation.
In this case, the performances achieved on differently supported catalysts indicate that the oxygen mobility is the determining factor in this reaction.
The introduction of gold on both TiO2 and CeO2 catalysts, lead to a higher oxygen mobility due to the weakening of both Fe-O and Ce-O bonds and consequently to enhanced methanol combustion. The catalytic activity was found to strongly depend on oxygen mobility and followed the same trend observed for catalysts reducibility.
Regarding CO PROX reaction, it was observed that Au/FeOx titania catalysts are less active than ceria ones, due to the lower reducibility of titania compared to ceria. In fact the availability of lattice oxygen involved in PROX reaction is much higher in the latter catalysts.
However, the CO PROX performances observed for ceria catalysts are not really high compared to data reported in literature, probably due to the very low Au/Fe surface ratio achieved with this preparation method.
CO preferential oxidation was found to strongly depend on Au particle size but also on surface oxygen reducibility, depending on the different oxide species which can be formed using different thermal treatment conditions or varying the iron loading over the support.
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Catalytic liquid- and gas-phase oxidations for the synthesis of intermediates and specialty chemicals: some examples of industrial relevanceGuidetti, Stefania <1982> 29 March 2010 (has links)
Nowadays, it is clear that the target of creating a sustainable future for the next generations requires to re-think the industrial application of chemistry. It is also evident that more sustainable chemical processes may be economically convenient, in comparison with the conventional ones, because fewer by-products means lower costs for raw materials, for separation and for disposal treatments; but also it implies an increase of productivity and, as a consequence, smaller reactors can be used. In addition, an indirect gain could derive from the better public image of the company, marketing sustainable products or processes.
In this context, oxidation reactions play a major role, being the tool for the production of huge quantities of chemical intermediates and specialties. Potentially, the impact of these productions on the environment could have been much worse than it is, if a continuous efforts hadn’t been spent to improve the technologies employed. Substantial technological innovations have driven the development of new catalytic systems, the improvement of reactions and process technologies, contributing to move the chemical industry in the direction of a more sustainable and ecological approach. The roadmap for the application of these concepts includes new synthetic strategies, alternative reactants, catalysts heterogenisation and innovative reactor configurations and process design.
Actually, in order to implement all these ideas into real projects, the development of more efficient reactions is one primary target. Yield, selectivity and space-time yield are the right metrics for evaluating the reaction efficiency. In the case of catalytic selective oxidation, the control of selectivity has always been the principal issue, because the formation of total oxidation products (carbon oxides) is thermodynamically more favoured than the formation of the desired, partially oxidized compound. As a matter of fact, only in few oxidation reactions a total, or close to total, conversion is achieved, and usually the selectivity is limited by the formation of by-products or co-products, that often implies unfavourable process economics; moreover, sometimes the cost of the oxidant further penalizes the process.
During my PhD work, I have investigated four reactions that are emblematic of the new approaches used in the chemical industry.
In the Part A of my thesis, a new process aimed at a more sustainable production of menadione (vitamin K3) is described. The “greener” approach includes the use of hydrogen peroxide in place of chromate (from a stoichiometric oxidation to a catalytic oxidation), also avoiding the production of dangerous waste. Moreover, I have studied the possibility of using an heterogeneous catalytic system, able to efficiently activate hydrogen peroxide. Indeed, the overall process would be carried out in two different steps: the first is the methylation of 1-naphthol with methanol to yield 2-methyl-1-naphthol, the second one is the oxidation of the latter compound to menadione. The catalyst for this latter step, the reaction object of my investigation, consists of Nb2O5-SiO2 prepared with the sol-gel technique. The catalytic tests were first carried out under conditions that simulate the in-situ generation of hydrogen peroxide, that means using a low concentration of the oxidant. Then, experiments were carried out using higher hydrogen peroxide concentration. The study of the reaction mechanism was fundamental to get indications about the best operative conditions, and improve the selectivity to menadione.
In the Part B, I explored the direct oxidation of benzene to phenol with hydrogen peroxide. The industrial process for phenol is the oxidation of cumene with oxygen, that also co-produces acetone. This can be considered a case of how economics could drive the sustainability issue; in fact, the new process allowing to obtain directly phenol, besides avoiding the co-production of acetone (a burden for phenol, because the market requirements for the two products are quite different), might be economically convenient with respect to the conventional process, if a high selectivity to phenol were obtained. Titanium silicalite-1 (TS-1) is the catalyst chosen for this reaction. Comparing the reactivity results obtained with some TS-1 samples having different chemical-physical properties, and analyzing in detail the effect of the more important reaction parameters, we could formulate some hypothesis concerning the reaction network and mechanism.
Part C of my thesis deals with the hydroxylation of phenol to hydroquinone and catechol. This reaction is already industrially applied but, for economical reason, an improvement of the selectivity to the para di-hydroxilated compound and a decrease of the selectivity to the ortho isomer would be desirable. Also in this case, the catalyst used was the TS-1. The aim of my research was to find out a method to control the selectivity ratio between the two isomers, and finally to make the industrial process more flexible, in order to adapt the process performance in function of fluctuations of the market requirements. The reaction was carried out in both a batch stirred reactor and in a re-circulating fixed-bed reactor. In the first system, the effect of various reaction parameters on catalytic behaviour was investigated: type of solvent or co-solvent, and particle size. With the second reactor type, I investigated the possibility to use a continuous system, and the catalyst shaped in extrudates (instead of powder), in order to avoid the catalyst filtration step.
Finally, part D deals with the study of a new process for the valorisation of glycerol, by means of transformation into valuable chemicals. This molecule is nowadays produced in big amount, being a co-product in biodiesel synthesis; therefore, it is considered a raw material from renewable resources (a bio-platform molecule). Initially, we tested the oxidation of glycerol in the liquid-phase, with hydrogen peroxide and TS-1. However, results achieved were not satisfactory. Then we investigated the gas-phase transformation of glycerol into acrylic acid, with the intermediate formation of acrolein; the latter can be obtained by dehydration of glycerol, and then can be oxidized into acrylic acid. Actually, the oxidation step from acrolein to acrylic acid is already optimized at an industrial level; therefore, we decided to investigate in depth the first step of the process. I studied the reactivity of heterogeneous acid catalysts based on sulphated zirconia. Tests were carried out both in aerobic and anaerobic conditions, in order to investigate the effect of oxygen on the catalyst deactivation rate (one main problem usually met in glycerol dehydration). Finally, I studied the reactivity of bifunctional systems, made of Keggin-type polyoxometalates, either alone or supported over sulphated zirconia, in this way combining the acid functionality (necessary for the dehydrative step) with the redox one (necessary for the oxidative step).
In conclusion, during my PhD work I investigated reactions that apply the “green chemistry” rules and strategies; in particular, I studied new greener approaches for the synthesis of chemicals (Part A and Part B), the optimisation of reaction parameters to make the oxidation process more flexible (Part C), and the use of a bioplatform molecule for the synthesis of a chemical intermediate (Part D).
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Morphological transitions in molecular and polymeric materials: patterning, fabrication, devicesCalò, Annalisa <1976> 03 June 2010 (has links)
This thesis individuates and characterizes irreversible transformations occurring in specific organic and oligomeric/polymeric thin films. These transformations are dewetting in discotic liquid crystals thin films and dewetting and smoothing in oligomeric and polyemeric films. Irreversible transformations are extensively characterized by means of optical and atomic force microscopy. In the case of discotic liquid crystals films the morphological characterization is performed sinchronically with electrical measurements of current during dewetting.
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Development of original analytical methods for the therapeutic drug monitoring of CNS druges: Antipsychotics, Antidepressants and Anxiolytics-hypnoticsMercolini, Laura <1979> 15 April 2010 (has links)
Great strides have been made in the last few years in the pharmacological treatment of neuropsychiatric disorders, with the introduction into the therapy of several new and more efficient agents, which have improved the quality of life of many patients. Despite these advances, a large percentage of patients is still considered “non-responder” to the therapy, not drawing any benefits from it. Moreover, these patients have a peculiar therapeutic profile, due to the very frequent application of polypharmacy, attempting to obtain satisfactory remission of the multiple aspects of psychiatric syndromes. Therapy is heavily individualised and switching from one therapeutic agent to another is quite frequent. One of the main problems of this situation is the possibility of unwanted or unexpected pharmacological interactions, which can occur both during polypharmacy and during switching. Simultaneous administration of psychiatric drugs can easily lead to interactions if one of the administered compounds influences the metabolism of the others. Impaired CYP450 function due to inhibition of the enzyme is frequent. Other metabolic pathways, such as glucuronidation, can also be influenced. The Therapeutic Drug Monitoring (TDM) of psychotropic drugs is an important tool for treatment personalisation and optimisation. It deals with the determination of parent drugs and metabolites plasma levels, in order to monitor them over time and to compare these findings with clinical data. This allows establishing chemical-clinical correlations (such as those between administered dose and therapeutic and side effects), which are essential to obtain the maximum therapeutic efficacy, while minimising side and toxic effects.
It is evident the importance of developing sensitive and selective analytical methods for the determination of the administered drugs and their main metabolites, in order to obtain reliable data that can correctly support clinical decisions. During the three years of Ph.D. program, some analytical methods based on HPLC have been developed, validated and successfully applied to the TDM of psychiatric patients undergoing treatment with drugs belonging to following classes: antipsychotics, antidepressants and anxiolytic-hypnotics. The biological matrices which have been processed were: blood, plasma, serum, saliva, urine, hair and rat brain. Among antipsychotics, both atypical and classical agents have been considered, such as haloperidol, chlorpromazine, clotiapine, loxapine, risperidone (and 9-hydroxyrisperidone), clozapine (as well as N-desmethylclozapine and clozapine N-oxide) and quetiapine. While the need for an accurate TDM of schizophrenic patients is being increasingly recognized by psychiatrists, only in the last few years the same attention is being paid to the TDM of depressed patients. This is leading to the acknowledgment that depression pharmacotherapy can greatly benefit from the accurate application of TDM. For this reason, the research activity has also been focused on first and second-generation antidepressant agents, like triciclic antidepressants, trazodone and m-chlorophenylpiperazine (m-cpp), paroxetine and its three main metabolites, venlafaxine and its active metabolite, and the most recent antidepressant introduced into the market, duloxetine. Among anxiolytics-hypnotics, benzodiazepines are very often involved in the pharmacotherapy of depression for the relief of anxious components; for this reason, it is useful to monitor these drugs, especially in cases of polypharmacy. The results obtained during these three years of Ph.D. program are reliable and the developed HPLC methods are suitable for the qualitative and quantitative determination of CNS drugs in biological fluids for TDM purposes.
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