Prostate cancer (PCa) is the second most common type of cancer in the male population globally. The effectiveness of clinical treatment of PCa depends on the stage at which the disease is detected. Therefore, diagnosing the disease in early stages is critical to increase the patient's survival rate. Electrochemical sensors are devices used in analytical tests that aim to investigate the presence of species in a given sample and emerge as an alternative method to quantify PCa biomarkers. Printed electrodes are an excellent alternative in the area of sensor development, as they are easy to prepare, versatile, and, applicable in several areas, in addition to having high selectivity and sensitivity. Therefore, in this work, two screen-printed electrochemical immunosensors capable of detecting and quantifying the biomarkers PSA and KLK2 was developed. First, inks based on graphite, carbon black, nail polish, and acetone were produced for printing the sensor, and ink based on silver, nail polish, and acetone for the construction of the quasi-reference electrode. The sensors containing the working, quasi-reference, and auxiliary electrodes were printed using the screen printing technique on polyethylene terephthalate (PET) support. The printed electrode was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and the results showed the potential application of the electrochemical sensor. The immunosensor was constructed with the addition of gold nanoparticles (AuNPs), antibodies (anti-PSA or anti-KLK2), and bovine serum albumin (BSA) to the working electrode, for later application in the detection of the antigen of interest. Two immunosensors were developed, one for PSA detection and the other for KLK2. The parameters optimized for the best performance of the immunosensors were: antibody incubation time, BSA and antigen, BSA concentration, pH, and support electrolyte concentration. By monitoring the electrochemical behavior of the potassium ferrocyanide probe in front of the immunosensor, it was possible to observe a reduction in the signal of the anodic current, which is due to the immobilization of the proteins that act as an insulator. The immunosensor proposed for PSA detection had an LOD equal to 0.55 ng mL-1 and a LOQ of 1.82 ng mL-1. The interferents did not significantly affect the current signal and the reproducibility showed a relative standard deviation of 5.9%. The immunosensor was applied to synthetic human serum samples by the addition and retrieval method, and the results obtained demonstrated accuracy and potential application in clinical analyses. The immunosensor proposed for the detection of KLK2 showed LOD 0.17 ng mL-1 and LOQ 0.55 ng mL-1. These results suggest a potential application for analysis in biological samples. In addition, the methodology presented enables the development of an immunosensor that is easy to prepare and inexpensive, with an approximate cost of R$ 1.71 per unit.

Polycristalline samples following the nominal formula (Gd1−xF ex)2CuO4 with x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 0.9 and 1.0 were prepared by solid state reaction at ambient atmosphere using high-purity Gd2O3, F e2O3 and CuO oxides. Samples of an approximatelly one gram were mixed and pressed into pellets of 10 mm of diameter using 6 Tons of pressure. The samples were sintered three times at 960 C/48 h and between each process they were grinded a pelleted again. In order to investigated the coexistence of magnetic phases in the samples were performed X-ray diffraction and 57Co Mössbauer spectroscopy experiments. XRD Rietveld refinement analysis in x = 0 reveals that this sample growthed in pure I4/mmm tetragonal Gd2CuO4 phase that is antiferromagnetic (AFM). For x = 0.2 and 0.4 the coexistence of the (AFM) tetragonal I4/mmm Gd2CuO4 and the (AFM) Pbmn orthorrombic GdF eO3 phases was observed; for x = 0.5 the sample shows only the (AFM) orthorrombic Pbmn GdF eO3 phase; for x = 0.6 occurs the coexistence of (AFM) Pbmn GdF eO3 and cubic ferrimagnetic (FI) Ia-3d Gd3F e5O12; for x = 0.8 and 0.9 the coexistence of the (FI) Ia-3d Gd3F e5O12 and the (FI) I41/amd:2 F e2CuO4; and finally, for x = 1 was obtained the (FI) I41/amd:2 tetragonal F e2CuO4 phase. Nominal stoichiometry permit us to estimated the relative quantity of each phases in each sample. Additionally, magnetization measurements as a function of magnetic field and temperature were performed in the samples. The magnetic properties of each phase for each the compounds were calculated using a Hamiltonian that contains the exchange interaction between magnetic sublattices formed by Gd-Fe, Fe-Fe and Gd-Gd ions and the Zeeman term, where it was considered as the total magnetic response the sum of the responds of each magnetic phase. In the coexistence of iron magnetic crystallographic sites the relative intensities between the corresponding hyperfine fields were used to improve the computational simulations. Furthermore, good agreement was found in the magnetization response and in the variation of magnetic entropy as a function of temperature and applied magnetic field, calculated from experimental magnetization measurements and from computational simulations. This methodology permit us to verify the amounts of each magnetic phase in each sample founded previously by nominal stoichiometry, XRD and Mössbauer measurements with good accuracy and from hyperfine field data and computational calculations the exchange parameters for each magnetic phase were obtained. Interpolating the experimental values of x and the relative quantities of the magnetic phases it is possible to construct a phase diagram that permits guide to preparing samples with two specific magnetic phases in any desire rate in order to prepared in a one only process composites to applications in the design of thermomagnetic devices.

Síntese de nanopartículas de quitosana
ligada ao poli(2-(diisopropilamina) etil metacrilato) para encapsulação do citral

SÍNTESE E CARACTERIZAÇÃO DE BOROFENO PARA O DESENVOLVIMENTO DE SENSORES ELETROANALÍTICOS

The growing global concern regarding the presence of dyes in wastewater and water resources is noteworthy because of their resistance, toxicity, and carcinogenic potential, which affect aquatic life and human health. Effective removal of these substances before disposal into the environment is crucial. In this study, graphitic carbon nitride (g-C₃N₄) photocatalysts were prepared to degrade methylene blue with and without sulfur doping. Five samples with different doping ratios were produced using urea and thiourea as precursors in the proportions of 100:0, 70:30, 50:50, 30:70, and 0:100%, respectively. This method allowed the cost-effective synthesis of materials through a simple two-step process: precursor pyrolysis followed by liquid-phase exfoliation via ultrasonication to produce nanosheets. The photocatalysts were characterized using experimental methods (UV-vis, PL, lifetime, PLQY, XRD, and FT-IR) and theoretical studies employing density functional theory (DFT). The results reveal that among the doped samples, T50U50 shows remarkable improvements, including an extended lifetime, increased quantum yield, reduced bandgap, efficient charge transfer, and notable degradation efficiency of up to 97% in 150 min, accompanied by a substantially faster reaction rate. Sulfur doping demonstrates its capability to provide electrons to the electronic structure, contributing to bandgap reduction and inducing the inclusion of additional electrons and spin polarization.

With the aim of studying first-order phase transitions of semi-classical spin models, in this work, an identity based on the Effective Field Theory (EFT) from the differential operator technique is proposed. By means of the Maxwell construction for the free energy of thermodynamic systems, the Effective Field Theory Identity (EFTI) can be used for calculating points in phase diagrams in which two distinct states present the same free energy value. First, the EFTI is applied to a generalization of the Blume-Capel model in order to present its effectiveness and make the procedures clearer. Following these calculations, the EFTI will be applied to two technological material structures that present first-order phase transitions. For a spin-3/2 Borophene structure, phase diagrams are obtained by means of the EFT and of the Mean-Field Theory (MFT), with the EFTI being used in the calculations of first-order phase transition lines in the EFT context. Finally, the EFTI is applied to a spin-1/2 system that presents first-order
phase transitions within the phenomenon known as "spin-crossover". The outcomes for this system are compared to some results present in the literature.

ESTUDO DE PROPRIEDADES MAGNÉTICAS A PARTIR DAS TEORIAS DE CAMPO MÉDIO E CAMPO EFETIVO: MATERIAIS SPIN-CROSSOVER E MODELO HÍBRIDO DE ISING NA REDE KAGOME

Biobased materials present great potential in the development of sustainable products. The
finite nature of materials and concerns about resource scarcity are motivating scientists and
engineers to explore alternative and sustainable technologies for various industries. Despite
renewable resources (RR) being widely investigated for their potential in composite material
and sandwich structure applications, there is a lack of life cycle assessment (LCA) studies to
better evaluate if the use of RR is effective to reduce environmental impacts (EIs). Fibre metal
laminates (FMLs) are sandwich structures that typically consist of high-stiffness facing sheets
adhered to low-density solid cores. Consequently, FMLs offer a low weight-to-strength ratio,
which makes them particularly attractive and suitable for use in the aerospace and automotive
industries. In this sense, biobased composite materials are investigated and used as cores in
FMLs panels. Additionally a LCA and eco-efficiency analysis are performed for better
understanding of the trade-off between mechanical performance and EIs. This research is
structured into three distinct phases. In Phase I, biocomposites are fabricated using Hay Tifton
85 grass fibres (i.e., Cynodon spp.) combined with castor oil polyurethane or epoxy matrices
and used as core for novel FMLs. Physical and mechanical tests are performed, and a full
factorial design is used to identify the effects of polymer type and fibre length on mechanical
properties. In Phase II, biocomposites are made using short random coir fibre to reinforce castor
oil cores in FMLs. These are compared to analogue composites and FMLs based on epoxy and
polyester, considering an ecodesign approach to characterize physical and mechanical
properties, and assess the fabrication process adopted. In Phase III, 12 FML panels designs are
investigated incorporating diverse combinations of aluminium skins (2024-T3 and 1200-H14),
polymer matrices (Epoxy, Polyester, and Castor oil Bio-PU), natural fibres (Sisal, Coir, and
Cynodon spp.), surface treatments for aluminium skins (Sanding, NaOH, and Washprimer), and

treatments for natural fibres (Ground, NaOH-treatment and Untreated) within an eco-
mechanical approach. The research findings indicate the potential of the castor oil matrix for

dynamic applications, while the epoxy matrix exhibits superior performance under static loads.
Fully biobased laminates show promise in comparison to epoxy polymer composites. The
quality of skin-core interfacial bonding significantly influences flexural behaviors in epoxy and
polyester FMLs. Regarding specific mechanical properties, coir-fibre-biopolymer FMLs
demonstrate the best performance across all responses, despite involving fewer processing steps
and lower material/energy demands during fabrication. Among the designs assessed, “FML12”
fabricated using 1200-H14 aluminium alloy, castor oil biopolymer, coir fibres, and subjected
only to sanding for AL skin treatment, while avoiding fibre treatments, consistently
demonstrates superior eco-efficiency indicators. This design promotes enhanced mechanical
performance and reduced environmental impact when compared to the REF scenario, which
represents the average characteristics (both environmental and mechanical) of assessed FMLs.

In order to enable the applicability of chitosan as an antifungal agent, soil fungi were isolated and identified to be used in its production. The results indicate high viability of the isolated strains for the production of fungal chitosan (FCS), obtaining a maximum yield of 40.59 mg chitosan/g of dry biomass. The chitosans obtained were characterized by IR-ATR and 13C NMRSS. They showed high degrees of deacetylation (GD), ranging from 68.8% to 88.5%. Compared to crustacean chitosan, those from R. stolonifer and C. elegans had lower viscosimetric molar masses (26.23 and 22.18 kDa). At the same time, the molar mass of chitosan M. pseudolusitanicus L. presented a value coinciding with that classified as having low molar mass. Regarding the in vitro antifungal potential against the dermatophyte fungus Microsporum canis (CFP 00098), fungal chitosans showed antifungal properties, inhibiting mycelial growth by up to 62.81%. Despite the diversity of properties presented by chitosan, its application in the incorporation of bioactive compounds may be limited. Thus, chemical modifications were made to its structure in order to obtain hydrogels sensitive to pH/temperature to be applied in a release system. Through IR-ATR and 13C NMRSS analysis, the coupling of the polymers PMEO₂MA and P(MEO₂MA-co-DPA) into the chitosan polymer chain was verified. The hydrogels obtained showed a high degree of swelling of up to 90% in 90 minutes. It was also observed that the degree of PDPA coupling in the material influences its swelling capacity. The more PDPA, the more swollen the material becomes at acidic pH. Furthermore, it was noted that the amount of PMEO₂MA can also regulate the performance of the material in terms of its thermosensitivity. It was found that the CS-g-P(MEO₂MA-co-DPA) hydrogel showed greater affinity with the compound thymol and response at pH= 8.5 and at temperatures between 30-35 ^oC. Therefore, this material has characteristics that allow it to be used in applications linked to the release of active compounds in tissues with dermatophytosis. Therefore, we investigated the coupling capacity of FCS R. stolonifer in the P(MEO₂MA-co-DPA) copolymer to obtain a hydrogel sensitive to pH/temperature. The synthesized hydrogel was characterized by IV-ATR and ¹³C RMNES, demonstrating the presence of functional groups and specific signals. Thermogravimetric analysis demonstrated that the FCS-g-P(MEO₂MA-co-DPA) hydrogel presents thermal events distinct from FCS. Based on the swelling profile, it was possible to observe the hydrogel's response at pH=8.5 and a temperature close to body temperature with a reduction in its volume. The FCS-g-P(MEO₂MA-co-DPA) hydrogel showed affinity for the compound thymol with an incorporation efficiency (IE) of 77%. When carrying out the thymol release kinetics test, behavior controlled by the Korsmeyer-Peppas kinetic model was observed, with high R² values (R² > 0.94). The evaluation of the in vitro antifungal potential against the dermatophyte fungus M. canis provided important results, in which inhibition of up to 85% of its mycelial growth was observed. Thus, this study suggests the potential of the FCS-g-P(MEO₂MA-co-DPA)thymol hydrogel for applications in the control of dermatophytosis caused by the fungus M. canis.

The study of alternative cementitious materials has been growing over the years. This is because the construction industry has shown itself to be an aggravating sector in terms of the environmental impacts generated, mainly due to the production of Portland cement. Another inconvenience related to this material is the continuous incorporation of dead load in the structures due to its density (~2300 kg/m³). However, materials called geopolymers are economically viable as a possible alternative to using Portland cement in certain applications. Geopolymers are produced by activating materials rich in alumina and silica in an amorphous state with alkaline solutions. The properties of these materials can be manipulated from the chemical and mineralogical composition of the raw material, the molar constitution of the alkaline solution, curing time and temperature. Among the precursor materials used in the manufacture of geopolymers, metakaolin stands out for its reactive potential in addition to its high availability in nature. This research investigated the production of a lightweight geopolymer composite, based on metakaolin, through the incorporation of a clay mineral called expanded vermiculite (EV). The effects of volumetric percentage factors (15%, 30% and 45%) of EV in two different particle sizes (medium and fine) were evaluated. The composites were cured at 60°C for 24 hours, and remained at laboratory temperature for 28 days. The composites obtained were subjected to mechanical strength and electron microscopy tests. Physical properties such as: water absorption, apparent porosity, bulk and volumetric density were evaluated. The behavior of the composite material when exposed to high temperatures (600°C) was also evaluated, since the aggregate used is considered a good thermal insulator and has good thermal stability. The volumetric percentage was the dominant factor that affected all the investigated response variables, whereas the particle size had a significant role only for porosity and water absorption. The compressive strength of the composite significantly reduced from 52.1 MPa (0% VE) to 19.2 MPa when incorporating 45% of fine EV. The bulk density was reduced by approximately 22% with maximum aggregate incorporation (1.71g/cm³) while the pure geopolymer matrix presented a density of 2.1g/cm³. It is observed that the dispersed phase contributed to reduce the embrittlement of the composite at high temperatures, it is believed that this occurrence is related to the reduction of internal thermal stresses.

The main objective of this work was to synthesize a biocatalytic material starting from magnetic nanoparticles and β-glucosidase enzyme for application in the conversion of isoflavones into soybean derivatives. The β-glucosidase enzyme was produced by the fungus Trichoderma yunnanense and partially purified using ion exchange chromatography. The immobilization of β-glucosidase was performed on magnetic nanoparticles modified with silanol and amino groups, where the immobilization maintained 58% of the relative activity of the purified enzyme. After the first cycle of use, the immobilized enzyme maintained 42% of the activity and around 20% of the activity for 3 subsequent cycles. After immobilization, biochemical characterization and material characterization were performed. The optimum temperature was 60 °C for both forms of the enzyme, free and immobilized. The optimal pH was also determined, being 6.5 and 5.5 for the free and immobilized enzymes, respectively. The free and immobilized enzymes showed sensitivity to most ions, losing activity. Exceptions were potassium chloride ions and copper sulfate which activated both enzymes. The immobilized enzyme showed better performance for thermostability at 50 °C, maintaining activity up to 280 minutes of pre-incubation, while the free enzyme remained active for 180 minutes. At 70 °C, the immobilized enzyme showed activity for up to 60 minutes of pre-incubation, while the free enzyme lost its activity completely. The characterization of the material was performed by scanning electron microscopy (SEM), infrared absorption spectroscopy and thermogravimetry. The micrographs revealed a smooth and homogeneous surface for the unmodified magnetic nanoparticles, and the material showed heterogeneity as groups were added. Magnetite, which was the material used as a magnetic nanoparticle for this work, showed a low rate of thermal degradation up to 800 °C. As the organic groups were added, the mass percentage of thermal degradation of the material increased. Little difference in the amount of thermal degradation was observed between the steps of addition of the amino group and immobilization of the enzyme.

In this work, four polymeric materials of chitosan (QT) coupled to poly[2- (diisopropylamino)ethyl methacrylate] (PDPA) (QT-PDPA) were synthesized, altering the amounts of potassium persulfate added during the synthesis. The objective was to develop a controlled release nanocarrier with pH responsive property that can encapsulate perillyl alcohol (POH) for application in cancer treatment. QT-PDPA 03 and QT-PDPA 04 were the materials that showed the highest coupling efficiency values. The characterizations were performed by FTIR, TGA, EDL and RMNES of the 13C core and showed that there was a coupling between QT and PDPA. The materials showed responsiveness to pH due to the results obtained in the solubility tests and in the stability analysis and average particle size in aqueous medium at pHs 4,5, 6,0 and 7,4. The zeta potential values were greater than 30 mV (in module) for all nanoparticles, indicating that they were stable. The encapsulation efficiency was higher for the four synthesized materials than for pure QT. The QT-PDPA 03, among the four synthesized materials, presented the best results, such as better encapsulation efficiency of POH (87%), average particle size between 99,7 and 218,8 nm and higher coupling efficiency of 26.12%. Thus, the QT-PDPA 03 material was selected to perform the POH release assay at pHs 4,5, 6,0 and 7,4 to simulate the lysosomal and blood tumor environment, respectively. The POH release profile was influenced by the pH change of the medium, because in acidic medium (pH 4,5) the POH release rate was higher than in neutral/basic medium (pH 7,4). Using the mathematical models of zero order, first order, Higuchi and Korsmeyer-Peppas, the release mechanisms were determined through the analysis of the correlation coefficient (R2). The release mechanism for pH 4,5 was first order, at pH 6,0 Korsmeyer-Peppas and pH 7,4 the Higuchi. These results demonstrated that the QTPDPA 03 material is pH responsive and has the potential to encapsulate POH and release it in a controlled manner.

Lead halide perovskites nanocrystals (NCs) have emerged as attractive light-harvesting and emitting materials for many applications. These NCs are characterized to have a broad absorption spectrum with a high absorption coefficient (>10⁵M^-1 cm^-1). Nevertheless, the radiative lifetime of these NCs is a few nanoseconds at room temperature, which can limit their application in charge- and energy-transfer-related applications. To obtain a high absorption coefficient and a long-lived excited state, triplet energy transfer (TET) to organic molecules has been developed as an effective means to store the excitation energy of NCs in long-lived molecular triplets. In the past 5 years, different approaches have been used for triplet sensitization of organic molecules via Dexter mechanism, but it requires that the acceptor triplet state-level lies at lower potentials than the conduction band level of the NCs. Moreover, this mechanism is only efficient for short distances (<1 nm). On the other hand, FRET is still efficient for longer distances such as (2 to 10 nm), but it requires a large spectral overlap between the absorption and emission spectra of acceptors and donors. For triplet sensitization, FRET is inefficient because triplet absorption is dipole forbidden. Since R6G dimers have singlet and triplet energy states close to each other, favoring intersystem crossing, we can take advantage of the large spectral overlapping between the emission of CsPbBr₃NCs and the singlet-state absorption of R6G dimers to access their triplet-state via FRET. Here, we synthesized colloidal dispersions of CsPbBr₃ perovskite NCs with a cubic shape and mean size of 10 nm. While the dimers of R6G were prepared by a very high concentrated solution of R6G in ethanol followed by a successive dilution of it into toluene. The dimers were characterized by their steady-state absorption spectrum with a band centered at 511 nm, which is well documented in the literature and typical of H-aggregates. We also observed the dimer emission band centered at 620 nm employing time-resolved photoluminescence (TR-PL), with a lifetime of 600 ps. Such a fast lifetime is due to the efficient intersystem crossing of the dimer. The emission of the NCs and absorption spectra of the dimers are very well overlapped, with a critical distance (R₀) of 5.5 nm, according to FRET formalism. When we mixture the colloidal dispersion of NCs with the R6G dimers, we observed that the dimers effectively quench the photoluminescence of the NCs, increasing the emission intensity of the dimer.  TR-PL also indicates that the quenching involved is dynamic and occurs by FRET. Therefore, after excitation, CsPbBr₃ NCs transfer their energy via FRET to the singlet excited state of R6G dimers, relaxing quickly to the triplet state. We probed the triplet state of the R6G dimers using µs-transient absorption spectroscopy.

Efeito da umidade nas propriedades físico-mecânicas de biocompósitos reforçados com fibras curta de coco

In this work, it was developed two sensitives, simple and low-costs printed paper-based electrochemical sensors as an effective alternative for the determination of the breast cancer biomarker CA 15-3 in human serum and saliva samples. The electrodes were fabricated using different techniques, conductive inks and modifications. The first one was the graphite sensor. Initially, graphite and silver/silver chloride inks were fabricated using nail polish and acetone. The silver/silver chloride ink includes an additional step called chlorination where the AgCl layer is deposited on top of Ag ink with bleach solution. Next the graphite sensor was fabricated by screen-printing method. The graphite ink was used to print the working and counter electrodes, and silver/silver chloride ink in the development of the reference electrode. Then the sensor was modified with gold nanoparticles, antibody anti-human CA 15-3 and bovine serum albumin, resulting in the immunosensor SPE/AuNP/BSA. The immunosensor presented a sensitivity of 0.01231 μA/U mL-1, LOD of 0.5626 U mL-1 and LOQ of 1.8755 U mL-1. The interfering substances did not affect significantly the current signal, with response variation of 4.94%, and the reproducibility showed a relative standard deviation of 5.65%. The immunosensor was used to determine the CA 15-3 concentration in human serum and saliva samples using the standard addition method. The applications showed satisfactory recoveries, demonstrating good precision and potential application of the SPE/AuNP/BSA in clinical analysis. Next, the carbon nanotube sensor was fabricated. For that a carbon nanotube ink was fabricated using multi-wall carbon nanotube (MWCNT) and both covalent and non-covalent functionalization. The covalent functionalization was performed in acid medium using H2SO4/HNO3 and the non-covalent functionalization used SDS and ultrasonication. The ink formulation combines the insertion of functional groups and absorption of the SDS hydrophobic tail in the CTN surface. The silver nanoparticle ink was synthesized using the polyol method, with silver nitrate, ethylene glycol and polyvinylpyrrolidone. Then the material was dried and re-dispersed the in methanol. The carbon nanotube sensor was fabricated using carbon nanotube ink in marker pen to print the working electrode, graphite pencil to print the counter electrode and graphite/silver nanoparticle ink in rollerball pen to print the quasi-reference electrode. The CNT sensor was printed in a paper substrate using handwriting technique. The carbon nanotube sensor was electropolymerized with o-phenylenediamine in presence of CA 15-3 to form imprinted sites. First, a layer of AuNP was applied, serving as a platform for incubation of CA 15-3. While the oPD was used as the monomer on the construction of the polymeric film. After the protein was extracted, leaving vacant sites for subsequent rebinding. The developed sensor, called CNE/AuNP/MIP, provided a sensitivity of 0.013936 μA/U mL-1, limits of detection of 1.16 U mL-1 and quantification of 3.87 U mL-1. The interference studies showed that the sensor can be specific for CA 15-3. While the reproducibility exhibited a RSD of the current response for CA 15-3 detection of 2.77%, indicating the precision of the sensor. Then the sensor was applied in determination of CA 15-3 in samples of serum and saliva. The use in serum presented good recovery, but the application in saliva was not satisfactory. Therefore, the sensor CNE/AuNP/MIP should be used in the determination of CA 15-3 in serum samples only.

In this thesis, we propose an Ising-like dis rete pseudo-spins Hamiltonian, with an open
boundary and a transverse eld applied at the edge of the system (Transverse Ising
Model, TIM), whi h has the same formal stru ture of a dis retized semi- lassi al version of the Bernevig-Hughes-Zhang model (BHZ) for topologi al insulators. We show
that there is a partial symmetry that onne ts the mean-eld results at T = 0 for the
BHZ model to the mean-eld results (also at T = 0) of the TIM model. We study the
thermodynami s of the model in the mean-eld approximation and show the similarity
of the results found for the mean values of pseudo-spins at the boundary of the system
with the density of harge arriers at the edge of 2D topologi al insulators. In parti ular, we ompared our results to experimental measurements on Iron-Germanium
Telluride. Our results suggest that the lassi al pseudo-spins model an be used to
des ribe, at least qualitatively, the behavior of transport measurements on topologi al
insulators.

The search for new adsorbent materials, which have greater chemical, physical and thermal stability, in addition to greater adsorption capacity, has been growing in the scientific research. The synthesis of core-shell materials has been widely explored and has shown to be advantageous in several areas, including applications as adsorbent material. In this work core shell materials were developed employing different colors (iron oxide, silica and metal-organic structure) and using molecularly imprinted polymers – MIPs – as a coating. The synthesized MIPs have the same reagents: terephthalic acids as a functional monomer, ethylene glycol dimethacrylate as a cross-linking agent, benzalkonium chloride as a surfactant, 4,4'-azo-bis-(4-cyano pentaenoic) as a radical initiator, and, finally, acetonitrile and dimethyl sulfoxide as solvents. However, the template molecule was varied, always using antihypertensive drugs (atenolol, carvedilol and amlodipine), which are widely used in society. Through the characterizations, it was possible to observe that the synthesized materials (MMIP, core@mMIP and MOF@mMIP) reached the objective of having a core-shell structure, in addition to demonstrating thermal stability and a surface with heterogeneous particles conducive to adsorption processes. All materials were used as adsorbents in sample preparation techniques, and these techniques (magnetic solid phase extraction, microextraction by packed sorbent and dispersive solid phase extraction) have the advantages of employing less sample and solvent volume and less mass. of adsorbent, so they produce little waste. The materials proved to be
good adsorbents, with recovery values when used in sample preparation greater than 70%. The methods developed with these materials and the sample preparation techniques followed by the analyzes in the analytical equipment are shown to be effective for the extraction of antihypertensive drugs from biological fluids.

The goal of this master's dissertation was to carry out systematic theoretical investigations aiming to improve the electrical properties of poly(p-phenylene), via strategic procedures intrinsic to molecular electronics and supramolecular chemistry. In the first part, semi-empirical methods and the Density Functional Theory (DFT) were used to investigate the energetic, electronic and structural properties of pristine and push-pull substituted poly(p-phenylene), and their respective molecular wires formed by β-cyclodextrin (β-CD). ). From the results obtained, via PBE1PBE/6-31G(d,p)//PM3 calculations, it was possible to conclude: (i) the values of the HOMO-LUMO gap, for the pristine and substituted poly(p-phenylenes), decreases as the number of monomeric units increases; (ii) the insertion of push-pull groups leads to a reduction in the HOMO-LUMO gap values, being the NH2/NO2 set the best in this regard (iii) the encapsulation process of pristine and substituted poly(pphenylenes does not alter their electric conductivities. Therefore, the strategies used in this first step were effective in improving the electrical properties of poly(p-phenylene), from the theoretical point of view. In the second part, DFT and TD-DFT calculations, at the PBE1PBE/6-31G(d,p) level of theory, were performed in order to investigate the effect of doping process, implicit and explicit, by removing electrons and by different dopant atoms (Na, K and Cl), on the electronic, structural and spectroscopic properties of poly(p-phenylene). According to the results obtained, it was possible to conclude that: (i) the doping processes, whether implicit or explicit, led to a considerable reduction in the HOMO-LUMO gap energies; (ii) among the different dopants analyzed, Cl proved to be the most efficient for increasing the conductivity of poly(pphenylene); (iii) from the UV-Vis spectra it was possible to observe the formation of polarons and bipolarons, thus evidencing the success of the doping process

Fluorine is a chemical element that was first discovered and isolated in 1986 by French chemist Henri Moissan. When fluorine is inserted into a carbon chain it adds several meaningful properties to this compound, which is now known as an organofluorinated compound. However, the production of these organofluorinated compounds currently requires the use of highly complex reagents or even reactions in extremely controlled environments in an attempt to overcome the difficulties in the fluorination processes, the low selectivity, which means that the elimination reactions compete with the nucleophilic substitution reactions, producing byproducts and decreasing the yield of the fluorinated product, as well as the amount of resources required to promote this type of reaction, since expensive reagents and time-consuming reactions are used. In the present work, theoretical calculations were used, at the DFT level with PBE, X3LYP and M06-2X functionals, of the fluorination reactions of ethyl bromide using supramolecular complexes of TBAF/bulky alcohols to understanding the role of controlled hydrogen bonds and increase the selectivity of the fluorination reactions, thus increasing the final yield, as well as understanding the influence of the volume of alcohol used in the formation of complexes with TBAF on the selectivity of the reaction. The calculations show that the use of supramolecular complexes of bulky TBAF/alcohols is a viable strategy despite the fact that the activation barrier for these reaction pathways higher than the activation barrier for nucleophilic fluorination using only TBAF. However, the activation barrier for the elimination reactions becomes even higher, providing better yields and higher selectivity of the organic compound fluorination process. The calculation of the global kinetics of the nucleophilic fluorination reactions, 4.39x10-6 mol L-1 s -1 , in toluene and 1.74x10-6 mol L -1 s -1 in acetonitrile, with the global kinetics of the elimination reactions, 9.20x10-9 mol L-1 s -1 in toluene and 5.53x10-7 mol L -1 s -1 in acetonitrile support this selectivity.

Dermatophytosis is a type of infection caused by dermatophyte fungi, a specialized group of keratinophilic fungi that are lodged in the nails, skin and hair. Many kinds of treatments have been developed, however, side effects or resistance to drugs are frequently reported. Essential oils have several biological activities, including bactericidal, antiviral, antifungal, among others. In general, essential oils have greater antifungal activity due to their constituents, such as monoterpenes. The great challenge of applying essential oils is to protect them from degradation, evaporation, improve their dispersions in an aqueous medium and obtain a controlled release. Encapsulation using modified chitosan-based materials is a possible alternative to overcome this problem. In this work, the synthesis of a graphitized chitosan nanogel with 3,4-methylenedioxycinnamic acid (MDCA) was carried out with the objective of encapsulating the monoterpenes carvacrol and thymol, aiming at preservation and better dispersion in aqueous medium, with the aim of developing a material that can be used to control the fungus Microsporum canis. Material characterizations were performed by FTIR, 13C-NMR, TGA, SEM and DLS. To assess the antifungal potential, the minimum inhibitory concentration (MIC) and the inhibition of M. canis mycelial growth (MIC/2, MIC, 2xMIC) of chitosan nanogel and MDCA encapsulated with monoterpenes analysis were performed. The results obtained by FTIR and NMR for the nanogel revealed the formation of a bond between chitosan and MDCA. The encapsulation efficiency calculation showed that the nanogel encapsulated with the monoterpenes carvacrol and thymol presented an encapsulation capacity between 12.9 and 13.3%, respectively. The DLS studies showed that the nanogel particles in aqueous medium presented nanometric sizes and good stability, before and after the encapsulation of monoterpenes. From the results obtained by SEM, differences in the morphology of the materials obtained can be observed in relation to the morphology presented by chitosan, in addition to well-defined spherical cavities being visualized in cross-sections of the chitosan nanogel graphited with MDCA, resulting from the presence of incorporation of monoterpenes. The QT-g-MDCA-Ca and QT-g-MDCA-Ti nanogels showed antifungal potential against the fungus Microsporum canis, being able to inhibit mycelial growth by 100.00 and 93.13%, respectively.

The main purpose of this work was to synthesize different materialsbased on polypyrrole (PPy) and verify their potential in adsorption studies and sample preparation using analytes with different pKa values.The mesoporous magnetic PPy (MMPPy) was developed to be used in studies of adsorption of the following adsorbates:ibuprofen (acid), caffeine (neutral) and bupropion (basic) present in aqueous solutions.For this, parameters such as pH of the aqueous solution, contact time/kinetics, concentration/isotherm and temperature were evaluated.Subsequently, MMPPy was double coated with hydrophilic monomers and casein, obtaining RA-MMPPy-HM-CAS.The coated material aims to exclude macromolecules present in complex matrices, facilitating sample preparation and analysis.RA-MMPPy-HM-CAS was used in magnetic solid phase extraction (MSPE) for simultaneous determination of diclofenac (acid), fipronil(neutral) and febantel (basic) in milk samples.Another PPy-based material developed was mesoporous PPy double coated with hydrophilicmonomers and bovine serum albumin, called RA-MPPy-HM-BSA.It was used in dispersive solid phase extraction (DSPE) and pipette-tip solid phase extraction (PT-SPE), in order to compare which of these two techniques was more efficient for simultaneous determination of pyriproxifen (acid), progesterone (neutral) and deltamethrin (basic) in chicken egg samples.In sample preparation techniques, the following parameters were optimized: pH and volumesample, washing solvent, amount of material, type and volume of elution solvent and contact time (MSPE and DSPE).The methods were validated including performance criteria such as linearity, limit of quantification (LOQ), precision, accuracy, robustness and stability and applied to milk (MSPE) and egg samples(PT-SPE)

Ca2Y8-x-y-z(SiO4)6O2: xEu3+ , yDy3+ , zTb3+ luminescent materials were prepared by the sol-gel method, followed by a solid-state reaction carried out at 1100 °C. Syntheses with simple doping, only with Eu3+, Dy3+ or Tb3+ ions, and codoping, with the combination of Eu3+/Dy3+or Eu3+/Tb3+ ions, were performed by varying, in all cases, the concentrations of these ions. The structural characterization of the materials, carried out by X-ray diffraction, infrared spectroscopy (IR) and Raman spectroscopy, proved the formation of oxyapatite-type silicates, with hexagonal type unit cell, belonging to the space group P63/m. In Raman and IR spectra, bending and stretching modes of [SiO4] 4- tetrahedral groups, characteristic of apatite-like structures was identified. The excitation and emission spectra of the synthesized materials showed bands referring to the 4f-4f interconfigurational transitions characteristic of each doping ion. In agreement with the emission bands displayed in the spectra of Eu3+ -doped apatites, these materials showed chromaticity coordinates in the red region, with high color purity, differing only in the emission intensity. Doping with Dy3+ ions resulted in color emissions in the blue, cyan, and white regions. The materials doped with Tb3+ ions exhibited emissions that varied from blue to green. Among single-doped materials, only Dy3+ -doped showed suppression of luminescence due to the increase in the concentration of doping ions inserted in the matrix. Spectroscopic measurements as a function of temperature proved the high thermal stability of apatites doped with Tb3+, Dy3+ and Eu3+ ions, in the face of minor changes in photoluminescent emission with increasing temperature. The energy transfer process in the codoped apatites was investigated by analyzing the excitation and emission spectra and the life-state curves of the excited state. Among the parameters that fundamentalized the efficiency of the energy transfer processes Dy3+→Eu3+ and Tb3+→Eu3+, we highlight a spectral overlap between the excitation spectrum of the activating ion, Eu3+, and the emission of the sensitizing ion, Dy3+ or Tb3+, in addition to the decrease in the lifetime of the co-doped materials with the increase in the concentration of the activator, in which the curves were monitored at the emission and excitation wavelengths of the sensitizing ion. The simultaneous incorporation of the Dy3+ and Eu3+ ions and the Tb3+ and Eu3+ ions resulted in emission spectra with characteristics of both doping ions, enabling the adjustment of the luminescent emission of each ion from the concentration and excitation wavelength. As a result of the combinations of ion emissions, there is a wide range of colors emitted in the visible region: green, red, orange, yellow, pink, cyan, white. The potential application of synthesized materials in solid-state lighting, especially white LEDs, is promising. This is justified due to its high luminescent intensity; diversity of emission colors, especially the single-phase white emission, and color temperatures, which expands the application possibilities; and the feasibility of associating these materials with UV-LED and blue LED chips, whose emission wavelengths can efficiently excite the synthesized apatites.

Semiconductors are materials of great interest to scientific human activities because many available technologies nowadays use these materials. In addition, the miniaturization of semiconductors on the nanoscale (10-9 m) opened, even more, the use of semiconductors in our growing demands for technology. However, the control of optoelectronic properties of semiconductors nanocrystals is not trivial being necessary a better comprehension of their photophysics, since many of these processes occur at very short timescales. In order to study and characterize them, it is suitable to use time-resolved spectroscopy techniques on the ultrafast timescale (10-15 -10-6 s). These generally rely on pulsed lasers with ultrashort pulses (10-15s). Two of these techniques are known as transient absorption and broadband fluorescence upconversion spectroscopies. In this thesis, we have used these both techniques to study the photohysical processes of full-inorganic perovskites CsPbBr3 colloidal nanoplatelets (CNPls) and, we have also used transient absorption spectroscopy to study quaternary quantum dots (QDs) based on Cu-In-Zn-S (CZIS). This thesis was written in five chapters to cover this subject. Chapters 1 and 2 are introductories. The former introduces the relevant theory for the following chapters, which will allow the readers to be familiarized with the main concepts and properties of semiconductors. Meanwhile, the second one gives a detailed explanation of ultrafast spectroscopy, including the setup description and data analysis. Chapter 2 also describes time-resolved spectroscopy applied in the carried out study. The following chapters placed in increasing complexity present the main results obtained for both kinds of nanoparticles. Chapter 3 consists of a review of the recent literature of perovskite nanocrystals contrasting their properties under strong and weak quantum confinement regimes. Chapter 4 presents a time-resolved photophysical study of CsPbBr3 CNPls. These materials are interesting because of their unique blue emission, strong exciton binding energy, large absorption cross-section, and fast hot exciton relaxation. These properties make them attractive for light-emitting devices. We synthesized these CNPLs by using a simple methodology at room temperature. The exciton, biexciton, and hot exciton dynamics were studied by means of fluorescence upconversion and transient absorption spectroscopies. Chapter 5 describes a timeresolved photophysical study of CZIS QDs. These materials are promising for a variety of applications because they are composed of less toxic elements. Here, we have studied three different samples in which we introduced more Zn2+ in the crystalline lattice of CZIS. Using transient absorption spectroscopy, we could study hole and electron trapping processes in these 9 nanoparticles as function of different concentrations of Zn. The Introduction of Zn increased the bandgap of the material and decreased the hole and electron trapping process.

This work aimed to develop polymeric materials based on porous polyaniline double coated with restricted access materials to be applied in different solid phase extraction techniques of drugs in biological matrices, which aims to exclude macromolecules present in complex matrices, facilitating sample preparation and analysis. In the first study, magnetic mesoporous polyaniline coated with hydrophilic monomers and bovine serum albumin (RA-MMPAni-HMBSA) was synthesized and, from the results obtained in the characterization techniques, it can be seen that the objective of synthesizing an adsorbent material with magnetic characteristics and with the ability to exclude proteins was successfully achieved, because by EDS, it is possible to prove the composition of the material at each step, by XRD it can be seen that the magnetic property was maintained and, by the results of TG , FTIR, wettability and protein exclusion it can be concluded that the material was coated with the restricted access materials. Furthermore, RA-MMPAni-HM-BSA was applied as an adsorbent material in the magnetic solid phase extraction (MSPE) of two coumarins, 4,7-dimethylcoumarin (DMC) and 7- methoxy-4-methylcoumarin (MMC) , present in rat plasma, showing good adsorptive and also magnetic capacity. For the optimization of the analytical method, some parameters were evaluated, such as pH and sample volume, washing solvent, amount of material, type and volume of elution solvent and contact time. Thus, the optimized conditions were: 500 µL of sample with pH equal to 2, 20 mg of adsorbent material, stirring for 1 min, water as washing solvent, acetonitrile as elution solvent (750 µL), obtaining recovery 72.9% for MMC and 98.0% for DMC. The method was validated and applied to a plasma samples from rat and then showed good results in terms of accuracy and precision, in addition to being reproducible for the identification and quantification of the analytes under study. In the second study, the mesoporous polyaniline coated with hydrophilic monomers and bovine serum albumin, called RA-MPAni-HM-BSA, was used in dispersive solid phase extraction (DSPE) and microextraction by packed sorbent (MEPS). In order to compare which of the two techniques would be more efficient for the extraction of two antiallergics, loratadine (LRT) and cetirizine (CTZ) in human urine. The DSPE method showed better recovery results (71.9% for CTZ and 79.1% for LRT) compared to the MEPS method (46.9% for CTZ and 85.8% for LRT). Therefore, the DSPE method was chosen to be validated and applied. The validation obtained results in accordance with the current standard and was successfully applied to real samples, finding concentrations equal to 0.111 and 0.041 µg mL-1 of two volunteers. Finally, the materials were efficient to be used as adsorbents in extraction techniques and from the characterizations you can see that the syntheses were carried out successfully.

Due to its peculiar characteristics, fluorine has attracted the attention of many researchers in the recent years. Although it is an abundant element in the crust of earth, it is in the form of poorly soluble salts, as CaF2, which makes difficult its incorporation to organic compounds. In the lab, the most common methods used to promote the fluorination of carbon chains are the nucleophilic substitutions (SN2). However, the fluoride ion also works as base and promotes elimination reactions (E2), doing necessary the development of catalysts to control its reactivity. Using theoretical methods, this work seeks to propose an effective catalyst for nucleophilic fluorination of aliphatic compounds with CsF and KF as fluoride sources. The catalyst must have the following characteristics: facility in solubilizing salt, source of fluoride; selectivity for SN2 products over E2; geometry that makes dimerization of the catalysts(MF) difficult; and easy decomplexation with the product to promote the catalytic cycle. Based on previous theoretical and experimental work, the study started with the penta(ethylene glycol) – PEG, a promising compound for good interacting with salt, due to the middle ether groups and the end hydroxyls of the chain. However, although leads to effective solubilization of the salt, it presents high activation barrier due to the strong interaction between hydroxyls and fluoride ion, and also the formation of dimers. Trying to modulate this interaction and decrease the dimerization, it was proposed to add methyl and phenyl groups at the end of the PEG chain. The new structures turned dimerization less favorable, but also reduced solubilization of the salt, increasing the activation barriers. A new study was initiated with a structure proposed by Carvalho and Pliego: a derivative of dibenzene-18-crown-6 with four hydroxyl groups strategically positioned to stabilize the fluoride ion and favor the fluorination process. In this work, the hidroxyl groups was replaced by thioureas, and the new structure was named thiourea-ether-crown or TE-crown. The new compound showed a promising activity, but also showed favorable dimerization. Further design work led to the addition of a butyl group to each thiourea group (thiourea-ether-crown-butyl – TEC-but). The formation of the dimer was unfavorable, and the new structure worked as an effective catalyst when the leaving group is the bromide. In the case of mesylate as leaving group, it worked as a promoter. The activation barrier remained around 26 kcal mol-1 , 4 kcal mol-1 lower than the barrier for the reaction promoted by crown ether. Thus, the main goal of this work was achieved. We designed a new catalyst for nucleophilic fluorination reaction, the TEC-but.

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The present work aimed to perform a theoretical investigation of the inclusion complexes formation involving β-cyclodextrins, primitives and replaced with two coumarin derivatives (DCUMs), the 4,7-dimethylcoumarin (DMC) and 7-methoxy-4 - methylcoumarin (MMC).In this way, the semi-empirical and Density Functional Theory (DFT) methodologies have been used, involving gas phase and DMSO solution calculations, in order to understand, at the molecular level, the main factors responsible for the formation and stabilization of the studied complexes, in 1:1, 1:2 and 2:1 stoichiometries. Three methodological procedures were applied: semi-empirical PM3, sequential PM3 / DFT, and DFT (B97D / 6-31G (d, p)). According to the structural and energetic results obtained, it was possible to conclude that factors such as: (i) inclusion depth, (ii) methoxy group (OCH3) presence, (iii) hydrogen bonds formation, (iv) π-π stacking formation and (v) polarity of the host molecule, directly influence the stability of the complexes. Among the studied stoichiometries, it has been found the 1:2 stoichiometry (two DMC analogues) presented the most negative complexation energy values, due mainly to the hydrogen bonds established between the guest molecules and the host, as well as the π-π stacking interactions observed between guest molecules. In addition, it has been found the substituted β-CDs complexes formed (carboxymethyl-β-CD and p-sulfonic acid-β-CD) presented more negative complexation energy values, thus indicating the formation of supramolecular structures more stable when compared to the primitive βCD. Finally, the development of this work has contributed significantly to the understanding and elucidation of cyclodextrins inclusion complexes formation with DCUMs. The theoretical results involving the early β-CD corroborated in good accordance with experimental data. Furthermore, the substituted β-CD have shown, at least from a theoretical point of view, a good alternative in order to obtain more stable inclusion complexes and purportedly more effective.

The Brazilian agrarian model makes the country's agricultural production process increasingly dependent on pesticides and chemical fertilizers. Currently, organophosphorus compounds (OPs) are one of the most widely used classes of pesticides worldwide. However, due to their chemical structure, OPs have great toxic effect on humans and others mammals, by irreversibly inhibit the acetylcholinesterase enzyme (AChE) activities. Thus, overexposure to these neurotoxic compounds through environmental pollution, bioaccumulation in soil, water and food, can result in serious ecological problems and cause damage to human and other living organism’s health. Therefore, the development of sensitive, fast, easy to prepare and execute methodologies for OPs detection is an extremely important concern. In this context, the objective of this work was to detect Diazinon (DZN), Malathion (MLT) and Chlorpyrifos (CLPF), compounds belonging to organophosphorus class, in samples of tap water, orange and apple, using an electrochemical sensor modified by a nanocomposite based on functionalized Carbon Nanotubes (NTCf) and Metal Nanoparticles (NPs). By combining these two classes of nanomaterials, it is expected to obtain a synergistic effect that adds the high catalytic power of NPs with the excellent electrical conductivity of NTC, enabling an improvement in the kinetics of redox processes, expanding the electrochemical signal and increasing the sensitivity of the sensor. In order to carry out the analyzes, the developed sensor was coupled to the Batch Injection Analysis System associated with the detection by Multiple Pulse Amperometry (BIA-AMP), because it allows high analytical frequency, good reproducibility, fast and accurate analyzes. The characterization of the modifying materials was performed by UV-Vis Spectroscopy, Fourier Transform Infrared Spectroscopy (FT IR), Scanning Electron Microscopy and X-Ray Diffraction. The electrochemical characterization was performed by Electrochemical Impedance Spectroscopy and Cyclic Voltammetry. The working electrode configuration that guaranteed the largest electroactive surface area, the least resistance to electron transfer and the greatest sensitivity was the Pyrolytic Graphite Electrode (EGP) modified by NTCf and AgNPs (EGP / NTCf-AgNP). In the BIA-AMP system, the OPs samples were injected directly on the modified working electrode surface, immersed in Britton-Robinson buffer solution 0.15 mol L -1 pH 6.0, by an electronic micropipette. The optimal potential for reducing OPs was found to be -1.3 V with 100 ms of application time. The optimal injection volume and injection speed were 250 µL and 300 µL s -1 , respectively. After optimizing all experimental and operational parameters, the developed sensor presented an analytical frequency of 71 determinations per hour (71 h -1 ), good reproducibility, high sensitivity, wide linear response range and detection limits of 3,54 x 10-7 mol L -1 to DZN, 8,94 x 10-7 mol L -1 to MLT and 5,33 x 10-7 mol L -1 to CLPF, values that are in accordance to the Maximum Residue Limit established by ANVISA. Finally, the sensor application was effective for organophosphate insecticides determination in tap water, orange and apple samples, with recovery values within the acceptance range established by the EPA. Therefore, it can be considered that the developed sensor proved to be an effective alternative with great potential and viability to be applied for DZN, MLT and CLPF determination in real samples.

Increasing energy demands, together with environmental crises and limited availability of fossil energy sources, cause a great need for renewable and clean forms of energy as well. Photovoltaic systems have been considered of great interest, since solar energy is considered a form of abundant, clean and renewable energy. Ternary quantum dots (QD) with chalcopyrite structure are considered promising materials for photovoltaic applications due to the high absorption of sunlight, and environmentally friendly chemical compositions. However, many methodologies of these materials’ synthesis use organic media, increasing toxicity and possibility of environmental impacts involved. In this work, environmentally friendly chalcopyrite CuInS2 QDs were synthesized in water, using the hydrothermal synthesis method, as well as a direct aqueous synthesis. Using selective precipitation, it was possible to obtain different materials fractions, with different optical properties and potential for different applications. To determine how the synthesis parameters influence the optical properties, conditions such as synthesis time, molar ratio of precursors, compositions, surface ligands, volume of synthesis, use of “shell”, among other parameters, were investigated. After characterization, some of the materials were used to sensitize TiO2 substrates, to be applied in solar cells. Sensitization was carried out by immersing the substrates in dispersions containing the QDs. QDs synthesized by the hydrothermal method were applied with and without fractionation. The solar cells resulting from the unfractionated sample demonstrate a relatively high open circuit voltage (VOC) of 0.53 V and a short circuit current density (JSC) of 13.62 mA / cm². A reasonably high fill factor was also obtained (about 0.6), characteristic of the good interface quality in the devices. The conversion efficiency obtained was 4.53% (best cell: 4.67%), which is the highest value achieved with ternary QD synthesized by hydrothermal method. The average efficiency of fractions obtained by the selective precipitation were 2.52% for the first fraction and 2.85% for the second fraction, which is similar to the majority of the results obtained for QD in aqueous medium. QD synthesized by direct aqueous synthesis were also applied to sensitize TiO2 substrates. QD using mercaptopropionic acid (MPA) as ligand showed conversion efficiency of about 2.75% and QD using thioglycolic acid (TGA) showed efficiency of 2.12%. It is observed that efficiencies above 2% were obtained with the synthesized samples, it is also considered the possibility of optimizations and, therefore, of improving these results. Thus, the use of a synthesis method simple, "green", and in aqueous medium, made it possible to obtain QD with potential for photovoltaic applications. In addition, direct aqueous synthesis proved to be a simple and fast method of obtaining QDs in good quality, as well as a way to obtain different nanocrystals, with varied composition and different surface ligands (MPA, TGA, Reduced Glutathione, Dihydrolipoic acid and a synthesized tripod ligand), having interesting optical properties and with potential for many technological applications.

Theoretical study of the anantioselective separation and the formation process of molecular printing polymers for bupropion and hydroxybpropion.