Sinthesys of heteroleptic zinc complexes for imaging in living cells

This thesis arose from an interest in luminescence heteroleptic bis(dipyrrinato) Zn (II) complexes and their application in cell imaging, due to their attractive and fascinating characteristics. Among imaging technologies, near-infrared fluorescence imaging has been dedicated immense attention owing to its low absorption and autofluorescence from surrounding organism and tissues in this specific spectral region, which minimize background interference and improve tissue depth penetration. An ideal near-infrared probe should be equipped with excellence chemical and photophysical properties. The target of this work is the synthesis of new heteroleptic bis(dipyrrinato) Zn (II) complexes having two main features: the emission in the near-infrared region and water-solubility. In order to purse these intentions, the low-energy emission was achieved by expansion of π-conjugation of simple dipyrrins using Knoevenagel condensation106 and tri(ethylene)glycol chain was introduced to increase the water solubility of the final complex. Photophysical and luminescent properties of the new complexes were investigated. Finally, with a view to a potential biological use of these new complexes in biological environments, their biocompatibility was tested using a cell viability assay: (3-(4,5-dimethylthiazol-2-yl)-2’-5’-diphenyltetrazolium bromide (MTT) assay.

Synthesis and electronic properties of luminescent silicon nanocrystals and copper indium sulphide quantum dots

In the last decades, nanomaterials, and in particular semiconducting nanoparticles (or quantum dots), have gained increasing attention due to their controllable optical properties and potential applications. Silicon nanoparticles (also called silicon nanocrystals, SiNCs) have been extensively studied in the last years, due to their physical and chemical properties which render them a valid alternative to conventional quantum dots. During my PhD studies I have planned new synthetical routes to obtain SiNCs functionalised with molecules which could ameliorate the properties of the nanoparticle. However, this was certainly challenging, because SiNCs are very susceptible to many reagents and conditions that are often used in organic synthesis. They can be irreversibly quenched in the presence of alkalis, they can be damaged in the presence of oxidants, they can modify their optical properties in the presence of many nitrogen-containing compounds, metal complexes or simple organic molecules. If their surface is not well-passivated, the oxygen can introduce defect states, or they can aggregate and precipitate in several solvents. Therefore, I was able to functionalise SiNCs with different ligands: chromophores, amines, carboxylic acids, poly(ethylene)glycol, even ameliorating functionalisation strategies that already existed. This thesis will collect the experimental procedures used to synthesize silicon nanocrystals, the strategies adopted to functionalise effectively the nanoparticle with different types of organic molecules, and the characterisation of their surface, physical properties and luminescence (mostly photogenerated, but also electrochemigenerated). I also spent a period of 7 months in Leeds (UK), where I managed to learn how to synthesize other cadmium-free quantum dots made of copper, indium and sulphur (CIS QDs). During my last year of PhD, I focused on their functionalisation by ligand exchange techniques, yielding the first example of light-harvesting antenna based on those quantum dots. Part of this thesis is dedicated to them.

Organic photosensitizers and nanostructured semiconductors for photoredox catalysis and artificial photosynthesis

Over the course of evolution, Nature has elegantly learned to use light to drive chemical reactions. On the other hand, humans have only recently started learning how to play with this powerful tool to carry out chemical transformations. In particular, a step forward was possible thanks to molecules and materials that can absorb light and trigger a series of processes that can drive chemical reactions. However, scarce elements are extensively employed in the design of most of these compounds and considerations on their scarcity and toxicity have sparked interest on alternatives based on earth-abundant elements. In this framework, the focus of this thesis has been the development and employment of heavy-metal free chromophores and of earth-abundant oxides. The first chapter regards the functionalization of boron-dipyrromethenes (BODIPYs) so as to allow access to their triplet excited state and tune their redox potentials, which was achieved thanks to the design of orthogonal donor-acceptor dyads. The BODIPY dyads were used to promote a photoredox reaction, and the mechanism of the reaction was clarified. In the second chapter, organic chromophores that display thermally-activated delayed fluorescence (TADF) were studied. These were used to perform enantioselective photoredox reactions, and a mechanistic investigation allowed to elucidate the fate of these photosensitizers in the reaction. Thanks to their stronger reducing power, it was possible to demonstrate the employability of TADF dyes in artificial photosynthesis, as well. Last, the oxidation of biomass-derived compounds was studied in a photoelectrochemical cell. For this purpose, hematite photoanodes were synthesized in collaboration with Prof. Caramori’s group at the University of Ferrara (Italy) and they were tested in the presence of a redox mediator. In addition to this, the possibility of repurposing a copper(II) water oxidation catalyst for the oxidation of biomass was investigated in collaboration with Prof. Llobet’s group at ICIQ (Tarragona, Spain).

3-Nitrophenol-4,4 '-bipyridyl N,N '-dioxide (2/1): a DFT study and CSD analysis of DPNO molecular complexes

The title 2:1 complex of 3-nitrophenol (MNP) and 4,4'-bipyridyl N, N'-dioxide (DPNO), 2C(6)H(5)NO(3)center dot C(10)H(8)N(2)O(2) or 2MNP center dot DPNO, crystallizes as a centrosymmetric three-component adduct with a dihedral angle of 59.40 (8)degrees between the planes of the benzene rings of MNP and DPNO (the DPNO moiety lies across a crystallographic inversion centre located at the mid-point of the C-C bond linking its aromatic rings). The complex owes its formation to O-H center dot center dot center dot O hydrogen bonds [O center dot center dot center dot O = 2.605 (3) angstrom]. Molecules are linked by intermolecular C-H center dot center dot center dot O and C-H center dot center dot center dot N interactions forming R(2)(1) (6) and R(2)(2) (10) rings, and R(6)(6) (34) and R(4)(4) (26) macro-rings, all of which are aligned along the [(1) over bar 01] direction, and R(2)(2) (10) and R(2)(1) (7) rings aligned along the [010] direction. The combination of chains of rings along the [(1) over bar 01] and [010] directions generates the three-dimensional structure. A total of 27 systems containing the DNPO molecule and forming molecular complexes of an organic nature were analysed and compared with the structural characteristics of the dioxide reported here. The N-O distance [1.325 (2) angstrom] depends not only on the interactions involving the O atom at the N-O group, but also on the structural ordering and additional three-dimensional interactions in the crystal structure. A density functional theory (DFT) optimized structure at the B3LYP/6-311G(d,p) level is compared with the molecular structure in the solid state.

Nutrition in bean plants and anthracnose intensity in function of silicon and copper application.

Nutrition in bean plants and anthracnose intensity in function of silicon and copper application. The objective of this work was to evaluate the effect of calcium silicate and copper sulfate on anthracnose intensity and nutrition of bean plants. The experiment was conducted using an experimental design in randomized blocks following a 4 x 4 factorial arrangement , (four levels of calcium silicate and four levels of copper sulfate) and two additional treatments (plants without inoculation and plants sprinkled with Benomyl). Four evaluations of the incidence and severity of anthracnose were done, in addition to measuring, total leaf area. At the end of the evaluations, incidence: and data were integrated over time, obtaining the area under disease progress curve (AUDPC). Contents of N, P, K, Ca, Mg, B, Cu, Fe, Mn, Zn, Si and lignin were determined in the aerial Part. A linear decrease of the intensity AUDPC was observed with the increase of the doses of calcium silicate. The severity AUDPC was influenced by the doses of copper, obtaining a reduction of 35% on the higher dosage. The supply of silicon and copper altered the content of the K, mg, S, Zn, Ca and Si in the aerial part of the bean plants.

Attainment and Characterization of Ternary Complexes of Simvastatin-Cyclodextrin-Hydrossoluble Polymers

The purpose of this study was to attain and characterize ternary complexes of simvastatin, beta-cyclodextrin (beta CD) and different polymers, and then select those that lead to a greater increase in drug solubility. The complexes were prepared with the co-evaporation method and the polymers used were polyethylene glycol 1500, polyethylene glycol 4000, povidone, copovidone, crospovidone, maltodextrin and hydroxypropyl methyl cellulose. The characterization of complexes was carried out through aqueous solubility, DSC and TG. There was an increase in solubility for all the complexes prepared with beta CD and the different polymers, but only when crospovidone and maltodextrin were used was there a significant difference observed between the solubility of the physical mixture and that of the complex. The DSC curves indicate that the non-complexed drug is even in the sample of the complex with higher solubility, thus none of the polymers was able to achieve a total complexation of the drug.

N-methylation of macrocyclic hexaaminecobalt(III) complexes

Reaction between formaldehyde and the pendant arm macrocyclic complex (trans-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine)cobalt(III) [CoL1](3+) yielded the diimine derivative trans-6,13-dimethyl-6.13-bis(methyleneamino)-1,4,8,11-tetraazacyclotetradecane (L-3) as its cobalt(III) complex. Reduction of the imines has been achieved with NaBH4 and the meso and rac cobalt(III) complexes of trans-6,13-dimethyl-6,13-bis(methylamino)-1,4,8,11-tetraazacyclotetradecane (L-5) have been prepared. Crystal structures of the macrocyclic complexes [CoL1][ClO4](3), [CoL3][ClO4](3) and meso-[CoL5][ClO4](3).2H(2)O were determined and some unusual structural, spectroscopic and electrochemical variations observed going from the parent hexaamine [CoL1](3+) to [CoL3](3+) (diimine) and ultimately to [CoL5](3+) (bis-N-methylated hexaamine).

The protease inhibitor cystatin C is differentially expressed among dendritic cell populations, but does not control antigen presentation

Dendritic cells (DC) undergo complex developmental changes during maturation. The MHC class H (MHC H) molecules of immature DC accumulate in intracellular compartments, but are expressed at high levels on the plasma membrane upon DC maturation. It has been proposed that the cysteine protease inhibitor cystatin C (CyC) plays a pivotal role in the control of this process by regulating the activity of cathepsin S, a protease involved in removal of the MHC H chaperone E, and hence in the formation of MHC H-peptide complexes. We show that CyC is differentially expressed by mouse DC populations. CD8(+) DC, but not CD4(+) or CD4(-)CD8(-) DC, synthesize CyC, which accumulates in MHC II(+)Lamp(+) compartments. However, II processing and MHC H peptide loading proceeded similarly in all three DC populations. We then analyzed MHC H localization and Ag presentation in CD8(+) DC, bone marrow-derived DC, and spleen-derived DC lines, from CyC-deficient mice. The absence of CyC did not affect the expression, the subcellular distribution, or the formation of peptide-loaded MHC II complexes in any of these DC types, nor the efficiency of presentation of exogenous Ags. Therefore, CyC is neither necessary nor sufficient to control MHC II expression and Ag presentation in DC. Our results also show that CyC expression can differ markedly between closely related cell types, suggesting the existence of hitherto unrecognized mechanisms of control of CyC expression.

Explicit evidence-based prescribing criteria - an important step in achieving quality therapeutics in nursing homes

Reaction between 5-(4-amino-2-thiabutyl)-5-methyl-3,7-dithianonane-1, 9-diamine (N3S3) and 5- methyl-2,2-bipyridine-5-carbaldehyde and subsequent reduction of the resulting imine with sodium borohydride results in a potentially ditopic ligand (L). Treatment of L with one equivalent of an iron( II) salt led to the monoprotonated complex [Fe(HL)](3+), isolated as the hexafluorophosphate salt. The presence of characteristic bands for the tris( bipyridyl) iron( II) chromophore in the UV/vis spectrum indicated that the iron( II) atom is coordinated octahedrally by the three bipyridyl (bipy) groups. The [Fe( bipy) 3] moiety encloses a cavity composed of the N3S3 portion of the ditopic ligand. The mononuclear and monomeric nature of the complex [Fe(HL)](3+) has been established also by accurate mass analysis. [Fe(HL)](3+) displays reduced stability to base compared with the complex [Fe(bipy)(3)](2+). In aqueous solution [Fe(HL)](3+) exhibits irreversible electrochemical behaviour with an oxidation wave ca. 60 mV to more positive potential than [Fe(bipy)(3)](2+). Investigations of the interaction of [Fe(L)](2+) with copper( II), iron( II), and mercury( II) using mass spectroscopic and potentiometric methods suggested that where complexation occurred, fewer than six of the N3S3 cavity donors were involved. The high affinity of the complex [Fe(L)](2+) for protons is one reason suggested to contribute to the reluctance to coordinate a second metal ion.

Chiral resolution of hexaamine cobalt(III) cages: Substituent effects on chiral discrimination

Chiral resolution of the cobalt cage complexes [Co(diNOsar)](3+) and [Co(diAMsarH(2))](5+) have been achieved by selective crystallization with the anion bis-mu-(R),(R)-tartratodiantimonate(III) ([Sb-2(R,R-tart)(2)](2-)) and also by column chromatography with Na-2[Sb-2(R, R-tart)(2)] as eluent. The X-ray crystal structures of Lambda-[ Co(diNOsar)][Sb-2(R, R-tart)(2)] Cl . 7H(2)O and Delta-[Co(diAMsarH(2))][Sb-2(R, R-tart)(2)](2)Cl . 14H(2)O are reported, which reveal an unexpected reversal of chiral discrimination when the cage substituent is changed from nitro (Lambda-enantiomer) to ammonio (Delta-enantiomer) and shows that the ammonio- substituted cage is capable of forming a three-point hydrogen-bonding interaction with each complex anion, whereas the nitro analogue can only form two hydrogen bonds with each [Sb-2(R, R-tart)(2)](2-) anion. During cation exchange chromatography of the racemic cobalt cage complexes with Na-2[Sb-2(R, R-tart)(2)] as eluent, Lambda-[Co(diNOsar)](3+) elutes first, which implies a tighter ion pairing interaction than for the Delta-enantiomer. On the other hand, Delta-[Co(diAMsarH(2))](5+) elutes first during chromatography under identical conditions, which is also consistent with a preferred outer-sphere complex formed between Delta-[Co(diAMsarH(2))](5+) and [Sb-2(R, R-tart)(2)](2-) relative to Lambda-[Co(diAMsarH(2))](5+) and [Sb-2(R,R-tart)(2)](2-).

Molybdenum Complexes Bearing the Tris(1-pyrazolyl)methanesulfonate Ligand: Synthesis, Characterization and Electrochemical Behaviour

The tris(1-pyrazolyl)methanesulfonate lithium salt Li(Tpms) [Tpms = SO3C(pz)(3)-] reacts with [Mo(CO)(6)] in NCMe heated at reflux to yield Li[Mo(Tpms)(CO)(3)] (1), which, upon crystallization from thf, forms the coordination polymer [Mo(Tpms)(CO)(2)(mu-CO)Li(thf)(2)](n) (2). Reaction of 1 with I-2, HBF4 or AgBF4 yields [Mo(Tpms)I(CO)(3)] (3), (Mo(Tpms)-H(CO)(3)] (5) or (Mo(Tpms)O-2](2)(mu-O) (7), respectively. The high-oxidation-state dinuclear complexes [{Mo(Tpms)O(mu-O)}(2)] (4) and [{Mo(tpms)OCl)(2)](mu-O) (6) are formed upon exposure to air of solutions of 3 and 5, respectively. Compounds 1-7, which appear to be the first tris(pyrazolyl)methanesulfonate complexes of molybdenum to be reported, were characterized by IR, H-1 and C-13 NMR spectroscopy, ESI-MS, elemental analysis, cyclic voltammetry and, in the cases of Li(Tpms) and compounds 2, 4.2CH(3)CN, 6.6CHCl(3) and 7, by X-ray diffraction analyses. Li(Tpms) forms a 1D polymeric structure (i.e., [Li(tpms)](n)} with Tpms as a tetradentate N2O2 chelating ligand that bridges two Li cations with distorted tetrahedral coordination. Compound 2 is a 1D coordination polymer in which Tpms acts as a bridging tetradentate N3O ligand and each Li(thf)(2)(+) moiety is coordinated by one bridging CO ligand and by the sulfonyl group of a contiguous monomeric unit. In 4, 6 and 7, the Tpms ligand is a tridentate chelator either in the NNO (in 4) or in the NNN (in 6 and 7) fashion. Complexes 1, 3 and 5 exhibit, by cyclic voltammetry, a single-electron oxidation at oxidation potential values that indicate that the Tpms ligand has an electron-donor character weaker than that of cyclopentadienyl.

Remoção de metais usando casca de amendoim

Mestrado em Engenharia Química

Luminol-doped nanostructured composite materials for chemiluminescent sensing of hydrogen peroxide

Silica based nanostructured composite materials doped with luminol and cobalt(II) ion were synthesized and characterized, resulting in a highly chemiluminescent material in the presence of hydrogen peroxide. A detection system with the CL light guided from the reaction tube to the photomultiplier tube using a one millimeter glass optical fiber was developed and assessed. A linear response was observed using a semi-logarithm calibration between 50–2000 µM hydrogen peroxide with 1 µM as the limit of detection.

Electrochemical porperties of (H5-C5Me5)-rhodium and – iridium complexes Bis(pyrazolyl)alkane ligands

The electrochemical properties of rhodium(III) 1-3 and iridium(III) 4-6 complexes containing bis(pyrazolyl)alkane ligands [MCp*Cl(R2C(3,5-R'2pz)2)]X (M = Rh (1) or Ir (4), R = R' = H, X = Cl; M = Rh (2) or Ir (5), R=H,R'=Me,X=Cl;M=Rh(3) or Ir (6), R=Me,R'=H,X=OTf;pz=pyrazolyl;Cp*=η5-C5Me5) were investigated by cyclic voltammetry and controlled potential electrolysis. They exhibit two sequential irreversible reductions assigned to the MIII → MII and MII → MI reductions, which are dependent on the methylation of the bis(pyrazolyl)alkane ligands.

Emprêgo do teste químico para o estudo da eliminação das gonadotropinas durante o ciclo menstrual

A chemical test previously described for the diagnosis of pregnancy was applied to the study of the excretion of gonadotropin in the urine during menstrual cycle. The chemical test is based on the selective adsorption by kaolim of the reducing substances biologically related to urinary gonadotropin. The active substance when acidified to pH 4.0 is adsorbed by the kolin and eluated with O.1N sodium hydroxide. The alkaline solution is treated by Somogyi's copper reagent and the excess not reduced is titrated by 0.005 N sodium thiosulfate. Gonadotropin is quantitatively addorbed by kaolin at pH 4.0 and eluated by alkaline solution as previously demonstrated by the A. (1). In the present paper the complete menstrual cycle was studied daily. It was observed that normally there are two distinct maxima of excretion. This study is based on 11 normal cycles (24-30 days) and 34 abnormal ones. Normal cycles showed a intramenstrual estrogens elimination from 200 to 260 mice units determinated by the Allen - Doisy full estrus smear test. The abnormal cycles belonging also to normal women showed much less estrogen excretion (14 to 25 mice units) Table II). In those cases with decreased estrogen excretion no fall in the curve after 14 th. day was observed. The A. suggest that the peaks of gonadotropin excretion is not related to the oculation but possibly due, the first one, to the follicle stimulating hormone and the second to the luteinizing hormone of hormone stimulating of the inerstitial tissue.