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Electrochemical potentials of a series of anthraquinone derivatives were studied in both aqueous solution and acetonitrile. The long term goal of this work was to find derivatives which could be reduced easily for studies of photoinduced electron transfer in DNA. Our immediate goal was to find the substitution group that gave the least negative redox potential value. Of all derivatives studied, the anthraquinone imides as a class had the least negative redox potentials, in the range of -0.600 to -0.550 V vs. SCE. One of the anthraquinones studied, one derivative (deoxyadenosine conjugated with an ethynyl linker to an anthraquinone with two ester substituents) was also in this range. A study of a series of anthraquinones conjugated with ethynyl and ethanyl linkers showed that the ethynyl linker was more effective than the ethanyl linker in lowering the redox potential of anthraquinone.

Anthraquinone (AQ) derivatives with relatively high reduction potentials have been synthesized to afford good candidates for electron transfer studies in DNA. Electron withdrawing groups on the anthraquinone ring gave derivatives with less negative reduction potentials. The anthraquinone imide (AQI) derivatives had reduction potentials less negative than AQ derivatives. The AQI ring system was subject to base-induced hydrolysis. Water-soluble sulfonated tetraarylporphyrins have been studied in a wide variety of contexts. Herein, we report the first synthesis of a pentasulfonated porphyrin bearing an internal cyclic sulfone ring. Treatment of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4) with fuming H2SO4 gave a structure consistent with initial sulfonation followed by dehydration to give a sulfone bridge between an ortho-position of one of the phenyl groups and a β-pyrrole position on the porphine ring (TPPS4Sc). The structure was established by ESI-MS and 1HNMR. The Soret absorption is red shifted by about 32 nm compared to that of TPPS4. Streptococcus pyogenes obtains iron by taking up heme from the environment during infection. One of the heme uptake pathways is the Sia or Hts pathway. The initial protein in this pathway is Shr, which has two heme-binding NEAT domains, NEAT1 nearer the N-terminus, and NEAT2 nearer the C-terminus. We report biophysical characteristics of these two NEAT domains. To assess stability of this domain towards heme release, denaturation studies of the Fe(II) and Fe(III) forms were performed. For each domain, both the Fe(II) and the Fe(III) forms behave similarly in thermal denaturation and guanidinium denaturation. Overall, NEAT2 is more stable than NEAT1. Spectral signatures, sequence alignment and homology modeling for both domains suggest that one of the axial ligands is methionine. NEAT2 autoreduces as the pH increases and autooxidizes as the pH decreases. Heme uptake from the host environment is the only iron acquisition pathway in S. pyogenes; inhibition of this pathway might be an approach to infection control. Compounds that might inhibit the heme uptake pathway were selected via virtual screening.

The synthesis of four homologous anthraquinones (AQ I-IV) bearing increasing lengths of polyethylene glycol (PEG) side chains and their binding to AT- and GC-rich DNA hairpins are reported. The molecules were designed such that the cationic charge is at a constant position and the ethylene glycol units chosen to allow significant increases in size with minimal changes in hydrophobicity. The mode and affinity of binding were assessed using circular dichroism (CD), nuclear magnetic resonance (NMR), surface plasmon resonance (SPR), and isothermal titration calorimetry (ITC). The binding affinity decreased as the AQ chain length increased along the series with both AT- and GC-rich DNA. ITC measurements showed that the thermodynamic parameters of AQ I-IV binding to DNA exhibited significant enthalpy-entropy compensation. The enthalpy became more favorable while the entropy became less favorable. The correlation between enthalpy and entropy may involve not only the side chains, but also changes in the binding of water and associated counterions and hydrogen bonding. The interactions of AQ I-IV with GC-rich DNA have been studied via molecular dynamics (MD) simulations. The geometry, conformation, interactions, and hydration of the complexes were examined. As the side chain lengthened, binding to DNA reduced the conformational space, resulting in an increase in unfavorable entropy. Increased localization of the PEG side chain in the DNA groove, indicating some interaction of the side chain with DNA, also contributed unfavorably to the entropy. The changes in free energy of binding due to entropic considerations (-3.9 to -6.3 kcal/mol) of AQ I-IV were significant. The kinetics of a homologous series of anthraquinone threading intercalators, AQT I-IV with calf thymus DNA was studied using the stopped-flow. The threading mechanisms of the anthraquinones binding to DNA showed sensitivity to their side chain length. Fitting of the kinetic data led to our proposal of a two step mechanism for binding of AQT I, bearing the shortest side chain, and a three step mechanism for binding of the three longer homologs. Binding involves formation of an externally bound anthraquinone-DNA complex, followed by intercalation of the anthraquinone for AQT I-IV, then isomerization to another complex with similar thermodynamic stability for AQT II-IV.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-10-11T14:54:00Z No. of bitstreams: 1 larissaalbuquerquedeoliveira.pdf: 6821961 bytes, checksum: e1edff2fb674ae0aef7703387d259bf8 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-10-16T13:50:15Z (GMT) No. of bitstreams: 1 larissaalbuquerquedeoliveira.pdf: 6821961 bytes, checksum: e1edff2fb674ae0aef7703387d259bf8 (MD5) / Made available in DSpace on 2017-10-16T13:50:15Z (GMT). No. of bitstreams: 1 larissaalbuquerquedeoliveira.pdf: 6821961 bytes, checksum: e1edff2fb674ae0aef7703387d259bf8 (MD5) Previous issue date: 2017-07-31 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A síntese de derivados antraquinônicos tem sido alvo de vários grupos de pesquisas por apresentarem diversas propriedades biológicas como anticancerígenas, anti-inflamatórias, imunossupressoras, antifúngicas, etc. Neste trabalho são descritas as sínteses de derivados antraquinônicos N-alquilados e O-alquilados com estruturas análogas à da mitoxantrona que possuem diferentes cadeias carbônicas a partir dos precursores 1,4-diaminoantraquinona, 1,4diidroxiantraquinona e 1,5-diamino-4,8-diidroxiantraquinona. Duas séries de compostos foram obtidas por reação de N-alquilação da 1,4-diaminoantraquinona e duas séries por reação de O-alquilação da 1,4-diidroxiantraquinona com epicloridrina. As etapas seguintes consistiram na formação de epóxidos via reação intramolecular de éter de Williamson e abertura destes utilizando-se aminas alifáticas, cíclicas e aromáticas. Após a purificação e caracterização dos compostos através de métodos espectroscópicos disponíveis (RMN de 1H, 13C, COSY, HMQC e Infravermelho), a primeira série de derivados antraquinônicos Nalquilados foi avaliada quanto às suas propriedades antibacterianas e citotóxicas e, posteriormente, os demais compostos também foram avaliados quanto as suas atividades citotóxicas. De um modo geral, as modificações estruturais propostas neste conjunto de moléculas mostraram um aumento na atividade antibacteriana e citotóxica para derivados contendo menor cadeia carbônica lateral, resultado oposto ao esperado para estas moléculas. Além disso, os resultados para estes compostos mostraram atividade citotóxica superior à da mitoxantrona, entretanto apresentaram citotoxicidade para a célula normal testada. / The synthesis of anthraquinone derivatives have been the target of several research groups because they have several biological properties as anticancer, anti-inflammatory, immunosuppressive, antifungal, etc. In this work is described the synthesis of N-alkylated and O-alkylated anthraquinone derivatives with structures analogous to mitoxantrone bearing different carbon chains from 1,4-diaminoanthraquinone, 1,4-dihydroxyanthraquinone and 1,5diamino-4, 8-dihydroxyanthraquinone. Two series of compounds were obtained by Nalkylation reaction of 1,4-diaminoanthraquinone and two series by O-alkylation reaction of 1,4-dihydroxyanthraquinone with epichlorohydrin. The following steps consisted in the formation of epoxides via the intramolecular reaction of Williamson's ether and opening thereof using aliphatic, cyclic and aromatic amines. After purification and characterization of the compounds by available spectroscopic methods (1H, 13C NMR, COSY, HMQC and Infrared), the first series of N-alkylated anthraquinone derivatives was evaluated for their antibacterial and cytotoxic properties and, subsequently, the other compounds were also evaluated for their cytotoxic activities. In general, the structural modifications proposed in this set of molecules showed an increase in the antibacterial and cytotoxic activity for derivatives containing less lateral carbonic chain, an opposite result than expected for these molecules. In addition, the results for these compounds showed higher cytotoxic activity than mitoxantrone, however, they showed cytotoxicity for the normal cell tested.

Les matériaux électrochromiques organiques ont été un domaine de recherche novateur au cours des dernières décennies. Ces composés qui répondent à un potentiel appliqué par un changement de couleur sont dits électrochromes. Leur intérêt est principalement dû à leur synthèse facile, à haut rendement et à leur aspect écologique par rapport à leurs homologues inorganiques. En règle générale, ces composés ne changent de couleur qu’avec un potentiel appliqué. Développer des composés qui changent à la fois leur couleur et leur fluorescence avec un potentiel appliqué pour une utilisation dans des dispositifs électrofluorescents reste un défi majeur. Dans cette étude, une série de composés contenant de la triphénylamine (TPA) et du benzothiadiazole (BZT) ont été évalués. Ils ont été couplés à différents groupes terminaux pour moduler les propriétés photophysiques et électrochimiques. Ces composés ont été entièrement caractérisés par spectroscopie d'absorption, spectroscopie de fluorescence, voltammétrie cyclique, spectroélectrochimie et diffraction des rayons X. Cela nous a permis d'examiner l'influence de leur structure sur les propriétés. Cela nous a également permis d'identifier les composés d'intérêt idéaux pour une utilisation dans des appareils fonctionnels. Les dispositifs contenant du TPA et du BZT sont idéalement employée pour la fabrication de « fenêtre intelligente ». Cela est dû à l'activité électrochimique du TPA ainsi qu'à la fluorescence à l'état solide du noyau BZT. Pour améliorer encore les propriétés des dispositifs, un système passif était le but ultime. Cela contraste avec les dispositifs actifs où un potentiel doit être appliqué en continu pour que la couleur induite soit cohérente. Dans ce but, des couches cathodiques ont été préparées et étudiées dans un dispositif et leur utilisation comme réservoir d'ions dans un dispositif électrochromique / électrofluorescent passif a été testée. Les résultats préliminaires ont montré que les dérivés d'anthraquinone avaient des propriétés idéales pour les couches cathodiques. / Organic electrochromic materials have been a hot area of research during the past decades. These compounds that respond to an applied potential with a color change are said to be electrochromic. Their interest is mainly because of the easy synthesis, convenient mass production, and eco-friendly preparation compared to their inorganic counterparts. Typically, these compounds change only their color with an applied potential. To develop compounds that change both their color and their fluorescence with a potential applied for use in electrofluorescent devices remains a major challenge. In this study, a series of compounds containing triphenylamine (TPA) and benzothiadiazole (BZT) were evaluated. They were coupled with different end groups to tune the photophysical and electrochemical properties. These compounds were fully characterized by absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry, spectroelectrochemistry, and X-ray diffraction along with other techniques. This allowed us to examine the influence of their structure on the properties. It also allowed us to identify the ideal compounds of interest for use in functioning devices. The devices containing TPA and BZT are ideally ‘smart window’ applications. This is due to the electrochemical activity by TPA as well as the solid state fluorescence of the BZT core. To further improve the properties of devices, a passive device was the ultimate goal. This is in contrast to active devices where a potential must be applied continuously for the induced color to be consistent. Towards this goal, cathodic layers were prepared and investigated in a device and their use as an ion reservoir in a passive electrochromic / electrofluorescent device was tested. Preliminary results, showed that anthraquinone derivatives had ideal properties for the cathodic layers.

Natural organic dyes suffer from degradation during the time. Therefore, the works of art need to be restored and the identification of dyes by analytical methods is important here. The possibilities of using three separation (thin-layer chromatography - TLC, capillary zone electrophoresis - CZE, and micellar electrokinetic chromatography - MEKC) and two spectroscopic (infrared microspectroscopy - IR and Raman microspectroscopy) methods for the identification of red dyes (acaroid, brazil, dragon blood, kamala, logwood, cochineal, madder, lac, and sandalwood) were studied and critically discussed. In TLC, under optimised conditions (silicagel with octadecyl, 80/20 (v/v) MeOH/1% TEA in 0.1 mol·dm-3 acetate buffer, pH 5, and 80/20 (v/v) MeOH/1% TEA in 0.025 mol·dm-3 tetraborate buffer, pH 7 and 9), the stain broadening of sandalwood, logwood, acaroid, dragon blood, and brazil was observed. Carminic acid, haematein and purpurin were not detected. A comparison of CZE and MEKC showed that MEKC was superior as it permits separation of all analytes, using 0.015 mol·dm-3 sodium dodecyl sulfate in 0.01 mol·dm-3 tetraborate buffer, pH 8.5, at a voltage of 20 kV. The developed method was validated and applied to the identification of dyes in Rubia tinctorum, Rubia cordifolia, and in the mycelium of fungi...

Density functional theory (using Becke's exchange and Lee-Yang-Parr's correlation functionals (BLYP)) and ab initio Hartree-Fock calculations were carried out in order to investigate the molecular structure and vibrational spectra of 9,10-anthraquinone and its perdeuterated analog. The calculated structural and spectral features are in good agreement with the available experimental results. Most of the BLYP/6-31G* non-CH(D) stretching frequencies are slightly lower than reliable experimental assignments; the mean absolute deviation is about 14 cm-1. On the basis of agreement between calculated and experimental results, assignments of the fundamental vibrational modes were examined and some reassignments were proposed. The calculated results can serve as a guide for a future experimental search for the missing fundamentals of the target molecules.

The full text will be available at the end of the extended embargo: 21st Feb 2026

Les matériaux électrochromes et électrofluorescents sont des matériaux dont les propriétés optiques peuvent être modulées par l’application d’un potentiel. La plupart de ces matériaux sont composés soit de polymères, de petites molécules organiques ou encore d’assemblages donneur-accepteur. L’anthraquinone est une petite molécule biosourcée catégorisée comme colorant, qui lorsqu’elle est fonctionnalisée permet une absorption de la lumière dans la région du visible. Elle présente des fonctions (carbonyle) qui peuvent subir des processus d’oxydo-réduction. Six dérivés d’anthraquinones ont été synthétisés sur lesquels ont été fixés diverses fonctions (amine, alcool, sulfure) sur des positions différentes du cycle aromatique (ortho et para). Dépendamment de la fonction fixée, les six dérivés présentent différentes absorptions (453 à 640 nm), mais toujours dans la région du visible. La caractérisation par électrochimie permet de connaître quels sont les processus réversibles et irréversibles. L’étude de la durée de vie en cyclage a pu montrer que tous les dérivés pouvaient être stables jusqu’à 300 cycles en phase de réduction (-0,81 à -1,54 V). Les propriétés électrochromiques des dérivés ont pu être démontrées par caractérisation spectroélectrochimique, suivie de leurs critères de performance électrochromique (113,3 à 781,2 cm².C-1). Il a été observé que les dérivés possèdent une certaine stabilité colorimétrique par la caractérisation en contraste optique (52,6 à 98,1 %). L’efficacité colorimétrique et la capacité électrochimique ont été calculées et ont permis de constater que certains dérivés étaient de très bons électrochromes. Certains dérivés de couleur jaune, cyan et magenta, ont permis de produire des mélanges binaires et tertiaires. Certains mélanges (tertiaires) démontraient jusqu’à huit transitions colorimétriques lors de l’application d’un potentiel passant de noir jusqu’à transparent. Des phénomènes d’émission ont été mesurés pour quelques dérivés les présentant. Tous les dérivés émissifs possèdent la propriété de solvatochromisme, permettant de moduler leur émission en fonction du solvant utilisé. Un seul dérivé a pu montrer des propriétés d’électrofluorescence. Dépendamment de la longueur d’onde d’excitation, soit l’émission subit des déplacements (hypsochromes et bathochromes), soit il y a désactivation de l’émission. Des calculs théoriques par DFT avec différents modèles ont permis une meilleure compréhension des phénomènes liés à la fonctionnalisation de l’anthraquinone. / The optical properties of electrochromic and electrofluorochromic materials can be modulated with an applied potential. Such organics materials are either molecular or polymer in structure and they usually have donor-acceptor constitutional components. Anthraquinone is a bio-based dye, which when functionalized, absorbs light in the visible region. Anthraquinone is also electroactive and it can be electrochemically reduced and oxidized. Six anthraquinone derivatives were synthesized to examine the effect of both the type of the heteroatom (amine, alcohol, and sulfide) and their regio-substitution on the opto-electronic properties. The absorption of the six anthraquinones varied between 453 and 640 nm in the visible region contingent on the heteroatoms and their regiosubstitution. The anthraquinones retained their reversible electrochemistry with the cathodic redox potential occurring between -0,81 and -1,54 V. The anthraquinones examined were electrochemically stable during 300 cycles of cathodic cyclic voltammetry. The electrochromic behavior of the anthraquinones was confirmed by spectroelectrochemistry and their electrochromic performance was evaluated. Electrochromic measurements confirmed the anthraquinones retained their coloration efficiency (113,3 to 781,2 cm².C-1) and contrast ratio (52,6 to 98,1 %) according to multiple spectroelectrochemical cycles. Leveraging color subtractive theory and the intrinsic primary colors of the anthraquinones (yellow, cyan, and magenta), the spectroelectrochemistry of binary and ternary mixtures of the anthraquinones was examined. Eight colorimetric transitions were possible with an applied potential, transitioning from a composite black color to colorless for the yellow + cyan + magenta ternary mixture. The fluorescence of the anthraquinones was solvatochromic with spectral shifts between 587 and 675 nm contingent on the solvent polarity. Only the 1,5-bis((2- hydroxyethyl)amino) anthraquinone was electrofluorochromic with its intrinsic weak emission being quenched with an applied negative potential. DFT calculations with different functionals helped understand the opto-electronic properties of the functionalized anthraquinones.