Atliktas palyginamasis dviejų kompleksinių sistemų - Cu|Cu(II), glicinas ir Cu|Cu(II), maleino rūgštis - elektrocheminių charakteristikų tyrimas. Nustatytos maleino rūgšties tirpalų pusiausvyrinės charakteristikos. Kiekybiniam titravimo kreivių aprašymui išvestos lygtys, kuriose įvertinti medžiagų bei krūvių balansai bei atsižvelgta į praskiedimo efektus. Jų taikymas pH-metrinių duomenų analizei davė tokias maleato anijonų protonizacijos konstantų reikšmes: log = 6,05, log = 7,48. Nustatyta, kad tirpaluose su 0,3 M K2SO4 priedu protonizuotų ligando formų stabilumas sumažėja (log = 5,75, log = 7,30). Cu(II) maleatinių kompleksų stabilumui nustatyti panaudotas spektrofotometrijos metodas ir pasiūlyta duomenų analizės procedūra. Ji remiasi kiekybiniu absorbcijos spektrų aprašymu, taikant lygtis, išplaukiančias iš valdomo harmoninio osciliatoriaus teorijos. Išanalizavus įvairių sudėčių tirpalų absorbcijos maksimumo dydžius, prieita išvados, kad rūgščiose terpėse vyrauja monoligandinis kompleksas, kurio koncentracinė stabilumo konstanta log b1 = 2,2. Atlikta sistemos Cu|Cu(II), maleino rūgštis pusiausvyrų termodinaminė analizė. Nustatyta, kad esant metalinio vario ir tirpalų sąlyčiui, sistemoje galimi gilūs virsmai, kurių metu iki 90 % Cu(II) transformuojasi į Cu(I). Teorines išvadas patvirtina eksperimentiniai duomenys, gauti spektrofotometrijos ir elektrocheminės kvarco kristalo mikrogravimetrijos metodais. Įvertinti Cu korozijos bei fazinių Cu2O sluoksnių susidarymo... [toliau žr. visą tekstą] / A comparative investigation of electrochemical characteristics of two complex systems, viz. Cu|Cu(II), glycine and Cu|Cu(II), maleic acid, was carried out. The equations were obtained for quantitative description of pH-metric and spectrophotometric data, which were used for determination of equilibrium characteristics in Cu(II)-maleic acid solutions. Thermodynamic analysis shows that deep changes are possible in this system resulting in 90 % transform of Cu(II) into Cu(I). The rates of Cu corrosion and Cu2O formation are estimated to be of the same order (nmol cm-2 s-1). Regularities of formal electrochemical kinetics, which account for the mass transport of chemically interacting particles and for step-wise charge transfer process, are suitable for interpretation of voltammetric data of the Cu|Cu(II), glycine system. Kinetic parameters Cu(II) glycinate complex depend on the nature of the supporting electrolyte: the exchange current density decreases and the cathodic charge transfer coefficient increases in the sequence: Li+ - Na+ - K+ - Cs+. To enhance the Cu(I) generation in maleic acid system, the pre-electrolysis procedure was applied. It was found that its effect depends on solution pH. Applied theoretical model describes satisfactorily the steady-state voltammetric characteristics of Cu|Cu(II), maleic acid system, but some contradictory results were obtained in the case of time-dependent processes. Theoretical and experimental problems to be solved are discussed.

Yes / To develop potential next-generation metal anticancer agents, we designed and synthesised five Cu(II) 2-pyridine-thiosemicarbazone complexes by modifying the hydrogen atom at the N-4 position of ligands, and then investigated their structure-activity relationships and anticancer mechanisms. Modification of the N-4 position with different groups caused significant differences in cellular uptake and produced superior antitumor activity. Cu complexes arrested the cell cycle at S phase, leading to down-regulation of levels of cyclin and cyclin-dependent kinases and up-regulation of expression of cyclin-dependent kinase inhibitors. Cu complexes exerted chemotherapeutic effects via activating p53 and inducing production of reactive oxygen species to regulate expression of the B-cell lymphoma-2 family of proteins, causing a change in the mitochondrial membrane potential and release of cytochrome c to form a dimer with apoptosis protease activating factor-1, resulting in activation of caspase-9/3 to induce apoptosis. In addition, Cu complexes inhibited telomerase by down-regulating the c-myc regulator gene and expression of the human telomerase reverse transcriptase. / Natural ScienceFoundation of China (31460232, 21431001, 21561017, 21462004),the Natural Science Foundation of Guangxi (2017GXNSFEA198002,AD17129007), IRT_16R15, Guangxi“Bagui”scholar program to HBSun, and High-Level Innovation Team and Distinguished Scholarprogram of Guangxi universities to F Yang.

Ressonância Paramagnética Eletrônica (RPE) e Absorção Ótica Eletrônica foram utilizadas para estudar-se os complexos de Cobre (II) com tris-hidroximetil aminometano em solução. A análise dos parâmetros de RPE e óticos medidos na solução a diversos pHs foi feita tendo-se à mão as curvas de formação dos complexos. Estas curvas foram construídas em função do pH da solução, usando os dados de equilíbrio químico publicado por K. S. Bai e Martell (J. Inorg. Nucl. Chem. 31 (1969) 1697-1707), numa faixa de concentração de tris na qual este reagente é usando como tampão em estudos biológicos e químicos. Determinou-se cinco conjunto de parâmetros de RPE (go, ao, a11 e A11, correspondentes a diferentes complexos de íon metálico. Cada um desses espectros é encontrado em determinados intervalos de pH, sendo possível associá-los aos complexos previstos nas curvas de formação. A maior estabilidade dos complexos que se formam a pHs mais altos segundo as constantes de equilíbrio é evidenciada pelos valores e go isotrópico (RPE) menores pelos desdobramentos hiperfino isotrópico ao (RPE) e de campo cristalino (ótica) maiores do que os encontrados nas soluções menos alcalinas. A formação do complexo quelato neutro a pH alcalino foi observada, e obteve-se seu tensor g, das medidas do cristal simples. Este tensor encontra-se em bom acordo com o valor de g isotrópico determinado em solução (go=1/3(gxx+gyy+gzz)). Existe evidência de que este complexo seja pentacoordenado). Observou-se similaridade entre os parâmetros para os complexos coordenados por: 2N e 1N+1 0‾ 3N e 2N+1 0&#8254 ; 4N e 2N+2 0&#8254. Isto leva à conclusão de que do ponto de vista energético a coordenação de nitrogênio Cu2+ e a coordenação do oxigênio negativo ao Cu2+ nestes complexos são equivalentes, pelo menos dentro de nossa resolução experimental. / Electron Paramagnetic Ressonance (EPR) and optical visible spectroscopies were used to study the complexes of Cu (II) íon with tris-hydroxymethylamino methane (tris) in solution. Analyses of EPR and optical parameters measured in solution were made using the calculated formation curvesof the complexes. These formation curves were calculated as function of the solution pH, on the basis of the equilibrium constants published by K.S. Bai and Martell (J. Inorg.Nucl. Chem. 31 (1969)-1967-1707), for a concentration of this normally employed in a buffer in biochemical studies. Five sets of EPR parameters ((go, ao, a11 e A11) were determined corresponding to different metal complexes. Each det is found in a characteristic pH range and it was possible to make a correlation of these complexes with the appear in the formation curve plot. The greater stability of the complexes in the high pH range is indicated by the values of go, wich are smaller and the values of the hyperfine splittings ao and the crystal field splittings (from optical measurements) which are greater tahn at the less alcaline solutions. The formation of the neural chelate complexa t alcaline pH was observed, and its g-factors were obtained from measurements with the single crystal. These g-factors agree very well with the solution value (go=1/3(gxx+gyy+gzz)) and the orthorombic symmetriy is obtained. Evidence is present that this complex is penta-coordinated. It was observed a similarity between the EPR parameters for the complexes coordinated by: : 2N e 1N+1 0‾ 3N e 2N+1 0&#8254 ; 4N e 2N+2 0&#8254. This lead us the conclusion that from the energetical point of view the coordination of Cu2+ to nitrogen or to negative oxigen in these cases are equivalent, at or our resolution is not sufficent to differentiate between them.

Cathodic processes occurring in the solutions containing Cu(II) tartaric complexes have been investigated. The equations accounting for the material balance have been constructed and used for the estimation of distribution of complexes and ligands in the bulk of solution. It was established that dominating particles in acidic media (pH < 3) are: Cu2+ and tartaric complex CuL, tartaric acid LH2 and its anion LH-. Potentials of non-polarized copper electrodes were found to be reversible and to follow Nernst equation. According to the analysis performed, surface oxide Cu2O is not able to form in acidic (pH < 3) media. Cathodic voltammograms obtained for the solutions of different acidity exhibit two characteristic current peaks arising from Cu(II) reduction and hydrogen evaluation. An analysis of voltammetric extrema shows that both processes are irreversible. Based on the regularities of the mass transport of chemically interacting substances, surface distribution of components has been simulated. These date were used for the transformation of experimental voltammograms into normalized Tafel plots. According to their analysis, the rate-controlling step of Cu(II) reduction is the transfer of the first electron onto Cu2+ aqua-complex. The values of kinetic parameters were found to be as follows: the cathodic charge transfer coefficient is equal to 0.33 and the exchange current density is equal to 50 mA cm-2. An analysis of the second current peak leads to the conclusion... [to full text]

Ressonância Paramagnética Eletrônica (RPE) e Absorção Ótica Eletrônica foram utilizadas para estudar-se os complexos de Cobre (II) com tris-hidroximetil aminometano em solução. A análise dos parâmetros de RPE e óticos medidos na solução a diversos pHs foi feita tendo-se à mão as curvas de formação dos complexos. Estas curvas foram construídas em função do pH da solução, usando os dados de equilíbrio químico publicado por K. S. Bai e Martell (J. Inorg. Nucl. Chem. 31 (1969) 1697-1707), numa faixa de concentração de tris na qual este reagente é usando como tampão em estudos biológicos e químicos. Determinou-se cinco conjunto de parâmetros de RPE (go, ao, a11 e A11, correspondentes a diferentes complexos de íon metálico. Cada um desses espectros é encontrado em determinados intervalos de pH, sendo possível associá-los aos complexos previstos nas curvas de formação. A maior estabilidade dos complexos que se formam a pHs mais altos segundo as constantes de equilíbrio é evidenciada pelos valores e go isotrópico (RPE) menores pelos desdobramentos hiperfino isotrópico ao (RPE) e de campo cristalino (ótica) maiores do que os encontrados nas soluções menos alcalinas. A formação do complexo quelato neutro a pH alcalino foi observada, e obteve-se seu tensor g, das medidas do cristal simples. Este tensor encontra-se em bom acordo com o valor de g isotrópico determinado em solução (go=1/3(gxx+gyy+gzz)). Existe evidência de que este complexo seja pentacoordenado). Observou-se similaridade entre os parâmetros para os complexos coordenados por: 2N e 1N+1 0&#8254; 3N e 2N+1 0&#8254 ; 4N e 2N+2 0&#8254. Isto leva à conclusão de que do ponto de vista energético a coordenação de nitrogênio Cu2+ e a coordenação do oxigênio negativo ao Cu2+ nestes complexos são equivalentes, pelo menos dentro de nossa resolução experimental. / Electron Paramagnetic Ressonance (EPR) and optical visible spectroscopies were used to study the complexes of Cu (II) íon with tris-hydroxymethylamino methane (tris) in solution. Analyses of EPR and optical parameters measured in solution were made using the calculated formation curvesof the complexes. These formation curves were calculated as function of the solution pH, on the basis of the equilibrium constants published by K.S. Bai and Martell (J. Inorg.Nucl. Chem. 31 (1969)-1967-1707), for a concentration of this normally employed in a buffer in biochemical studies. Five sets of EPR parameters ((go, ao, a11 e A11) were determined corresponding to different metal complexes. Each det is found in a characteristic pH range and it was possible to make a correlation of these complexes with the appear in the formation curve plot. The greater stability of the complexes in the high pH range is indicated by the values of go, wich are smaller and the values of the hyperfine splittings ao and the crystal field splittings (from optical measurements) which are greater tahn at the less alcaline solutions. The formation of the neural chelate complexa t alcaline pH was observed, and its g-factors were obtained from measurements with the single crystal. These g-factors agree very well with the solution value (go=1/3(gxx+gyy+gzz)) and the orthorombic symmetriy is obtained. Evidence is present that this complex is penta-coordinated. It was observed a similarity between the EPR parameters for the complexes coordinated by: : 2N e 1N+1 0&#8254; 3N e 2N+1 0&#8254 ; 4N e 2N+2 0&#8254. This lead us the conclusion that from the energetical point of view the coordination of Cu2+ to nitrogen or to negative oxigen in these cases are equivalent, at or our resolution is not sufficent to differentiate between them.

Tesis por compendio / [EN] This PhD thesis entitled “Novel approaches for the development of chromofluorogenic chemosensors for detection of Cu(II) and biothiols” is devoted to the synthesis, characterization and coordination behaviour of new chromofluorogenic probes for the recognition and detection of Cu(II) cations and biothiols (glutathione, cysteine and homocysteine). These new probes, which selectively detect Cu(II) cation through colour and/or emission changes, are constructed using a paradigm in which the binding units are included into the signalling unit structure. Besides, some of the Cu(II) complexes of these new probes are used for the chromo-fluorogenic detection of biothiols using displacement reactions. The first chapter of this PhD thesis gives an overview about the conceptual framework in which are located the studies presented in this thesis, which combine concepts related with supramolecular chemistry, optical sensors and molecular probes. In the second chapter, the general objectives of this PhD thesis are presented. The third chapter is devoted to the synthesis and characterization of 4-(4,5- diphenyl-1H-imidazole-2-yl)-N,N-dimethylaniline, a chromo-fluorogenic probe for selective Cu(II) detection in aqueous environment. Water-acetonitrile 1:1 (v/v) solutions of this probe presented a marked absorption band at ca. 320 nm that is selectively red-shifted (to 490 nm reflected in a colour change from colourless to reddish-brown) upon addition of Cu(II) cation. This shift was ascribed to the formation of a non-emissive 1:1 stoichiometry complex in which Cu(II) coordinated with the nitrogen atoms of the imidazole ring. Besides, this Cu(II) complex was used for the selective and sensitive detection of glutathione, which induced the disappearance of the 490 nm absorption with a marked colour change from reddish-brown to colourless. Also a marked emission at 455 nm was observed after glutathione addition. These optical changes were ascribed to a glutathione-induced demetallation process which generated the free probe. In addition, the Cu(II) complex detected glutathione with a remarkable limit of detection as low as 2.0 μM. The fourth chapter presented an imidazole-based probe functionalized with two thiophene subunits for the selective detection of Cu(II) cation and biothiols. Water-acetonitrile 9:1 (v/v) solutions of the free probe showed an absorption band at 320 and a marked emission at 475 nm. Of all the cations tested, only Cu(II) induced an emission quenching with a significant colour change from colourless to deep blue (appearance of a new absorption band centred at 555 nm). These remarkable optical changes were ascribed to the formation of 1:1 stoichiometry complexes in which the metal cation coordinated with the nitrogen atoms of the imidazole heterocycle. Besides, the optical response of the Cu(II) complex was tested in the presence of selected amino acids. Of all the amino acids tested, only glutathione, cysteine and homocysteine induced a marked bleaching of the complex solution with a remarkable growing of an emission band centred at 475 nm. These optical changes were ascribed to a demetallation process induced by the coordination of biothiols with Cu(II). Furthermore, viability assays indicated the non-toxicity of the probe for HeLa cells. Also, the probe was successfully employed to detect Cu(II) in HeLa cells using confocal microscopy. The fifth chapter presented the synthesis and characterization of three probes containing N,N-diphenylanilino (as a donor group) and different π-spacers (benzene and thiophene) connected with aldehyde moieties. Absorption spectra of the three probes in acetonitrile showed an intense absorption band in the UVvisible region (360-420 nm range) which can be attributed to an intramolecular charge-transfer transition as consequence of the presence of N,N-diphenylanilino electron donor moiety directly linked to (hetero)aromatic bridges functionalized with the aldehyde electron acceptor group. Of all the cations tested, only Cu(II) induced the appearance of marked near infrared absorption bands in the 750- 1075 nm interval. Besides, the three probes are moderately emissive (with bands in the 540-580 nm interval) and only Cu(II) cation was able to induce a fluorescence quenching. The optical changes were ascribed to the formation of 1:1 stoichiometry complexes in the which Cu(II) cation probably interacted with the oxygen atom of the aldehyde functional group. Finally, using sodium dodecyl sulfate (20 mM)-acetonitrile 9:1 v/v mixtures, these probes were solubilized and were successfully used for the detection of Cu(II) in aqueous environments. Two 2,4,5-triaryl imidazole probes for the selective recognition of Cu(II) and biothiols were presented in the sixth chapter. Both probes presented marked absorption bands in the UV zone (320-350 nm range) and were moderately emissive in acetonitrile. Of all the cations tested, only Cu(II) induced the appearance of red shifted absorptions and the quenching of the emission bands. Job’s plots indicated the formation of 1:1 stoichiometry complexes in which Cu(II) cation interacted with the nitrogen atoms of the imidazole heterocycle located in the core of both probes. The probe containing furan rings was able to detect Cu(II) in water-acetonitrile 1:1 v/v solutions and the complex formed was also used to detect biothiols in aqueous environment (by marked colour changes and the appearance of a moderate emission). Again, the optical response obtained in the presence of biothiols was ascribed to a demetallation process. Finally, the seventh chapter of this PhD thesis is devoted to the final conclusions and future perspectives that the results presented in this work could open in the field of optical probes for the detection of metal cations and biomolecules in aqueous environments / [ES] Esta tesis doctoral, que lleva por título “Nuevas aproximaciones para el desarrollo de sensores cromo-fluorogénicos para la detección de Cu(II) y biotioles” aborda la síntesis, caracterización y estudio de la capacidad coordinante de nuevos sensores cromo-fluorogénicos para el reconocimiento y la detección del catión Cu(II) y de biotioles (glutatión, cisteína y homocisteína). Estos nuevos sensores, que son capaces de detectar de forma selectiva Cu(II) mediante cambios de color y/o de fluorescencia, están construidos mediante un paradigma que consiste en integrar los grupos coordinantes dentro de la estructura de la unidad indicadora. Además, los complejos de Cu(II) de los nuevos sensores se han empleado para la detección cromo-fluorogénica de biotioles mediante reacciones de desplazamiento. El primer capítulo de esta tesis doctoral está dedicado a la introducción de los conceptos básicos de la química supramolecular, los sensores ópticos y las sondas moleculares, necesarios para entender el marco en el que se encuadran los resultados obtenidos. Por otra parte, en el segundo capítulo, se presentan los objetivos generales de esta tesis doctoral. En el tercer capítulo se describe la síntesis y caracterización de compuesto 4- (4,5-difenil-1H-imidazol-2-il)-N,N-dimetilanilina, un sensor cromo-fluorogénico que es capaz de detectar de forma selectiva el catión Cu(II) en medios acuosos. Así, disoluciones del sensor en agua-acetonitrilo 1:1 (v/v) muestran una banda de absorción intensa centrada en 320 nm que es desplazada hacia el rojo (hasta 490 nm) desplazamiento que se ve reflejado en un cambio de color de incoloro a marón-rojizo de forma selectiva al adicionar el catión Cu(II). Este desplazamiento es debido a la formación de un complejo no fluorescente con estequiometría 1:1 donde el Cu(II) coordina con los átomos de nitrógeno del imidazol. Además, este complejo de Cu(II) se ha empleado para la detección selectiva de glutatión ya que este biotiol es capaz de inducir la desaparición de la banda de absorción a 490 nm (asociada a un cambio de color de marrón-rojizo a incoloro). En presencia de glutatión también se produce un aumento de fluorescencia a 455 nm. Estos cambios ópticos son adscritos a un proceso de demetalación del complejo inducido de forma selectiva por el glutatión (la cisteína y la homocisteína son incapaces de producir esta respuesta). Finalmente, el complejo es capaz de detectar glutatión con una alta sensibilidad con un límite de detección de 2,0 μM. En el capítulo cuarto de esta tesis se describe otro sensor óptico basado en el imidazol, en este caso funcionalizado con dos tiofenos, que es capaz de detectar de forma selectiva al catión Cu(II) y biotioles. En este caso disoluciones del sensor en agua-acetonitrilo 9:1 v/v están caracterizadas por la presencia de una banda de absorción a 320 nm y por una fluorescencia intensa a 475 nm. De nuevo, de todos los cationes ensayados, sílo el Cu(II) es capaz de inducir una desactivación completa de la emisión y un cambio de color en la disolución de incoloro a azul asociado con la aparición de una banda desplazada hacia el rojo a 555 nm. Estos cambios de color y de fluorescencia son debidos a la formación de complejos de estequiometría 1:1 en los que el Cu(II) coordina con los átomos de nitrógeno de imidazol. Además, también se estudió la respuesta óptica del complejo de Cu(II) en presencia de aminoácidos. En este caso, solo el glutatión, la cisteína y la homocisteína produjeron una decoloración intensa juntamente con la aparición de una banda de emisión a 475 nm. Estos cambios son debidos a un proceso de demetalación del complejo debido a la coordinación de los biotioles con el catión Cu(II). Teniendo en cuenta una posible aplicación de este sensor para detectar Cu(II) en medios biológicos se comprobó, mediante ensayos de viabilidad, que no presenta toxicidad aparente en células HeLa. Además, mediciones de microscopia confocal demuestran que el sensor puede ser empleado con éxito para detectar Cu(II) en células HeLa. En el quinto capítulo esta tesis doctoral se abordó la síntesis y caracterización de tres sensores conteniendo grupos N,N-difenilanilino (dador de electrones) y diferentes espaciadores π (benceno y tiofeno) conectados con grupos aldehído (aceptor de electrones). Los espectros UV-visible de estos tres receptores en acetonitrilo presentan bandas de absorción (de transferencia de carga debido a la presencia de la agrupación dadora de electrones N,N-difenilanilino conectada con puentes heteroaromáticos conteniendo grupos aldehído electrón aceptores) intensas en el intervalo que va de los 360 a los 420 nm. Se estudió el comportamiento de estos sensores en presencia de cationes y sólo el Cu(II) fue capaz de inducir la aparición de bandas en la zona infrarroja cercana en el intervalo entre 750 y 1075 nm. Además, los tres sensores son poco fluorescentes (con bandas localizadas en el intervalo entre 540 y 580 nm) y sólo el catión Cu(II) es capaz de desactivar la emisión. De nuevo, los cambios ópticos observados son debidos a la formación de complejos de estequiometría 1:1 en los que el catión Cu(II) interacciona con el átomo de oxígeno de los grupos aldehído. Estos sensores se pueden solubilizar en medios acuosos empleando dodecil sulfato. De esta forma, son capaces de detectar Cu(II) en mezclas docedil sulfato (20 mM)- acetonitrilo 9:1 v/v. Dos sensores basados en 2,4,5-triaril imidazol (conteniendo furanos y 1,10- fenantrolina), capaces de detectar Cu(II) y biotioles, se describen en el capítulo sexto. Disoluciones de los dos sensores en acetonitrilo muestran bandas de absorción en el intervalo que va de los 320 a los 350 nm siendo además ligeramente fluorescentes. De todos los cationes empleados en el estudio, sólo el Cu(II) es capaz de inducir la aparición de nuevas bandas de absorción desplazadas hacia el rojo junto con la desactivación de la emisión de los sensores. Estos cambios son asignados a la formación de complejos de estequiometría 1:1 en los que el Cu(II) interacciona con los átomos de nitrógeno del imidazol. El sensor conteniendo furanos es capaz de detectar Cu(II) en agua-acetonitrilo 1:1 v/v y el complejo formado se ha empleado con éxito para detectar biotioles (glutatión, cisteína y homocisteína) mediante cambios de color y aparición de fluorescencia. De nuevo, la respuesta óptica obtenida en presencia de biotioles se debe a un proceso de demetalación del complejo de Cu(II). Finalmente, el capítulo séptimo de esta tesis doctoral está dedicado a las conclusiones finales y a las perspectivas futuras que el trabajo que aquí se expone puede abrir en el campo de los sensores ópticos para la detección de cationes metálicos y biomoléculas en agua o en medios acuosos. / [CA] Aquesta tesi doctoral, que porta per títol “Noves aproximacions per al desenvolupament de sensors cromo-fluorogènics per a la detecció de Cu(II) i biotiols” aborda la síntesi, caracterització i estudi de la capacitat coordinant de nous sensors cromo-fluorogènics per al reconeixement i la detecció del catió Cu(II) i de biotiols (glutatió, cisteïna i homocisteïna). Aquests nous sensors, que són capaços de detectar de forma selectiva Cu(II) mitjançant canvis de color i/o de fluorescència, estan construïts mitjançant un nou paradigma que consisteix a integrar els grups coordinants dins de l'estructura de la unitat indicadora. A més, els complexos de Cu(II) dels nous sensors s'han emprat per a la detecció cromofluorogènica de biotiols mitjançant reaccions de desplaçament. El primer capítol d'aquesta tesi doctoral està dedicat a la introducció dels conceptes bàsics de la química supramolecular, els sensors òptics i les sondes moleculars, necessaris per a entendre el marc en el qual s'enquadren els resultats obtinguts. D'altra banda, en el segon capítol, es presenten els objectius generals d'aquesta tesi doctoral. En el tercer capítol es descriu la síntesi i caracterització de compost 4-(4,5- difenil-1H-imidazol-2-il)-N,N-dimetilanilina, un sensor cromo-fluorogènic que és capaç de detectar de forma selectiva el catió Cu(II) en medis aquosos. Així, dissolucions del sensor en aigua-acetonitril 1:1 (v/v) mostren una banda d'absorció intensa centrada en 320 nm que és desplaçada cap al roig (fins a 490 nm, desplaçament que es veu reflectit en un canvi de color d'incolor a marrórojenc) de forma selectiva en addicionar el catió Cu(II). Aquest desplaçament és degut a la formació d'un complex no fluorescent amb estequiometria 1:1 (en aquest complex el Cu(II) coordina amb els àtoms de nitrogen del imidazol). A més, aquest complex de Cu(II) s'ha emprat per a la detecció selectiva de glutatió ja que aquest biotiol és capaç d'induir la desaparició de la banda d'absorció a 490 nm (associada a un canvi de color de marró-rojenc a incolor). En presència de glutatió també es produeix un augment de fluorescència a 455 nm. Aquests canvis òptics són adscrits a un procés de demetal·lació del complex induït de forma selectiva pel glutatió (la cisteïna i la homocisteïna són incapaces de produir aquesta resposta). Finalment, el complex és capaç de detectar glutatió amb una alta sensibilitat ja que el límit de detecció és 2.0 μM. En el capítol quart d'aquesta tesi es descriu un altre sensor òptic basat en el imidazol, en aquest cas funcionalitzat amb dos tiofens, que és capaç de detectar de forma selectiva al catió Cu(II) i als tres biotiols. En aquest cas dissolucions del sensor en aigua-acetonitril 9:1 v/v estan caracteritzades per la presència d'una banda d'absorció a 320 nm i per una fluorescència intensa a 475 nm. De nou, de tots els cations assajats, només el Cu(II) és capaç d'induir una desactivació completa de l'emissió i un canvi de color en la dissolució d'incolor a blau (associat amb l'aparició d'una banda desplaçada cap al roig a 555 nm). Aquests canvis de color i de fluorescència són deguts a la formació de complexos d'estequiometria 1:1 en els quals el Cu(II) coordina amb els àtoms de nitrogen d'imidazol. A més, també es va estudiar la resposta òptica del complex de Cu(II) en presència d'aminoàcids. En aquest cas, només el glutatió, la cisteïna i l'homocisteïna van produir una descoloració intensa juntament amb l'aparició d'una banda d'emissió a 475 nm. Aquests canvis són deguts a un procés de demetal·lació del complex degut a la coordinació dels biotiols amb el catió Cu(II). Tenint en compte una possible aplicació d'aquest sensor per a detectar Cu(II) en mitjans biològics es va comprovar, mitjançant assajos de viabilitat, que no presenta toxicitat aparent en cèl·lules HeLa. A més, mesures de microscòpia confocal demostren que el sensor pot ser emprat amb èxit per a detectar Cu(II) en cèl·lules HeLa. En el cinquè capítol d'aquesta tesi doctoral, es va abordar la síntesi i caracterització de tres sensors contenint grups N,N-difenilanilino (donador d'electrons) i diferents espaiadors π (benzè i tiofè) connectats amb grups aldehid (acceptor d'electrons). Els espectres UV-visible d'aquests tres receptors en acetonitril presenten bandes d'absorció (de transferència de càrrega a causa de la presència de l'agrupació donadora d'electrons N,N-difenilanilino connectada amb ponts heteroaromàtics contenint grups aldehid electró acceptors) intenses en l'interval que va dels 360 als 420 nm. Es va estudiar el comportament d'aquests sensors en presència de cations i sols el Cu(II) va ser capaç d'induir l'aparició de bandes en la zona infraroja pròxima en l'interval entre 750 i 1075 nm. A més, els tres sensors són poc fluorescents (amb bandes localitzades en l'interval entre 540 i 580 nm) i només el catió Cu(II) és capaç de desactivar l'emissió. De nou, els canvis òptics observats són deguts a la formació de complexos d'estequiometria 1:1 en els quals el catió Cu(II) interacciona amb l'àtom d'oxigen dels grups aldehid. Aquests sensors es poden solubilitzar en medis aquosos emprant dodecil sulfat. D'aquesta forma, són capaços de detectar Cu(II) en mescles docedil sulfat (20 mM)-acetonitril 9:1 v/v. Dos sensors basats en 2,4,5-triaril imidazol (contenint furans i 1,10- fenantrolina), capaços de detectar Cu(II) i biotiols, es descriuen en el capítol sisè. Dissolucions dels dos sensors en acetonitril mostren bandes d'absorció en l'interval que va dels 320 als 350 nm sent a més lleugerament fluorescents. De tots els cations emprats en l'estudi, només el Cu(II) és capaç d'induir l'aparició de noves bandes d'absorció desplaçades cap al roig juntament amb la desactivació de l'emissió dels sensors. Aquests canvis són assignats a la formació de complexos d'estequiometria 1:1 en els quals el Cu(II) interacciona amb els àtoms de nitrogen de l'imidazol. El sensor contenint furans és capaç de detectar Cu(II) en aiguaacetonitril 1:1 v/v i el complex format s'ha emprat amb èxit per a detectar biotiols (glutatió, cisteïna i homocisteïna) mitjançant canvis de color i aparició de fluorescència. De nou, la resposta òptica obtinguda en presència de biotiols es deu a un procés de demetal·lació del complex de Cu(II). Finalment, el capítol setè d'aquesta tesi doctoral està dedicat a les conclusions finals i a les perspectives futures que el treball que ací s'exposa pot obrir en el camp dels sensors òptics per a la detecció de cations metàl·lics i biomolècules en aigua o en medis aquosos. / Essam Elsayed Mohamed Okda, H. (2020). Novel approaches for the development of chromo fluorogenic chemosensors for detection of Cu(II) and biothiols [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/139078 / Compendio

Neste trabalho estudou-se a formação de complexos da tirosina e de seus dipeptídeos tirosil-glicina e glicil-tirosina com o íon Cu2+. Para a caracterização destes complexos foram utilizadas as técnicas espectroscópicas de Absorção ótica na região do visível (400 a 800 nm), Ressonância paramagnética eletrônica em duas temperaturas (ambiente e &#8764-150&#176C) e a técnica de fluorescência. No caso da tyr os dados experimentais obtidos pela espectroscopia de RPE sugerem a formação de pelo menos duas espécies distintas de complexos além do cobre hidratado. Os complexos propostos foram: o CuL4 (ao redor de pH 3,5) e o CuL2 (na faixa de pH 4,0 e 12,0). Já para os dipeptídeos são evidenciados três tipos diferentes de complexos. São propostos os seguintes complexos: CuL2 (ao redor de pH 4,5), CuL (H2O) (na faixa de pH 7,0 e 12,0) e CuL(OH)22- (acima de pH 12,0). Os espectros de RPE mostram claramente que com o aumento de pH, ocorre a complexação do Cu2+ com os dipeptídeos. Em pHs altos (acima de pH 10,0) surgem nestes espectros uma estrutura superhiperfina de 5 linhas típicas para a coordenação de Cu2+ com dois nitrogênios. Quanto a tirosina, o espectro de seu complexo com Cu2+, não apresenta estrutura superhiperfina, sendo o sinal obtido, típico do complexo com Cu2+. Da mesma forma que foi observado por RPE, pode-se observar pelos espectros óticos, que em pHs baixos (2,0 a 3,5) para os dipeptídeos, os espectros apresentam uma banda larga e mal-resolvida, característica do íon de Cu2+ livre em solução. Observou-se também um deslocamento do máximo das bandas para o azul, apresentando características típicas das transições d-d correspondentes às várias espécies de complexos do metal em equilíbrio. Os dados de fluorescência foram muito informativos. As titulações da tyr e dos dipeptídeos puros em função do pH permitiram a determinação dos valores de pKs dos grupos ionizáveis. O efeito de supressão de fluorescência devido ao paramagnetismo do cobre foi usado tanto para a determinação da estequiometria quanto para a determinação das constantes de associação dos complexos dos dipeptídeos com Cu2+ em dois pHs fixos (pH 7,0 e 9,0). Encontrou-se complexos com a seguinte estequiometria (ligante/metal) : 2:1 e 1:1 respectivamente para a tyr e para os dipeptídeos nestes pHs. Um modelo simples de equilíbrio foi desenvolvido e estimou-se as constantes de associação da ordem de 107M-1 para os complexos de dipeptídeos- Cu2+. / The main goal of this work was to study the formation of the complexes of tyrosine and its dipeptides tyrosil-glycil and glycil-tyrosine with the transition metal íon Cu2+. The characterization of these complexes was performed through the use of spectroscopic techniques: optical absorption, electron paramagnetic resonance at both room temperature and -150&#176C and fluorescence emission. The EPR spectroscopy suggested for tyrosine two distints species. The following complexes were proposed: CuL4 (pH 3,5) and CuL2 (in the range of pH between 4,0-12,0). Three different complexes were evidentiated for dipeptides- Cu2+: CuL2 (pH 4,5); CuL(H2O) (in the range of pH between 7,0-12,0) and CuL(OH)22- (above pH 12,0). EPR spectra shows clearly the complexation of Cu2+ to the dipeptides. Both at intermediate and high pHs and specially above pH 10,0 a superhyoerfine structure of five lines typical for coordination of copper to two nitrogens was observed. In the case of the aminoacid no superhyperfine structure is observed. EPR data suggest that in a wide pH range between 7,0 and 11,0 the complex formed by the dipeptides was CuL(H2O). Electronic optical absorption was measured at room temperature as a function of pH in the range 2,0-13,0. It was observed that at low pHs (2,0 3,5) the spectra for the dipeptides was characterized by a broad not well resolved band around 800 nm characteristic of hidrated free Cu2+ in water solution. EPR spectra are in agreement with this observation. Increase of pH leads to a blue shift in the absorption band maximum and as a consequence to typical spectra for d-d transitions of the various species of complexes of cooper in equilibrium in solution. Fluorescence data were also very informative. The pure tyr and dipeptides tritation allowed to determine pKs values of ionizable groups. The effect of fluorescence suppression due to paramagnetic copper was used both to establish the stoichiometry of the complexes and the association constants. The stoichiometry of the complexes was determined as 2:1 and 1:1 ligand:metal for tyrosine and the dipeptides respectively at pH 7,0 and pH 9,0. A simple equilibrium model was developed and the association constants for the Cu2+ dipeptides complexes at pH 7,0 and pH 9,0 were estimated to be around 107M-1.

Neste trabalho são apresentados estudos em três diferentes sistemas utilizando-se as técnicas de Ressonância Paramagnética Eletrônica (RPE) e absorção eletrônica. No primeiro estudou-se a formação dos possíveis complexos entre o aminoácido aliina, extraído do alho, e o íon cobre (II). Os dados de RPE e absorção eletronica no visível (400-1100 nm) foram utilizados para caracterizar os diferentes complexos obtidos. No segundo utilizou-se o monocristal do complexo dicloro bis (benzil difenil fosfinóxido) Cobre (II) e efetuaram-se medidas de RPE variando-se a direção de aplicação do campo magnético no monocristal. Os auto-valores encontrados para as componentes do tensor g&#175 foram: g1= 2,0891; g2= 2,4554 e g3= 2,0767. Com base nos dados de RPE e cristalográficos e usando a teoria de campo cristalino foi proposto dxy como estado fundamental para o íon cobre (II) neste complexo. Fez-se também um estudo preliminar observando-se as variações no centro ativo de hemoproteínas moduladas pelo grau de hidratação. Metahemoglobina bovina e metamioglobina eqüina liofilizadas foram usadas e o sinal de RPE do íon ferro (III) monitorado. Dos espectros de RPE das duas proteínas são observadas pelo menos duas simetrias para o íon ferro (III), uma axial caracterizada por um valor de g próximo de 6 e outra caracterizada por g= 4,3 correspondendo a simetria rômbica. A intensidade dos sinais mostrou-se muito sensíveis ao grau de hidratação. Metahemoglobina e metamioglobina apresentaram comportamentos distintos dos sinais de RPE e sugeriu-se serem eles devido as diferenças estruturais entre as duas proteínas / In this work studies in three different systems using Electron Paramagnetic Resonance (EPR) and eletronic absorption techniques are presented. The formation of possible complexes between the amino acid aliin, extracted of garlic, and the copper (II) íon was studied in the first work. EPR and visible eletronic absorption (400-1100 nm) data were utilized to characterize the different complexes obtained. In the second work a crystal of the complex dichloro bis (benzyl diphenyl phosphinoxide) copper (II) was used and the EPR measures were made for different directions of application of the magnetic field in the crystal. The eigenvalues obtained for the g&#175 tensor components were: g1= 2,0891; g2= 2,4554 and g3= 2,0767. Using EPR and crystallographic data and crystal field theory dxy was proposed as the ground state of the copper (II) íon in this complex. A preliminary study was also made observing changes at the active Center of the hemeproteins modulated by the hydration degree. Lyophilized bovine methemoglobin ande quine metmyoglobin were used and the EPR signal of the iron (III) íon monitored. Or both proteins the EPR spectra corresponding to at least two iron symmetries were observed, one axial characterized by a g value near 6.0 and another characterized by g= 4,3 corresponding to rhombic symmetry. The intensity of these signals were very sensitive to the hydration degree. Metmyoglobin and methemoglobin showed distint behaviors of the EPR signals and it was suggested that they were due to structural differences between the two proteins

A comparative investigation of electrochemical characteristics of two complex systems, viz. Cu|Cu(II), glycine and Cu|Cu(II), maleic acid, was carried out. The equations were obtained for quantitative description of pH-metric and spectrophotometric data, which were used for determination of equilibrium characteristics in Cu(II)-maleic acid solutions. Thermodynamic analysis shows that deep changes are possible in this system resulting in 90 % transform of Cu(II) into Cu(I). The rates of Cu corrosion and Cu2O formation are estimated to be of the same order (nmol cm-2 s-1). Regularities of formal electrochemical kinetics, which account for the mass transport of chemically interacting particles and for step-wise charge transfer process, are suitable for interpretation of voltammetric data of the Cu|Cu(II), glycine system. Kinetic parameters Cu(II) glycinate complex depend on the nature of the supporting electrolyte: the exchange current density decreases and the cathodic charge transfer coefficient increases in the sequence: Li+ - Na+ - K+ - Cs+. To enhance the Cu(I) generation in maleic acid system, the pre-electrolysis procedure was applied. It was found that its effect depends on solution pH. Applied theoretical model describes satisfactorily the steady-state voltammetric characteristics of Cu|Cu(II), maleic acid system, but some contradictory results were obtained in the case of time-dependent processes. Theoretical and experimental problems to be solved are discussed. / Atliktas palyginamasis dviejų kompleksinių sistemų - Cu|Cu(II), glicinas ir Cu|Cu(II), maleino rūgštis - elektrocheminių charakteristikų tyrimas. Nustatytos maleino rūgšties tirpalų pusiausvyrinės charakteristikos. Kiekybiniam titravimo kreivių aprašymui išvestos lygtys, kuriose įvertinti medžiagų bei krūvių balansai bei atsižvelgta į praskiedimo efektus. Jų taikymas pH-metrinių duomenų analizei davė tokias maleato anijonų protonizacijos konstantų reikšmes: log = 6,05, log = 7,48. Nustatyta, kad tirpaluose su 0,3 M K2SO4 priedu protonizuotų ligando formų stabilumas sumažėja (log = 5,75, log = 7,30). Cu(II) maleatinių kompleksų stabilumui nustatyti panaudotas spektrofotometrijos metodas ir pasiūlyta duomenų analizės procedūra. Ji remiasi kiekybiniu absorbcijos spektrų aprašymu, taikant lygtis, išplaukiančias iš valdomo harmoninio osciliatoriaus teorijos. Išanalizavus įvairių sudėčių tirpalų absorbcijos maksimumo dydžius, prieita išvados, kad rūgščiose terpėse vyrauja monoligandinis kompleksas, kurio koncentracinė stabilumo konstanta log b1 = 2,2. Atlikta sistemos Cu|Cu(II), maleino rūgštis pusiausvyrų termodinaminė analizė. Nustatyta, kad esant metalinio vario ir tirpalų sąlyčiui, sistemoje galimi gilūs virsmai, kurių metu iki 90 % Cu(II) transformuojasi į Cu(I). Teorines išvadas patvirtina eksperimentiniai duomenys, gauti spektrofotometrijos ir elektrocheminės kvarco kristalo mikrogravimetrijos metodais. Įvertinti Cu korozijos bei fazinių Cu2O sluoksnių susidarymo... [toliau žr. visą tekstą]

Neste trabalho são apresentados estudos em três diferentes sistemas utilizando-se as técnicas de Ressonância Paramagnética Eletrônica (RPE) e absorção eletrônica. No primeiro estudou-se a formação dos possíveis complexos entre o aminoácido aliina, extraído do alho, e o íon cobre (II). Os dados de RPE e absorção eletronica no visível (400-1100 nm) foram utilizados para caracterizar os diferentes complexos obtidos. No segundo utilizou-se o monocristal do complexo dicloro bis (benzil difenil fosfinóxido) Cobre (II) e efetuaram-se medidas de RPE variando-se a direção de aplicação do campo magnético no monocristal. Os auto-valores encontrados para as componentes do tensor g&#175 foram: g1= 2,0891; g2= 2,4554 e g3= 2,0767. Com base nos dados de RPE e cristalográficos e usando a teoria de campo cristalino foi proposto dxy como estado fundamental para o íon cobre (II) neste complexo. Fez-se também um estudo preliminar observando-se as variações no centro ativo de hemoproteínas moduladas pelo grau de hidratação. Metahemoglobina bovina e metamioglobina eqüina liofilizadas foram usadas e o sinal de RPE do íon ferro (III) monitorado. Dos espectros de RPE das duas proteínas são observadas pelo menos duas simetrias para o íon ferro (III), uma axial caracterizada por um valor de g próximo de 6 e outra caracterizada por g= 4,3 correspondendo a simetria rômbica. A intensidade dos sinais mostrou-se muito sensíveis ao grau de hidratação. Metahemoglobina e metamioglobina apresentaram comportamentos distintos dos sinais de RPE e sugeriu-se serem eles devido as diferenças estruturais entre as duas proteínas / In this work studies in three different systems using Electron Paramagnetic Resonance (EPR) and eletronic absorption techniques are presented. The formation of possible complexes between the amino acid aliin, extracted of garlic, and the copper (II) íon was studied in the first work. EPR and visible eletronic absorption (400-1100 nm) data were utilized to characterize the different complexes obtained. In the second work a crystal of the complex dichloro bis (benzyl diphenyl phosphinoxide) copper (II) was used and the EPR measures were made for different directions of application of the magnetic field in the crystal. The eigenvalues obtained for the g&#175 tensor components were: g1= 2,0891; g2= 2,4554 and g3= 2,0767. Using EPR and crystallographic data and crystal field theory dxy was proposed as the ground state of the copper (II) íon in this complex. A preliminary study was also made observing changes at the active Center of the hemeproteins modulated by the hydration degree. Lyophilized bovine methemoglobin ande quine metmyoglobin were used and the EPR signal of the iron (III) íon monitored. Or both proteins the EPR spectra corresponding to at least two iron symmetries were observed, one axial characterized by a g value near 6.0 and another characterized by g= 4,3 corresponding to rhombic symmetry. The intensity of these signals were very sensitive to the hydration degree. Metmyoglobin and methemoglobin showed distint behaviors of the EPR signals and it was suggested that they were due to structural differences between the two proteins