Visible-light metallaphotoredox strategies for organic transformations through the cleavage of Csp3-Cl bonds

Recentment, la generació de radicals actius mitjançant metodologies fotocatalítiques amb llum visible ha permès la construcció d’una gran varietat d’enllaços CC. La inèrcia dels cloroalcans ha impedit el seu ús com a socis d'acoblament predominants tant en reaccions d'acoblament creuat convencionals com fotocatalítiques. De fet, s’han desenvolupat escassos exemples que utilitzin clorurs d’alquil inactivats com a fragments de síntesi, els quals presenten limitacions a l’hora d’aplicar-se de manera general. En aquesta direcció, aquesta tesi descriu el desenvolupament d’una nova família de complexos tetradentats de Co i Ni capaços d’activar diferents clorurs d’alquil. La disponibilitat, versatilitat i modelatge d’aquests lligands ens permet la modificació controlada de la primera esfera de coordinació del metall a partir del canvi de les propietats electròniques i estructurals del lligand. La col.lecció de divuit nous complexos de Co i Ni significa un nou escenari per al desenvolupament de metodologies sintètiques.Recientemente, la generación de radicales activos mediante metodologías fotocatalíticas con luz visible ha permitido la construcción de una gran variedad de enlaces CC. La inercia de los cloroalcanos ha impedido su uso como socios de ensamblaje predominantes tanto en reacciones de ensamblaje cruzado convencionales como fotocatalíticas. De hecho, se han desarrollado escasos ejemplos que utilicen cloruros de alquilo inactivados como fragmentos de síntesis, que presentan limitaciones a la hora de aplicarse de forma general. En esta dirección, esta tesis describe el desarrollo de una nueva familia de complejos tetradentados de Co i Ni capaces de activar diferentes cloruros de alquil. La disponibilidad, versatilidad y modelado de estos ligandos permite la modificación controlada de la primera esfera de coordinación del metal a partir del cambio de las propiedades electrónicas y estructurales del ligando. La colección de dieciocho nuevos complejos de Co i Ni significa un nuevo escenario para el desarrollo de metodologías sintéticas.Recent photocatalytic methods based on the visible-light-induced generation of reactive radicals have allowed the construction of a large variety of CC bonds. The inertness of chloroalkanes has precluded them as prevailing coupling partners in both conventional and photocatalytic cross-coupling reactions. In fact, few examples of using unactivated alkyl chlorides as building blocks have been developed, presenting limitations in their applicability for a general methodology. In this line, this thesis describes the development of a new familiy of tetradentate aminopyridine Co and Ni complexes able to activate different chloroalkanes. The ligand availability, modularity and versatility let us the tune the first coordination sphere of the metal by changing the electronic and structural features of the ligand. A collection of eighteen new Co and Ni complexes have been studied presenting a playground for synthetic methodology development

Influència dels electròlits i el pH en el comportament fàsic de les mescles aquoses de gelatina/maltodextrina, per obtenir emulsions del tipus aigua-en-aigua

Treballs Finals de Grau de Química, Facultat de Química, Universitat de Barcelona, Any: 2016, Tutors: Maria Sarret Pons, Jordi Esquena Moret i Yoran BeldengrünThe main objective of this work is to study the effect of different electrolytes and pH on the spontaneous formation of water-in-water emulsions. Water-in-water (W/W) emulsions are a less known group of emulsions which are based on the immiscibility of two compounds which are soluble in water. Although they are thermodynamically unstable, W/W emulsions could be kept for some time due to its kinetic metastability, without any surfactant. Subsequently, obtaining microgels from these emulsions could offer a new type of encapsulation with delayed release of active ingredients or drugs. In this work, aqueous mixtures of gelatin and maltodextrin have been studied from its phase diagrams. Initially, the study of electrolytes has been made following the Hofmeister series, thereby, according to the capacity of hydration of ions, studying salts with different free energy of hydration (CsNO3 i LiCl). It was expected that salts had opposite effect on the phase separation of the system, but it was observed that the two salts favour the miscibility of polymers and the precipitation of a coacervate. Then, the effect of pH by adding acetic acid has been studied, observing an interesting result: acid medium favours the miscibility between the polymers, without precipitation. This phenomenon opens a new way: the neutralization of acid medium with sodium hydroxide could favour the spontaneous formation of emulsions. It has been verified that the addition of NaOH produces an instantaneous phase separation, however, obtaining emulsions from this phase separation has not been ensured. Due to the high system instability, many experimental factors could affect the formation of these emulsions. Future further work is required with more detailed studie