Synthesis and applications of porphyrinoids: a journey into the multifaceted chemistry of pyrrolic macrocycles

Nella vasta famiglia dei macrocicli polipirrolici, le porfirine ed i corroli rivestono un ruolo di primo piano, grazie al fatto che, nel corso degli ultimi decenni, sono state messe a punto molte strategie sintetiche volte ad ampliare la gamma delle possibili molecole target. Un altro elemento degno di nota è la loro versatilità, che ne ha permesso un ampio utilizzo in differenti campi di applicazione. Lo studio della reattività di questi composti, ed il loro possibile impiego in diversi campi di applicazione, sono stati gli obiettivi di questo lavoro di tesi. Il capitolo 1 è centrato sull’impiego delle porfirine come materiale sensibile per i sensori chimici. In particolare si è studiata la morfologia di film monomolecolari depositati su oro, ottenuti mediante legame covalente tra la superficie del metallo ed una porfirina opportunamente funzionalizzata (SAM - Self Assembled Monolayer). L’esatta morfologia del film organico è stata studiata mediante l’impiego di numerose tecniche spettroscopiche. Un'altra linea di ricerca ha riguardato la formazione, la caratterizzazione e l’utilizzo di aggregati supramolecolare di porfirine. E’ stato notato che, in determinate condizione, porfirine funzionalizzate con gruppi carichi tendono a formare aggregati aventi struttura ben definita. L’interazione dell’aggregato con ioni in soluzione o con VOCs (Volatile Organic Compounds) in fase gassosa, porta ad un’alterazione della sua geometria e quindi ad una variazione delle caratteristiche spettrali, molto più intensa rispetto a quanto sia possibile osservare con le singole unità costituenti l’aggregato stesso. Alla luce delle proprietà illustrate, questo materiale è stato impiegato come strato sensibile per l’analisi di VOCs mediante l’impiego della tecnica CSPT. Il capitolo 2 è centrato sullo studio della reattività dei corroli. I corroli sono tetrapirroli, che condividono con le porfirine la facilità di sintesi, a differenza di molti altri porfirinoidi che sono invece ottenibili soltanto attraverso lunghe e difficoltose procedure sintetiche. Si è così pensato di usare il corrolo come materiale di partenza per ottenere un altro macrociclo tetrapirrolico, l’isocorrolo, attraverso l’ottimizzazione di una strategia sintetica one-step. Finora non è stata mai messa a punto una procedura generalizzata per la demetallazione dei metallo corroli; infatti i complessi dei corroli sono spesso degli intermedi inevitabili per il raggiungimento di composti differentemente funzionalizzati. La ricerca di una procedura di demetallazione non troppo aggressiva nei confronti dei substrati, può infatti aprire la strada ad una più ampia gamma di funzionalizzazione di questo inusuale macrociclo. Nel capitolo 3, sono state gettate le basi per l’ottenimento di una metodologia di sintesi dei triaril-tetrabenzocorroli. I tetrabenzocorroli sono considerati corroli espansi. L’espansione dell’aromaticità di questi composti, così come si osserva nel caso delle tetrabenzoporfirine, causa uno spostamento verso il rosso delle bande di assorbimento e di emissione; questa proprietà è interessante poiché è una caratteristica chiave per lo sviluppo di fotosensibilizzatori per l’impiego nella PDT (Photo Dynamic Therapy), una tecnica non invasiva e non tossica per il trattamento di tumori e di altre malattie.Among the large plethora of polypyrrolic macrocycles, porphyrins and corroles hold a noteworthy role; indeed, in the last three decades, several synthetic strategies have been pursued, expanding in this way the library of available compounds, and consequently, the studies concerning their chemistry. Moreover, it is impossible to neglect the versatility of these macrocycles, which encouraged their exploitation in several field of research. The aim of this thesis concerns the reactivity of porphyrins and corrole derivatives, and the exploitation of such molecules in different field of application. Chapter 1 deals with the exploitation of porphyrin derivatives as sensitive material for chemical sensors. In detail, we studied the morphology of self assembled porphyrin monolayer (SAM), by covalently linking of suitable functionalised macrocycles onto the gold surface. This was accomplished by means of several spectroscopic techniques. The formation, the characterization and the exploitation of porphyrins-based supramolecular aggregates, has been also taken into consideration. It is known that, under particular conditions, charged porphyrin derivatives strongly self-interact, forming supramolecular structures with a well defined tubular like shape. These porphyrin nanotubes are able to interact either with cations in solution, or with VOCs (Volatile Organic Compounds) in gas phase. As a consequence of these interactions, the geometry of the assembly changes, resulting in a change of the nanotube spectral and optical features. These changes are larger in magnitude, compared to those featured by the separated components. The use of this system as organic sensitive material, has been carried out by CSPT system (Computer Screen Photoassisted Technique). Chapter 2 is focused on corroles reactivity. Differently from porphyrins and corroles, others porphyrinoids are achievable only by difficult and tedious synthetic procedures. We surmised that the use common triarylcorroles as starting material, could be a successful strategy to obtain different tetrapyrrolic macrocycles, namely isocorrole, in a single step-synthesis. In this chapter the refinement procedure for demetalation of corroles complexes is also described. The achievement of the free-base corrole, by demetalation procedure, has been so far a very hard task; indeed metallo-corroles are too often unavoidable intermediates of choice for the achievement of differently functionalised derivatives. The quest of a “substrate friendly” demetalation procedure, may open the way to a wide range of functionalizations of this unusual macrocycle. In Chapter 3, the basis for an efficient methodology of triaryl-tetrabenzocorroles synthesis, have been described. Tetrabenzocorroles are regarded as expanded corroles. The expansion of the aromaticity of these molecules, such as occurs for by analogy with the tetrabenzoporphryin case, leads to a red shift of their absorption and emission bands; this should be a very interesting property, as it is the key feature for the development of photosensitizers amenable of use in PDT (Photo Dynamic Therapy), a non invasive and low-toxicity technique for the treatment of tumours and others diseases

Experimental Realization of Polarization Qutrits from Non-Maximally Entangled States

Based on a recent proposal [Phys. Rev. A 71, 062337 (2005)], we have experimentally realized two photon polarization qutrits by using non-maximally entangled states and linear optical transformations. By this technique high fidelity mutually unbiased qutrits are generated at a high brilliance level.Comment: RevTex, 8 pages, 6 figure

Realization and characterization of a 2-photon 4-qubit linear cluster state

We report on the experimental realization of a 4-qubit linear cluster state via two photons entangled both in polarization and linear momentum. This state was investigated by performing tomographic measurements and by evaluating an entanglement witness. By use of this state we carried out a novel nonlocality proof, the so-called ``stronger two observer all versus nothing'' test of quantum nonlocality.Comment: 4 pages, 4 figure

Recent advances in chemical sensors using porphyrin-carbon nanostructure hybrid materials

Porphyrins and carbon nanomaterials are among the most widely investigated and applied compounds, both offering multiple options to modulate their optical, electronic and magnetic properties by easy and well-established synthetic manipulations. Individually, they play a leading role in the development of efficient and robust chemical sensors, where they detect a plethora of analytes of practical relevance. But even more interesting, the merging of the peculiar features of these single components into hybrid nanostructures results in novel materials with amplified sensing properties exploitable in different application fields, covering the areas of health, food, environment and so on. In this contribution, we focused on recent examples reported in literature illustrating the integration of different carbon materials (i.e., graphene, nanotubes and carbon dots) and (metallo)porphyrins in heterostructures exploited in chemical sensors operating in liquid as well as gaseous phase, with particular focus on research performed in the last four years

Surface functionalization of extracellular vesicle nanoparticles with antibodies: a first study on the protein corona "variable"

To be profitably exploited in medicine, nanosized systems must be endowed with biocompatibility, targeting capability, the ability to evade the immune system, and resistance to clearance. Currently, biogenic nanoparticles, such as extracellular vesicles (EVs), are intensively investigated as the platform that naturally recapitulates these highly needed characteristics. EV native targeting properties and pharmacokinetics can be further augmented by decorating the EV surface with specific target ligands as antibodies. However, to date, studies dealing with the functionalization of the EV surface with proteins have never considered the protein corona "variable", namely the fact that extrinsic proteins may spontaneously adsorb on the EV surface, contributing to determine the surface, and in turn the biological identity of the EV. In this work, we explore and compare the two edge cases of EVs modified with the antibody Cetuximab (CTX) by chemisorption of CTX (through covalent binding via biorthogonal click-chemistry) and by formation of a physisorbed CTX corona. The results indicate that (i) no differences exist between the two formulations in terms of binding affinity imparted by molecular recognition of CTX versus its natural binding partner (epidermal growth factor receptor, EGFR), but (ii) significant differences emerge at the cellular level, where CTX-EVs prepared by click chemistry display superior binding and uptake toward target cells, very likely due to the higher robustness of the CTX anchorage

β-nitro-5,10,15-tritolylcorroles

Functionalization of the β-pyrrolic positions of the corrole macrocycle with -NO 2 groups is limited at present to metallocorrolates due to the instability exhibited by corrole free bases under oxidizing conditions. A careful choice of the oxidant can limit the transformation of corroles into decomposition products or isocorrole species, preserving the corrole aromaticity, and thus allowing the insertion of nitro groups onto the corrole framework. Here we report results obtained by reacting 5,10,15-tritolylcorrole (TTCorrH 3) with the AgNO 2/ NaNO 2 system, to give mono- and dinitrocorrole derivatives when stoichiometry is carefully controlled. Reactions were found to be regioselective, affording the 3-NO 2TTCorrH 3 and 3,17-(NO 2) 2TTCorrH 3 isomers as the main products in the case of mono- and disubstitution, in 53 and 20% yields, respectively. In both cases, traces of other mono- and disubstituted isomers were detected, which were structurally characterized by X-ray crystallography. The influence of the β-nitro substituents on the corrole properties is studied in detail by UV-visible, electrochemical, and spectroelectrochemical characterization of these functionalized corroles. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations of the ground and excited state properties of these β-nitrocorrole derivatives also afforded significant information, closely matching the experimental observations. It is found that the β-NO 2 substituents conjugate with the π-aromatic system of the macrocycle, which initiates significant changes in both the spectroscopic and redox properties of the so functionalized corroles. This effect is more pronounced when the nitro group is introduced at the 2-position, because in this case the conjugation is, for steric reasons, more efficient than in the 3-nitro isomer. © 2012 American Chemical Society

Synthesis and applications of porphyrinoids: a journey into the multifaceted chemistry of pyrrolic macrocycles

Nella vasta famiglia dei macrocicli polipirrolici, le porfirine ed i corroli rivestono un ruolo di primo piano, grazie al fatto che, nel corso degli ultimi decenni, sono state messe a punto molte strategie sintetiche volte ad ampliare la gamma delle possibili molecole target. Un altro elemento degno di nota è la loro versatilità, che ne ha permesso un ampio utilizzo in differenti campi di applicazione. Lo studio della reattività di questi composti, ed il loro possibile impiego in diversi campi di applicazione, sono stati gli obiettivi di questo lavoro di tesi. Il capitolo 1 è centrato sull’impiego delle porfirine come materiale sensibile per i sensori chimici. In particolare si è studiata la morfologia di film monomolecolari depositati su oro, ottenuti mediante legame covalente tra la superficie del metallo ed una porfirina opportunamente funzionalizzata (SAM - Self Assembled Monolayer). L’esatta morfologia del film organico è stata studiata mediante l’impiego di numerose tecniche spettroscopiche. Un'altra linea di ricerca ha riguardato la formazione, la caratterizzazione e l’utilizzo di aggregati supramolecolare di porfirine. E’ stato notato che, in determinate condizione, porfirine funzionalizzate con gruppi carichi tendono a formare aggregati aventi struttura ben definita. L’interazione dell’aggregato con ioni in soluzione o con VOCs (Volatile Organic Compounds) in fase gassosa, porta ad un’alterazione della sua geometria e quindi ad una variazione delle caratteristiche spettrali, molto più intensa rispetto a quanto sia possibile osservare con le singole unità costituenti l’aggregato stesso. Alla luce delle proprietà illustrate, questo materiale è stato impiegato come strato sensibile per l’analisi di VOCs mediante l’impiego della tecnica CSPT. Il capitolo 2 è centrato sullo studio della reattività dei corroli. I corroli sono tetrapirroli, che condividono con le porfirine la facilità di sintesi, a differenza di molti altri porfirinoidi che sono invece ottenibili soltanto attraverso lunghe e difficoltose procedure sintetiche. Si è così pensato di usare il corrolo come materiale di partenza per ottenere un altro macrociclo tetrapirrolico, l’isocorrolo, attraverso l’ottimizzazione di una strategia sintetica one-step. Finora non è stata mai messa a punto una procedura generalizzata per la demetallazione dei metallo corroli; infatti i complessi dei corroli sono spesso degli intermedi inevitabili per il raggiungimento di composti differentemente funzionalizzati. La ricerca di una procedura di demetallazione non troppo aggressiva nei confronti dei substrati, può infatti aprire la strada ad una più ampia gamma di funzionalizzazione di questo inusuale macrociclo. Nel capitolo 3, sono state gettate le basi per l’ottenimento di una metodologia di sintesi dei triaril-tetrabenzocorroli. I tetrabenzocorroli sono considerati corroli espansi. L’espansione dell’aromaticità di questi composti, così come si osserva nel caso delle tetrabenzoporfirine, causa uno spostamento verso il rosso delle bande di assorbimento e di emissione; questa proprietà è interessante poiché è una caratteristica chiave per lo sviluppo di fotosensibilizzatori per l’impiego nella PDT (Photo Dynamic Therapy), una tecnica non invasiva e non tossica per il trattamento di tumori e di altre malattie.Among the large plethora of polypyrrolic macrocycles, porphyrins and corroles hold a noteworthy role; indeed, in the last three decades, several synthetic strategies have been pursued, expanding in this way the library of available compounds, and consequently, the studies concerning their chemistry. Moreover, it is impossible to neglect the versatility of these macrocycles, which encouraged their exploitation in several field of research. The aim of this thesis concerns the reactivity of porphyrins and corrole derivatives, and the exploitation of such molecules in different field of application. Chapter 1 deals with the exploitation of porphyrin derivatives as sensitive material for chemical sensors. In detail, we studied the morphology of self assembled porphyrin monolayer (SAM), by covalently linking of suitable functionalised macrocycles onto the gold surface. This was accomplished by means of several spectroscopic techniques. The formation, the characterization and the exploitation of porphyrins-based supramolecular aggregates, has been also taken into consideration. It is known that, under particular conditions, charged porphyrin derivatives strongly self-interact, forming supramolecular structures with a well defined tubular like shape. These porphyrin nanotubes are able to interact either with cations in solution, or with VOCs (Volatile Organic Compounds) in gas phase. As a consequence of these interactions, the geometry of the assembly changes, resulting in a change of the nanotube spectral and optical features. These changes are larger in magnitude, compared to those featured by the separated components. The use of this system as organic sensitive material, has been carried out by CSPT system (Computer Screen Photoassisted Technique). Chapter 2 is focused on corroles reactivity. Differently from porphyrins and corroles, others porphyrinoids are achievable only by difficult and tedious synthetic procedures. We surmised that the use common triarylcorroles as starting material, could be a successful strategy to obtain different tetrapyrrolic macrocycles, namely isocorrole, in a single step-synthesis. In this chapter the refinement procedure for demetalation of corroles complexes is also described. The achievement of the free-base corrole, by demetalation procedure, has been so far a very hard task; indeed metallo-corroles are too often unavoidable intermediates of choice for the achievement of differently functionalised derivatives. The quest of a “substrate friendly” demetalation procedure, may open the way to a wide range of functionalizations of this unusual macrocycle. In Chapter 3, the basis for an efficient methodology of triaryl-tetrabenzocorroles synthesis, have been described. Tetrabenzocorroles are regarded as expanded corroles. The expansion of the aromaticity of these molecules, such as occurs for by analogy with the tetrabenzoporphryin case, leads to a red shift of their absorption and emission bands; this should be a very interesting property, as it is the key feature for the development of photosensitizers amenable of use in PDT (Photo Dynamic Therapy), a non invasive and low-toxicity technique for the treatment of tumours and others diseases

MCD and MCPL Characterization of Luminescent Si(IV) and P(V) Tritolylcorroles: The Role of Coordination Number

Two triarylcorrole complexes, (hydroxy)[5,10,15- tritolylcorrolato]silicon-(TTC)Si(OH) and (dihydroxy)[5,10,15- tritolylcorrolato]phosphorous-(TTC)P(OH)2, have been investigated by magnetic circular dichroism (MCD) and magnetic circularly polarized luminescence (MCPL). The spectroscopic investigations have been combined with explicit calculation of MCD response through time-dependent density functional theory (TD-DFT) formal- ism. This has allowed us to better define the role of molecular orbitals in the transitions associated with the Soret and Q bands. Besides and more importantly, MCD has made it possible to follow the titration process of (TTC)Si(OH) in dimethyl sulfoxide (DMSO) solution with NaF and of (TTC)P(OH)2 in dichloromethane solution with alcohols in a complementary and, we dare say, more sensitive way with respect to absorption and fluorescence data. Finally, the MCPL spectra and the ancillary TD-DFT calculations have allowed us to characterize the excited state of (TTC)Si(OH)