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Nell’approfondire i contenuti di questo manoscritto, si potrebbe inizialmente percepire un’eterogeneità nel lavoro presentato. Pertanto, illustreremo il filo conduttore di questo percorso di dottorato, sintetizzato in cinque capitoli, in cui vengono esplorati lo sviluppo di nano-materiali confinati e la loro applicazione in chimica organica di sintesi. Il quadro comune tra gli argomenti trattati è l’impegno nello sviluppo di procedure chimiche sostenibili, con particolare attenzione verso un’accurata selezione di solventi green e a sforzi per il loro riciclo. Il primo Capitolo introduce i lettori all’incapsulazione, tecnologia avente molteplici applicazioni e che consiste nell’incorporazione di principi attivi in uno strato esterno di rivestimento. L’argomento ha riguardato lo sviluppo di una procedura scalabile per la sintesi di micro- e nanocapsule, con una significativa enfasi sulla sostenibilità del processo. Sono esaminate varie metodologie di reticolazione, seguite da una estensiva caratterizzazione morfologica, termica e chimica delle risultanti capsule. Il Capitolo 2 ha esplorato l’applicabilità di questi materiali sia in cosmetica sia in catalisi. Comuni specie di palladio e/o leganti sono stati incapsulati nel guscio polimerico con l’obiettivo di assemblare innovativi nanoreattori, la cui attività catalitica è stata esplorata in ambienti acquosi eterogenei in reazioni di cross-coupling. Questi nanoreattori hanno operato efficientemente con carichi minimi di metallo e senza la necessità di ulteriori solventi organici. Parallelamente, il progetto si è concentrato sulla ricerca di condizioni di reazione sostenibili per reazioni di coupling Pd-catalizzate per la costruzione di legami C-C (Sonogashira, Ch. 3) e C-B (Borilazioni di Miyaura, Ch. 4). In questi casi, gli esperimenti sono condotti in catalisi omogenea in acqua. Le procedure sintetiche sono semplici e riproducibili e coinvolgono l’utilizzo di piccole quantità di un catalizzatore di Pd econom, In delving into the contents of this manuscript, one might initially perceive a certain heterogeneity in the presented work. Thus, we will illustrate the common thread of this PhD journey, summarised into five chapters where the development of confined nano- materials and their application in synthetic organic chemistry are explored. Specifically, we aim at providing a comprehensive overview of the dynamic aspects of self-assembling materials, ranging from simple amphiphilic compounds to macromolecules. The common frame across all the discussed topics is clearly the commitment to sustainable chemical procedures, with specific attention paid on the accurate selection of green solvents and efforts towards their recyclability. The initial Chapter introduces readers into the world of encapsulation, a well-known technology having diverse applications and involving the incorporation of active ingredients within an outer coating layer. The topic dealt with the development of a straightforward and scalable procedure for the synthesis of bio-based micro- and nanocapsules by originally modifying the solvent evaporation method, with a significant emphasis on ensuring the sustainability of the process. Various crosslinking methodologies are examined, followed by an extensive chemical, morphological and thermal characterization of resulting capsules. Chapter 2 explored the applicability of these materials both in cosmetics and in catalysis. In this regard, common palladium sources and/or ligands are incorporated within the polymer shell with the aim of assembling innovative nanoreactors. Their catalytic activity in aqueous heterogeneous environments is efficiently investigated in cross-coupling reactions, as Suzuki-Miyaura and Sonogashira couplings. These nanoreactors operated efficiently with minimal metal loadings and without the need for additional organic solvent. Simultaneously, the project concerned the exploration for mild and green conditions for Pd-catalysed coupling re

Il doping molecolare è essenziale per migliorare le proprietà elettriche dei semiconduttori organici. Ai fini applicativi sono necessari materiali di tipo n e di tipo p aventi proprietà elettriche comparabili, ma le prestazioni di semiconduttori e droganti di tipo n sono ancora inferiori. E’ dunque necessario colmare questo divario. Tra i droganti di tipo n, il derivato a base benzimidazolina N-DMBI-H (4-(1,3-dimetil-2,3-diidro-1H-benzoimidazol-2-il)-N,N-dimetilanilina) è uno dei più promettenti. Le prestazioni di questo composto sono però limitate dalla sua scarsa miscibilità con molti semiconduttori, che ne causa la segregazione dalla matrice conduttiva e ne riduce l’efficienza di drogaggio, e dalla mancanza di una completa razionalizzazione del suo meccanismo di doping, cruciale per un suo miglior utilizzo. Il mio lavoro di dottorato ha avuto dunque come obiettivo approfondire la comprensione dei processi di doping mediati da N-DMBI-H e trovare strategie per aumentarne l’efficienza. Una prima linea di ricerca ha riguardato l'uso di tecniche di rilevamento di H2 per lo studio del meccanismo di doping di N-DMBI-H. Con questo metodo, è stata dimostrata l'evoluzione di H2 come possibile processo collaterale del doping non catalizzato mediato da questo dopante, prima solo ipotizzata. E’ stata poi analizzata la dipendenza del processo dal semiconduttore utilizzato e dalle condizioni di attivazione e sono stati studiati i siti reattivi coinvolti nella formazione di H2. E' stata inoltre dimostrata la generalità del metodo di rilevazione di idrogeno, estendendone l'uso allo studio del meccanismo di drogaggio del drogante di tipo p tris(pentafluorofenil)borano (BCF). Una seconda parte del lavoro ha riguardato l’analisi dell'impatto dei prodotti di ossidazione di N-DMBI-H sulle prestazioni di materiali drogati con questo composto. E’ stato dimostrato che questi prodotti di degradazione funzionano da agenti di nucleazione per il drogante, migliorandone la distribuzi, Molecular doping is essential to improve charge transport properties of organic semiconductors for applications in several optoelectronic devices. Both efficient n-type and p-type materials are required in sight of applications, but the performances of n-type semiconductors/dopants systems still lag behind the p-type ones and more effort is required to close this gap. Among the n-type dopants, the benzimidazoline derivative N-DMBI-H (4-(1,3-Dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)-N,N-dimethylaniline) is one of the most promising. The performances of this compound are however limited by a low miscibility with most semiconductors, that causes its segregation from the host and reduces its doping efficiency, and by the lack of a full rationalization of its doping mechanism, that is crucial for its efficient use. My PhD work thus aimed at deepening the understanding of N-DMBI-H mediated doping processes and at finding strategies to increase their efficiency. A first research line concerned the use of H2 detection techniques to study N-DMBI-H doping mechanism. Through this innovative approach, we demonstrated H2 evolution as possible collateral process of uncatalyzed doping mediated by N-DMBI-H, which was previously only hypothesized. We then investigated the doping reaction dependence on the semiconductor counterpart and activation conditions and delved into the reactive sites involved in the H2 formation process. We also proved the potentiality and generality of the H2 detection method, extending its use to the study of the doping mechanism of the p-type dopant tris(pentafluorophenyl)borane (BCF). A second research topic concerned the analysis of the impact of N-DMBI-H oxidation impurities on the performances of n-type doped polymers. We demonstrated that these degradation products are not detrimental for performances but behave as nucleating agents for N-DMBI-H, improving its distribution in the conductive host and increasing the doping efficiency. We extended the

The use of scintillators for the detection of ionizing radiation is a critical aspect in many fields, including medicine, nuclear monitoring, and homeland security. Recently, lead halide perovskite nanocrystals (LHP-NCs) have emerged as promising scintillator materials. However, the difficulty of affordably upscaling synthesis to the multigram level and embedding NCs in optical-grade nanocomposites without compromising their optical properties still limits their widespread use. In addition, fundamental aspects of the scintillation mechanisms are not fully understood, leaving the scientific community without suitable fabrication protocols and rational guidelines for the full exploitation of their potential. In this work, we realize large polyacrylate nanocomposite scintillators based on CsPbBr3 NCs, which are synthesized via a novel room temperature, low waste turbo-emulsification approach, followed by their in situ transformation during the mass polymerization process. The interaction between NCs and polymer chains strengthens the scintillator structure, homogenizes the particle size distribution and passivates NC defects, resulting in nanocomposite prototypes with luminescence efficiency >90%, exceptional radiation hardness, 4800 ph/MeV scintillation yield even at low NC loading, and ultrafast response time, with over 30% of scintillation occurring in the first 80 ps, promising for fast-time applications in precision medicine and high-energy physics. Ultrafast radioluminescence and optical spectroscopy experiments using pulsed synchrotron light further disambiguate the origin of the scintillation kinetics as the result of charged-exciton and multiexciton recombination formed under ionizing excitation. This highlights the role of nonradiative Auger decay, whose potential impact on fast timing applications we anticipate via a kinetic model.

Depto. de Química en Ciencias Farmacéuticas, Fac. de Farmacia, TRUE, pub

The use of scintillators for the detection of ionizing radiation is a critical aspect in many fields, including medicine, nuclear monitoring, and homeland security. Recently, lead halide perovskite nanocrystals (LHP-NCs) have emerged as promising scintillator materials. However, the difficulty of affordably upscaling synthesis to the multigram level and embedding NCs in optical-grade nanocomposites without compromising their optical properties still limits their widespread use. In addition, fundamental aspects of the scintillation mechanisms are not fully understood, leaving the scientific community without suitable fabrication protocols and rational guidelines for the full exploitation of their potential. In this work, we realize large polyacrylate nanocomposite scintillators based on CsPbBr3 NCs, which are synthesized via a novel room temperature, low waste turbo-emulsification approach, followed by their in situ transformation during the mass polymerization process. The interaction between NCs and polymer chains strengthens the scintillator structure, homogenizes the particle size distribution and passivates NC defects, resulting in nanocomposite prototypes with luminescence efficiency >90%, exceptional radiation hardness, 4800 ph/MeV scintillation yield even at low NC loading, and ultrafast response time, with over 30% of scintillation occurring in the first 80 ps, promising for fast-time applications in precision medicine and high-energy physics. Ultrafast radioluminescence and optical spectroscopy experiments using pulsed synchrotron light further disambiguate the origin of the scintillation kinetics as the result of charged-exciton and multiexciton recombination formed under ionizing excitation. This highlights the role of nonradiative Auger decay, whose potential impact on fast timing applications we anticipate via a kinetic model.

Cesium lead halide perovskite nanocrystals of general formula CsPbX3 are having tremendous impact on a vast array of technologies requiring strong and tunable luminescence across the visible range and solutions processing. The development of plastic scintillators is just one of the many relevant applications. The syntheses are relatively simple but generally unsuitable to produce a large amount of material of reproducible quality required when moving from proof-of-concept scale to industrial applications. Wastes, particularly large amounts of lead-contaminated toxic and flammable organic solvents, are also an open issue. We describe a simple and reproducible procedure enabling the synthesis of luminescent CsPbX3 nanobricks of constant quality on a scale going from 0.12 to 8 g in a single batch. We also show complete recycling of the reaction wastes, leading to dramatically improved efficiency and sustainability.

Il mio Progetto di dottorato si è incentrato sul potenziamento di strategie sintetiche in soluzione per la produzione di colloidi con applicazioni come materiali colloidali. Esso si è strutturato in due linee di ricerca all’apparenza differenti ma concettualmente interconnesse tra loro. In primo luogo, lo sviluppo di una procedura sintetica di nanocristalli colloidali CsPbBr3 che fosse intrinsecamente scalabile, versatile e affidabile ad ogni scala. L’aspetto fondamentale su cui verte è stata l’introduzione di un turbo-emulsore, il cui utilizzo non è mai stato riportato nel campo dei nanocristalli. Per prima cosa, abbiamo corroborato il suo contributo innovative rispetto all’agitazione magnetica generalmente utilizzata, dimostrando che per volumi superiori al litro, il suo utilizzo diventa indispensabile. Successivamente, abbiamo approfonditamente studiato l’impatto di differenti parametri sintetici sulle proprietà delle risultanti dispersioni colloidali, acquisendo un punto di vista completo e controllabile a nostro favore sul meccanismo con cui avviene il processo: incremento della viscosità del mezzo di reazione, effetto della temperature, sostituzione dei leganti acidi e amminici. Abbiamo inoltre ottimizzato un processo di recupero degli scarti di sintesi che permette di riutilizzarli quasi direttamente per riprodurre la sintesi, senza diminuire la qualità dei materiali ottenuti. Infine, abbiamo testato preliminarmente I materiali in celle solari, evidenziando una maggiore compatibilità con il campo dell’indoor, e abbiamo depositato una domanda di brevetto per scintillatori nanocompositi ultraveloci che preservano le loro proprietà sotto irradiazione da raggi gamma fino ad 1 MGy. La seconda linea di ricerca parallela consiste nello sviluppo di un approccio fotochimico per la trasformazione di micelle formate da surfattanti commerciali in oggetti nanometrici stabilizzati core-shell che possono essere applicati in rilascio controllato di farmaci, catalisi, My research was centred on the enhancement of synthetic strategies via wet methods intended for production of colloids having applications as functional materials. The overall project is composed by two distinct but conceptually connected research lines. Firstly, the development of unprecedentedly scalable, versatile and reliable synthetic strategy for high quality colloidal CsPbBr3 nanocrystals. The key advantage of the method is the original introduction of a high shear homogenizer. We firstly corroborated the improvement with respect to generally used magnetic stirring, showcasing its requirement when working with volumes that exceed 1 L. Successively, we deeply studied the impact of processing parameters on the properties of colloidal dispersions to gain a full insight and completely rule over the synthetic mechanism: increased medium viscosity, temperature, acid and amine ligands substitution during synthesis. We also optimized a waste recovery process that allows to almost directly reuse unreacted species remaining after the synthesis to perform the reaction again and without decreasing output nanocrystals properties. Finally we preliminary tested these materials in solar cells, deducing better compatibility with indoor target and patented a new type of nanocomposite scintillator able to preserve its properties to gamma irradiation doses up to 1 MGy. The second research line deals with the development of photochemical approaches for the transformation of micelles of commercially available surfactants into crosslinked core-shell amphiphilic nano-hosts, intended for applications in controlled release, catalysis and imaging. We exploited the formation of a semi-interpenetrated network between the branched, cheap, commercial tween 80 and the photopolymerized co-surfactant APE-4 (2-(tetrahydropyranyl)oxy tetraethylene glycol methacrylate) to freeze the specific association colloid formed. We firstly optimized efficiency of photopolymerization process under 365 nm i

The photon upconversion based on sensitized triplet–triplet annihilation (sTTA-UC) is a spin-flip mechanism exploited to recover the energy stored on dark triplet states in conjugated systems. In this process, a high-energy fluorescent singlet is created through the collision and fusion of two low-energy triplets belonging to different diffusing molecules. Its high yield in solution under low excitation intensity and noncoherent light highlighted the huge potential of sTTA-UC to provide a breakthrough in solar technologies. However, its diffusion-limited nature restrains its efficiency in the solid state. To overcome this issue, we propose a single-molecule system that is able to host simultaneously more than one triplet, thus enabling a diffusion-free intramolecular TTA. We obtain the first direct demonstration of intramolecular triplet fusion by tailored photoluminescence spectroscopy experiments, thus opening the way to realize a new family of single-molecule upconverters with huge potential in solar and lighting technologies by accessing the natural triplets’ energy reservoir.

Perovskite solar cells (PSCs) are experiencing tremendous interest due to compatibility with solution processing on a wide range of substrates and very high efficiency. The hole transport layer (HTL) plays a fundamental role in such multistack cells. We propose new branched and polymeric organic HTL derivatives with sustainable synthesis and performances exceeding those of Spiro-OMeTAD, the standard in the field.

Il mio progetto di dottorato è focalizzato sullo sviluppo di inchiostri a base acquosa costituiti da nanoparticelle (NPs) polimeriche per applicazioni optoelettroniche ed elettroniche. In particolare, lo scopo della mia ricerca è la preparazione di strati attivi di dispositivi fotovoltaici organici (OPV) sostenibili. Questo obiettivo è raggiunto attraverso sospensioni acquose di NPs processabili in acqua, preparate a partire da miscele di polimeri semiconduttori donatori e accettori di elettroni. Gli inchiostri acquosi sono stati ottenuti attraverso il metodo della miniemulsione, modificato affinché non fosse necessaria l'aggiunta di surfattanti per garantire la stabilità colloidale. L'approccio sviluppato prevede l'utilizzo di copolimeri a blocchi (BCPs) anfifilici del tipo rod-coil, caratterizzati da un blocco rigido (un polimero semiconduttore di tipo p) legato covalentemente a un segmento flessibile idrofilo in grado di interagire con il mezzo acquoso, stabilizzando le interfacce acquose/non acquose. I BCPs anfifilici sono in grado di auto-assemblarsi sia puri che in miscela con materiali accettori, portando alla formazione di nanostrutture costituite da domini con dimensioni adatte alla percolazione della carica nello strato attivo della cella solare organica (OSC). In primo luogo, come materiali elettron-donatori sono stati considerati dei polimeri low band-gap (LBG). Nella parte iniziale della tesi è descritta la sintesi di quattro BCPs basati sul polimero poli[2,6-(4,4-bis-(2-etilesil)-4H-ciclopenta[2,1-b;3,4-b']ditiofene)-alt-4,7(2,1,3-benzotiazolo)] (PCPDTBT), con un segmento di poli-4-vinilpiridina (P4VP) come coil. I BCPs sono stati utilizzati in miscela con il derivato fullerenico PC61BM come materiale elettron-accettore per ottenere inchiostri acquosi, che sono stati poi depositati per fabbricare strati attivi. In seguito, sono stati condotti diversi esperimenti per trovare la correlazione tra la morfologia interna e la composizione delle NPs con, My PhD project is focused on the development of polymeric nanoparticle-based aqueous inks for optoelectronic and electronic applications. Specifically, the aim of my research is the fabrication of sustainable active layers of organic photovoltaic (OPV) devices processable in water. This goal is reached through water-processable nanoparticle (WPNP) aqueous suspensions, prepared from semiconducting polymers as electron-donor and acceptor materials. The aqueous inks are obtained through a modified miniemulsion method, which unlike the standard process does not imply the addition of any surfactant to ensure the colloidal stability. The adapted approach involves the use of amphiphilic rod-coil block copolymers (BCPs), characterized by a rigid block (a p‐type semiconducting polymer) covalently linked to a hydrophilic flexible segment able to interact with aqueous medium, stabilizing the aqueous/non-aqueous interfaces. The amphiphilic BCPs are able to self-assemble both neat and in blend with acceptor materials, leading to the formation of nanostructures consisting of domains with dimensions suitable for the charge percolation in the resulting active layer of the organic solar cell (OSC). Primarily, low-band-gap (LBG) polymers were considered as electron donor materials to match the solar radiation absorption. Firstly, the synthesis of four different poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b’]dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT)-based amphiphilic BCPs, with a tailored segment of poly-4-vinylpiridine (P4VP) as coil, was presented. The BCPs were used in blend with the [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as acceptor material to prepare WPNP aqueous inks, which were deposited to obtain the active layers. The correlation between the internal morphology and composition of the WPNPs, and the dimensions of the donor/acceptor nanodomains with the efficiency of the resulting OSCs was deeply studied. In a second time, we explored ot

The Suzuki-Miyaura reaction between the aryl halide (1) and the phenyl boronic acid (2), in the presence of the palladium(0) complex (3) as catalyst, gives the cross-coupling product (4) in quantitative yield when performed in basic aqueous solution of the nonionic surfactant Kolliphor-EL (K-EL). The partition between the aqueous and micellar environments of the species of this reaction has been investigated by means of Molecular Dynamics (MD) simulations. Starting from the K-EL molecules dispersed in water, a micelle model has been generated by MD simulations, adopting the 2016H66 force field. Reagent and product species have been described with the same force field, once the reliability of this force field has been tested comparing the n-octanol/water partition free energies calculated from the MD and Free Energy Perturbation (FEP) method with those obtained from the quantum-mechanical SMD method. The potential of mean force for the transfer process between water and the micellar phase of the different species has been calculated by the MD simulations and the Umbrella Sampling (US) method. The overall picture that emerges from these results confirms that the molecular species involved in this reaction prefers the micellar environment and concentrates in different but close zones of the micelle. This supports the experimental evidence that the use of suitable surfactant agents promotes reactivity, allowing micelles to behave as nanoreactors in which reactive species are solubilized and enhance their local concentration.