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The research has been focused on tailoring novel photosensitizers, ranging from organic molecules to carbon nanostructure, such as perylene bisimides (PBIs) and carbon nanodots (CNDs): At first it was developed a fast and efficient protocol for the microwave assisted synthesis of perylene bisimides. Imidation reactions of the perylenebisanhydride were performed using a large variety of amines, such as alkylamines, amino alcohols, heteroarylamines, and amino acids. With the powerful tool we developed, we targeted more complex applications. We designed a novel photocatalytic system mimicking the PSII oxygen evolving center. Our approach was based on the unprecedented combination of metal-free perylene bisimides (PBI) as photosensitizers with totally inorganic polyoxometalates (POMs) as catalysts. Oxygen evolution was observed with well-behaved kinetics, long operation time (> 8h), and conversion yields up to >98%. Moreover, we proposed comprehensive structural picture of a perylenebisimide hydrogel, suggesting that its long-range conductivity is limited by charge-transfer between electronic backbones. We revealed nano-crystalline ribbons as the electronic and structural backbone between which charge transfer was mediated by polar solvent bridges. We exemplified this effect with gas sensing, where exposure to polar vapor changes conductivity by five orders of magnitude, emphasizing the crucial role of the interplay between structural motif and surrounding medium for the rational design of devices based on nano-crystalline hydrogels. Jumping to carbon nanostructure we were interested into mastering optical, electronical and structural properties of carbon dots. Thus, we synthesized and characterized green emissive CNDs using organic chromophores, such as boron-dipyrromethenes, as starting materials and we exploited them as tracker in NK cells. Notably, it was optimized a synthetic protocol for the green emissive CNDs that can be extended for the preparation of a library of multicolored CNDs. Furthermore, we prepared and characterized a redox library of CNDs with tunable energy levels by adding to the reaction mixture commercially available quinones and employing a bottom-up MW-assisted hydrothermal treatment. Benzoquinone-, naphthoquinone- and anthraquinone-based carbon nanodots exhibited interesting electrochemistry with oxidation potentials between 1..48 V and 0.98 V vs SCE and reducing one in the range -1.52 V and -2.05 V vs SCE. Finally, we reported the structural and optical modifications happening during the reaction. We identified the core-shell structure of these carbon dots and synthesized novel CNDs with controlling the size of the soft shell that we believe it is the responsible for the optical properties that characterize these interesting nanoparticles.

As the natural-born photoelectrolyzer for oxygen delivery, photosystem II (PSII) is hardly replicated with man-made constructs. However, building on the "quantasome" hypothesis (Science 1964, 144, 1009-1011), PSII mimicry can be pared down to essentials by shaping a photocatalytic ensemble (from the Greek term "soma" = body) where visible-light quanta trigger water oxidation. PSII-inspired quantasomes (QS) readily self-assemble into hierarchical photosynthetic nanostacks, made of bis-cationic perylenebisimides (PBI2+) as chromophores and deca-anionic tetraruthenate polyoxometalates (Ru4POM) as water oxidation catalysts (Nat. Chem. 2019, 11, 146-153). A combined supramolecular and click-chemistry strategy is used herein to interlock the PBI-QS with tetraethylene glycol (TEG) cross-linkers, yielding QS-TEG(lock) with increased water solvation, controlled growth, and up to a 34096 enhancement of the oxygenic photocurrent compared to the first generation QS, as probed on 3D-inverse opal indium tin oxide electrodes at 8.5 sun irradiance (lambda > 450 nm, 1.28 V vs RHE applied bias, TOFmax = 0.096 +/- 0.005 s(-1), FEO2 > 95%). Action spectra, catalyst mass-activity, light-management, photoelectrochemical impedance spectroscopy (PEIS) together with Raman mapping of TEG-templated hydration shells point to a key role of the cross-linked PBI/Rn4POM nanoarrays, where the interplay of hydrophilic/hydrophobic domains is reminiscent of PSII-rich natural thylakoids.

The deposition of perylene diimide-based aggregates (PDI) onto wide band gap n-type Sb-doped SnO2 (ATO) was investigated with the aim of finding efficient and versatile dye-sensitized platforms :for photoelectrochemical solar fuel generation. These ATO-PDI photoanodes displayed hydrolytic stability in a wide range of pH (from 1 to 13) and revealed superior perforthances (up to 1 mA/cm(2) net photocurrent at 1 V vs SCE) compared to both WO3-PDI and: undoped SnO2-PDI when used in a photoelectrochemical setup for HBr splitting. Although ATO, SnO2, and WO3 are endowed with similar conduction band edge energetics, in ATO the presence-of a:significant density of intrabandgap states, whose occupancy Varies with the applied potential, plays a substantial role in tuning the efficiency of photoinduced charge separation and collection. Furthermore, the investigation of the charge injection kinetics confirmed that, even in the absence of applied bias, ATO and WO3 are the best substrates for the-oxidative quenching of poorly reducing PDI excited states, with at least a fraction of them injecting within

Herein, the synthesis and the photophysical and redox properties of a new perylene bisimide (PBI) species (L), bearing two 1,10-phenanthroline (phen) ligands at the two imide positions of the PBI, and its dinuclear Ru(II) and Os(II) complexes, [(bpy)2Ru(μ-L)Ru(bpy)2](PF6)4 (Ru2; bpy = 2,2′-bipyridine) and [(Me2-bpy)2Os(μ-L)Os(Me2-bpy)2](PF6)4 (Os2; Me2-bpy = (4,4′-dimethyl)-2,2′-bipyridine), are reported. The absorption spectra of the compounds are dominated by the structured bands of the PBI subunit due to the lowest-energy spin-allowed π–π* transition. The spin-allowed MLCT transitions in Ru2 and Os2 are inferred by the absorption at 350–470 nm, where the PBI absorption is negligible. The absorption band extends towards the red region for Os2 due to the spin-forbidden MLCT transitions, intensified by the heavy osmium center. The reduction processes of the compounds are dominated by two successive mono-electronic PBI-based processes, which in the metal complexes are slightly shifted compared to the free ligand. On oxidation, both metal complexes undergo an apparent bi-electronic process (at 1.31 V vs. SCE for Ru2 and 0.77 V for Os2), attributed to the simultaneous one-electron oxidation of the two weakly-interacting metal centers. In Ru2 and Os2, the intense fluorescence of L subunit (λmax, 535 nm; τ, 4.3 ns; Φ, 0.91) is fully quenched, mainly by photoinduced electron transfer from the metal centers, on the ps timescale (time constant, 11 ps in Ru2 and 3 ps in Os2). Such photoinduced electron transfer leads to the formation of a charge-separated state, which directly decays to the ground state in about 70 ps in Os2, but produces the triplet π–π* state of the PBI subunit in 35 ps in Ru2. The results provide information on the excited-state processes of the hybrid species combining two dominant classes of chromophore/luminophore species, the PBI and the metal polypyridine complexes, and can be used for future design on new hybrid species with made-to-order properties.

A water soluble naphthalenediimide (NDI) selectively interact with small diameter single-walled carbon nanotubes (SWCNTs), as demonstrated by Raman, along with absorption and emission spectroscopies

The aggregation of a water soluble, dicationic perylene bisimide derivative was studied by means of absorption and emission spectroscopies, X-ray and neutron scattering techniques as well as electron microscopy. The results provide evidence for the existence of higher order molecular aggregates in solution, potentially utilizable in device fabrication as super molecular building blocks.

The coupling of a polycationic Mn(III)-porphyrin, with a dinuclear Mn2(II,II)L2 core (HL = 2-{[[di(2-pyridyl)methyl](methyl)amino]methyl}phenol), results in a dual Superoxide Dismutase (SOD) and Catalase (CAT) functional analogue, Mn2L2Pn+, enabling a detoxification cascade of the superoxide anion and hydrogen peroxide into benign H2O and O2. The SOD/CAT artificial manifolds, joined in one asset, exhibit a peak catalytic performance under physiological conditions, with log kcat(O2• –) ≥ 7 and kcat(H2O2)/KM = 1890. The dual-enzyme (dizyme) concept allows for a built-in self-protection against the irreversible bleaching of the porphyrin unit (>75% protection), readily induced by H2O2 (200 μM, 20 equiv, in buffer solution, pH 7.8). We show herein that incubation of the photosynthetic green algae, Chlamydomonas reinhardtii, with the synthetic dizyme (as low as 0.1 μM), prevents H2O2 accumulation under high-light illumination conditions, thus providing antioxidant surveillance and photoprotection.

Perylene-3,4,9,10-tetracarboxylic acid bisimides have been widely studied as industrial pigments. Lately, these dyes have drawn considerable attention because of applications as photocatalysts and organic semi-conductors. Here, we report a novel method for fast and efficient synthesis of many different perylenebisimides, based on microwave-assisted reactions.