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Catechols have been largely investigated as antiaggregating agents toward β-amyloid peptide. Herein, as a follow up of a previous series of hydroxycinnamic derivatives, we synthesized a small set of dihydroxy isomers for exploring the role of the reciprocal position of the two hydroxyl functions at a molecular level.

A family of dinuclear tricarbonyl rhenium (I) complexes containing bridging 1,2-diazine ligand and halide anions as ancillary ligands and able to catalyze CO2 reduction is presented. Electrochemical studies show that the highest catalytic efficiency is obtained for the complex containing the 4,5-bipenthyl-pyridazine and iodide as ancillary halogen ligands. This complex gives rise to TOF=15 s−1 that clearly outperforms the values reported for the benchmark mononuclear Re(CO)3Cl(bpy) (11.1 s−1). The role of the substituents on the pyridazine ligand and the nature of the bridging halide ligands on the catalytic activity have been deeply investigated through a systematic study on the structure-properties relationship to understand the improved catalytic efficiencies of this class of complexes.

The inhibition of the Epidermal Growth Factor (EGFR) represents one of the most promising strategies in non-small cell lung cancer (NSCLC) therapy. The recently identified C797S mutation causes resistance of EGFRsupL858R/T790M/supagainst osimertinib, the latest approved third generation EGFR inhibitor. The identification of small molecules capable of selectively inhibiting the T790M mutations also in the late-onset C797S mutation is a desirable strategy and novel chemical structures might provide new insight in the overcoming resistance mechanisms. Here we report the identification of a novel mutant-selective privileged molecular core; guided by a structure-based drug design, a flavone skeleton has been rationally modified, and a virtual library generated. Reversible EGFR inhibitors targeting both L858R/T790M and L858R/T790M/C797S mutations with a higher affinity with respect to the wild type one are discovered via a three-track virtual screening. Selected hits were synthesized and tested in an activity-based enzyme assay against wild-type EGFR, L858R/T790M, as well as L858R/T790M/C797S. The results showed that a nitroflavone-based compound inhibits the phosphorylation of EGFR mutants at low-micromolar concentration showing selectivity over the wild type ones. Structurally similar flavone analogues have been synthesized and the following inhibition assays underlied the importance of both the presence and position of the nitrophenoxy moiety.

Carbon nanotubes (CNTs) are currently under active investigation for their use in several biomedical applications, especially in neurological diseases and nervous system injury due to their electrochemical properties. Nowadays, no CNT-based therapeutic products for internal use appear to be close to the market, due to the still limited knowledge on their fate after delivery to living organisms and, in particular, on their toxicological profile. The purpose of the present work was to address the distribution in the brain parenchyma of two intranasally delivered MWCNTs (MWCNTs 1 and a-MWCNTs 2), different from each other, the first being non electroconductive while the second results in being electroconductive. After intranasal delivery, the presence of CNTs was investigated in several brain areas, discriminating the specific cell types involved in the CNT uptake. We also aimed to verify the neuroprotective potential of the two types of CNTs, delivering them in rats affected by early diabetic encephalopathy and analysing the modulation of nerve growth factor metabolism and the effects of CNTs on the neuronal and glial phenotypes. Our findings showed that both CNT types, when intranasally delivered, reached numerous brain areas and, in particular, the limbic area that plays a crucial role in the development and progression of major neurodegenerative diseases. Furthermore, we demonstrated that electroconductive MWCNTs were able to exert neuroprotective effects through the modulation of a key neurotrophic factor and probably the improvement of neurodegeneration-related gliosis.

The neutral ligand 1,2,4-triazolo[1,5-a]pyrimidine (tp) has been employed to prepare a new coordination compound of Fe(III), [FeCl3(tp)2]n (1). Compound 1 was investigated by single crystal X-ray diffraction and found to be a coordination polymer forming a ladder structure based on metal–ligand interactions, while H-bonding and aromatic interactions contribute to the supramolecular self-assembly into a 3D nanostructured material. The polymeric assembly is retained also in solution, where a metallo-supramolecular polymer based on coordinative metal–ligand binding is present, as shown by dynamic light scattering (DLS) measurements. The redox properties of the Fe(III) coordination polymer have also been investigated in different solvents and its nanowire structure has been assessed by Atomic Force Microscopy (AFM) imaging of the species deposited onto a freshly cleaved mica surface.

The synthesis of π‐extended porphyrins containing anthracenyl moieties still represents an important challenge. Here, we report on the synthesis of a series of unsubstituted naphthyl‐, pyrenyl‐ and anthracenyl‐fused zinc porphyrin derivatives. To this aim, meso‐substitued porphyrins are synthesized and the fusion of the PAHs (Polycyclic Aromatic Hydrocarbon) on the β‐positions are performed through thermally induced dehydro‐aromatization. The fused zinc‐porphyrin derivatives are fully characterized and their optical absorption and photoluminescence properties are reported. We also demonstrate that zinc can be removed from the porphyrin core, giving rise to pure C, H, N materials. This work constitutes the first step towards the synthesis of the fully‐fused tetra‐anthracenylporphyrin., A series of π‐extented porphyrins are synthesized by thermal cyclodehydrogenation of porphyrins functionalized with unsubstituted PAHs. The fused porphyrin derivatives can be demetalated to give rise to the unsubstituted and metal‐free porphyrin dyes.

Planar and curved polycyclic aromatic hydrocarbons (PAHs) represent an interesting class of compounds with physical chemical properties particularly appealing, as good organic semiconductors and molecular model of larger carbon nano- structures. Investigation of the heterogeneous electron transfer in these systems lets to probe their electronic properties and the reactivity of the corresponding generated carbanions and carbocations that can form new bonds, thus leading to different carbon systems. A particular focus is on the intrinsically high reactivity of carbocations which induces a series of reactions building up new carbon–carbon bonds, thus allowing to enlarge the initial molecular unit into a nanostructure. This represents a new and convenient way to exploit the electro- chemically triggered reactivity into the synthesis of carbon nanostructured materials.

Synthetic nitrone spin-traps are being explored as therapeutic agents for the treatment of a wide range of oxidative stress-related pathologies, including but not limited to stroke, cancer, cardiovascular, and neurodegenerative diseases. In this context, increasing efforts are currently being made to the design and synthesis of new nitrone-based compounds with enhanced efficacy. The most researched nitrones are surely the ones related to α-phenyl-tert-butylnitrone (PBN) and 5,5-dimethyl-1-pyrroline N-oxide (DMPO) derivatives, which have shown to possess potent biological activity in many experimental animal models. However, more recently, nitrones with a benzoxazinic structure (3-aryl-2H-benzo[1,4]oxazin-N-oxides) have been demonstrated to have superior antioxidant activity compared to PBN. In this study, two new benzoxazinic nitrones bearing an electron-withdrawing methoxycarbonyl group on the benzo moiety (in para and meta positions respect to the nitronyl function) were synthesized. Their in vitro antioxidant activity was evaluated by two cellular-based assays (inhibition of AAPH-induced human erythrocyte hemolysis and cell death in human retinal pigmented epithelium (ARPE-19) cells) and a chemical approach by means of the α,α-diphenyl-β-picrylhydrazyl (DPPH) scavenging assay, using both electron paramagnetic resonance (EPR) spectroscopy and UV spectrophotometry. A computational approach was also used to investigate their potential primary mechanism of antioxidant action, as well as to rationalize the effect of functionalization on the nitrones reactivity toward DPPH, chosen as model radical in this study. Further insights were also gathered by exploring the nitrone electrochemical properties via cyclic voltammetry and by studying their kinetic behavior by means of EPR spectroscopy. Results showed that the introduction of an electron-withdrawing group in the phenyl moiety in the para position significantly increased the antioxidant capacity of benzoxazinic nitrones both in cell and cell-free systems. From the mechanistic point of view, the calculated results closely matched the experimental findings, strongly suggesting that the H-atom transfer (HAT) is likely to be the primary mechanism in the DPPH quenching.

Chiral electroanalysis could be regarded as the highest recognition degree in electrochemical sensing, implying the ability to discriminate between specular images of an electroactive molecule, particularly in terms of significant peak potential difference. A groundbreaking strategy was recently proposed, based on the use of "inherently chiral" molecular selectors, with chirality and key functional properties originating from the same structural element. Large differences in peak potentials have been observed for the enantiomers of different chiral molecules, also of applicative interest, using different selectors, all of them based on atropisomeric biheteroaromatic scaffolds of axial stereogenicity. However, helicene systems also provide inherently chiral building blocks with attractive features. In this paper the enantiodiscrimination performances of enantiopure inherently chiral films obtained by electrooxidation of a thiahelicene monomer with helicoidal stereogenicity are presented for the first time. The outstanding potentialities of this novel approach are evaluated towards chiral probes with different chemical nature and bulkiness, in comparison with a representative case of the so far exploited class of inherently chiral selectors with axial stereogenicity. It is also verified that the high enantiodiscrimination ability holds as well for electron spins, as for atropisomeric selectors.

The impact of nanotechnology and nanosystems on analytical science is hardly overlooked. In the search for ever-increasing sensitivity in biomedical sensors, nanoparticles have been playing a unique role as, e.g., ultrabright labels in clinical analysis (markers, tumor cells, and pharmaceuticals) and in the detection of pathogenic microorganisms, toxic agents, and pesticides in the environmental field and food products. Coupling such nanosystems with electrochemiluminescence (ECL), which naturally brings improved signal-to-noise ratio compared to photoluminescence, with minimized effects due to light scattering and luminescence background, has brought about new systems and strategies for analytes determination, even in very complex matrices, such as urine, blood or lysate. Among the several nanosystems, dye-doped silica nanoparticles (DDSNs) have proved as very promising and versatile nanomaterials in ECL-based bioanalytical platforms. The increase of the number of complexes active in the generation of the ECL signals together with an even larger increase in the signal stability, represents in fact a promising strategy towards ultrasensitive ECL. Approaches based on ECL generation on the nanoscale using luminophore-reporter-modified DNA-based nanoswitches (i.e., molecular beacon) has been additionally investigated and, in this context, the development of innovative amplification-free detection methods represents a significant breakthrough compared to existing PCR-based methodologies, allowing the integration of nucleic acid detection on portable and low-cost sensor devices, and enabling the massive diagnostic screening.

A donor/acceptor dyad was obtained by linking Nile Red and fullerene to a calix[4]arene scaffold. The dyad was spectroscopically characterized, both with steady-state and ultrafast transient absorption experiments, as well as with electrochemical and spectroelectrochemical techniques. We demonstrate extremely fast and efficient formation of a long-lived excited triplet localized on the fullerene moiety in this system, occurring in about 80 ps in toluene and 220 ps in chloroform. The mechanism of this process is investigated and discussed. The spectroscopic and electrochemical characterization suggests the occurrence of electron transfer from Nile Red to fullerene, leading to the formation of a charge-separated state. This state lives very briefly and, because of the small interaction between the electron donor and acceptor, promotes a singlet/triplet state mixing, inducing charge recombination and efficient triplet formation.

Electrochemiluminescence (ECL) is a powerful transduction technique that has rapidly gained importance as a powerful analytical technique. Since ECL is a surface-confined process, a comprehensive understanding of the generation of ECL signal at a nanometric distance from the electrode could lead to several highly promising applications. In this work, we explored the mechanism underlying ECL signal generation on the nanoscale using luminophore-reporter-modified DNA-based nanoswitches (i.e., molecular beacon) with different stem stabilities. ECL is generated according to the "oxidative-reduction" strategy using tri-n-propylamine (TPrA) as a coreactant and Ru(bpy)32+ as a luminophore. Our findings suggest that by tuning the stem stability of DNA nanoswitches we can activate different ECL mechanisms (direct and remote) and, under specific conditions, a "digital-like" association curve, i.e., with an extremely steep transition after the addition of increasing concentrations of DNA target, a large signal variation, and low preliminary analytical performance (LOD 22 nM for 1GC DNA-nanoswtich and 16 nM for 5GC DNA-nanoswitch). In particular, we were able to achieve higher signal gain (i.e., 10 times) with respect to the standard "signal-off" electrochemical readout. We demonstrated the copresence of two different ECL generation mechanisms on the nanoscale that open the way for the design of customized DNA devices for highly efficient dual-signal-output ratiometric-like ECL systems.

The presence of non-hexagonal rings in the honeycomb carbon arrangement of graphene produces rippled graphene layers with valuable chemical and physical properties. In principle, a bottom-up approach to introducing distortion from planarity of a graphene sheet can be achieved by careful insertion of curved polyaromatic hydrocarbons during the growth of the lattice. Corannulene, the archetype of such non-planar polyaromatic hydrocarbons, can act as an ideal wrinkling motif in 2D carbon nanostructures. Herein we report an electrochemical bottom-up method to obtain egg-box shaped nanographene structures through a polycondensation of corannulene that produces a new conducting layered material. Characterization of this new polymeric material by electrochemistry, spectroscopy, electron microscopy (SEM and TEM), scanning probe microscopy, and laser desorption-ionization time of flight mass spectrometry provides strong evidence that the anodic polymerization of corannulene, combined with electrochemically induced oxidative cyclodehydrogenations (Scholl reactions), leads to polycorannulene with a wavy graphene-like structure., A bottom-up synthesis of wavy graphene structures obtained through an anodic polymerization process, combined with an electrochemically triggered oxidative cyclodehydrogenation, of the bowl-shaped polyaromatic hydrocarbon corannulene.

Electrochemiluminescence (ECL) is a powerful transduction technique with a leading role in the biosensing field due to its high sensitivity and low background signal. Although the intrinsic analytical strength of ECL depends critically on the overall efficiency of the mechanisms of its generation, studies aimed at enhancing the ECL signal have mostly focused on the investigation of materials, either luminophores or coreactants, while fundamental mechanistic studies are relatively scarce. Here, we discover an unexpected but highly efficient mechanistic path for ECL generation close to the electrode surface (signal enhancement, 128%) using an innovative combination of ECL imaging techniques and electrochemical mapping of radical generation. Our findings, which are also supported by quantum chemical calculations and spin trapping methods, led to the identification of a family of alternative branched amine coreactants, which raises the analytical strength of ECL well beyond that of present state-of-the-art immunoassays, thus creating potential ECL applications in ultrasensitive bioanalysis., Electrochemiluminescence (ECL) is a leading technique in biosensing. Here the authors identify an ECL generation mechanism near the electrode surface, which they exploit in combination with the use of branched amine coreactants to improve the ECL signal beyond the state-of-the-art immunoassays.

Electrochemiluminescence (ECL) is a leading technique in bioanalysis.[1] It is a luminescent phenomenon where the excited species are produced with an electrochemical stimulus rather than with a light excitation source. For this reason, ECL displays improved signal-to-noise ratio compared to photoluminescence, with minimized effects due to light scattering and luminescence background.[2] Chasing ever-increasing sensitivities, ECL can ideally be coupled to nanotechnology to develop new strategies for clinical applications and analyte determination also in real and complex matrices.[3] In particular, dye-doped silica nanoparticles (DDSNs) present many advantages: they can be easily synthesized, are hydrophilic and are prone to bioconjugation thanks to silica chemistry. With this approach we were able to achieve extremely bright systems and DDSNs allow the 8.5 fold increase of ECL intensity.[4] In DDSNs, light emission is influenced by the combination of several factors that make DDSNs complex multichromophoric structures. However, when ECL comes into play, the scenario is even more complicated due to the coreactant−NP interactions effect. Such complex scenario was approached at the theoretical level by developing suitable mechanistic models for ECL generation[5] while, at the same time, the influence of doping level on ECL efficiency was evaluated. Our results showed that the ECL intensity of a nanosized system cannot be merely incremented acting on doping, since other parameters come into play. These studies support the application in ECL microscopy providing valuable indications for the design of more efficient ECL nano- and micro-sized labels towards more sensitive ECL-based immunoassay for bioanalysis applications. [6] References [1] W. Miao, “Electrogenerated Chemiluminescence and Its Biorelated Applications”, Chem. Rev., 2008, vol. 108, pp. 2506–2553. [2] Z. Liu, W. Qi, G. Xu, “Recent advances in electrochemiluminescence”, Chem. Soc. Rev., 2015, vol. 44, pp. 3117–3142. [3] C. Ma, Y. Cao, X. Gou, J. J. Zhu, “Recent progress in electrochemiluminescence sensing and imaging”, Anal. Chem., 2015, vol. 92, pp. 431-454. [4] G. Valenti, E. Rampazzo, S. Bonacchi, L. Petrizza, M. Marcaccio, M. Montalti, L. Prodi, F. Paolucci, “Variable Doping Induces Mechanism Swapping in Electrogenerated Chemiluminescence of Ru(bpy) 3 2+ Core–Shell Silica Nanoparticles”, J. Am. Chem. Soc., 2016, vol. 138, pp. 15935–15942. [5] E. Daviddi, A. Oleinick, I. Svir, G. Valenti, F. Paolucci, C. Amatore, “Theory and Simulation for Optimising Electrogenerated Chemiluminescence from Tris(2,2′-bipyridine)-ruthenium(II)-Doped Silica Nanoparticles and Tripropylamine”, ChemElectroChem, 2017, vol. 4, pp. 1719–1730. [6] A. Zanut, F. Palomba, M. Rossi Scota, S. Rebeccani, M. Marcaccio, D. Genovese, E. Rampazzo, G. Valenti, F. Paolucci, L. Prodi, "Dye‐Doped Silica Nanoparticles for Enhanced ECL‐Based Immunoassay Analytical Performance", Angew. Chemie Int. Ed., 2020, vol. 132, pp. 22042-22047 Figure 1

Salophens and Salens are Schiff bases generated through the condensation of two equivalents of salicylaldehyde with either 1,2-phenylenediamines or aliphatic diamines, respectively. Both ligands have been extensively exploited as key building blocks in coordination chemistry and catalysis. In particular, their metal complexes have been widely used for various catalytical transformations with high yield and selectivity. Through the modification of the phenol unit it is possible to tune the steric hindrance and electronic properties of Salophen and Salen. The introduction of long aliphatic chains in salicylaldehydes can be used to promote their self-assembly into ordered supramolecular structures on solid surfaces. Herein, we report a novel method towards the facile synthesis of robust and air-stable [Al(Salophen)] derivatives capable of undergoing spontaneous self-assembly at the graphite/solution interface forming highly-ordered nanopatterns. The new synthetic approach relies on the use of [MeAlIII (Salophen)] as a building unit to introduce, via a simple acid/base reaction with functionalized acidic phenol derivatives, selected frameworks integrating multiple functions for efficient surface decoration. STM imaging at the solid/liquid interface made it possible to monitor the formation of ordered supramolecular structures. In addition, the redox properties of the Salophen derivatives functionalized with ferrocene units in solution and on surface were unraveled by cyclic voltammetry. The use of a five-coordinate aluminum alkyl Salophen precursor enables the tailoring of new Salophen molecules capable of undergoing controlled self-assembly on HOPG, and thereby it can be exploited to introduce multiple functionalities with subnanometer precision at surfaces, ultimately forming ordered functional patterns.

A comparison was made between two plant peroxidases, cationic horseradish peroxidase (HRP) and anionic tobacco peroxidase (TOP), combined with a highly cationic osmium polymer [Os(4,4′-dimethyl-2,2′-bipyridine)2poly(N-vinylimidazole)10Cl]+ 2/+([Os(dmp)PVI]+/2 +) to develop highly sensitive, stable and selective hydrogen peroxide biosensors. The two different plant peroxidases were individually immobilized onto graphite rod (G) electrodes by a three steps drop-casting procedure consisting of the subsequent deposition of an aqueous solution of ([Os(dmp)PVI]+/2 +), followed by a solution of poly(ethyleneglycol) diglycidyl ether (PEGDGE), used as a cross linking agent and finally an aliquot of a solution of cationic HRP or anionic TOP to make HRP/PEGDGE/[Os(dmp)PVI]+/2 +/G and TOP/PEGDGE/[Os(dmp)PVI]+/2 +/G based electrodes, respectively. Electrochemical experiments were carried out to investigate the influence of the surface charge of the enzyme and the charge of the polymer on the efficiency of the electron transfer (ET) between the enzyme and the wiring redox polymer and the efficiency for electrocatalytic reduction of H2O2. In the case of HRP a decrease in the ET rate was observed due to the repulsion between this enzyme and the polymer, both positively charged, whereas with TOP there was an enhanced ET rate due to the attraction between the anionic enzyme and the cationic polymer. The effects of enzyme loading and pH were investigated. Both peroxidase modified electrodes exhibited a wide dynamic response range (1–500 μM H2O2) and a low detection limit (0.3 μM H2O2). The TOP based electrode showed a higher sensitivity (470 nA μM− 1cm− 2) compared to that of the HRP based electrode (300 nA μM− 1cm− 2) and an improved long-term stability (decrease in 17.3% upon 30 days compared with 50% for HRP). Both enzyme electrodes showed a response time of 3 s. The HRP based sensor was more sensitive to the presence of phenolic compounds acting as alternative electron donors, whereas the TOP based sensor was virtually interference free. Both HRP and TOP based electrodes were successfully tested in contact lens cleaning samples and real “spiked” samples from different sources such as tap water, milk and dairy products.

The n-type organic semiconductor phenyl-C61-butyric acid methyl ester (PCBM), a soluble fullerene derivative well investigated for organic solar cells and transistors, can undergo several successive reversible, diffusion-controlled, one-electron reduction processes. We exploited such processes to shed light on the correlation between electron transfer properties, ionic and electronic transport as well as device performance in ionic liquid (IL)-gated transistors. Two ILs were considered, based on bis(trifluoromethylsulfonyl)imide [TFSI] as the anion and 1-ethyl-3-methylimidazolium [EMIM] or 1-butyl-1-methylpyrrolidinium [PYR14] as the cation. The aromatic structure of [EMIM] and its lower steric hindrance with respect to [PYR14] favor a 3D (bulk) electrochemical doping. As opposed to this, for [PYR14] the doping seems to be 2D (surface-confined). If the n-doping of the PCBM is pursued beyond the first electrochemical process, the transistor current vs. gate-source voltage plots in [PYR14][TFSI] feature a maximum that points to the presence of finite windows of high conductivity in IL-gated PCBM transistors.

Targeted delivery of vitamins to a desirable area is an active branch in a modern pharmacology. The most important and difficult delivery of vitamin B

Immunoassay is probably the primary in vitro technique employed in medical diagnostics. Its different setups include often the well-known and sensitive analytical method based on electrochemiluminescence (ECL), and approaches relying on nanotechnology have the potentiality to further enhance ECL signal response and detection capability. With this intent, we studied the ECL behavior of dye-doped silica-poly(ethylene glycol) core-shell nanoparticles (DDSNPs) doped with neutral Ru(II) complexes in a very large doping range. We found that nanoparticles maintain comparable morphology and dimensions as the amount of Ru(II) neutral complexes that are covalently linked to their silica matrix increases; meanwhile, ECL shows an enhanced response. The 9-fold ECL signal amplification obtained when compared with [Ru(bpy)3]2+-doped silica nanoparticles is due to the synergy between the behavior of neutral Ru(II) complex and the DDSNP architecture: these results pave the way for the development of more efficient probes in ECL technology.

Targeted delivery of vitamins to a desirable area is an active branch in a modern pharmacology. The most important and difficult delivery of vitamin B12 is that to bone marrow and nerve cells. Herein we present a first step towards the development of two types of smart carriers, polymer capsules and lyotropic liquid-crystalline nanosystems, for vitamin B12 targeted delivery and induced release. A vitamin B12 encapsulation technique into nanoengineered polymeric capsules produced by layer-by-layer assembling of polymeric shells on CaCO3 templates has been developed. The effectiveness of the process was demonstrated by optical absorption spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and small-angle X-ray diffraction. TEM and AFM analyses performed on capsules after their drying, confirmed the presence of the vitamin B12 inside the capsules in the form of crystalline nanoaggregates, 50–300 nm in diameter. Soft lipid nanovectors consisting of amphiphilic phytantriol molecules, which in water excess spontaneously self-assembly in 3D well-ordered inverse bicontinuous cubic bulk phase, were used as alternative carriers for vitamin B12. It was shown that about 30% of the vitamin added in the preparation of the soft lipid system was actually encapsulated in cubosomes and that no structural changes occurred upon loading. The Vitamin stabilizes the lipid system playing the role of its structure-forming element. The biocompatible nature, the stability and the feasibility of these systems make them good candidates as carriers for hydrophilic vitamins.

Electrochemiluminescence (ECL) is a leading technique in bioanalysis.[1] Since the excited species are produced with an electrochemical stimulus rather than with a light excitation source, ECL displays improved signal-to-noise ratio compared to photoluminescence, with minimized effects due to light scattering and luminescence background. The most challenging breakthrough in the development of analytical electrochemiluminescence (ECL) applications was reported from Bard and co workers that presented for the first time the generation of ECL with a coreactant.[1] This finding opened the application of ECL to large literature and transformed ECL from an academic curiosity to a real application and industrial success. In this context, the only real used materials for the ECL analytical and commercial application are tripropylamine (TPrA) as sacrificial ”oxidative-reductant” coreactant and Ruthenium(II)-tris(2,2’-bipyridine) ([Ru(bpy)3]2+) as emitting species. In this case the mechanism for the ECL generation was proposed by Bard and still nowadays the only one accepted.[2],[3] Here we show an additional, and very efficient, mechanism pathway for the generation of ECL by using TPrA as coreactant. Thanks to the combination between ECL and microscopy we experimentally prove the alternative mechanism with the standard [Ru(bpy)3]2+/TPrA system.[3],[4] These mechanistic findings allow us to propose alternative amines as coreactant enhancing the ECL signal of more than one order of magnitude. The reported results, besides contributing to a better understanding of the mechanisms operating in the chemiluminescence generation, also pave the way for the development of very highly efficient ECL coreactants for ultrasensitive bioanalysis.[5] [1] Miao W.; Choi J. P.; Bard A. J., J. Am. Chem. Soc. 2002, 124, 14478-14485 [2] Sentic M.; Milutinovic M.; Kanoufi F.; Manojlovic D.; Arbault S.; Sojic N., Chem. Sci. 2014, 5, 2568-2572 [3] Valenti G.; Scarabino S.; Goudeau B.; Lesch A.; Jović M.; Villani E.; Sentic M.; Rapino S.; Arbault S.; Paolucci F.; Sojic N., J. Am. Chem. Soc. 2017, 139, 16830-16837. [4] a) Valenti G.; Zangheri M.; Sansaloni S. E.; Mirasoli M.; Penicaud A.; Roda A.; Paolucci F., Chem. Eur. J., 2015, 21, 12640–12645; b) Zanut A.; Fiorani A.; Rebeccani S.; Kesarkar S.; Valenti G., Anal. Bioanal. Chem., 2019, 411(19), 4375-4382. [5] Zanut A. at al Nature Commun. 2020, 11, 2668 Figure 1

Different substituted ferrocene–guanine conjugates were prepared, and their electrochemical behavior was investigated. A new approach for the introduction of ferrocene in guanine’s 9-position through a quite effective SN1-type reaction was disclosed. The electrochemical behavior of the various derivatives can be used as standard for the quantification and analysis of DNA strands.

A donor acceptor dyad composed of a BF2-chelated dipyrromethene (BODIPY) and a C-60 fullerene has been newly synthesized and characterized. The two moieties are linked by direct addition of an azido substituted BODIPY on the C-60, producing an imino fullerene BODIPY adduct. The photoinduced charge transfer process in this system was studied by ultrafast transient absorption spectroscopy. Electron transfer toward the fullerene was found to occur selectively exciting both the BODIPY chromophore at 475 nm and the C-60 unit at 266 nm on a time scale of a few picoseconds, but the dynamics of charge separation was different in the two cases. Eletrochemical studies provided information on the redox potentials of the involved species and spectroelectrochemical measurements allowed to unambiguously assign the absorption band of the oxidized BODIPY moiety, which helped in the interpretation of the transient absorption spectra. The experimental studies were complemented by a theoretical analysis based on DFT computations of the excited state energies of the two components and their electronic couplings, which allowed identification of the charge transfer mechanism and rationalization of the different kinetic behavior observed by changing the excitation conditions.

Tuning the intermolecular interactions among suitably designed molecules forming highly ordered self-assembled monolayers is a viable approach to control their organization at the supramolecular level. Such a tuning is particularly important when applied to sophisticated molecules combining functional units which possess specific electronic properties, such as electron/energy transfer, in order to develop multifunctional systems. Here we have synthesized two tetraferrocene-porphyrin derivatives that by design can selectively self-assemble at the graphite/liquid interface into either face-on or edge-on monolayer-thick architectures. The former supramolecular arrangement consists of two-dimensional planar networks based on hydrogen bonding among adjacent molecules whereas the latter relies on columnar assembly generated through intermolecular van der Waals interactions. Scanning Tunneling Microscopy (STM) at the solid-liquid interface has been corroborated by cyclic voltammetry measurements and assessed by theoretical calculations to gain multiscale insight into the arrangement of the molecule with respect to the basal plane of the surface. The STM analysis allowed the visualization of these assemblies with a sub-nanometer resolution, and cyclic voltammetry measurements provided direct evidence of the interactions of porphyrin and ferrocene with the graphite surface and offered also insight into the dynamics within the face-on and edge-on assemblies. The experimental findings were supported by theoretical calculations to shed light on the electronic and other physical properties of both assemblies. The capability to engineer the functional nanopatterns through self-assembly of porphyrins containing ferrocene units is a key step toward the bottom-up construction of multifunctional molecular nanostructures and nanodevices.

The Oxygen Reduction Reaction (ORR) is a fundamental process for sustaining life as well as it is utilized in the field of energy conversion and biosensing analysis. The process, exploited in fuel cells and metal-air based batteries, proceeds at a very slow kinetic rate requiring a catalyst to reduce the activation barrier. Platinum is an ideal catalyst but it is neither cheap nor environmentally friendly. The prospect of an alternative to Platinum is intriguing and has yielded considerable research in the past decade. Amongst the most promising materials as catalysts, carbon-based systems, such as carbon nanotubes (CNT) and graphene derivatives, are particularly intriguing. Synthetic strategies allow to produce tunable graphene-based materials, starting from graphene oxide (GO) and reducing the oxidized groups of GO, in presence of compounds capable of adding functional groups or heteroatoms to the carbon lattice. We were particularly interested in the material obtained by doping GO with nitrogen and boron through its reduction in presence of idrazine and borazine. Such doped reduced graphene oxides (rGO) show almost the same electronic properties as graphene, with some X-C (X= N or B) regions within the graphene lattice that have a useful dipole moment which helps the interaction between the oxygen molecule and the catalytic substrate; thus, such sites represent those active for the ORR catalysis. We report here the investigation of the electrochemical behavior of a selection of such material and their electrocatalytic activity for the ORR.

Carbon nanostructures, such as nanotubes and graphenes, represent a very promising class of new materials in the field of nanotechnology. In principle, graphenes could be obtained following a bottom-up approach by synthesizing large polycyclic aromatic hydrocarbons (nanographenes) starting from suitable precursors. Their subsequent intermolecular condensation into progressively more extended structures can produce macroscopic graphene films. Amongst the polycyclic aromatic hydrocarbons, Corannulene is a bowl-shaped species recalling the fullerene surface. It is particularly intriguing, for its unique redox and luminescent properties, to develop new materials. The electrochemical reduction and oxidation processes have been reinvestigated in our lab over a large range of experimental conditions. Concerning the oxidation, it is completely irreversible and this brings about a rapid fouling and passivation of the electrode surface. The adoption of suitable solvents and electrolytes, with very high oxidation resistance and low nucleophilicity, allowed to explore the reactivity of the electrogenerated corannulene carbocations. The interesting redox, spectroelectrochemical, luminescence and electrochemiluminesce properties of corannulene and derivative species, together with the structure of their electrochemically generated films, will be discussed.

The electrochemiluminescence (ECL) performances were comparatively investigated at flat and nanoporous gold (NPG) electrodes of different thicknesses (120 and 200 nm) and roughness factors (fr). The phenomena were studied using either tripropylamine (TPrA) or peroxydisulfate (S2O82−) as sacrificial coreactant and Ruthenium (II)-tris(2,2′-bipyridine) as emitting species. The experiments performed using TPrA showed, at first glance, a linear dependence of the ECL emission with respect to the effective surface area of the NPG electrodes. However, ECL signals were not stable in the measuring conditions, presumably due to amine absorption on the metal surface, leading to electrode corrosion and modification of the surface morphology. The experiments made using peroxydisulfate as coreactant provided conversely a stable ECL response, about proportional to the effective electrode surface area, in the considered range of thicknesses.

Summary Electrochemiluminescence (ECL) is luminescence induced by an electrochemical stimulus. As an analytical technique, ECL represents an ideal marriage between electrochemical and spectroscopic methods. In this review, we highlight some of the most recent developments in the field of ECL employing doped nanomaterials as emitters, particularly the strategies to design-doped nanomaterials and the advantage of their use over single luminophores for ECL signal enhancement, which is desirable for highly sensitive bio- and immuno-assays as well as environmental investigations.

The coupling of nanomaterials, and nanoparticles in particular, with one of the most powerful transduction techniques, electrochemiluminescence (ECL), i.e., chemiluminescence triggered by electrochemical reactions at electrodes, has recently provided sensing tools with unprecedented sensitivity limits. This review aims to give an overview of the state of the art in the field over the last 5 years, i.e., a time span covering over 80% of the scientific production in this context. The results herein discussed would demonstrate that the use of nanoparticles in the ECL technique represents one of the most interesting research lines for the development of ultrasensitive analytical tools, offering an insight to recognize and select the best nanomaterials for ECL signal amplification, with particular emphasis in biosensing. (C) 2018 Elsevier B.V. All rights reserved.

The electrochemistry of a family of recently synthesized isoalloxazine cyclophanes containing anthraquinones, variously substituted and linked by aliphatic chains of different lengths, has been studied. The redox behavior of such species was elucidated by complementing the voltammetric studies with DFT molecular modelling. In these cyclophanes (mimicking the active centers of enzymes), the distance between chromophores and their reciprocal orientations were found to significantly modify their redox properties. Inter-moiety π−π stacking plays an important role in the electrochemical behavior by modulating the orbital energies, which leads to an inversion of the localization of the first reduction, with the anthraquinone being reduced before the more electron-accepting flavine.

The history of light emission triggered by electrochemical reactions, the so-called electrogenerated chemiluminescence (ECL), spans over 50 years and the relevance of the molecular approach to the development of the field can hardly be overlooked. Molecular electrochemists’ contribution has mainly focused on unraveling fundamental aspects associated to the mechanisms of ECL as well as on singling out new luminophores/coreactants systems to achieve higher efficiency and stability, with important consequences in the analytical exploitation of this technique. The latest and most important investigations on electrogenerated chemiluminescence which concern, in particular, inorganic and organic luminophores and the relevant mechanistic models and simulations are briefly reviewed.

Molecular and electronic structure, reduction electron transfer and coordination abilities of a polycyclic aromatic hydrocarbon (PAH) having a planar naphtho-group fused to the corannulene bowl have been investigated for the first time using a combination of theoretical and experimental tools. A direct comparison of naphtho[2,3-a]corannulene (C28 H14 , 1) with parent corannulene (C20 H10 , 2) revealed the effect of framework topology change on electronic properties and aromaticity of 1. The presence of two reduction steps for 1 was predicted theoretically and confirmed experimentally. Two reversible one-electron reduction processes with the formal reduction potentials at -2.30 and -2.77 V versus Fc+/0 were detected by cyclic voltammetry (CV) measurements, demonstrating accessibility of the corresponding mono- and dianionic states of 1. The products of the singly and doubly reduced napththocorannulene were prepared using chemical reduction with Group 1 metals and isolated as sodium and rubidium salts. Their X-ray diffraction study revealed the formation of "naked" mono- and dianions crystallized as solvent-separated ion products with one or two sodium cations as [Na+ (18-crown-6)(THF)2 ][C28 H14- ] and [Na+ (18-crown-6)(THF)2 ]2 [C28 H142- ] (3⋅THF and 4⋅THF, respectively). The dianion of 1 was also isolated as a contact-ion complex with two rubidium countercations, [{Rb+ (18-crown-6)}2 (C28 H142- )] (5⋅THF). The structural consequences of adding one and two electrons to the carbon framework of 1 are compared for 3, 4 and 5. Changes in aromaticity and charge distribution stemming from the stepwise electron acquisition are discussed based on DFT computational study.

In the present work we numerically simulated the electrogenerated chemiluminescence (ECL) from a Ru(bpy)32+-doped silica nanoparticle (Ru-DSNP) in buffer containing tripropylamine (TPrA). Experimental study reported from Zanarini et al showed that ECL intensity for the Ru-DSNP/TPrA system exhibits two emission waves while the potential of working electrode is swept in positive direction. The first ECL wave with a peak at ~0.9 V (vs. Ag|AgCl) is triggered by TPrA oxidation and is governed by the deprotonation equilibrium of TPrA cation radical (TPrA•+ = TPrA• + H+). We present a model for the description of the first ECL wave, which also takes in consideration the influence on the deprotonation equilibrium of the electrode surface functionality. This model indicated that the detachment of a Ru-DSNP (initially bound to the electrode surface via alkylthiols linkers) from the electrode surface and the subsequent electrode surface oxidation facilitate the radical deprotonation on the electrode surface causing the ECL quenching. The second ECL wave having its peak at ~1.2 V is triggered by direct Ru(bpy)32+ oxidation. We modeled the second ECL wave as related to the electron hopping mechanism between Ru(bpy)32+ labels inside the Ru-DSNP. The results of the numerical simulations indicate that electrode surface functionality modification, which occurs during potential sweep, and the electron hopping mechanism between Ru(bpy)32+ labels play important roles in defining the Ru-DSNP/TPrA ECL signal

Self-assembled monolayers (SAMs) are widely used in the field of nanotechnologies and (bio)sensors. The monolayer surface properties are tailored by employing several techniques. A large set of SAM post-modification routes are commonly performed to adapt them to a variety of nano-technological and bio-technological studies as well as to several bio-sensoristic applications. Here, we report a procedure to locally modify SAMs by electrochemical desorption of alkanethiols in order to create microsized spots of bare gold area without affecting the surrounding monolayer stability. The tip of the scanning electrochemical microscope (SECM) was employed to draw microstructured pattern according to a defined geometry. The time stability of the pattern was also tested. Furthermore, the patterned surface was post-functionalized using the same alkanethiol or a ferrocene-terminated thiol, in order to tune the surface reactivity of the microstructure. The local surface properties, including reactivity and electron transfer kinetics toward redox mediator reduction, were characterized by SECM.