External trigeminal neurostimulation in patients with chronic migraine.

Aim: To assess the safety and efficacy of external trigeminal neurostimulation (e-TNS) as an add-on treatment in chronic migraine (CM) prophylaxis. Materials & methods: A prospective observational open-label study was conducted on CM patients observed at baseline and 3 months after starting daily sessions of 20 min with e-TNS (Cefaly®). Results: A total of 24 volunteers affected by CM according to the ICHD-3 were included. At the 3 month follow-up, a >30% reduction of headache days was observed in four (16.5%) of 24 patients; a marginal headache improvement was observed in ten (42%) patients, with no or minor adverse effects (four of 24 patients). Conclusion: e-TNS may constitute a safe preventive treatment in CM, its limited efficacy is not statistically significant.

Migraine is one of the most prevalent and disabling diseases in the world. In chronic migraine cases, patients have headache ≥15 days/month, of which at least eight are migraines, for >3 months and often develop a medication overuse headache because of the excessive intake of drugs. Preventive therapies include, among others, peripheral nerve stimulation. In our study, 24 patients affected by chronic migraine were asked to use a peripheral nerve stimulation device (Cefaly^®) for 20 min daily for 3 months. During this period, we evaluated the efficacy and safety of the treatment using specific headache diaries in which patients collect information about their symptoms and disability. Our results show a limited and not statistically significant reduction in headache days in a group of patients ('responders') without serious adverse reactions.

Does the bank-firm human relationship still matter for SMEs? The game-changing role of digitalization.

Noteworthy contributions have highlighted that human contact is a considerable factor in bank-firm relationships. It allows the acquisition of soft information, which alleviates information asymmetries and increases the use of bank debt. The advent of digital technologies in the information collection process open new horizons and change the role of personal contacts in bank-firm interactions, as entrepreneurs visit bank branches less frequently. This study uses a large sample of Italian SMEs from 2011 to 2020 and finds that the rapid increase and use of digital instruments have reduced the positive influence of physical closeness between banks and SMEs on the indebtedness levels. Interestingly, our study has also found that the COVID-19 crisis did not amplify this moderating effect. Results support theories that human contact is an important factor in bank-firm relationships because it allows the acquisition of soft information, which alleviates information asymmetries and increases the use of bank debt. Our study suggests that close human ties are still extremely relevant and digitalization should be exploited to support the collection of the kind of qualitative soft information that is crucial in debt negotiations.

Boron Nitride-Doped Polyphenylenic Organogels.

Herein, we describe the synthesis of the first boron nitride-doped polyphenylenic material obtained through a [4 + 2] cycloaddition reaction between a triethynyl borazine unit and a biscyclopentadienone derivative, which undergoes organogel formation in chlorinated solvents (the critical jellification concentration is 4% w/w in CHCl3). The polymer has been characterized extensively by Fourier-transform infrared spectroscopy, solid-state 13C NMR, solid-state 11B NMR, and by comparison with the isolated monomeric unit. Furthermore, the polymer gels formed in chlorinated solvents have been thoroughly characterized and studied, showing rheological properties comparable to those of polyacrylamide gels with a low crosslinker percentage. Given the thermal and chemical stability, the material was studied as a potential support for solid-state electrolytes. showing properties comparable to those of polyethylene glycol-based electrolytes, thus presenting great potential for the application of this new class of material in lithium-ion batteries.

Supramolecular template-directed synthesis of triazole oligomers.

Sandwich complexes formed by two zinc porphyrins and a diamine ligand (DABCO) have been used as a supramolecular template to direct the synthesis of triazole oligomers. Monomer units equipped with two polymerizable functional groups, an alkyne and an azide, were attached to the template via ester bonds between a phenol unit on the monomer and benzoic acid units on the porphyrin. Self-assembly of the zinc porphyrins by addition of DABCO led to a supramolecular complex containing four of the monomer units, two on each porphyrin. CuAAC oligomerisation was carried out in the presence of a chain capping agent to prevent intermolecular reactions between the templated products, which carry reactive chain ends. The templated-directed oligomerisation resulted in selective formation of a duplex, which contains two identical chains of triazole oligomers connecting the porphyrin linkers. The effective molarity for the intramolecular CuAAC reactions on the template is 3-9 mM, and because the triazole backbone has a direction, the product duplex was obtained as a 4 : 1 mixture of the parallel and antiparallel isomers. Hydrolysis of the ester bonds connecting the oligomers to the template gave a single product, the phenol 2-mer, in excellent yield. The introduction of a supramolecular element into the template considerably broadens the scope of the covalent template-directed oligomerisation methodology that we previously developed for the replication of sequence information in synthetic oligomers.

The role of government policies for Italian firms during the COVID-19 crisis.

This paper aims to respond to this research question: "How effective have government incentives been in preserving firm profitability and growth during the COVID-19 crisis?". We used a large, representative sample of Italian companies, which has produced a deeper study than the macro analyses provided by national statistics. Results shows that government policies alleviated the negative effects of the pandemic on troubled companies, but it was not enough to maintain the same financial health as firms that did not need this support. Small companies were the most adversely affected by the pandemic.

BN-Doped Metal-Organic Frameworks: Tailoring 2D and 3D Porous Architectures through Molecular Editing of Borazines.

Building on the MOF approach to prepare porous materials, herein we report the engineering of porous BN-doped materials using tricarboxylic hexaarylborazine ligands, which are laterally decorated with functional groups at the full-carbon 'inner shell'. Whilst an open porous 3D entangled structure could be obtained from the double interpenetration of two identical metal frameworks derived from the methyl substituted borazine, the chlorine-functionalised linker undergoes formation of a porous layered 2D honeycomb structure, as shown by single-crystal X-ray diffraction analysis. In this architecture, the borazine cores are rotated by 60° in alternating layers, thus generating large rhombohedral channels running perpendicular to the planes of the networks. An analogous unsubstituted full-carbon metal framework was synthesised for comparison. The resulting MOF revealed a crystalline 3D entangled porous structure, composed by three mutually interpenetrating networks, hence denser than those obtained from the borazine linkers. Their microporosity and CO2 uptake were investigated, with the porous 3D BN-MOF entangled structure exhibiting a large apparent BET specific surface area (1091 m2 g-1 ) and significant CO2 reversible adsorption (3.31 mmol g-1 ) at 1 bar and 273 K.

BN-Patterning of Metallic Substrates through Metal Coordination of Decoupled Borazines.

We report on the synthesis of pyridine-terminated borazine derivatives, their molecular self-assembly as well as the electronic properties investigated on silver and copper surfaces by means of scanning tunneling microscopy and X-ray photoelectron spectroscopy. The introduction of pyridine functionalities allows us to achieve distinct supramolecular architectures with control of the interdigitation of the molecules by surface templating. On silver surfaces, the borazine derivatives arrange in a dense-packed hexagonal structure through van der Waals and H-bonding interactions, whereas on Cu(111), the molecules undergo metal coordination. The porosity and coordination symmetry of the reticulated structure depends on the stoichiometric ratio between copper adatoms and the borazine ligands, permitting an unusual three-fold coordinated Cu-pyridyl network. Finally, spectroscopy measurements indicate that the borazine core is electronically decoupled from the metallic substrate. We thus demonstrate that BNC-containing molecular units can be integrated into stable metal-coordination architectures on surfaces, opening pathways to patterned, BN-doped sheets with specific functionalities, for example, regarding the adsorption of polar guest gases.

Borazino-Doped Polyphenylenes.

The divergent synthesis of two series of borazino-doped polyphenylenes, in which one or more aryl units are replaced by borazine rings, is reported for the first time, taking advantage of the decarbonylative [4 + 2] Diels-Alder cycloaddition reaction between ethynyl and tetraphenylcyclopentadienone derivatives. Because of the possibility of functionalizing the borazine core with different groups on the aryl substituents at the N and B atoms of the borazino core, we have prepared borazino-doped polyphenylenes featuring different doping dosages and orientations. To achieve this, two molecular modules were prepared: a core and a branching unit. Depending on the chemical natures of the central aromatic module and the reactive group, each covalent combination of the modules yields one exclusive doping pattern. By means of this approach, three- and hexa-branched hybrid polyphenylenes featuring controlled orientations and dosages of the doping B3N3 rings have been prepared. Detailed photophysical investigations showed that as the doping dosage is increased, the strong luminescent signal is progressively reduced. This suggests that the presence of the B3N3 rings engages additional deactivation pathways, possibly involving excited states with an increasing charge-separated character that are restricted in the full-carbon analogues. Notably, a strong effect of the orientational doping on the fluorescence quantum yield was observed for those hybrid polyphenylene structures featuring low doping dosages. Finally, we showed that Cu-catalyzed 1,3-dipolar cycloaddition is also chemically compatible with the BN core, further endorsing the inorganic benzene as a versatile aromatic scaffold for engineering of molecular materials with tailored and exploitable optoelectronic properties.

Synthesis and Optoelectronic Properties of Hexa-peri-hexabenzoborazinocoronene.

The first rational synthesis of a BN-doped coronene derivative in which the central benzene ring has been replaced by a borazine core is described. This includes six C-C ring-closure steps that, through intramolecular Friedel-Crafts-type reactions, allow the stepwise planarization of the hexaarylborazine precursor. UV/Vis absorption, emission, and electrochemical investigations show that the introduction of the central BN core induces a dramatic widening of the HOMO-LUMO gap and an enhancement of the blue-shifted emissive properties with respect to its all-carbon congener.

Boron-nitrogen doped carbon scaffolding: organic chemistry, self-assembly and materials applications of borazine and its derivatives.

Discovered by Stock and Pohland in 1926, borazine is the isoelectronic and isostructural inorganic analogue of benzene, where the C[double bond, length as m-dash]C bonds are substituted by B-N bonds. The strong polarity of such heteroatomic bonds widens the HOMO-LUMO gap of the molecule, imparting strong UV-emitting/absorption and electrical insulating properties. These properties make borazine and its derivatives valuable molecular scaffolds to be inserted as doping units in graphitic-based carbon materials to tailor their optoelectronic characteristics, and specifically their semiconducting properties. By guiding the reader through the most significant examples in the field, in this feature paper we describe the past and recent developments in the organic synthesis and functionalisation of borazine and its derivatives. These boosted the production of a large variety of tailored derivatives, broadening their use in optoelectronics, H2 storage and supramolecular functional architectures, to name a few.