The new inherently chiral material shows outstanding chirality manifestations with chiral probes, as well as with circularly polarized light components and electron spins.

The surface-assisted synthesis of gold-organometallic hybrids on the Au(111) surface both by thermo- and light-initiated dehalogenation of bromo-substituted tetracene is reported. Combined X-ray photoemission (XPS) and scanning tunneling microscopy (STM) data reveal a significant increase of the surface order when mild reaction conditions are combined with 405 nm light irradiation.

By a combination of scanning tunneling microscopy, X-ray spectroscopic techniques and density functional theory calculations, we prove the formation of extended patterns of parallel, graphene nanoribbons with alternate zig-zag and armchair edges and selected width by surface-assisted Ullmann coupling polymerization and dehydrogenation of 1,6-dibromopyrene (CHBr). Besides the relevance of these nanostructures for their possible application in nanodevices, we demonstrate the peculiarity of halogenated pyrene derivatives for the formation of nanoribbons, in particular on Ag(110). These results open the possibility of tuning the shape and dimension of nanoribbons (and hence the correlated electronic properties) by choosing suitably tailored or on-purpose designed molecular precursors.

On-surface synthesis of thin organic and organometallic films in a bottom-up fashion has become a promising approach for the development of new nanotechnologies. In this work we studied 5,11-dibromotetracene (C18H10Br2) as a prototypical case of rodlike polyaromatic molecules functionalized with two bromine atoms on the sides. The adsorption and temperature-stimulated transformations of dibromotetracene assemblies on Ag(110) have been investigated by a combination of synchrotron radiation X-ray photoemission spectroscopy (XPS), near-edge X-ray absorption spectroscopy (NEXAFS), scanning tunneling microscopy (STM), and density functional theory (DFT) calculations. Upon the contact with the Ag substrate, the Br-C bonds are promptly cleaved at room temperature, and Ag-coordinated protopolymers are formed along the [001] substrate direction. The organometallic dimers and trimers remain on the surface up to 523 K. The stabilization of the protopolymers is driven by the substrate anisotropy and weak interactions with nearby Br atoms. The short oligomers formed at elevated temperatures are weakly bounded to the substrate and desorb before covalent structures can be formed

During infection, bacteria use an arsenal of resistance mechanisms to negate antibiotic therapies. In addition, pathogenic bacteria form surface-attached biofilms bearing enriched populations of metabolically dormant persister cells. Bacteria develop resistance in response to antibiotic insults; however, nonreplicating biofilms are innately tolerant to all classes of antibiotics. As such, molecules that can eradicate antibiotic-resistant and antibiotic-tolerant bacteria are of importance. Here, we report modular synthetic routes to fluorine-containing halogenated phenazine (HP) and halogenated acridine (HA) agents with potent antibacterial and biofilm-killing activities. Nine fluorinated phenazines were rapidly accessed through a synthetic strategy involving (1) oxidation of fluorinated anilines to azobenzene intermediates, (2) SNAr with 2-methoxyaniline, and (3) cyclization to phenazines upon treatment with trifluoroacetic acid. Five structurally related acridine heterocycles were synthesized using SNAr and Buchwald–Hartwig approaches. From this focused collection, phenazines 5g, 5h, 5i, and acridine 9c demonstrated potent antibacterial activities against Gram-positive pathogens (MIC = 0.04–0.78 μM). Additionally, 5g and 9c eradicated Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis biofilms with excellent potency (5g, MBEC = 4.69–6.25 μM; 9c, MBEC = 4.69–50 μM). Using real-time quantitative polymerase chain reaction (RT-qPCR), 5g, 5h, 5i, and 9c rapidly induce the transcription of iron uptake biomarkers isdB and sbnC in methicillin-resistant S. aureus (MRSA) biofilms, and we conclude that these agents operate through iron starvation. Overall, fluorinated phenazine and acridine agents could lead to ground-breaking advances in the treatment of challenging bacterial infections.

A series of 2,2’‐biindole‐based inherently chiral electroactive monomers are comparatively investigated with their 3,3’ analogues as an excellent study case of two equivalent redox centres interacting through a torsional barrier. The twin peak potential splitting observed in voltammetry for the first oxidation of the biheteroaromatic core accounts for the energy barrier height: the lower the barrier, the larger the peak potential splitting, with modulation by solvent and temperature. The height of the energy barrier is determining for the electrochemical and spectroscopic features of the monomers as well as for their configurational stability and applicability for enantioselection purposes. The 3,3’ monomers, featuring large twin peak splittings in CV, are “trópos” systems with a low torsional barrier, so they cannot exist as stable enantiomers at room temperature. Instead their 2,2’ isomers, with much smaller twin peak splittings, are “átropos” systems and can be separated by enantioselective HPLC into stable enantiomers, providing powerful “inherently chiral” selectors with outstanding enantioselection properties in chiral electroanalysis and electrochemistry as well as in chiroptical spectroscopy, with fascinating reciprocal correlations.

An easy and cost-effective method is presented to functionalize graphene through thermally activated dimerization of 2,5-diaryltetrazoles. Consistently with the experimental spectroscopic results, theoretical calculations demonstrate that during the thermal treatment a dimerization process to tetrazine is energetically more favorable than covalent grafting. Since both the functionalization method by thermal activation and the use of tetrazoles have never been considered before to prepare graphene-based chemiresistors, this represents a promising approach to develop graphene-related sensing platforms. Five different 2,5-diaryltetrazoles have been tested here for the effective functionalization of low-defect graphene layers on silicon nitride. Based on these layers, an array of sensors has been prepared for testing upon ammonia exposure. The tests on the sensing performances clearly show sensitivity to ammonia, extending the current range of ammonia detection with a graphenebased chemiresistor down to the sub-ppm range, as results from a benchmarking with data available in the literature. Furthermore, all sensors perform better than bare graphene. Density functional theory (DFT) calculations, carried out on a model of the best performing layer of the array, provided the theoretical framework to rationalize the sensing mechanism and disclose a dual role played by the tetrazine molecules, (i) acting as ammonia concentrators and (ii) mediating the electron transfer between ammonia and graphene.

Fluorinated unsymmetrical acridines are efficiently prepared by means of a tandem micellar Buchwald–Hartwig amination followed by an acid-promoted cyclization. The overall process is advantageous with respect to previously described protocols both in terms of efficiency and sustainability. The role of the cosolvent in the amination step is highlighted, demonstrating that rather than resorting to highly expensive catalysts, Buchwald–Hartwig aminations can be straightforwardly carried out by tuning the reaction site polarity.