Unravelling the Role of Structural Factors in the Luminescence Properties of Persulfurated Benzenes.

Room temperature phosphorescence rarely occurs from pure organic molecules, especially in the solid-state. A strategy for the design of highly emissive organic phosphors is still hard to predict, thus impeding the development of new functional materials with the desired optical properties. Herein, we analyze a family of alkyl and aryl-substituted persulfurated benzenes, the latter representing a class of organic solid-state triplet emitters able to show very high emission quantum yield at room temperature.

"The Sulfur Dance" Around Arenes and Heteroarenes - the Reversible Nature of Nucleophilic Aromatic Substitutions.

We disclose the features of a category of reversible nucleophilic aromatic substitutions in view of their significance and generality in dynamic aromatic chemistry. Exchange of sulfur components surrounding arenes and heteroarenes may occur at 25 °C, in a process that one may call a "sulfur dance". These SAr systems present their own features, apart from common reversible reactions utilized in dynamic covalent chemistry (DCC).

A high-sensitivity long-lifetime phosphorescent RIE additive to probe free volume-related phenomena in polymers.

The photophysical behaviour of phosphorescent rigidification-induced emission (RIE) dyes is highly affected by their micro- and nanoenvironment. The lifetime measure of RIE dyes dispersed in polymers represents an effective approach to gain valuable information on polymer free volume and thus develop materials potentially able to self-monitor physical ageing and mechanical stresses.

Persulfurated Benzene-Cored Asterisks with π-Extended ThioNaphthyl Arms: Synthesis, Structural, Photophysical and Covalent Dynamic Properties.

The synthesis of regioisomeric asterisks (5) and (6) incorporating a benzene core with six 1-naphthylthio or six 2-naphthylthio arms are reported in search for new materials with optoelectronic properties. The consequences on the extension of a π system surrounding a persulfurated benzene core provide a new avenue to study the structural, photophysical, and chemical properties of such family of all-organic phosphors. It also diverts the persulfuration mechanism after two radical cyclizations for making a [5]dithiohelicene by-product (7) and favors dynamic sulfur component exchange reactions surrounding the core.

Unbalanced 2D Chiral Crystallization of Pentahelicene Propellers and Their Planarization into Nanographenes.

The chiral self-assembly of trispentahelicene propellers on a gold surface has been investigated in ultrahigh vacuum by means of scanning tunneling microscopy and time-of-flight secondary ion mass spectrometry. The trispentahelicene propellers aggregate into mirror domains with an enantiomeric ratio of 2 : 1. Thermally induced cyclodehydrogenation leads to planarization into nanographenes, which self-assemble into closed-packed layers with two different azimuths.

Highly Emissive Water-Soluble Polysulfurated Pyrene-Based Chromophores as Dual Mode Sensors of Metal Ions.

Pyrene-based materials have gained considerable attention as stimuli-responsive chemical sensors. We designed a polysulfurated arene system based on a tetra(phenylthio)pyrene core decorated with four carboxylic acid units. Three different regioisomers, ortho, meta and para were studied in organic and aqueous solution.

Stereoselective Syntheses, Structures, and Properties of Extremely Distorted Chiral Nanographenes Embedding Hextuple Helicenes.

We report a molecular design and concept using π-system elongation and steric effects from helicenes surrounding a triphenylene core toward stable chiral polycyclic aromatic hydrocarbons (PAHs) with a maximal π-distortion to tackle their aromaticity, supramolecular and molecular properties. The selective syntheses, and the structural, conformational and chiroptical properties of two diastereomeric large multi-helicenes of formula C H having a triphenylene core and embedding three [5]helicene units on their inner edges and three [7]helicene units at their periphery are reported based on diastereoselective and, when applicable, enantiospecific Yamamoto-type cyclotrimerizations of racemic or enantiopure 9,10-dibromo[7]helicene. Both molecules have an extremely distorted triphenylene core, and one of them exhibits the largest torsion angle recorded so far for a benzene ring (twist=36.

A turn-on phosphorescent sensor of Pb in water by the formation of a coordination polymer.

Hexakis(phenylthio)benzene compounds carrying six carboxylic acid groups at their periphery combine aggregation-induced phosphorescence, water-solubility and metal-binding properties: the para-isomer is a selective and sensitive turn-on phosphorescent sensor of Pb2+ ions in water.

Delaying Anticancer Drug Delivery by Self-Assembly and Branching Effects of Minimalist Dendron-Drug Conjugates.

Self-assembly of a covalently-bound lipophilic drug to a dendronic scaffold for making organic nanoparticles is reported as a proof of concept in nanovectorization. A minimalist structural approach with a small PEG-dendron conjugated to paclitaxel (PTX), incorporating safe succinic and gallic acids, is efficient to provide the expected anticancer bioactivity, but also significantly retards and targets intracellular delivery of PTX in 2D and 3D lung cancer cell cultures. A branching effect of dendrons is crucial, when compared to linear PTX conjugates.

Chiral Nanographene Propeller Embedding Six Enantiomerically Stable [5]Helicene Units.

A one-step synthesis of a nanographene propeller with a D-symmetry was obtained starting from 7,8-dibromo[5]helicene by Yamamoto nickel(0) couplings. It afforded a chiral polyaromatic hydrocarbon (PAH) embedding six enantiomerically stable [5]helicene units. This dense accumulation of helical strain resulted in a distorted geometry, but stable stereochemistry.

Selective Metalations of 1,4-Dithiins and Condensed Analogues Using TMP-Magnesium and -Zinc Bases.

TMPMgCl·LiCl and TMPZnCl·LiCl allow facile magnesiation and zincation, respectively, of the 1,4-dithiin scaffold, producing polyfunctionalized 1,4-dithiins. A subsequent metalation of these S-heterocycles can also be achieved with the same TMP bases, leading to 2,3-disubstituted-1,4-dithiins. The Mg- and Zn-TMP bases allow as well the successful metalation of 1,4,5,8-tetrathianaphthalene and 1,4,5,6,9,10-hexathiaanthracene.

Molecular size and electronic structure combined effects on the electrogenerated chemiluminescence of sulfurated pyrene-cored dendrimers.

The electrochemistry, photophysics, and electrochemically generated chemiluminescence (ECL) of a family of polysulfurated dendrimers with a pyrene core have been thoroughly investigated and complemented by theoretical calculations. The redox and luminescence properties of dendrimers are dependent on the generation number. From low to higher generation it is both easier to reduce and oxidize them and the emission efficiency increases along the family, with respect to the polysulfurated pyrene core.

Gold nanoparticles prepared by laser ablation in aqueous biocompatible solutions: assessment of safety and biological identity for nanomedicine applications.

Due to excellent biocompatibility, chemical stability, and promising optical properties, gold nanoparticles (Au-NPs) are the focus of research and applications in nanomedicine. Au-NPs prepared by laser ablation in aqueous biocompatible solutions present an essentially novel object that is unique in avoiding any residual toxic contaminant. This paper is conceived as the next step in development of laser-ablated Au-NPs for future in vivo applications.

Expeditive synthesis of trithiotriazine-cored glycoclusters and inhibition of Pseudomonas aeruginosa biofilm formation.

Readily accessible, low-valency glycoclusters based on a triazine core bearing D-galactose and L-fucose epitopes are able to inhibit biofilm formation by Pseudomonas aeruginosa. These multivalent ligands are simple to synthesize, are highly soluble, and can be either homofunctional or heterofunctional. The galactose-decorated cluster shows good affinity for Pseudomonas aeruginosa lectin lecA.

Synthesis, characterization, and metal ion coordination of a multichromophoric highly luminescent polysulfurated pyrene.

We have designed a new multichromophoric system based on a tetra(phenylthio)pyrene core appended with four terpyridine units. The system behaves as a molecular antenna that collects light with the peripheral units and funnels the energy to the very highly luminescent core. The addition of metals ions to the investigated system can not only switch the direction of the intramolecular energy transfer, but also control the formation of three-dimensional nanoscopic objects in a dual function.

Turn-on phosphorescence by metal coordination to a multivalent terpyridine ligand: a new paradigm for luminescent sensors.

A hexathiobenzene molecule carrying six terpyridine (tpy) units at the periphery has been designed to couple the aggregation induced phosphorescence, displayed by the core in the solid state, to the metal binding properties of the tpy units. Upon Mg(2+) complexation in THF solution, phosphorescence of the hexathiobenzene core is turned on. Metal ion coordination yields the formation of a supramolecular polymer which hinders intramolecular rotations and motions of the core chromophore, thus favoring radiative deactivation of the luminescent excited state.

How do multivalent glycodendrimers benefit from sulfur chemistry?

Sulfur-containing glycodendrimers have steadily emerged over a few decades and this review describes the first survey of this field. Although the contribution of sulfur chemistry to glycodendrimers could be seen at the moment as a development of various linking strategies, there is more than synthesis because the presence of sulfur itself modulates unique photophysical and electrochemical properties. This fact has long been recognized in materials science, for instance.

One hundred years of helicene chemistry. Part 1: non-stereoselective syntheses of carbohelicenes.

Carbohelicenes belong to a class of fascinating, chiral, and helicoidal molecules, which have a rich history in chemistry since the very beginning of the 20th century. A renewed interest in polyaromatic chemistry and new synthetic challenges toward the search for innovative physical, biological, chemical and opto-electronic properties have brought high motivation in this field of studies. Theoretical insights gained from polyaromatic, chiral, conjugated and distorted π-systems are also responsible for this development.

One hundred years of helicene chemistry. Part 3: applications and properties of carbohelicenes.

Carbohelicenes are a class of fascinating chiral helical molecules which have a rich history in chemistry. Over a period of almost 100 years, chemists have developed many methods to prepare them in a racemic or in a non-racemic form. They also possess a series of interesting chiral, physical, electronic and optical properties.

One hundred years of helicene chemistry. Part 2: stereoselective syntheses and chiral separations of carbohelicenes.

Carbohelicenes generally incorporate a helical, distorted, conjugated, polyaromatic system with ortho-fused benzenoid rings, which is a fundamental molecular characteristic of this class of compounds. They have been described as "molecules in distress" due to their distortion. The generation of a chiral helicity in helicenes was observed because of a severe intramolecular steric strain.

Two-dimensional nanostructured growth of nanoclusters and molecules on insulating surfaces.

Noncontact atomic force microscopy (nc-AFM), Kelvin probe force microscopy (KPFM) and first principle calculations show that the nanostructured (001) Suzuki surface of Cd(2+) doped NaCl can be used to confine the growth of palladium clusters and functionalized brominated pentahelicene molecules into only the Suzuki regions, which contain the impurities. The Suzuki surface is an ideal model surface for nanostructuring metal clusters and molecules.

Arylthio-substituted coronenes as tailored building blocks for molecular electronics.

The electron transport through molecules in molecular devices is typically influenced by the nature of the interfaces with the contacting electrodes and by the interactions between neighbouring molecules. It is a major goal of molecular electronics to adjust the electronic function of a molecular device by tailoring the intrinsic molecular properties and the interfacial and intermolecular interactions. Here, we report on the tunability of the electronic properties of coronene derivatives, namely dodecakis(arylthio)coronenes (DATCs), which are found to exhibit a three-dimensional aromatic system.

Expeditive syntheses of functionalized pentahelicenes and NC-AFM on Ag(001).

One of the shortest and most efficient routes toward a series of functionalized pentahelicenes is reported. Benzylic (dibromo)methine coupling is an important entry into functional helicene chemistry. It allowed a mono- or a double functionalization by some metal-catalyzed Ar-C, Ar-S, Ar-CN, and Ar-I bond formations.

Glycosylated asterisks are among the most potent low valency inducers of Concanavalin A aggregation.

A new class of sulfurated, semi-rigid, radial and low-valent glycosylated asterisk ligands with potential dual function as ligand and probe has some of the highest inhibition potencies of Con A-induced hemagglutination, by using a cross-linking mechanism of Con A which amplifies the enhancement to near nanomolar concentrations with the alpha-d-mannose asterisk.

Polysulfurated pyrene-cored dendrimers: luminescent and electrochromic properties.

We have synthesized a novel class of dendrimers, consisting of a polysulfurated pyrene core with appended poly(thiophenylene) dendrons (PyG0, PyG1, and PyG2, see Scheme 1), which exhibit remarkable photophysical and redox properties. In dichloromethane or cyclohexane solution they show a strong, dendron-localized absorption band with a maximum at around 260 nm and a band in the visible region with a maximum at 435 nm, which can be assigned to the pyrene core strongly perturbed by the four sulfur substituents. The dendrimers exhibit a strong (Phi=0.