Synthesis and Cytotoxicity Studies of Br-Substituted Salphen Organic Compounds.

We present the synthesis and characterization of organic Salphen compounds containing bromine substituents at the para/ortho-para positions, in their symmetric and non-symmetric versions, and describe the X-ray structure and full characterization for the new unsymmetrical varieties. We report for the first time antiproliferative activity in metal-free brominated Salphen compounds, by evaluations in four human cancer cell lines, cervix (HeLa), prostate (PC-3), lung (A549) and colon (LS 180) and one non-cancerous counterpart (ARPE-19). We assessed in vitro cell viability against controls using the MTT assay ((3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide)) and determined the concentration required for 50 % growth inhibition (IC ), together with their selectivity vs.

Turing patterns by supramolecular self-assembly of a single salphen building block.

In the 1950s, Alan Turing showed that concerted reactions and diffusion of activating and inhibiting chemical species can autonomously generate patterns without previous positional information, thus providing a chemical basis for morphogenesis in Nature. However, access to these patterns from only one molecular component that contained all the necessary information to execute agonistic and antagonistic signaling is so far an elusive goal, since two or more participants with different diffusivities are a must. Here, we report on a single-molecule system that generates Turing patterns arrested in the solid state, where supramolecular interactions are used instead of chemical reactions, whereas diffusional differences arise from heterogeneously populated self-assembled products.

Acrylic Polymers Containing a Nickel Salphen Complex: An Approach to Supramolecular and Macromolecular Systems.

Invited for this month's cover are Prof. Martha Escárcega-Bobadilla and Prof. Gustavo Zelada-Guillén, collaborators from the National Autonomous University of Mexico (UNAM).

Acrylic Polymers Containing a Nickel Salphen Complex: An Approach to Supramolecular and Macromolecular Systems.

The synthesis, characterization and crystallographic analysis is reported of a new Nickel Salphen complex and its radical copolymerization with n-butyl acrylate and methyl methacrylate to produce novel host macromolecules with tunable association against guest anions. Spectrophotometric titrations of the complex and of the polymers revealed that a supramolecular regulation of guest-binding accessibility was enabled by the number of Ni-Salphen units per chain. The latter content in turn, determined the chain size and molecular weight uniformity upon polymerization, and likely increased the strength in interchain/intrachain non-covalent interactions over the nickel center and the acrylic domains.

Control of pH-Responsiveness in Graphene Oxide Grafted with Poly-DEAEMA via Tailored Functionalization.

Polymer-grafted nanomaterials based on carbon allotropes and their derivatives (graphene oxide (GO), etc.) are typically prepared by successive reaction stages that depend upon the initial functionalities in the nanostructure and the polymerization type needed for grafting. However, due to the multiple variables involved in the functionalization steps, it is commonly difficult to predict the properties in the final product and to correlate the material history with its final performance.

Synthesis of a Novel Zn-Salphen Building Block and Its Acrylic Terpolymer Counterparts as Tunable Supramolecular Recognition Systems.

In this work, we present the synthesis of a novel Zn-Salphen complex containing an allyl group, which was used as building block in the further preparation of a new family of functional terpolymers. These polymers were obtained through radical co-polymerization with methyl metacrylate (MMA) and -butyl acrylate (BuA) in different ratios. The supramolecular recognition behavior of each polymer was evaluated via potentiometric measurements against selected anions in aqueous media.

Grafting Multiwalled Carbon Nanotubes with Polystyrene to Enable Self-Assembly and Anisotropic Patchiness.

We demonstrate a straightforward protocol to graft pristine multiwalled carbon nanotubes (MWCNTs) with polystyrene (PS) chains at the sidewalls through a free-radical polymerization strategy to enable the modulation of the nanotube surface properties and produce supramolecular self-assembly of the nanostructures. First, a selective hydroxylation of the pristine nanotubes through a biphasic catalytically mediated oxidation reaction creates superficially distributed reactive sites at the sidewalls. The latter reactive sites are subsequently modified with methacrylic moieties using a silylated methacrylic precursor to create polymerizable sites.

Nanorings and rods interconnected by self-assembly mimicking an artificial network of neurons.

Molecular electronics based on structures ordered as neural networks emerges as the next evolutionary milestone in the construction of nanodevices with unprecedented applications. However, the straightforward formation of geometrically defined and interconnected nanostructures is crucial for the production of electronic circuitry nanoequivalents. Here we report on the molecularly fine-tuned self-assembly of tetrakis-Schiff base compounds into nanosized rings interconnected by unusually large nanorods providing a set of connections that mimic a biological network of neurons.

Supramolecular bulky phosphines comprising 1,3,5-triaza-7-phosphaadamantane and Zn(salphen)s: structural features and application in hydrosilylation catalysis.

The use of the commercially available, bifunctional phosphine 1,3,5-triaza-7-phosphaadamantane (abbreviated as PN3) in conjunction with a series of Zn(salphen) complexes leads to sterically encumbered phosphine ligands as a result of (reversible) coordinative Zn-N interactions. The solid state and solution phase behaviour of these supramolecular ligand systems have been investigated in detail and revealed their stoichiometries in the solid state observed by X-ray crystallography, and those determined in solution by NMR and UV-Vis spectroscopy. Also, upon application of these supramolecular bulky phosphines in hydrosilylation catalysis employing 1-hexene as a substrate, the catalysis data infer the presence of an active Rh species with two coordinated, bulky PN3/Zn(salphen) assembly units having a maximum of three Zn(salphen)s associated per PN3 scaffold, with an excess of bulky phosphines hardly affecting the overall activity.

A recyclable trinuclear bifunctional catalyst derived from a tetraoxo bis-Zn(salphen) metalloligand.

A tetraoxo bis-Zn(salphen) supramolecular host can bind various divalent metal salts, thereby providing access to trinuclear bifunctional systems that incorporate both Lewis acid sites and dynamically bound nucleophilic anions. The formation of these trinuclear species was investigated and their stability features were also determined. The application of these trinuclear complexes as bifunctional catalysts was evaluated in the formation of cyclic organic carbonates from epoxides and CO(2).

Metal-directed assembly of chiral bis-Zn(II) Schiff base structures.

Tetra-Schiff bases derived from (chiral) bis-salphen ligand scaffolds furnish, upon metalation with appropriate metal reagents, their multinuclear structures with associated Zn(OAc)(2) or Zn(OH)(2) fragments. The tendency of retaining these salts was investigated using four different (chiral) bis-salphen scaffolds. The presence of the additional Zn ions was supported by NMR studies, mass determinations and X-ray crystallography showing in two cases the possible mode of coordination within these multinuclear structures.

Versatile switching in substrate topicity: supramolecular chirality induction in di- and trinuclear host complexes.

Supramolecular chirality effects have been achieved both for ditopic and monotopic substrates by using a programmable bis-salphen scaffold that incorporates either two or three Zn nuclei. The dinuclear host shows preferential chirogenesis in the presence of ditopic systems, whereas effective chirality transfer to the trinuclear complex is realized through monotopic binding. The mode of binding in the trinuclear host has been investigated through X-ray crystallography, CD measurements, UV/Vis spectroscopy, and DFT analysis.

A new languidulane diterpenoid from Salvia mexicana var. mexicana.

From the aerial parts of Salvia mexicana var. mexicana, two C-10 epimers (α and β) of salvimexicanolide were isolated. Our interpretation of the data, especially the 13C NMR, led us to conclude that the previously described 13C-NMR spectrum of the α-epimer was not accurately assigned and it actually corresponds to the β-epimer.