Functional supramolecular tetrathiafulvalene-based films with mixed valences states

Tetrathiafulvalene molecules substituted with a carboxylic acid group (TTFCOOH) were bound as redox-active moieties into a poly(4-vinyl pyridine) (P4VP) skeleton through non-covalent interactions (hydrogen bonds). The aspect of the resulting P4VP-TTFCOOH films showed a uniform and smooth morphology. Moreover, the redox function of TTFCOOH in P4VP-TTFCOOH was demonstrated using tetrachloroauric acid, iron(III) perchlorate and iodine vapors as doping agents. The oxidized states of TTFCOOH as well as the mixed valance state TTFCOOH0-TTFCOOH+• were generated in a controlled manner in solid state, resulting in an organic film capable of charge transport. The charge transport along the organic donor molecules hydrogen bonded to the polymer matrix was demonstrated employing Electrostatic Force Microscopy (EFM)Postprint (author's final draft

Preferred Formation of Minority Concomitant Polymorphs in 2D Self‐Assembly under Lateral Nanoconfinement

Control over polymorph formation in the crystallization of organic molecules remains a huge scientific challenge. Now, preferential formation is presented of one polymorph, formed by chiral molecules, in controlled two‐dimensional (2D) nanoconfinement conditions at a liquid–solid interface. So‐called nanocorrals to control concomitant polymorph formation were created in situ via a nanoshaving protocol at the interface between 1‐phenyloctane and covalently modified highly‐oriented pyrolytic graphite (HOPG). The preferentially formed polymorphs, which were less stable in the large‐scale monolayers, could be selected simply by varying the orientation of the square nanocorrals with respect to the HOPG lattice

Varied nanostructures from a single multifunctional molecular material

The control of the morphology of nanostructures formed from a single component molecular material incorporating electron accepting and donating moieties is shown, from both solution and gel states. The compound comprises one tetrathiafulvalene (TTF) and two pyrene units which act as the [small pi]-electron rich and deficient units, respectively, and which are united by amide-containing linkers whose additional role is to aide aggregation by hydrogen bonding. This role was demonstrated by IR and NMR spectroscopy. The gels were deposited onto surfaces and the solvent allowed to evaporate, leaving films formed by meshes of fibres with different morphologies in accord with the different solvents used to form the materials. Doping of these xerogels with iodine vapour afforded conducting films whose characteristics were probed with current sensing atomic force microscopy (CS-AFM), providing current maps and I-V curves which show how dramatically the processing solvent can influence the electronic properties of these xerogel-derived materials

Enhancing singlet oxygen generation by self-assembly of a porphyrin entrapped in supramolecular fibres

Singlet oxygen (SO) is one of the reactive oxygen species that is effective in various uses, including performing chemical reactions, treating water impurities, and aiding in medicinal therapy. The generation of SO is often efficient in solution, although generation from the solid phase in nanomaterials is less reliable. Here, we report the preparation of hybrid supramolecular materials that incorporate a photosensitizer within their nanostructured fibers and demonstrate their high efficiency in promoting SO formation. The incorporation of tetrakis(4-carboxyphenyl)porphyrin within the nanofibers of a bis-imidazolium gelator was proved by various techniques, including super-resolution radial fluctuations (SRRF) microscopy, which shows the location of the chromophore precisely. SO is generated from the dispersed nanofibers far more efficiently than the dissolved porphyrin; a 14-fold higher rate is observed initially. These results point to an effective approach to the generation of SO for several applications, from optimizing synthetic protocols to photomedicine

Synthesis beyond the redox-active tetrathiafulvalene (TTF) molecule: From a topological control in TTF based macrocycles, towards functional chemical systems

Date du colloque&nbsp;: 05/2009</p

Hierarchical Self-Assembly of Supramolecular Helical Fibres from Amphiphilic C3-Symmetrical Functional Tris(tetrathiafulvalenes)

The preparation and self-assembly of the enantiomers of a series of C3-symmetric compounds incorporating three tetrathiafulvalene (TTF) residues is reported. The chiral citronellyl and dihydrocitronellyl alkyl chains lead to helical one dimensional stacks in solution. Molecular mechanics and dynamics simulations combined with experimental and theoretical circular dichroism support the observed helicity in solution. These stacks self-assemble to give fibres that have morphologies that depend on the nature of the chiral alkyl group and the medium in which the compounds aggregate. An inversion of macroscopic helical morphology of the citronellyl compound is observed when compared to analogous 2-methylbutyl chains, which is presumably a result of the stereogenic centre being further away from the core of the molecule. This composition still allows both morphologies to be observed, whereas an achiral compound shows no helicity. The morphology of the fibres also depends on the flexibility at the chain ends of the amphiphilic components, as there is not such an apparently persistent helical morphology for the dihydrocitronellyl derivative as for that prepared from citronellyl chains

1,4-Bis[3-chloro-2-(chloro­meth­yl)prop­yl]benzene

The title mol­ecule, C14H18Cl4, possesses a crystallographically imposed inversion centre, which coincides with the centre of benzene ring. In the absence of classical inter­molecular inter­actions, van der Waals forces help the mol­ecules to pack in the crystal

catena-Poly[[bis­(μ-3-carboxy­benzoato)bis­(1,10-phenanthroline)tricopper(II)]-di-μ3-isophthalato]

The title copper coordination polymer, [Cu3(C8H4O4)2(C8H5O4)2(C10H8N2)2]n, was synthesized by reacting Cu(NO3)2, isophthalic acid and 1,10-phenanthroline under hydro­thermal conditions. The trinuclear unit presents a central almost planar CuO4 chromophore with the cation on a symmetry center, and two symmetry-related CuN2O3 groups with the metal centre in a distorted square-pyramidal environment. These units are bridged by isophthalate ligands into one-dimensional double-chain coordination polymers which are, in turn, connected by various π–π stacking inter­actions (face-to-face distance ca 3.45 Å) and O—H⋯O hydrogen bonds, forming a three-dimensional supra­molecular network

Towards more sustainable synthesis of diketopyrrolopyrroles

The alkylation of 1,4-diketo-3,6-arylpyrrolo[3,4-c]pyrroles (ArDPP) is one of the most important steps in the synthesis of soluble materials based on these molecules and the polymers derived from them (that are employed widely in putative organic solar cells). Here we report an improvement in their method of synthesis replacing habitual solvent and base. Compared with more usual conditions, we employed acetonitrile as solvent to give higher or similar yields, with less toxic and hazardous waste, lower reaction time and temperature, and allows recycling of unreacted starting materials. Unlike dimethylformamide and N-methylpyrrolidone, which are the most commonly employed solvents. Our reaction conditions have been tested on three different ArDPPs (Ar = thiophene, phenyl and 4-methoxyphenyl) with a variety of linear and branched alkyl reagents. The results show similar and improved results in comparison with the published reports while reducing the waste and hazard of the reaction, as well as simplifying the purification of the products in many cases. Overall this method has lower environmental impact, is more cost effective and requires neither the use of dry solvent nor inert atmosphere