Synthesis, Photophysical Characterization, and Self-Assembly of Hexa-peri-hexabenzocoronene/Benzothiadiazole Donor-Acceptor Structure.

Hexa-peri-hexabenzocoronene (HBC) substituted by six benzothiadiazole (BTZ) units with ethynylene bridges is synthesized as a new donor-acceptor (D-A) motif. The C≡C bridges significantly reduce the dihedral angles between HBC and BTZ, and thus, lead to a planar molecular conformation as predicted by density functional theory calculations. The optoelectronic properties are investigated by UV/Vis absorption and emission spectroscopies with absorption and emission maxima at 424 and 650 nm, respectively, demonstrating the tunable electronic structures of HBC through the attachment of electron-withdrawing BTZ units.

Sustainable Electronic Materials: Reversible Phototuning of Conductance in a Noncovalent Assembly of MWCNT and Bioresource-Derived Photochromic Molecule.

Tuning the microstructure, conductance, band gap of a single molecule with an external stimuli such as light have vital importance in nanoscale molecular electronics. Azobenzene systems are inimitable light responsive molecules suitable for the development of optically modulated materials. In this work we have demonstrated the development of an optically active Multiwalled Carbon Nanotube (MWCNT)-hybrid material by the noncovalent functionalization of azo based chromophore derived from cardanol, a bioresource material.

Effect of the bulkiness of the end functional amide groups on the optical, gelation, and morphological properties of oligo(p-phenylenevinylene) π-gelators.

Herein, we describe the role of end functional groups in the self-assembly of amide-functionalized oligo(p-phenylenevinylene) (OPV) gelators with different end-groups. The interplay between hydrogen-bonding and π-stacking interactions was controlled by the bulkiness of the end functional groups, thereby resulting in aggregates of different types, which led to the gelation of a wide range of solvents. The variable-temperature UV/Vis absorption and fluorescence spectroscopic features of gelators with small end-groups revealed the formation of 1D H-type aggregates in CHCl(3).

Synthesis of structurally well-defined and liquid-phase-processable graphene nanoribbons.

The properties of graphene nanoribbons (GNRs) make them good candidates for next-generation electronic materials. Whereas 'top-down' methods, such as the lithographical patterning of graphene and the unzipping of carbon nanotubes, give mixtures of different GNRs, structurally well-defined GNRs can be made using a 'bottom-up' organic synthesis approach through solution-mediated or surface-assisted cyclodehydrogenation reactions. Specifically, non-planar polyphenylene precursors were first 'built up' from small molecules, and then 'graphitized' and 'planarized' to yield GNRs.

Light-induced Ostwald ripening of organic nanodots to rods.

Ostwald ripening allows the synthesis of 1D nanorods of metal and semiconductor nanoparticles. However, this phenomenon is unsuccessful with organic π-systems due to their spontaneous self-assembly to elongated fibers or tapes. Here we demonstrate the uses of light as a versatile tool to control the ripening of amorphous organic nanodots (ca.

Rational design of nanofibers and nanorings through complementary hydrogen-bonding interactions of functional pi systems.

A simple protocol to create nanofibers and -rings through a rational self-assembly approach is described. Whereas the melamine-oligo(p-phenylenevinylene) conjugate 1a self-aggregates to form ill-defined nanostructures, conjugate 1b, which possesses an amide group as an additional interactive site, self-aggregates to form 1D nanofibers that induce gelation of the solvent. AFM and XRD studies have shown that dimerization through the melamine-melamine hydrogen-bonding interaction occurs only for 1b.

Role of complementary H-bonding interaction of a cyanurate in the self-assembly and gelation of melamine linked tri(p-phenyleneethynylene)s.

Melamine-functionalized tri(p-phenyleneethynylene) self-assembles to form opaque and weak gels in aliphatic solvents which turned transparent and stable upon addition of a cyanurate, affording supramolecular nanostructures with distinct physical properties.

Reversible self-assembly of entrapped fluorescent gelators in polymerized styrene gel matrix: erasable thermal imaging via recreation of supramolecular architectures.

The reversible shift of emission in fluorescent molecular gelators has been explored for the preparation of a composite polymer film useful for erasable thermal imaging and secret documentation. A gelation-assisted photopolymerization of styrene allowed the entrapment of the fluorescent gelator molecules within a polystyrene matrix with a weak green fluorescence, which upon heating above the T(g) of the polymer resulted in high-contrast fluorescence images due to the strong blue fluorescence of the individual molecules. The blue emission from the disassembled oligo(p-phenylenevinylene) molecules (OPVs) could be reversed to the green emission of the self-assembled OPVs by exposing the polymer film to chloroform vapors.

Solvent-directed self-assembly of pi gelators to hierarchical macroporous structures and aligned fiber bundles.

Morphology variation: The Boc-alanine linked OPV exhibits an unprecedented formation of periodic macroporous honeycomb structures in chloroform and aligned fiber bundles in toluene (see SEM images). This represents a unique example for a distinct morphology change of an organogelator from macroporous honeycomb to aligned fiber bundles upon changing the solvent.