The Chemistry of Organic Nanomaterials

Electrochemical Sensor for Detecting Ultratrace Nitroaromatic Compounds Using Mesoporous SiO2-Modified Electrode

An electrochemical sensor for ultratrace nitroaromatic compounds (NACs) using mesoporous SiO2 of MCM-41 as sensitive materials is reported. MCM-41 was synthesized and characterized by scanning electron microscope, transmission electron microscopy, and small-angle X-ray diffraction. Glassy carbon electrodes modified with MCM-41 show high sensitivity for cathodic voltammetric detection of NACs (including 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB), 2,4-dinitrotoluene, and 1,3-dinitrobenzene) down to the nanomolar level. The high sensitivity is attributed to the strong adsorption of NACs by MCM-41 and large surface area of the working electrode resulting from MCM-41 modification. The voltammetric response is fast, and the detection of NACs can be finished within 14 s. SiO2 nanospheres were similarly used to modify glassy carbon electrodes for electrochemical detection of TNT and TNB. The detection limit of SiO2 nanosphere-modified electrodes is lower than that of MCM-41-modified electrodes, possibly due to the smaller surface area of SiO2 nanospheres than mesoporous MCM-41. The results show mesoporous SiO2-modified glassy carbon electrodes, particularly MCM-41-modified electrodes, open new opportunities for fast, simple, and sensitive field analysis of NACs.

Hexa-peri-hexabenzocoronenes by Efficient Oxidative Cyclodehydrogenation: The Role of the Oligophenylene Precursors

[reaction: see text] Oligophenylene precursors based on 1,3,5-tris-(2'-biphenyl)ylbenzene (4a) and 1,4-bis-(2'-biphenyl)yl-2,5-diphenylbenzene (5a) were prepared and utilized for efficient hexabenzocoronene (HBC) synthesis by cyclodehydrogenations. Parent HBC 6a was efficiently synthesized from the 1,3,5-tris-(2'-biphenyl)ylbenzene precursor, and novel D(3)(h)() symmetrical HBCs were prepared from 1,3,5-tris-(2'-biphenyl)ylbenzenes with various substitution types. For the preparation of a tert-butyl containing HBC 7 with D(2)(h)() symmetry, a two-step cyclodehydrogenation was required because of changes in the spin density distribution.

Suzuki Coupling Reaction of 1,6,7,12-Tetrabromoperylene Bisimide

1,6,7,12-Tetrabromoperylene-3,4,9,10-tetracarboxylic acid bisanhydride and the corresponding tetrabrominated perylene bisimide were first synthesized with high yields. The Suzuki coupling reaction of novel tetrabromoperylene bisimide with phenylbonoric acid was studied. The four bromines in the bay position of the perylene core were substituted successfully to yield 1,6,7,12-teraphenylperylene bisimide. The photochemical properties of the novel perylene bisimides were studied and presented.

Self-Assembling of n-Type Semiconductor Tri(phenanthrolino)hexaazatriphenylenes with a Large Aromatic Core

[reaction: see text] Large disk-shaped aromatic tri(phenanthrolino)hexaazatriphenylenes 5a, 5b, and 5c with six butyl, dodecyl, and 4-octylphenyl groups, respectively, were self-assembled both in solution and film state to form one-dimensional aggregates. Their n-type semiconducting nature was indicated from CV measurement, in which the first reduction potentials were evaluated at around -1.7 V (vs Fc/Fc(+)) in dichloromethane.

STM Investigation of Alkylated Thiotriphenylene Monolayers at the Solid–Liquid Interface: Structure and Dynamics

We describe a STM investigation of the structure and dynamics of alkylated thiotriphenylene monolayers at the solid–liquid interface. This discotic system was found to pack into two coexisting structural motifs on the basal plane of graphite. The interpretation of the intra-molecular contrast in the STM images showed a large contribution of electronic levels localized on the sulfur atoms bridging the conjugated core with the aliphatic side-chains. The temporal evolution of domain boundaries in a polycrystalline monolayer, explored by recording series of subsequent STM images, revealed an Ostwald ripening phenomenon, namely coarsening in two-dimensional molecular polycrystals.

Columnar liquid crystalline π-conjugated oligothiophenes

Polycatenar oligothiophenes possessing three alkoxy chains at each terminal self-organise into columnar liquid crystalline phases, and one-dimensional columnar stacks can be oriented uniaxially by mechanical shearing in the mesophases.

Synthetic method for multifunctionalized oligoarenes using pinacol esters of hydroxyphenylboronic acids

A synthetic method for multifunctionalized oligoarenes using rapid Suzuki-Miyaura coupling of pinacol esters of hydroxyphenylboronic acids and subsequent triflation of the hydroxy group was developed.

Functional organogels from highly efficient organogelator based on perylene bisimide semiconductor

A new n-type semiconducting perylene bisimide dye has been synthesized that gelates a broad variety of organic solvents to afford well-defined nano- and mesoscopic helical fibers and bundles.

Surface-assisted one-dimensional self-assembly of a perylene based semiconductor molecule

Chloroform-vapor annealing of thin films of propoxyethyl perylene tetracarboxylic diimide (PE-PTCDI, an n-type semiconductor) deposited on glass or mica leads to formation of well-defined one-dimensional self-assemblies (e.g. nanobelts), which show optically uniaxial properties as demonstrated by the linearly polarized emission.

Functional polymers: scanning force microscopy insights

Scanning force microscopy (SFM) and related techniques make it possible to visualize polymer systems with a molecular resolution. Beyond imaging, they also enable the unveiling of a variety of (dynamic) physico-chemical properties of both isolated polymer chains and their supramolecular architectures, including structural, mechanical and electronic properties. This article reviews recent progress in the use of SFM on polymers, with a particular emphasis on the mechanical properties of copolymers and single polymer chains, as well as on the bottom-up fabrication of supramolecular polymeric (helical) nanostructures in particular based upon pi-conjugated macromolecules as building blocks for nanoelectronics. Through a detailed understanding of the polymer behavior, we propose solutions for the generation of organic functional (nano)systems.

Microwave-enhanced multiple Suzuki couplings toward highly luminescent starburst monodisperse macromolecules

A facile and powerful microwave-enhanced multiple Suzuki coupling methodology has been developed and a novel series of highly luminescent six-arm monodisperse macromolecules have thus been prepared with high yield and purity.