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Performing bottom-up synthesis by using molecules adsorbed on a surface is an effective method to yield functional polycyclic aromatic hydrocarbons (PAHs) and nanocarbon materials. The intramolecular cyclodehydrogenation of hydrocarbons is a critical process in this synthesis; however, thus far, its elementary steps have not been elucidated thoroughly. In this study, we utilize the metal tip of a low-temperature noncontact atomic force microscope as a manipulable metal surface to locally activate dehydrogenation for PAH-forming cyclodehydrogenation. This method leads to the dissociation of a H atom of an intermediate to yield the cyclodehydrogenated product in a target-selective and reproducible manner. We demonstrate the metal-tip-catalyzed dehydrogenation for both benzenoid and nonbenzonoid PAHs, suggesting its universal applicability as a catalyst for nanographene synthesis.

The adsorption configurations of heptahelicene ([7]H) molecules on Cu(001) are investigated with noncontact atomic force microscopy (ncAFM) and scanning tunneling microscopy (STM). Because of the suppression of thermal diffusion at 5 K, racemic [7]H molecules exist as monomers, dimers, trimers, and tetramers on the surface. The terminal naphthaleno part of the molecule is attached horizontally to the substrate so that the two benzene ring centers are located at the hollow sites, whereas the other terminal is protruded toward a vacuum. A procedure for picking a [7]H molecule up from the surface (vertical manipulation) enables us to functionalize the tip apex to enhance the spatial resolution of ncAFM. The ncAFM images with the helicene tip clarify that whereas the tetramers are homochiral, the dimers and trimers are heterochiral. In contrast, homochiral dimers and trimers are unobservable probably because of the rapid formation of the stable homochiral tetramers. Thus, ncAFM imaging can identify the geomet...

The orientation and electronic structure of multilayered graphene nanoribbons with an armchair-edge (AGNRs) were determined by low-temperature scanning tunneling microscopy in this study. The orientation of AGNRs was found to be an edge-on structure when positioned as a top layer, while previous reports showed a face-on structure for monolayered AGNRs on Au(111). According to density functional theory calculations, AGNRs in a top layer preferentially form as edge-on structures rather than face-on structures due to the balance of CH-π and π-π interactions between AGNRs. Scanning tunneling spectroscopy and density functional theory calculations revealed that the electronic structures of multilayered AGNRs are similar to those in a gas-phase due to the lack of interaction between AGNRs and the Au(111) substrate. The observation of AGNRs in mutilayers might suggest the conformation-assisted mechanism of dehydrogenation when there is no contact with the Au(111) substrate.

A total synthesis of (-)-kainic acid starting from the commercially available 2-azetidinone is described. The key delta-lactone intermediate was concisely prepared from the commercially available azetidinone through the Reformatsky-type reaction and an introduction of a glycine moiety. The construction of the functionalized pyrrolidine ring was executed by a one-pot sequential elimination-Michael addition protocol of a beta-amino-delta-lactone intermediate with high diastereoselectivity.

Stable gold film electrodes were fabricated by a combination of sputtered gold and an epoxy adhesion layer on a glass substrate using the template-stripped technique. An XRR scan analysis indicated the thickness and roughness of the gold layer to be on the order of 10 nm and subnanometer, respectively. In spite of their small thickness, the electrode had sufficient conductivity and stuck to the subject during the electrochemical measurements as did the usual gold working electrodes.

The quantum contact through which the electronic conductance is quantized by 2e2/h was chemically formed in a beaker. This preparation method needed only conventional tools in a common laboratory. ...

We propose new strategy to facilitate the fabrication of conjugated polymer fiber with higher oriented structures, which focused on electrospinning of a blend solution of regioregular poly(3-hexylthiophene) (rr-P3HT) and poly(vinyl pyrrolidone) (PVP). SEM observation revealed that the blend system forms homogeneous composite nanofibers. This system exhibits the specific feature of strong interchain contribution of P3HT from UV-vis absorption, fluorescence spectroscopic, XRD, and photoelectron spectrometric (for HOMO levels) investigations. We also demonstrate the removal of the PVP component from the P3HT/PVP composite fibers through the selective extraction and such strong interchain stacking of pristine P3HT fiber mat can be remarkably maintained.

We demonstrate that ultrafast modulation of second-harmonic (SH) intensity from a Langmuir-Blodgett (LB) film consisting of a ruthenium complex is possible by laser irradiation of thefilms. The switching of the second-harmonic intensity is demonstrated to occur in less than 2 ps by a picosecond pump-probe experiment. Results from time-resolved fluorescence studies of the LB film correlate quantitatively with those of the second-harmonic generation (SHG). The mechanism of the photoinduccd SHG switching is ascribed to the change of molecular hyperpolarizability of the ruthenium complex on going from the ground state to the excited state