Yoshito Tobe

m-Diethynylbenzene macrocycles (DBMs), buta-1,3-diyne-bridged [4n]metacyclophanes, have been synthesized and their self-association behaviors in solution were investigated. Cyclic tetramers, hexamers, and octamers of DBMs having exo-annular octyl, hexadecyl, and 3,6,9-trioxadecyl ester groups were prepared by intermolecular oxidative coupling of dimer units or intramolecular cyclization of the corresponding open-chain oligomers. The aggregation properties were investigated by two methods, the 1H

At the liquid/graphite interface triangular and rhombic phenylene-ethynylene macrocycles substituted by alkyl chains self-assemble to form porous two-dimensional (2D) molecular networks of honeycomb and Kagomé types, respectively, or close-packed non-porous structures via alkyl chain interdigitation as the directional intermolecular linkages. Factors that affect the formation of the 2D molecular networks, such as alkyl chain length, solvent, solute concentration, and co-adsorption of guest molec

Recognition and selection are of fundamental importance for the hierarchical assembly of supramolecular systems. Coronene induces the formation of a hydrogen-bonded isophthalic acid supramolecular macrocycle, and this well-defined heterocluster forces, in its turn, DBA1 to form a van der Waals stabilized honeycomb lattice, leading to a three-component 2D crystal containing nine molecules in the unit cell. The recognition and selection events enable efficient error correction and healing in redun

"Kekulene" is a doughnut-like shaped polycyclic aromatic hydrocarbon consisting of cyclically arrayed benzene rings. It has attracted a great deal of theoretical interest because it is regarded as an ideal model to study conjugation circuits of π electrons, i.e. whether they delocalize locally in benzene rings or globally throughout the molecule. Though kekulene was synthesized in 1978, it was the only known compound of this class of compounds for a long time. Recently, new kekulene-related mole

The development of the chemistry of non-alternant non-benzenoid hydrocarbons is reviewed in connection with the International Symposium on Novel Aromatic Compounds (ISNA) and the author's personal anecdotes. Past molecules include the classics of this class of compounds, pentalene, azulene, and heptalene, and the structurally integrated congeners such as indacenes formed by benzannelation and benzinterposition, which were extensively studied during the last century. Indenofluorene isomers constr

We propose a scheme of rate control for continuous UDP flow with moderate fairness. First, per-packet relative one-way trip time (ROTT) of a UDP stream at a receiver on the Internet is investigated extensively, and it is found that spikes with successive plots, which we call spike-trains, often appear on a time-ROTT graph. Also, congestion-related losses are found to be strongly correlated only to the spike-trains and the path status is effectively identified by such spike-trains. Based on these

Intriguing association behavior in solution is exhibited by the rigid macrocycle 1. For instance, it reacts with organic cations to give ternary complexes of the composition (1⋅cation)⋅1, and with analogous macrocycles without cyano groups it forms heteroaggregates. R=CO₂ C₈ H₁₇ .

A tetramesityl derivative of hitherto unknown tetracyclopenta[def,jkl,pqr,vwx]tetraphenylene (TCPTP), which is a potential tetraradicaloid hydrocarbon, was synthesized. Theoretical calculations based on spin-flip time-dependent density functional theory predict that the closed-shell D2h form of TCPTP is more stable than the open-shell D4h form with its slightly tetraradical character. The tetramesityl derivative (Mes)4 -TCPTP exhibits remarkable antiaromaticity as a result of the peripheral 20-π

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXT[16.16.16](1,3,5)Cyclophanetetracosayne (C60H6): A Precursor to C60 FullereneYoshito Tobe, Nobuko Nakagawa, Koichiro Naemura, Tomonari Wakabayashi, Tadamasa Shida, and Yohji AchibaView Author Information Department of Chemistry Faculty of Engineering Science Osaka University, Toyonaka, Osaka 560, Japan Division of Chemistry, Graduate School of Science Kyoto University, Kyoto 606-01, Japan Department of Chemistry Tokyo Metropolitan University Hach

Butadiyne-bridged [4(4)](2,6)pyridinophane and [4(6)](2, 6)pyridinophane derivatives were synthesized, and their heteroassociations with the corresponding metacyclophanes and complexations with organic cations were investigated.

Synthesis of 13,14-dimesitylbenz[c]indeno[2,1-a]fluorene (9b), a 2,3-naphthoquinodimethane derivative isolated for the first time, was achieved. The X-ray crystallographic structure and spectroscopic and electrochemical properties of 9b indicate substantial singlet biradical character which is higher than that of 11,12-dimesitylindeno[2,1-a]fluorene (8b), in accord with the quantum chemical study. Cycloadditions with oxygen and dichlorodicyano-p-benzoquinone took place at the inner naphthalene c

We present herein the synthesis and properties of the largest hitherto unknown graphyne fragment, namely trigonally expanded tetrakis(dehydrobenzo[12]annulene)s (tetrakis-DBAs). Intramolecular three-fold alkyne metathesis reactions of hexakis(arylethynyl)DBAs 9 a and 9 b using Fürstner's Mo catalyst furnished tetrakis-DBAs 8 a and 8 b substituted with tert-butyl or branched alkyl ester groups in moderate and fair yields, respectively, demonstrating that the metathesis reaction of this protocol i

Abstract Supramolecular self-assembly in two-dimensional (2D) spaces on solid surfaces is the subject of intense current interest because of perspectives for various applications in nanoscience and nanotechnology. At the liquid/graphite interface, we found by means of scanning tunneling microscopy molecules with a rigid triangular core, a twelve-membered phenylene-ethynylene macrocycle called dehydrobenzo[12]annulene (DBA), substituted by six flexible alkoxy chains self-assembled to form hexagon