Atsushi Gunji

Selective and Efficient Iodination of the p-Positions of Calix[4]arene Derivatives

Abstract Selective and very convenient methods of iodination of calix[4]arenes using ICl or NIS have been demonstrated, preparing mono(p-iodo) and 1,3-di(p-iodo) derivatives of calix[4]arenecrown-4 and -5, as well as mono(p-iodo) derivative of tris(O-propyl)calix[4]arene in good yields.

SYNTHESIS AND STRUCTURE OF A BIFURAN-CONTAINING P-QUATERPHENOQUINONE : AN UNUSUAL O-CIS 2,2'-BIFURAN CONFORMATION IN THE CRYSTALLINE STATE

Abstract 5,5′-bis(3,5-di-tert-butyM-oxo-2,5-cyclohexadien-1-ylidene)-5,5′-dihydro-2,2′-bifuran has been synthesized. This heteroquaterphenoquinone has been proved to exist in an unusual O-cis bifuran conformation in the solid state by X-ray crystallography.

Synthesis and properties of monolithic photorefractive carbazole-derived calix[4]arenes

As a new class of multi-functional compounds, three kinds of calix[4]arene molecules were newly synthesized: calix[4]arenes containing two 3-nitro-N-allyl carbazoles, two N- allyl carbazoles and one of each at the lower rim. These compounds take cone conformation in solution because of the 1,3-di-O-substitution at the lower rim. Those compounds take amorphous state as proved by differential scanning calorimetry and powder X-ray diffraction and they can be made into films without supporting the polymer matrix. Second- harmonic generation signals were observed in the films of the two calix[4]arenes containing nitro groups after electric poling at a temperature above glass transition point. Enhancement of d33 in the calix[4]arene with nitrocarbazole derivatives compared with the calix[4]arene with both carbazole and nitrocarbazole derivatives was observed, which might be attributed partially to some extent to the conformational regulation between the two carbazole chromophores. Using two beam couple experiment, photorefractive effect was observed in the film of the calix[4]arene with both carbazole and nitrocarbazole derivatives doped with 2,4,7-trinitro-9-fluorenone. This is the first report on the photorefractive property of calix[4]arene compound.

Molecular and Crystal Structure and Properties of Te-Containing p-Terphenoquinone Analogues

Abstract p-Terphenoquinone analogues containing a quinonoid type of tellurophene skeleton in the central position have been prepared with a view to developing a new type of organic pnotoconductive materials having amphoteric redox properties. X-ray structure analysis showed that each molecule exhibited an asymmetric boat conformation owing to the bent structure of the whole ring system and the opposite twisting of two terminal rings. The molecular packing manner in the crystals depends on the substituents on the terminal quinonoid rings. These compounds were electrically amphoteric and afforded radical cation salts and CT complexes by electrochemical or chemical oxidation or by the reaction with an appropriate electron acceptor, respectively. Preliminary experimental results on the photoconductive properties of the neutral compound along with the electrical and magnetic properties of the radical cation salts and CT complexes are described.

Photorefractive properties of conjugated carbazole polymers

We discussed the electric and optical properties of three types of conjugated carbazole polymers: substituted polyacetylene with carbzole moiety, main-chain polymers having conjugated carbazole trimer units, and triindole units. Substituted polyacetylenes can be expected to show the enhanced optoelectronic responses due to the extended conjugated systems in the main chain and the additional chromophores in the side chain. The hole mobility of a substituted polyacetylene containing carbazole moiety was determined to be about 10-4 cm2/Vs with the electric field of 4 x 105 V/cm by time-of-flight technique, while polyvinylcarbazole showed hole mobility of about 10-6 cm2/Vs. The carrier mobility is presumably enhanced by the extended conjugation system. Hyperbranched polymers with carbazole trimer units exhibited the enhanced two beam coupling gain of 60 cm-1 in comparison with main-chain polymer with carbazole units. Since triindole is an electron-donative molecule containing three carbazole substructures with smaller ionization energy than that of carbazole, we can expect the application to a variety of optical and electrical materials. Main-chain polymers with triindole units exhibited the two-beam coupling gain of over 100 cm-1. Therefore, theses conjugated carbazole polymers are one of the good candidates for the new class of electronic and photonic materials.