Yukiko Muramatsu

Preparation of new main-chain type poly(anthraquinone)s having alkoxyl groups and their liquid crystalline behaviour

New main-chain type poly(5,8-dialkoxyanthraquinone-1,4-diyl)s have been prepared by using a Ni(0) complex. They take an ordered structure assisted by side-chain crystallinity. The ordered structure has been elucidated by X-ray diffraction pattern. Their d spaces and the relationship between the d space and the number of carbon atoms in the alkoxyl side chain indicate that these polymers take an end-to-end packing mode and their main chain has an s-trans conformation. These polymers exhibit liquid crystalline behaviour at a wide range of temperature.

Electrical conductivity of π-conjugated polymers with nitro substituents

π-Conjugated polymers bearing nitro substituent(s), e.g., poly(aryleneethynylene) (PAE) type polymers and poly(4,8-dinitroanthraquinone-1,5-diyl) P(4,8-NO2-1,5-AQ), show semiconducting properties with electrical conductivities of an order of 10−7 to 10−6 S · cm−1 at room temperature without special oxidation and reduction of the polymer. P(4,8-NO2-1,5-AQ) shows a large shift of phase in alternating current (ac) measurements and a unique magnetism at low temperature.

Ultraviolet Photoelectron Spectroscopy of n-Type Conducting Polymers

Abstract Ultraviolet photoelectron spectra were measured using synchrotron radiation for four kinds of π -conjugated polymers, poly(pyridine-2,5-diyl)[Ppy], poly(2,2′-bipyridine-5,5′-diyl)[Pbpy], poly(2-methylantraquinone-1,4-diyl)[P(2Me-1,4-AQ)], and poly(antraquinone-1,5-diyl)[P(1,5-AQ)], which exhibit n-type electrically conducting properties. Upon K-doping of Pbpy, two new states appeared in the originally empty energy gap. This finding indicates that bipolaron bands are formed in K-doped Pbpy. While K-doped Ppy also shows similar gap states, it requires higher dopant concentration to create bipolaron bands than in the case of K-doped Pbpy. The UPS spectra of K-doped P(2Me-1,4-AQ) also show similar gap states, while it is almost absent in K-doped P(1,5-AQ). The changes in electronic structure of these polymers are discussed based on the conformational difference between these polymers.

ULTRAVIOLET PHOTOELECTRON SPECTROSCOPY OF POLY(ANTHRAQUINONE)S AND POLY(1,10-PHENANTHROLINE-3,8-DIYL); THEIR ELECTRONIC STRUCTURE AND K-DOPED STATES

Abstract Ultraviolet photoelectron spectra were measured for two classes of π-conjugated systems, poly(anthraquinone)s [poly(2-methylanthraquinone-1,4-diyl) [P(2Me-1,4-AQ)], poly(anthraquinone-1,5-diyl) [P(1,5-AQ)]], and poly(1,10-phenanthroline-3,8-diyl) (PPhen). Upon K-doping of PPhen, two new states, which could be assigned to bipolaron bands, appear in the originally empty energy gap. In the case of K-doped P(2Me-1,4-AQ), a new state appeared in the energy gap region. On the other hand, P(1,5-AQ) showed poor reactivity to the dopant in comparison with P(2Me-1,4-AQ). The electronic structures of the neutral and K-doped states of these polymers were analyzed using semiempirical MO calculations. The electronic structure of PPhen-metal complex was also examined.

Combinatorial synthesis of pi-conjugated polymer thin films for functional material research

Vacuum evaporation (VE) and pulsed laser deposition (PLD) were examined as film preparation methods for (pi) - conjugated polymers with photoluminescent property. A variety of (pi) -conjugated polymer films were deposited under various conditions within a single experiment by using combinatorial mask technology for optimization of preparation conditions, e.g. evaporation temperature of VE and laser power density of PLD.