Soichi Misumi

Intramolecular electron donor-acceptor interactions in the excited state of (anthracene)-(CH2)n-(N,N-dimethylaniline) systems

Abstract Effects of the geometrical restrictions on the intramolecular CT (charge transfer) interactions in the excited state have been investigated for the (anthryl)-(CH 2 ) n -( p -N,N-dimethylaminophenyl) systems ( n =0, 1, 2, 3). The solvent-induced structure change and the level reversal between the locally excited state of anthracene and the CT state during the excited state lifetime have been demonstrated.

On the Solvent-Induced Changes of Electronic Structures of Intramolecular Exciplexes

Effects cf solvent polarity upon the electron donor-acceptor interactions in the excited state of p-(CH3)2N C6H4(CH2)n-(9-anthryl) (n=0, 1, 2, 3) and p-(CH3)2NC6H4-(CH2)n-(1-pyrenyl) (n=1, 2, 3) have been investigated by means of fluorescence spectral measurements and theoretical calculations based on some simplified models. The solvent-induced electronic structural changes during the excited state lifetime have been demonstrated for some of the above intramolecular exciplexes.

Picosecond time-resolved observation of photoinduced charge separation from the singlet excited state of porphyrin-quinone model systems

Abstract The charge transfer state formed from the S 1 state of porphyrin- p -benzoquinone (BQ) model systems in solution has been observed combining octaethylporphyrin and BQ by methylene chains of various lengths. The lifetime of the electron transfer state depends upon the length of the methylene chain and the nature of the solvent.

Synthetic macrocyclic ligands. IV. Lithium ion-characteristic coloration of a “crowned” dinitrophenylazophenol☆

Abstract A “crowned” dinitrophenylazophenol shows a characteristic coloration only with lithium ion of alkali metal ions, as if an indicator.

Synthesis of new donors containing two TTF moieties

Abstract New donors in which two TFF units are oriented with some dihedral angle have been designed to form highly conductive CT complexes with increasing in dimensionality of transport property in the solid state. These “TTF-dimers” have been prepared in a moderate yield by cross coupling between two trithiocarbonates or two dithiolium salts. Cyclic voltammetry showed reversible redox potential waves for all donors and also indicated that their donor ability are slightly reduced compared with those of corresponding “TTF-monomers” such as TMT-TTF and trimethylene-TTF. All “TTF-dimers” form CT complexes with DDQ and not with TCNQ, supporting the reduction of donor ability. Electrical conductivities of CT complexes with DDQ were measured on their compressed pellets.

Intramolecular excimer fluorescence, its solvent dependence, and photodimerization of 1,2-dianthrylethanes

Abstract Both 1,2-di(1-anthryl)ethane (I) and 1,2-di(9-anthryl) ethane (II) show two types of excimer fluorescence spectra under different conditions; one with peak at 460 nm (type-1) and the other with peak at 530 nm (type-2). Furthermore, the type-1 excimer emission shows a peculiar dependence upon the solvent polarity.

Synthetic macrocyclic ligands. III. Synthesis of a quinone-hydroquinone redox system incorporated with complexing ability toward cations

Abstract Two quinones bridged with a polyether chain and the corresponding hydroquinones were synthesized, and their redox reaction and complexations with sodium and potassium ions were observed.

Deselenation of diselenacyclophanes —a new synthetic method of [2.2]cyclophanes—

Abstract Several diselena[3.3]cyclophanes were prepared by coupling of bisselenocyanates and bis(bromomethyl)benzenes in good yields. The benzyne Stevens rearrangement-Raney Ni hydrogenolysis method gave good yields of double- and triple-layered cyclophanes from the diselenides, though the flash pyrolysis method gave them in low yields.

Syntheses of a series of octaethylporphyrin-benzoquinone linked molecules as a model for the primary process of photosynthesis

Abstract To clarify the primary process of photosynthesis, a series of model compounds, in which an octaethylporphyrin and a benzoquinone ring are connected with different lengths of a polymethylene chain, were synthesized and their photophysical properties were investigated.

Electronic structure and dynamical behavior of some intramolecular exciplexes

Photo-primary processes were investigated for some excited electron-donor acceptor model systems by means of laser spectroscopy. Fluorescence rise and decay curves, Sn←S1 as well as Tn←T1 spectra of (CH3)2N-C6H4-(CH2)n-(1-pyrenyl) exciplexes were examined in various solvents of different polarities. The results have indicated that the sandwich structure is not necessary for the intramolecular charge transfer in polar solvents and that the electronic structure of the exciplex becomes more polar in solvents with higher polarity.