Juro Ojima

Synthesis and Properties of Tris(octaethylporphyrin)s Connected with Vinylene Groups

Tris(octaethylporphyrin)s, in which two octaethylporphyrin (OEP) rings are connected with vinylene groups at α,γ- and α,β-meso positions of the central OEP ring, were synthesized. The tris(OEP)s have similar conformational and configurational structures to the corresponding vinylene group-connected bis(OEP). Examination of both 1H NMR and electronic absorption spectra of the tris(OEP)s showed the behavior reflecting the highly symmetrical structure and the mutual interaction between the three OEP rings through the vinylene linkages.

The synthesis of methano-bridged bisdehydro [18]-, -[20]-, -[22]-, and -[24] annulenes

Abstract Title annulenes were synthesized by Wittig reaction of cyclohepta-1,3,5-triene-1,6-dialdehyde or its vinylogous dialdehydes with 5-methylpenten-2-yn-4-yltriphenylphosphonium bromide, followed by intramolecular oxidative couplings of the resulting acyclic compounds, and they proved to be diatropic or paratropic, corresponding to the number of peripheral π-electrons.

Trimethylbisdehydro[23]- and -[25]annulenones

Abstract Syntheses of trimethylbisdehydro [23]- and -[25]annulenones have been described, and the examination of their 1 H NMR spectra suggests the diatropicity and the paratropicity of the 25-membered and 25-membered rings, respectively.

Syntheses and properties of a trimethyltetradehydro[23]annulenone and a trimethyltetradehydro[25]annulenone

The syntheses of 2,9,14-trimethyl-10,11,12,13-tetradehydrocyclotricosenone (6) and 2,11,16-trimethyl-12,13,14,15-tetradehydrocyclopentacosenone (7) are described. Examination of the 1H n.m.r. spectra indicates that (6) is diatropic, whereas (7) is paratropic, and these ring currents are increased by dissolution in deuteriotrifluoroacetic acid.

Optical Nonlinearities of Macrocyclic Conjugated Systems

Abstract The second and third order optical nonlinear responses of macrocyclic conjugated systems were experimentally investigated in terms of their possible application as a thin film processable materials with large nonlinear optical properties. The third order optical susceptibility, χ(3)1111(-3ω;ω,ω,ω), for the macrocyclic conjugated structural class of annulenes with an 18-28 membered ring size: tetradehydromethano -[ 18 ]-, -[22]-, -[24]-, -[28]-annulene was determined systematically by optical third harmonic generation measurements of molecularly doped polymer films, at a wavelength of 1.907 ωm. The third order optical response was found to increase with increased size of the macrocyclic conjugated structure in a manner analogous to the behavior of conjugated linear chains. The isotropically averaged third-order polarizabilities of annulenes molecules were calculated from the doping concentration dependence of (-3ω;ω,ω,ω) and are found to possess a power law dependence on the annulene ring size. Linear and nonlinear optical properties of novel cross-conjugated π-electrons systems were determined by spectroscopic methods. Second-order polarizabilities (β) of 14,14-dicyano-5,10-dimethyl-6,8 bisdehydrotridecafulvene and their vinylogues were obtained by using a two-level quantum mechanical model, where required the excited state dipole moments were estimated by a solvatochromic method. These macrocyclic conjugated systems have highly polarizable structures and β values which increase with increasing of number of exocyclic double bonds.

Syntheses and properties of a trimethyltetradehydro[21]annulenone and its benzannulated derivatives

The syntheses of 2,9,14-trimethyl-10,11,12,13-tetradehydrocycloheneicosenone (3), 19-methyl-20,21,22,23-tetradehydrobenzocycloheneicosen-11-one (4), and 10-methyl-22,23,24,25-tetradehydredibenzo[a,g]cycloheneicosen-11-one (5) are described. The influence of α-methyl substitution and benzannulatien on the structure and tropicity of the tetradehydro[21]annulenone ring system is discussed in view of the 1H n.m.r, and u.v. spectra of these annulenones, as well as those of the dimethylannulenone (2).

Synthesis and properties of a trimethyltetradehydro[17]annulenone and its benzannelated derivatives

Syntheses of 2,7,12-trimethyl-8,9,10,11-tetradehydrocycloheptadecenone (5), 10,15-(6) and 8,15-dimethyl-16,17,18,19-tetradehydrobenzocycloheptadecen-9-one (7), and 8-methyl-18,19,20,21-tetradehydrodibenzo[a,g]cycloheptadecen-9-one (8) are described. The 1H n.m.r. spectra of these annulenones and related compounds indicate that the skeleton of the tetradehydro[17]annulenone ring system is more planar and less strained than that of the corresponding [13]annulenones.