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Boronium complexes bearing a 9-borabicyclononane framework with a bipyridine-type ligand display photoinduced solid-state coloring behavior. While the identity of the substituents on the boron atom is critical to gain photoresponsive capability, modifying the nitrogen-containing ligand structure and its substituents provides a wide variation in the photoinduced solid color.

Based on the fact that anthracene (Anth) possesses much higher similarity in electron-releasing ability to porphyrin nucleus than the other polyacenes, the dimeric octaethylporphyrin (OEP) derivatives 4 and 5 (OEP–Anth–OEP) were synthesized and their structure–property relationships were examined, as compared with related OEP dimers 1 – 3 . Among them, the derivative 4 showed enormously high electronic communication between two terminal OEP rings, potentially providing a suitable unit of the electronic structure for molecular design of the OEP devices operating with less energy and with higher sensitivity to outside stimuli.

Tris(4-amino-2,6-dimethylphenyl)borane (1), a triarylborane bearing an unsubstituted amino group on all of its aryl substituents, and related triarylboranes were synthesized via Ullmann condensation. The facile dehydration reactions of 1 with benzaldehyde and nitrosobenzene gave tris[4-(benzylidenamino)-2,6-dimethylphenyl]borane and tris[2,6-dimethyl-4-(phenylazo)phenyl]borane, respectively. These triarylboranes bear an extended π-conjugated system bridged by a nitrogen-containing π-linker on each of their aryl groups. UV–vis absorption spectra and theoretical calculations revealed that the π-conjugated system of the triarylborane was effectively extended by utilizing the reactivity of the amino groups.

An extended π-electronic conjugation system of the 1,1′-bis[ p -( N,N- dimethylaminophenyl)butadiynyl]ferrocene derivative 1 has been synthesized, with our integrated cross-coupling reaction between the corresponding TMS-protected acetylenes in one-pot. Quantitative 1 H NMR and UV–vis spectral studies of 1 have been performed, providing a methodology for molecular functions transformable by a proton-mediated reversible conformation control.

An extended π-electronic conjugation system of 1,1′-bis(diacetylene-group) connected ferrocene–thiophene derivative has been synthesized, with our integrated reaction between the corresponding TMS-protected acetylenes in one-pot. Its electronic properties have been examined, suggesting a cooperatively functional behavior of the diacetylene-group connected constituents.

Orientational isomers of the octaethylporphyrin–dihexylbithiophene–pyridine system (OEP–DHBTh–Py) connected with the diacetylene linkage were synthesized. The spectral measurements were performed under neutral and acidic conditions, clearly proving that the orientation of DHBTh affects not only the electronic structures of OEP–DHBTh–Py but also their proton-mediated spectral changes.

Orientational isomers of the octaethylporphyrin–dihexylbithiophene–fullerene derivative (OEP–DHBTh–C 60 ) connected with the diacetylene linkage were synthesized. The electronic and electrochemical properties were studied, proving that the orientation of DHBTh affects not only the electronic structures of OEP–DHBTh–C 60 but also their molecular motional behaviors evidently.

The tetramer of octaethylporphyrin nickel complex [OEP(Ni)], connected with diacetylene and ethylene linkages, was synthesized. Its structural and electronic properties were studied, proving that two constituents of the diacetylene-group connected OEP(Ni) dimer face to each other in s-cis conformation about the ethylene linkage but not so closely as to induce a transannular π-electronic interaction between them.

Orientational isomers of the diacetylene-group connected dihexybithiophene (DHBTh) derivatives have been synthesized, in which the different octaethylporphyrin (OEP(M); M=Ni or Pd) rings are attached at the ends. Reflecting the unsymmetrical structural feature, the peculiar electronic properties of the extended OEP(Ni)–DHBTh–OEP(Pd) system were observed.

Octaethylporphyrin (OEP) was combined with 2-substituted 3-hexylthiophenes (HTh) by diacetylene linkage to afford the highly extended conjugation system (HTh–OEP). Their absorption spectral properties were examined, proving that the electronic structure of OEP is affected by the more electron-withdrawing substituents through the diacetylene linkage more dramatically. The substituent effect on the HTh–OEP conjugation system is much outstanding, as compared with that on the corresponding benzene system (Bzn–OEP).

The octaethylporphyrin (OEP) tetramer connected with both diacetylene and vinylene linkages was synthesized by an oxidative homo-coupling of the terminal acetylene of the vinylene-group connected OEP dimer. The electronic spectral and electrochemical studies were performed, proving that the hybridized OEP tetramer remains the characteristic properties of the vinylene-group connected OEP dimer more intensively as compared with the diacetylene-group connected OEP dimer.

A new type of hybridized dihexylbithiophene-octaethylporphyrin derivative (DHBTOEP) connected with the 1,3-butadiyne linkage was synthesized by oxidative cross-coupling of the corresponding terminal acetylenes. The absorption spectra and electrochemical properties of the DHBTOEP hybrid were examined, clearly proving that the orientation of two 3-hexylthiophene rings of DHBT plays an important role in electronic communication between the two terminal OEP rings.

5,10-Dimethyl[13]annulenone, the first monocyclic annulenone larger than tropone, was synthesized by catalytic partial hydrogenation of 5,10-dimethylbisdehydro[13]annulenone. The 1H NMR data indicate that the compound is completely atropic. Molecular mechanics studies suggest the nonplanarity of the ring and thus the lack of peripheral conjugation.

The push-pull dihexylbithiophenes with HH and H-T orientations were synthesized. From the solvent effect of their electronic absorption spectra, it was indicated that the stabilization energies due to solvent polarity were almost the same between these orientational isomers in spite of a large difference of the molecular planarity for conjugation between them.

The two isomers of tetrakisbridged dimethoxybiphenylophanes, 1 and 2, have been synthesized. With respect to the longest wavelength absorption bands due to the biphenyl chromophores, the cross-orientation isomer exhibited the marked bathochromic shift, while the parallel-orientation isomer the typical exciton splitting. Their transannular properties in solution were further confirmed by X-ray crystal analysis.

10,12-Bisdehydro-3-isopropyl-9,14-dimethyl[14]- and -11,16-dimethyl[16]annuleno[a]azulene in which the conjugated 14- and 16-membered rings are fused to azulene ring, have been synthesized. It was found that the fusion of azulene ring suppresses the diatropicity of [4n+2], 14π-electron system to a smaller extent than benzene ring.

Dissolution of the title compound (1) in CF3CO2D-CD2Cl2 formed a cationic species which showed extensive isomerization. 1 recovered by neutralization existed as a mixture of isomers different from the initial one indicating that the latter formed under kinetic control.

Metallocubanes are shown to be available by a transmetalation procedure in which amide-activated cubanes are treated with LiTMP and a metal chloride. They are excellent precursors for new subsituted cubanes.

[n](6,9)Purinophanes 2a–c were synthesized and their unusual reactivity toward nucleophiles was explained by the stereoelectronic effect in the fairly rigid tetrahedral intermediate.

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.

Several cyclophanes were prepared by photodeselenation of diselena[3.3]cyclophanes with hexamethylphosphorus triamide in excellent yields, compared with the other chalcogen-atom extrusion methods.

A novel cage compound was obtained by irradiation of a quadruple-layered dithiacyclophane and showed thermally reverse reaction.