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The diacetylene-group connected chromatic system of [octaethylporphyrin]-[spacer]-[Lewis base] triads (OEP-SPC-LB) was conclusively studied, in which a trigger-like interaction of the terminal LB with trifluoroacetic acid (TFA) dramatically affects the inherent electronic properties of OEP. The 1H NMR, IR, and electronic absorption spectral properties of these OEP derivatives were examined, and were contemplated in view of a cooperative effect of SPC and LB on their OEP nucleus. Based on the results from this study, the structural elements for molecular design will be proposed in order to improve their reversible spectral changes between neutral and acidic media in terms of sensitivity, stability, and visibility to TFA.

In contrast to the facile synthon ethynylferrocene for diacetylene ferrocene (Fc) derivatives, 1,1′-diethynylferrocene for the corresponding 1,1′-bis(diacetylene-group)-connected Fc derivatives is ...

Orientational isomers of the octaethylporphyrin–dihexylbithiophene (OEP–DHBTh) derivatives connected with a diacetylene linkage were synthesized, with various electron-withdrawing substituents X at...

A p-chloranil dimer (pCh2) has been synthesized. The first reduction potential of pCh2 shifted to a more positive value than that observed for the p-chloranil monomer (pCh1) and was more negative t...

A mixture of biquinone (QQn) and bihydroquinone (HHn) bearing tert-butyl substituents at 5,5′- (n = 1) and 6,6′-positions (n = 2) yields hydroquinonylquinone (HQn) as an equilibrium product by quin...

Octaethylporphyrin–dihexylbithiophene–dimethylaniline triads were synthesized. The triads showed color change from green to yellow upon addition of trifluoroacetic acid. VT-NMR and UV–vis measureme...

An extended π-electronic conjugation system of dihexylbithiophene–octaethylporphyrin [OEP–(DHBT)n–OEP; n = 1–5], all the chromophores in which are connected with the linkage of 1,3-butadiyne (diacetylene), was synthesized by an oxidative cross-coupling reaction of the corresponding terminal acetylenes. Absorption spectral and electrochemical properties of the OEP–(DHBT)n–OEP system were examined. The results proved that the orientation of two 3-hexylthiophene (3HTh) rings of DHBT plays an important role in electronic communications between the two terminal OEP rings.

Various mixed complexes of vinylene-bridged bis- and tris(octaethylporphyrin)s (bis(OEP)-(M1-M2) and tris(OEP)-(M1-M2-M3)) with d8 transition-metal ions M(II) (M: M1, M2, and M3 = Ni or Pd or Pt) were synthesized by step-by-step and selective metallations of the respective free-bases (FB) with limited amounts of the metallation reagent. Metallation of tris(OEP)-(H2-H2-H2) started in the central OEP ring, with the vinylene linkages of the product retaining the same (E,E)-configuration as those in FB. On the other hand, metallation of (E)-bis(OEP)-(H2-H2) afforded the corresponding (E)-bis(OEP)-(M1-M2) predominantly, while metallation of (Z)-bis(OEP)-(H2-H2) was accompanied by a ready isomerization of the vinylene linkage to afford each pair of (E)- and (Z)-isomeric complexes under the similar conditions. Electronic absorption spectra of tris(OEP)-(M1-M2-M3) proved to be affected especially by the central OEP-M2 ring and by the heavier metals more intensively, resulting in the largest splitting of the Soret...

Complexes of vinylene-bridged bis- and tris(octaethylporphyrin)s (bis(OEP)–M and tris(OEP)–M) with d8 transition-metal ions (M = Ni(II), Pd(II), and Pt(II)) were synthesized. Metalation of (E)-bis(OEP)–H2 was carried out under the same conditions as for the corresponding octaethylporphyrin complex (OEP–M), to afford a mixture of complexes bearing the vinylene-linkages with (E)- and (Z)-configurations. On the other hand, metalation of tris(OEP)–H2 afforded the single product of which two vinylene-linkages remained holding the same (E,E)-configuration as that in the free-base. 1H NMR spectra varied more drastically for (Z)-bis(OEP)–M, with respect to those of OEP–M, while electronic absorption spectra did more drastically for the (E)-isomers. Their electronic properties at the ground state were examined, proving that the interaction between the constituent OEP rings through the vinylene-linkages is more intensive for tris(OEP)–M than for bis(OEP)–M and more intensive for the Ni complex than for the Pd and P...

2,2′-(Dihexyl-2,2′-bithienylidene-5,5′-diylidene)bis(propanedinitrile)s (dihexylbithienoquinonoid derivatives), in which two 3-hexylthiophene moieties are connected with head-to-tail (HT) and tail-to-tail (TT) orientations, were synthesized. HT bithienoquinonoid was isolated in a single form together with a small amount of its bromo derivative, similarly to the case for the head-to-head (HH) orientational isomer. On the other hand, TT isomer exhibited a peculiar feature in solution, affording an equilibrium mixture of two geometrical isomers. Electronic and electrochemical properties of these bithienoquinonoids were studied and compared with those of HH isomer. The results proved that all these bithienoquinonoid compounds possess highly polarizable and electron-acceptable properties. HH bithienoquinonoid was reduced through one two-electron transfer process, while HT and TT isomers were reduced through two one-electron transfer processes via stable radical anions to the corresponding dianions.

In N-phenyl-9-triptycylamine (6), “gear rotation” (GR) and “isolated rotation” (IR) have almost the same free-energy barriers of ca. 45.2 kJ mol−1, while the nitrogen inversion is fast throughout the whole temperature range and thus the nitrogen is regarded as planar on the NMR timescale. In N-methyl-N-phenyl-9-triptycylamine (7), the internal motions are fast on the NMR time scale even at the lowest attainable temperature. In N-benzyl-N-phenyl-9-triptycylamine (8), the GR process has a free-energy barrier of ca. 36 kJ mol−1 and the passing of the benzyl group over an o-benzeno group has a higher barrier than GR. N-2-Biphenylyl-9-triptycylamine (9), which is obtained during the course of the synthesis of 6, shows a dynamic behavior presumably ascribable to GR with the free-energy barrier of 70 kJ mol−1.

The unsymmetrically substituted bi- and quaterthiophene derivatives were synthesized. The unsymmetrically substituted bithiophenes carrying the electron-withdrawing substituent X on one of the outer thiophene rings exhibited the maxima of absorption bands at the longer wavelengths than the symmetrically disubstituted bithiophene derivatives, while the unsymmetrical quaterthiophenes had such maxima at the shorter wavelengths than the corresponding symmetrical ones. The trend of bathochromic shift of the longest wavelength absorption bands due to the electron-withdrawing substituent X was more pronounced in case of bi- or quaterthiophenes bearing push–pull substituents. The unsymmetrical quaterthiophenes exhibited the greater third-order nonlinear optical (TNLO) properties than the corresponding bithiophenes, similarly to the case between the symmetrical bi- and quaterthiophenes. However, the TNLO properties of the unsymmetrical bi- and quaterthiophenes showed no dependence on the electron-withdrawing stren...

The catalytic partial hydrogenation of the 5,10-dimethyl-6,8-bisdehydro[13]annulenone using Pd–BaSO4 afforded the 5,10-dimethyl[13]annulenone together with two isomeric 5,10-dimethyl-6-dehydro[13]annulenones. The dimethyl[13]annulenone, which is the first example of a monocyclic non-dehydro annulenone derivative larger than tropone, was found to be atropic on the basis of 1H NMR spectra. Molecular mechanics studies indicate the extensive deviation of the molecular skeleton from planarity and help to explain the lack of peripheral conjugation. Attempts to obtain the [15]annulenone and the [17]annulenone from the bisdehydro[15]annulenone and the bisdehydro[17]annulenone, respectively, were unsuccessful.

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.

14-Methyl-10,12-bisdehydro-4,9-methano-1H-[17]annulen-1-one, 14-methyl-10,12-bisdehydro-4,9-methano-1H-[19]annulen-1-one, and 16-methyl-12,14-bisdehydro-6,11-methano-1H-[21]annulen-1-one, as well as their methylated and benzannelated derivatives, were synthesized and their tropic properties were studied by NMR and UV spectra under neutral and acidic conditions. The tropicity in these compounds was found to be lower than in their non-bridged monocyclic counterparts. Thus the methano-bridge works to decrease the planarity of the peripherally conjugated system.

The two types of highly-ordered oligo(3-hexylthiophene)s in head-to-head orientation, a series of α,ω-disubstituted oligothiophenes and a series of bis(dicyanomethylene)oligothienoquinonoids, were synthesized. The properties of these compounds are discussed on the basis of the electronic spectra and cyclic voltammetry.

A bismethano-bridged bisdehydro[21]annulenone, tricyclo[15.4.1.16,11]tricosa-6,8,10,12,15,17,19,21-octaene-2,4-diyn-14-one, was synthesized. X-ray crystallography reveals the syn orientation of the two methano bridges. Two conformers are present in solution in a 97:3 ratio, the major isomer being the one existing in the crystalline state. Paratropicity of this compound in CDCl3 and in CF3CO2D is discussed.

Stereodynamics of N-benzyl-N-methyl-9-aminotriptycene is studied by 1H and 13C dynamic NMR spectroscopy. The energy barriers to internal motion are governed by the eclipsing interaction between an N-alkyl group and an o-benzeno bridge of the triptycene moiety together with the intrinsic barrier to nitrogen inversion.

A series of (porphyrin)–(C≡C)2–C6H4–R1 (R1 = NO2, H, Me, and OMe) were synthesized by the oxidative coupling of ethynyl porphyrins and phenylacetylenes in the presence of copper(II) acetate in pyridine. Electronic and electrochemical spectra of the compounds with R1 = H, Me, and OMe are quite similar, while pronounced change was observed for the compound with R1 = NO2, especially for the meso-substituted one, indicating that intramolecular charge transfer is responsible for the difference.

A bisdehydro[14]annuleno[c]furan and a tetrakisdehydro[14]annuleno[14]annulene have been synthesized; their properties and effects of annelation on annulene rings are discussed on the basis of 1H NMR and electronic spectra. Attempts to synthesize the related [14]annuleno[16]annuleno[14]annulene are also described.

Cationic rearrangement of 1,4-bis(diarylhydroxymethyl)pentacyclo[4.2.0.02,5.03,8.04,7]octanes (1) in formic acid gave new cage compounds, 8,8-diaryl-2-diarylmethylene-exo-5-(formyloxy)tetracyclo[4.3.0.03,9.04,7]nonan-7-ols (3) and new cage-degradation products, 5,5-diaryl-4-[4-(diarylmethylene)-2-cyclobutenyl]-2-cyclopenten-1-ones (4) along with Wagner–Meerwein rearrangement products, pentacyclo[5.3.0.02,5.03,9.04,8]decanes (5; C2-bishomocubanes) and pentacyclo[5.3.0.02,6.03,9.04,8]decanes (6; D2h-bishomocubanes). 9,9-Diaryl-4-(diarylhydroxymethyl)pentacyclo[4.3.0.02,5.03,8.04,7]nonan-1-ols (2) gave 4, 5, and 6 without the formation of 3. A Wagner–Meerwein 1,2-bond shift of 1 gave key intermediates 2 which were converted into 3 via homoallylic rearrangement, into 4 via pinacol–pinacolone-like rearrangement, or into 5 and 6 via Wagner–Meerwein rearrangement.

A methanodehydro[24]annulenedione with a 1,4-dichlorobutatriene moiety was synthesized. The compound formed a highly stable dicationic species in D2SO4, which showed the strongest diatropicity hitherto reported for 22π-electron aromatic systems.

The cationic rearrangement of 1-bromo-4-[hydroxybis(4-methoxyphenyl)methyl]pentacyclo[4.3.0.02,5.03,8.04,7]nonane-9-spiro-2′-[1,3]dioxolane (1) in formic acid gave 4-bromo-1-formyloxy-10,10-bis(4-methoxyphenyl)pentacyclo[5.3.0.02,6.03,9.04,8]decane-5-spiro-2′-[1,3]dioxolane in 27% yield along with 5-bromo-9-formyloxy-10,10-bis(4-methoxyphenyl)pentacyclo[5.3.0.02,5.03,9.04,8]decane-6-spiro-2′-[1,3]dioxolane in 55% yield. The reaction of 1 with p-toluenesulfonic acid or hydrochloric acid in methanol also afforded 4-bromo-1-methoxy-10,10-bis(4-methoxyphenyl)pentacyclo[5.3.0.02,6.03,9.04,8]decane-5-spiro-2′-[1,3]dioxolane together with 5-bromo-9-methoxy-10,10-bis(4-methoxyphenyl)pentacyclo[5.3.0.02,5.03,9.04,8]decane-6-spiro-2′-[1,3]dioxolane. With respect to migration of the C4–C5 bond in the pentacyclo[4.3.0.02,5.03,8.04,7]nonane (homocubane) skeleton to pentacyclo[5.3.0.02,6.03,9.04,8]decane (D2h-bishmocubane), a rearrangement into the bishomocubane system in driven by a concomitant release of strain; also...

Synthesis of 7,8:13,14-dibenzo-2,9,11-trisdehydro[16]annulene-1,4-dione is described. Attempts to prepare diaza[18]annulene derivatives by ring expansion of the dibenz[16]annulenedione and its dimethyl analog are also described. Examination of 1H NMR spectra indicates that the dibenz[16]annulenedione shows no ring current effect.

Configurational and conformational isomerism in the bisdehydro[15]annulenones were studied in CDCl3 and CF3CO2D–CD2Cl2 solutions by 1H NMR spectroscopy. The 7,12-dimethyl compound with the initial “all-E” configuration isomerized in both media at ambient temperature to give an equilibrium mixture of isomers but the trimethyl derivatives retained their original configuration under the similar conditions. The charge distribution in the deuterated species was discussed on the basis of the 13C NMR spectra.

A potential 18π-electron system, 11,16-dimethyl-12,14-bisdehydro-1,6-methano[20]annulene-7,20-dione was synthesized and its 1H NMR spectral behavior in CDCl3, CF3CO2D, and D2SO4 was studied. The energy barrier to the methylene flipping was highly dependent on the medium.

The first example of fuluvalene derivative containing two monocyclic large-membered rings, 1-(5,10-dimethyl-6,7,8,9-tetradehydrocyclotridecen-1-ylidene)-7,12-dimethyl-8,9,10,11-tetradehydrocyclopentadecene, has been synthesized. Examination of 1H and 13C NMR spectra indicates that the tridecapentadecafulvalene derivative shows no ring current effect but polyolefinic character.

The first synthesis and the physical properties of diphenoquinonophanes is reported along with their spectral evidences.

The title azafulvene analogs were synthesized by the reaction of the corresponding annulenones with N,N′-bis(trimethylsilyl)carbodiimide. The 1H NMR spectra reveal that these compounds show larger tropicity than the corresponding dicyanofulvenes and annulenones.

The vinylogues of 14,14-dicyano-5,10-dimethyl-6,8-bisdehydrotridecafulvene have been synthesized and the effect of increasing exocyclic double bonds upon the paratropicity of the thirteen-membered ring is discussed by comparing the polarizability of 2,2-dicyanovinyl, 4,4-dicyano-1,3-butadienyl, and 6,6-dicyano-1,3,5-hexatrienyl groups.

The Si–H bond was introduced onto the surface of MCM-41 by reduction of the butoxylated MCM-41. The hexyl and phenylalkyl-functionalized MCM-41s were obtained by reaction of the Si–H introduced MCM...

Mono-, di-, and trimetallic Pd(II) complexes of the etheno-bridge porphyrin trimer 1 were prepared. It was found that the metalation of 1 first occurred in the inner porphyrin ring. The trimetallic Pd(II) trimer 6 exibited splitting of the Soret band and complete disappearance of the weak bands ranging from 600 to 1000 nm unlike the corresponding free-base and Ni(II) porphyrin trimers.

13C Dynamic NMR study of N-phenyl-9-triptycylamine (3) reveals that “gear rotation” and “isolated rotation” in 3 have almost the same free-energy barriers of ca. 10.8 kcal mol−1.

Four types of purinophanes (1, 2, 7, and 10) where a 6-thiopurine ring is bridged between S6- and 9-positions or between S6- and 7-positions were synthesized. Among them (6,9)purinophanes (1, 7, and 10) showed unusual high reactivity toward nucleophiles (MeNH2, Me2NH, OH−) at 6-position to give acyclic compounds. The increased rate constants of these compounds against (6,7)purinophanes 2 and 9-methyl-6-(methylthio)purine could not be explained by molecular strain, neighboring group participation, or some electronic effect due to faced π-systems, but successfully explained by the stereoelectronic effect proposed by Deslongchamps. The rate of the reactions in 1, 7, and 10 was increased with an increase in rigidity of the tetrahedral intermediate where lone pairs of two adjacent heteroatoms orient antiperiplanar to the departing group.

The flash vacuum pyrolysis of benzyl phenyl selenides gave bibenzyls and diphenyl diselenide in excellent yields. This type of reaction was successfully applied to the synthesis of the title compounds.

Syntheses of cyclic diselenides through diselenolates and the following deselenation reactions by means of three ways were studied. The preparation of the cyclic diselenides in the presence of excess sodium borohydride gave thirty-eight diselenides containing diselena[3.3]cyclophanes and alicyclic diseleno compounds in high yields in addition to two triple-bridged selenacyclophanes. Photodeselenation of the diselenides in tris(dimethylamino)phosphine afforded series of [2.2]cyclophanes in much higher yields than those of the other two methods, i.e. benzyne-Stevens rearrangement/Raney nickel hydrogenolysis and pyrolytic deselenation at ca. 650 °C. The present study demonstrates that the photodeselenation method, combined with the synthesis of their precursor diselenides, is much superior to the conventional dechalcogenation methods.

The titled tetrathiacyclophane was prepared by improved synthetic methods and its molecular structure previously reported was corrected by 1H-NMR and X-ray analyses.

Pyrolyses of a series of selenides and diselenides were studied. Selenides and diselenides bound with an active methylene group like benzyl gave a variety of substituted bibenzyls and related ethane derivatives in high yields. Other diselenides were easily caused to cleave to give various aromatic and aliphatic olefins in good yields together with elemental selenium. Lepidopterene, [2.2]paracyclophane, and benzocyclobutene were prepared by thermal cleavage of their corresponding phenylselenomethyl-substituted compounds as an application of the pyrolysis concerned.