Here we report a new class of discrete nanotubular object formed by self-assembly of amphiphilic hexa-peri-hexabenzocoronene (HBC) derivatives. The nanotubes are characterized by an aspect ratio greater than 1000 and has a uniform, 14 nanometers wide, open-ended hollow space, which is an order of magnitude larger than those of carbon nanotubes. The wall is 3 nanometers thick, consisting of helical arrays of the pi-stacked graphene molecule, whose exterior and interior surfaces are both covered by hydrophilic triethylene glycol chains. The graphitic nanotube is redox active, and a single piece of the nanotube across 180 nanometer-gap electrodes shows, upon oxidation, an electrical conductivity. By taking advantage of the chemically accessible structure, we also succeeded in the fabrication of novel graphitic nanotubes with various interesting properties.

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One of the definite features in polyrotaxanes, in which many cyclic compounds are threaded onto a linear polymeric chains capped with bulky end-groups, is non covalent bonds between the cyclic compounds and the polymeric chain. The cyclic compounds may rotate and/or slide along the polymeric chain. Also, the cyclic compounds can be dethreaded from the chain to loose the supramolecular structure if the terminal end groups are cleaved by any stimulus. Such a "mobile" nature seen in polyrotaxanes would be fascinating when considering the emergence of nano-biological functions. One example would be to enhance multivalent interaction with biological receptors: "mobile" ligands conjugated to the cyclic compounds can effectively bind receptor proteins in a multivalent manner. In order to expand this concept to more practical application, cytocleavable polyrotaxanes is one of our interests as a carrier to deliver DNA to the nucleus of cells.

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For tetrabenzoporphyrin (TBP), thin films are fabricated by dissolving a precursor molecule, tetrabicycloporphyrin, in organic solvents. Spin cast films of precursor exhibit amorphous, insulating behavior, following a thermal anneal in either vacuum or N2, the amorphous film is converted into polycrystalline TBP, with crystal sizes exceeding 1 micrometer. OFETs using TBP and its metal salts display field effect mobility, ranging from 10^-2 cm^2/Vs to 1 cm^2/Vs depending on metals and on/off current ratios exceeding 10^5.

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Recently, we have reported that linear p-conjugated molecules having trifluoromethylphenyl groups at the terminal positions are promising candidates for n-type FET materials. Electron deficient nitrogen-heterocycles such as thiazole, thiazolothiazole and benzothiadiazole have been used to improve electron mobilities and reduce threshold voltages of FET devices. We have now prepared thiazole-containing co-oligomers with trifluoromethylphenyl groups and fabricated FET devices. FET characteristics are strongly dependent on the nitrogen positions of thiazole rings. The derivative with 2-(4-trifluoromethylphenyl)thiazole units afforded a high performance n-type FET device with a high mobility and a low threshold voltage.

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In order to develop solution-processible OFET materials based on TTF derivatives, bis(pyrrolo[3,4-d])tetrathiafulvalene (PyTTF) has been introduced N-alkyl chains.
A series of PyTTFs with a various length of alkyl chain were synthesized. The OFET devices based spin-coated thin-film of PyTTFs showed typical p-channel FET characteristics in air with mobility as high as 1.7 * 10^-2 cm²V^-1s^-1. X-ray analyse of the thin-films and single crystals clarify that PyTTFs with long alkyl chains form conductive layers which consist of two-dimensional intermolecular interactions on the substrate. The calculations of overlap integral support this result.

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We have developed oligothiophene molecular wires which are fully insulated by bulky groups at every thiophenes. Oligothiophenes bearing bulky silyl group or spiro substituted fluorene were synthesised. About latter oligomers we succeeded in introducing terminal group by cross coupling method. Molecular structure from X-ray crystalography and red shift of absorption maxima indicated that these oligomers keep effective conjugation length and planarity. To evaluate insulation effect, electronic absorption spectra of chemically oxidated spesies at -50 degC was mearsuresd. Wlile non insulated ones showed paeks attributable to dimeric species, insulated ones showed no dimeric peaks proving these molecular wires have effective insulation effect for ideal single molecular erectronics.

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p-Conjugated materials have been of great interest due to their potential applications in electronics, photonics, and optoelectronics. Thus, great effort has focused on the development of novel conjugated system based on the oligothiophens and related compounds. On the other hand the cyclophane skeleton could provide a unique molecular structure. Here we report the synthesis and characterization of [3.3]metacyclophanes having the oligothiophene unit to obtain the novel p-stacked system. The structure of the [3.3]metacyclophanes is supposed to assume the syn conformation, thus, stacked oligothophene chains could be realized using this structure. The oligothiophene chains (n=1,2,3) have been introduced in the skeleton of the [3.3]Metacyclophane. The excimer emissions were observed for the [3.3]Metacyclophanes carrying the oligothiophene chains (n=2,3). The X-ray analyses have also been carried out to confirm the molecular structure.

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In the research field of organic field-effect transistors, thiophene oligomers have been promising candidate for over 20 years. The solubility of organic semiconducting materials is an important consideration in low cost electronic devices. Our focus in designing organic semiconductors has been to impart solubility to the materials. The synthesis, comparative physicochemical properties, and solid-state structures of oligothiophene derivatives differing in oligothiophene core length are discussed. The FET devices were fabricated with bottom contact configuration. The film of thiophene decamer and dodecamer showed high hole mobilities and high on/off ratio, which are the example of p-type FETs using spincoat fabricated films. Single-crystal X-raydiffraction data for thiophene hexamer and octamer are also presented and compared.

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We attempt to construction of new type of multi-steps reversible redox systems containing organic and organometallic redox active flagments by using multi-ferrocene compounds bridged by thiophene spacers. We have synthesized several ferrocene dimmers 2a-c, Anti-, Syn-3 and Anti-, Syn-4 by palladium catalyzed cross-coupling reactions of corresponding dibromo derivatives with ferrocenyl zinc chloride. The structure of Anti-3 has been determined by X-ray crystallographic analysis. The crystal structure showed coplanarity and double bond character reflected the formation of fulvalene structure between the bonded cyclopentadienyl ring of ferrocene and the thieno[3,2-b]thiophene. Electrochemical properties of the ferrocene dimer bridged by thiophene spacers by cyclic voltammetry will be discussed.

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An ion-radical salt, (ESBN)₂ClO₄, obtained from the electrochemical oxidation of a spin-polarized donor; ESBN, exhibited large negative magnetoresistance (-70% at 2 K in 9 T), in spite of the absence of metal ions. The fact that the magnetoresistance of the salt could be scaled by the magnetization of the sample clearly shows the interplay between pi-conduction electrons and pi-localized spins. The absolute value of magnetoresistance decreased monotonously with increasing temperature and it became almost negligible at 20 K. These data indicate that the degree of the exchange interaction between organic localized spins and conduction electrons is ca. 20 K. Thus the ionradical salt (ESBN)₂ClO₄ can be regarded as the first example of a co-existing system of magnetism and conductivity, derived from pi-conduction electrons and pi-localized spins of organic donor radical salt.

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Radical-substituted radical cations with strong intramolecular ferromagnetic interactions are attractive compounds as spin building blocks of magnetic materials. We now report syntheses and magnetic behaviors of TOT^·+, TOTNN^·+ and TOTIN^·+ with the magnetic- (FeCl₄^-, FeBr₄^-) or non-magnetic (GaCl₄^-, GaBr₄^-) anions. TOTMX₄ (M = Ga, Fe; X = Cl, Br) were synthesized by chemical oxidation of TOT using thianthrene radical cations with the corresponding counter anions. TOTFeBr₄ and TOTNNFeCl₄ showed interesting magnetic behaviors at low temperature. Detailed studies are in progress.

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This time, the dendrimer and the linear polymer with many stable organic radicals were designed as a candidate for the novel MRI agents consisting of purely organic molecules. For the purpose, by using the ion-exchange reaction for the introduction of radicals, novel ionic radical-dendrimers, NN-G1, NN-G2, NN-G3, and radical-polymers, [ImNN]_n[PAA_n], were easily obtained. These dendrimers and polymers in aqueous solutions were investigated the water-proton longitudinal (T₁) relaxation time by pulse-NMR spectrometry. The preparations of the ionic radical-dendrimers and radical-polymers, and the relation between the relaxivity and the molecular size will be discussed in this presentation.

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We have successfully developed a new hybrid material called "Claist Radical Trapping Sheet" composed of a clay film and a radical capturing reagent such as nitrone spin traps or stable nitroxyl radicals which are intercalated betweeen the clay layers in the film. Radical capturing experiments with various reactive radicals such as OH,hydroxylethyl,or 2-cyano-2-propyl radicals by using this Claist Radical Trapping Sheet have been carried out. It was shown that Claist Radical Trapping Sheet has a splendid feature suitable for capturing and identifying the reactive radical species, because captured radical species are so stable to suvive for a long period (>month) and are not likely to degrade in the sheet. We are now in the underway to apply these radical capturing experiments using this sheet to characterize the reactive radical species in the environmental nanoparticles generated by diesel exhaust gas.

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Because of strong phosphorescence at room temperature, platinum porphyrin (PtPor) has been attracting much attention as a component for advanced materials. However, a few synthetic and structural information was reported so far. In this study, a systematic synthetic study of PtPor was carried out. Furthermore, rare Pt(IV)Pors were also characterized by single crystal diffraction studies.

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Meta-ethynylpyridine polymers and oligomers have been studied their saccharide recognition with forming CD-active helical complexes. Herein we report the new design of oligomers in which glycoside moiety is intramolecularly linked to the ethynylpyridine oligomer through a spacer to rigidify the helical structure. Those glycoside-linked oligomers were prepared via Williamson synthesis and Sonogashira reactions, and varied in the sort of the glycoside and the lengths of the spacer and the ethynylpyridine moieties. During the CD experiments, it was found that the glycoside-linked oligomers display strong induced CDs to indicate the rigid formation of intramolecular helical complex. In the cases of -mannoside-linked oligomers, strong CD was observed even for 6-meric one, and the treatment with Grubbs catalyst could fix the CD activity of 14-mer.

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Nanoscale self-assemblies of pi-conjugated acyclic receptors can be modulated by external chemical stimuli. Of the acyclic anion receptors, C₃-bridged oligopyrroles with pi-conjugated planar structures show efficient anion binding by means of NH and bridging CH sites with inversion of two pyrrole rings. Aryl-substituted receptors have been obtained in 80-90% from the corresponding arylpyrroles and malonyl chloride in CH₂Cl₂ and subsequent treatment with BF₃OEt₂. Binding mode using NH, bridging CH, and o-CH has been confirmed by 1H NMR, DFT calculations, and X-ray analyses. Based on pi-pi stacking structure in solid state of methoxy substituted derivative, the derivatives with long alkyl chains yield supramolecular organogels from octane, which are transformed to solution state by addition of anion.

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We report new organogelator 1 and its self-association behavior in solution. 1 showed the gelation properties for organic solvents such as methylcyclohexane, acetone, and dimethylsulfoxide etc. FE-SEM observation of the xerogel of 1, prepared from acetone, revealed that 1 formed well-developed fibers with the diameter of about 200 nm. To gain the detailed information of the gelation process, the self-association behavior of 1 in solution was investigated by using UV-vis and 1H NMR spectroscopies. These results indicated that flat aromatic compound 1 stacked in a columnar fashion along its C3 axis via stacking and dipole-dipole interaction.

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Diarylethene derivatives with PEG side chains as amphiphilic groups were synthesized and their self-assembling and photochromic reactivity was investigated. Synthesized diarylethenes showed photochromism in organic solvents and even in water. When asymmetric methyl groups were introduced nearby aromatic core, induced circular dichroism (ICD) switching was observed in water upon photoirradiation, which was not observed in ethyl acetate. An aqueous solution of the amphiphilic diarylethene derivatives showed LCST behavior upon heating. Due to the different LCST of the two isomers, the LCST of the solution can be controlled by the irradiation of the appropriate wavelength of light. This photo-induced LCST change was more clearly observed for compound 2, which have amide groups nearby its aromatic core, and the LCST difference was up to 22 ºC. Furthermore, additive effect for the LCST change was also discussed.

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Tris-urea 1 functioned as a low molecular weight gelator for a variety of polar organic solvents including acetone, and methanol. Brief sonication of a mixture of 1 and an appropriate solvent gave a stable translucent gel. An acetone gel of 1 became a homogeneous solution in response to the addition of anions. The minimum amount of anion necessary for the gel-sol transition was peculiar to the anion species. A linear relationship was demonstrated between the amount of anion and the total binding constant of 1 with the anion. Re-gelation occurred by addition of boron trifluoride etherate (BF3•OEt2) and irradiating ultrasound of the acetone solution of 1 and F–. Re-gelation caused by BF3•OEt2 was specific for solutions containing F– or AcO–; solutions containing Cl–, Br–, or I– remained unchanged after the same treatment.

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We designed a new class of hexabenzocoronene derivatives with a long alkyl chain, whose termini are attached to oligo(oxyethylene) moieties with a different chain length. All compounds formed a hexagonal columnar mesophase in a broad temperature range, and the liquid crystalline phases were retained even below room temperature. We also found that the hexabenzocoronene derivatives showed interesting optoelectronic properties in their mesophases.

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We have recently disclosed that oligoresorcinols form a stable double helix in water through non-covalent interactions. Upon addition of various oligosaccharides to aqueous solutions of the oligoresorcinols, the double helix of the oligoresorcinol nonamer (9merH) was unwound and the single strand of 9merH subsequently formed a hetero-double helix with the oligosaccharides. A bias in the twist sense of the hetero-double helices was induced, reflecting the chirality of the saccharides. The hetero-double helix formation was highly sensitive to the structures of the saccharides such as glucoside linkage pattern and chain length. On the other hand, beta-cyclodextrin (beta-CyD), or a cyclic maltoheptaose, unwound the double helix of 9merH and the resulting single strand threaded the beta-CyD to form a twisted [3]pseudorotaxane with a helix sense bias. Upon the addition of an adamantane, the single strand of 9merH was expelled out of the beta-CyD wheels, thus regenerating the double helix.

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In this study, we showed that boronic ester formation can be used to achieve the dynamic self-assembly of organic molecules through dynamic covalent bond formation. When a tetrol 1 and 1,4-benzenedi(boronic acid) 2 were mixed in methanol, insoluble polymers were precipitated. However, when the same reaction was carried out in methanol/toluene (2:1), a new product, 2 + 2 complex of tetrol 1 and di(boronic acid) 2, was formed selectively. Furthermore, when benzene was employed instead of toluene, another complex, presumably 3 + 3 complex of 1 and 2, was obtained without the formation of 2 + 2 complex or polymer.
Furthermore, it is possible to freeze or free the equilibration between these two host molecules under appropriate conditions. Thus, in the presence of methanol, these two complexes could be interconverted in nearly quantitative yield, while the interconversion did not occur at all in the absence of methanol.

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Rotaxanes consisting of sec-ammonium salt axle and crown ether wheel are generally synthesized in high yields. The ammonium-crown ether rotaxanes, therefore, can be used in various systems. However, neutralization of sec-ammonium-type rotaxane to free amine-type rotaxane has never been attained, and therefore we have examined the neutralization of sec-ammonium type rotaxane via protection and deprotection on the nitrogen atom. sec-Ammonium-type rotaxane 1 was treated with TrocCl and Et₃N to give neutral N-Troc rotaxane 4 in a good yield. The Troc goup was removed by treatment with zinc in acetic acid. The resulted acetate was neutralized with sodium bicarbonate to yield sec-amine type rotaxane 2 as the first sec-amine-type rotaxane. According to our recent report on the N-methylation of sec-ammonium rotaxane 1 tert-ammonium-type rotaxane 5 prepared. This tert-ammonium was easily neutralized by DBU to tert-amine-type rotaxane 6.

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We have previously reported the imine-bridged rotaxanes1) whose submolecular mobility could be regulated by the imine-bond formation/cleavage. Here we report the preparation and their shuttling properties of novel imine-bridged rotaxanes with triethyleneglycol stations as noncovalent interaction type stations. [2]Rotaxanes 3 and 7 were exclusively generated upon adding TFA to the corresponding imine-bridged rotaxane in CDCl3. VT-NMR and 2D-ROESY measurements of the [2]rotaxane revealed that the macrocycle was located in the triethyleneglycol stations.

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Herein we developed new methodologies for the syntheses of highly insulated and soluble conjugated polymers by polymerization of fixed [1]rotaxanes and prepared by self-inclusion of guest-branched cyclodextrin permethylates.[1]Rotaxanes were characterized by ROESY NMR, MALDI-TOF mass spectrum. Polymerization of [1]rotaxanes were confirmed by GPC, MALDI-TOF mass, UV-vis, and NMR spectrum.

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Perfluorinated carbon chains are known to adopt a helical structure due to electro steric repulsion of fluorine atoms in the relative 1,3-positions of the crystalline state, which was first demonstrated by X-ray crystallography. However, clear experimental evidence for the helical structure in solution has not been reported. In chiroptical analysis studies by vibrational circular dichroism (VCD), we report the synthesis of biased helical perfluorinated side chains by the addition of chiral headgroups (e.g. PhCH(OH)(CF2)7CF3) and observe helical structures in solution by VCD. In particular, we determined its helicity by utilizing the C-F characteristic VCD band with the density functional theory based molecular orbital calculations, which was supported by an X-ray crystallographic study. The theoretical calculation suggested that the diastereomeric excess of the P diastereomer (with right-handed helical side chain) was approximately 16% de.

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We have systematically examined the applicability of the time-dependent density functional theory (TD-DFT) to the simulation of the electronic circular dichroism (CD) spectra of a variety of donor-acceptor compounds. The CD spectra of these chiral molecules were simulated by the TD-DFT calculations with several functionals of varying amounts of "exact" Hartree-Fock exchange as well as with a series of larger basis-sets. The experimental oscillator and rotatory strengths were best reproduced by the BH-LYP/TZV2P method. The SCS-MP2 energies were used for the Boltzmann averaging of the conformers where necessary. For most of the chiral compounds tested, the chosen method gave excellent agreement with the experimental CD spectra, but some chiral molecules required the more sophisticated RI-CC2 calculations to give the satisfactory results. The relevant transition moments and electronic configuration were also investigated by the TD-DFT methods.

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We have focused on optically active oligonaphthalenes which are constructed by a repeating dimerization reaction of 2,3-(dioxyfunctionalized)naphthalenes having several types of side chains. The pathway for the induction of axial chirality in the dimerization reaction is controlled by the kind of side chain on naphthalene, which seemingly does not influence chiral induction. In this presentation, we wish to demonstrate the synthesis of 32mer possessing butoxy groups and the determination of chirality based on a CD exciton chirality method using tetraphenylporphyrin as a powerful chromophore.

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We studied structures and stereochemistry of two types of chiral anthracene-acetylene cyclic oligomers, which were synthesized by Sonogashira and Eglington couplings. The first structure is cyclic tetramers 1, where an 1,5-anthracene or naphthalene unit is connected by three 1,8- and 9,10-anthracene units. These compounds took C2 symmetric structures, and enantiomers of 1b and 1c were successfully resolved by chiral HPLC. The barrier to enantiomerization of 1b was determined to be 114 kJ/mol. The second structure is macrocyclic compound 2 with six anthracene units, which has unique D2 symmetric figure-eight structure. Enantiomers of 2 were also resolved by chiral HPLC, and underwent no racemization at 90 degrees C. These high barriers to racemization are discussed on the basis of the molecular rigidity and steric effects.

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The tetraarylterephthalamide hosts 1 were designed and prepared as a novel class of signaling hosts based on the dynamic molecular recognition mechanism, which afford chiroptical signaling based on the propeller-shaped structure of biased helicity. Conformational change of the hosts 1 from the anti (non-propeller)- to syn (propeller)-form upon complexation with chiral bidentate bis(ammonium) guests (R,R)/(S,S)-3 induced strong Cotton effects, which is in accord with the chiral propeller structure in the complexes. The point chiralities in the chiral guests 3 determine the preferred helical-orientation of the amide groups in the complex, that is transmitted through the four aryl blades on the periphery of the central benzene ring of the host.

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The absolute configuration of a three-layered [3.3]paracyclophane ([3.3]PCP), 1, has been determined from a comparison of experimental chiroptical properties and density functional theory (DFT) calculations. Racemic three-layered [3.3]PCP was synthesized and completely resolved into its enantiomers. The enantiomers exhibited significantly intense CD signals in the 200-300 nm region. X-ray analysis of (R)-1 revealed that the [3.3]PCP units take on a boat-boat conformation in the solid state. Conformational analysis was carried out to obtain seven possible conformers for (R)-1. All the conformers have a negative value for [a]D and essentially identical CD spectra to each other. These calculated results for (R)-1 reproduced well the experimental optical properties for (R)-1. A simple model comprising two p-xylenes and durene was used to explain the origin of the optical activities of the three-layered cyclophane system.

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Cholic acid (CA) and its derivatives form inclusion compounds with chiral compounds as well as achiral compounds. The guest molecules are often included in channel-like chiral cavities created by the host molecules. We report here that CA derivatives recognized chirality of aromatic amines. A single X-ray crystallography revealed crystal structures of CA derivatives with 1-Phenylalkylamines. The most remarkable feature is that CA/ClPEA was obtained in more than 99% ee by the recrystallization from the racemate. The intermolecular distance between CA's carboxyl group and ClPEA's a-hydrogen was 2.4. This distance indicates that CH/O interaction worked each other and this interaction was important to recognize chirality.

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In 1996 we reported the first instance in which enantiomeric resolution by simple recrystallization of a racemic crystal from organic solvents was feasible; this unusual symmetry-breaking enantiomeric resolution phenomenon regarded as an event of complexity system was referred to as Preferential Enrichment [1].
Recently we have found a new type of polymorphic transition (gamma to alpha 1-form) inducing Preferential Enrichment for the compounds 3-5 having a phenoxy group at the terminal position of the ammonium cation (Figure) [2]. Here we report the mode of polymorphic transition with respect to the terminal para-fluorophenoxy derivatives and the effects of seed crystals on the compounds which cannot show Preferential Enrichment by themselves.
[1] Top. Curr. Chem. 2007, 269, 53-82. [2] Cryst. Growth Des., in press.

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We have found that stereoselectivity of a solid-state photocyclization of 2-(arylthio)-3-methylcyclo- hexene-1-ones can be switched by changing the reaction temperature and employing the so-called "heavy-atom effect". The reaction products depend on the substituent (X) at the 2-position of the phenylthio moiety. At RT, crystals of 1 (X = Me) gave only the trans product, whereas 3 (X = Br) only the cis product. Compound 2 (X = Cl) gave both the trans and the cis products in 63 and 37 %, respectively. Time course experiments revealed the possibility of two reaction pathways, which leads us to switch the reaction stereoselectivity. In fact, at 0 ºC only the trans product was produced for both 2 and 3. Further, photocyclization of mixed crystals (1.3) and (2.3) at RT gave only the cis isomers.

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Recently, we have succeeded to prepare azacalix[6]arene with N-H bridges. A single crystal of this molecule suitable for X-ray crystallographic analysis was obtained by slow crystallization from CH2Cl2/Hexane. The compound crystallizes with one molecule of hexane in a monoclinic form. In the solid state, azacalix[6]arene exhibits a conformational preference for a 1,2,3-alternate conformation which is stabilized by intramolecular bifurcated MeO..(N)H..OMe hydrogen bonds. Of further interest is intermolecular NH..OMe hydrogen bond, by which molecular assemblies with one-dimensional nanochannel structure are established. In the nanochannel, molecules of hexane are surrounded by the "wall" of the aromatic rings. Crystalline powder, which was obtained after heating the single crystals of azacalix[6]arene, exhibited selective sorption of gasous carbon dioxide. The synthesis, crystal structure, and gas sorption behavior of azacalix[6]arene will be reported.

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In the course of studies on tetrakis(heteroaryl)methanes, we have synthesized tetrakis(4-pyridylmethane (2) from tris(4-pyridyl)methyl anion and 4-chloropyridine. It should be noted that the crystal structure of the silver(I) complex of 2, prepared from an equimolar mixture of 2 and AgBF₄, is featured by three-dimensional, non-interpenetrated diamondoid network structure. We have also synthesized phenyl-(2-pyridyl)-(3-pyridyl)-(4-pyridyl)methane (3) as a prototypal chiral molecule based on tetraarylmethane framework. The optical signs expected for a pair of enantiomers. The calculated CD curve for (R)-3 based on time-dependent density functional theory (TDDFT) reproduces one of the experimantal CD spectra of 3, and suggests that the absolute configuration of the first-eluted fraction is R-isomer.

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Some N-{2-[bis(pentafluorophenyl)boryl]benzylidene}anilines (1) were synthesized. Teteracoordinate states of the boron atoms of azomethines 1 were confirmed by ¹¹B NMR spectra in CDCl₃. Crystal structures of 1 were determined by the X-ray crystallographic analysis. In the fluorescence spectra in hexane, 1 showed their emission maxima at 460 nm, 466 nm, and 500 and 527 nm, respectively. Their fluorescence properties will be reported.

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We proposed the set of ⁷⁷Se NMR chemical shifts (delta(Se)) for planar conformer in aryl selenides (ArSeR), for the better understanding of delta(Se), employing 9-(arylselanyl)anthracenes (ATC). We prepared a new triptycene system (TPC), 9-(arylselanyl)triptycenes (1). The delta(Se) of 1 are measured under various conditions containing temperature variations. The temperature dependence of d(Se) of 1 is shown to be much less than that of the ATC system. The results show that the planar structure around the ArSe group in 1 is much more stable, relative to the ATC system. The plot of delta(Se) of 1 versus those of the ATC system gave an excellent correlation. Compilation of these results demonstrates that the set of delta(Se) in 1 serve as a highly reliable standard for the planar structures of aryl selenides. Applications of delta(Se) of the planar conformers of arylselanyl groups will also be presented.

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We have synthesized the first stable 9-Anthryldiphosphene derivatives 1 and 2. The P=P double-bond characters of 1 and 2 were confirmed by the spectroscopic and X-ray crystallographic analyses. The dihedral angles of the anthryl moiety and the PPC plane were ca. 80deg, indicating the less effective pai-electron conjugation between the P=P and anthryl moieties in the solid states. On the other hand, in the UV-vis spectra in hexane, the absorptions assigned as pai-pai* electron transitions (from pai orbital of anthracene to pai* orbital of the P=P moieties) were observed around 530 nm, indicating the electronic correlation between the anthryl moieties and the P=P units. In addition, 1a was found to exhibit fluorescent emission (quantum yield: 1.2*10-3, lifetime: ca. 10ns).

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We will report on alkylation reactions of 2,3,6,7,14,15-hexamethyl-9,10-diheteratriptycenes and their structures. The reaction of tris(2-bromo-4,5-dimethylphenyl)stibine or tris(2-bromo-4,5-dimethylphenyl) phosphine with t-BuLi and then with SbCl₃ or PCl₃, gave 9,10-distibatriptycene 1, 9,10-diphosphatriptycene 2, and 9-phospha-10-stibatriptycene 3. Reaction of 2 with methyl iodide afforded P-methylated compound 4 at 60 degree, though compound 3 reacted with methyl iodide at 40 degree to give P-methylated compound 5. Treatment of 5 with NaBF₄ provided BF₄^- salts 6 easily. Reaction of 6 with bromine gave compound 7 which existed as an intramolecular salt composed of a methylphosphonium cation, R₃PMe⁺, and a tribromostiborate anion, R₃SbBr₃^-.

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Novel arylene-ethynylene molecules 1-3 have been synthesized. These molecules are highly fluorescence. DFT calculations showed that molecules 1 and 2 are more stable in the coplanar form than in the twisted form as in the cases of typical arylene-ethynylene molecules such as 9,10-bis(phenylethynyl)anthracene, meanwhile quarternized molecule 3 has another conformation, i.e. a perpendicularly twisted form. Because the pai-conjugation length depends on the coplanarity of the molecules, 1 and 2 have long pai-conjugation system, while 3 has restricted pai-conjugation system. When TFA, as a proton source, was added into the solution of 1, the cationic charge was introduced into the p-conjugated system. The conformational change from the coplanar form to the twisted form occurs and absorption and fluorescence spectra exhibited blue-shifted. Subsequently, triethylamine, as a base, was added, the spectra were reverted to the starting spectrum.

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In this study, we developed a simple and novel process for the construction of aromatic ring-layered polymers comprising [2.2]paracyclophane and xanthene compounds. Synthesis, characterization, and optical properties of this class of polymers were investigated in detail. The titled polymers were synthesized by the reaction of diethynyl[2.2]paracyclophane 1, diiodoxanthene 2, and ethynylarenes 3-10 as an end-capping reagent, which afforded the corresponding polymers P3-10 consisting of layered benzene rings. The face-to-face structure is attributed to a restricted rotary motion of two aromatic rings attached to 4,5-positions of a xanthene skeleton due to steric hindrance. The optical properties were examined, and energy and electron transfer from the layered [2.2]paracyclophane to the terminal units via the through-space interaction were observed.

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We are developing the chemistry of the photo-functional molecules related to the Vargula (Cypridina) bioluminescence. Especially, imidazopyrazinone, amidopyrazine, and pyrazinamine are important as the core structures of the luciferin, oxyluciferin, and etioluciferin. They function as a colored, fluorescent, or chemiluminescent dye. In this study, we focus on construction of pi-conjugated molecules assembled with these core structures for finding a novel photo-functional property. In this paper, we report the synthesis, structures, and spectroscopic properties of bis derivatives of pyrazinamine, amidopyrazine, and imidazopyrazinone, and will talk about the structure-function relationships of these pi-conjugated molecules.

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To establish the design concept of piezochromic luminescence materials, several perylene derivatives were synthesized according to the design to incorporate two demanding factors for molecular packing, a planar fluorescence core (an interplane distance = c.a. 0.35 nm) and two hydrogen bonding sites R-NHCO-( an interplane distance = c.a. 0.47 nm) into single molecular structure. The solid sample 1c, 1d and 2 that had an ordered molecular assembly by intermolecular hydrogen bondings exhibited a yellow solid-state luminescence upon irradiation of UV-light. On the other hand, the solid samples 1a and 1b showed orange luminescence. Pressing the solid samples of 1d and 2 caused emission color change from yellow to orange. X-ray and IR spectra showed that the ordered structure of the yellow-luminescent solid was disordered by pressing. Relations between alkyl side chains, molecular packing and solid-state luminescence were discussed.

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We developed a new chromic system that responds to both photoexcitation and electron transfer, tetrakis[2-methyl-5-(methylthio)thien-3-yl]ethene(1b).
A colorless solution of 1b in CH2Cl2 turned quickly to orange (lambda = 489 nm) when irradiated with UV light. The 489-nm band completely disappeared when the solution was exposed to Vis light. A similar absorption band in cyclohexane also disappeared by heating. These results demonstrate that 1b are photochromic in solution.
Electrochromic properties of 1b were investigated by using cyclic voltammetry. In contrast, the cyclic voltammogram of 1b in CH3CN showed an ECE mechanism; i) oxidation of 1b to 1b•+, ii) cyclization of 1b•+ to 2b•+, and iii) reduction of 2b•+ to 2b. Considering that cycloreversion of 2b to 1b occurs thermally, the observations conclude that 1b shows electrochromic behavior.

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Several compounds containing novel spacers of bis(2-ethynyl-3-thienyl)arene type were prepared as follows. 1,4-Di(3-thienyl)benzene was prepared by Suzuki coupling between 1,4-diiodobenzene and 3-thiophene boronic acid. Selective halogenation of 2-position of the thiophene ring was achieved by using NIS in the presence of AIBN. Trialkylsilylethynyl groups were introduced by Sonogashira reaction with ethynyltrimethylsilane. Desilylation with TBAF afforded 1,4-bis(2-ethynyl3-thienyl)benzene. Advantage of the spacer was then demonstrated by introducing functionalized alkyl groups to the 5-position of the thiophene ring.

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We designed and synthesized the molecular gears based on double-decker porphyrinato metal complex(DD). The molecular gears have plural rotors and are able to propagate information of the rotation from one rotor to another. In the DD which metal is La(III), the unilateral porphyrin has one inner proton. It is known that the oscillation frequency is reduced when the inner proton is interacted with or removed by a base(e.g. pyridine, triethylamine). So we evaluated the behavior of rotation in the molecular gears based on La(III)DD before and after the addition of base by VT NMR spectroscopy and other spectroscopic methods. In this presentation, we report the ability of distributing information of molecular gears.

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We previously reported the structural transformation of the two-dimensional molecular networks of dehydrobenzo[12]annulene derivative from a non-porous linear network to a porous honeycomb network in response to addition of planer aromatic compounds such as coronene. In this presentation, the transformation of networks of DBAs with longer alkyl chain by the use of larger condensed aromatic compound as guest was investigated. The mixtures of DBAs and larger condensed aromtic guest showed similar linear to honeycomb structural transformation induced by co-adsorbed guest. At the same time, the number of adsorbed guest and its the spatial alignment within a hexagonal void changed depending on the size of the void.

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Electron-accepting pyromellitic diimide-based macrocycle was designed and synthesized, and the inclusion behavior with aniline as pi-donor was investigated. In the chloroform solution, it was revealed that the macrocycle can include aniline in the macrocyclic cavity by cahrge-transfer interactions from NMR and UV/vis spectral experiments. Especially, in the solid state, the macrocycle forms a cyclic aniline trimer via self-complementary NH-pi interactions. Moreover, the macrocycle with 1D pi-system in the pyromellitic diimide moieties was synthesized and the structural and fundamental properties were examined.

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We synthesized molecular tweezers composed of two dibenzocyclooctatetraene units, and syn conformers can interact electron-deficient aromatic guests in solution and in the solid state. These compounds were observed as an equilibrium mixture of anti and syn conformers by ring inversion of cyclooctatetraenes (COT) in solution, and substituents group at COT units increase ring inversion energy to lead to the separation of NMR signals of anti and syn conformers at room temperature. In this presentation, properties and binding ability of the molecular tweezers will be discussed in detail.

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