The synthesis of spirocycles has attracted a great attention because of their unique structures, difficulty of constructions, and versatile biological activities. We report here the development of the new tandem reactions consist of oxidative coupling of 2-naphthlos followed by framework rearrangement promoted by FeCl3·6H2O to afford extraordinary spirocycles.

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We reported the dynamic behavior of anthracene-acetylene cyclic oligomers with variously substituted anthracene units. The rotational barrier of anthracene groups and spectroscopic properties of these oligomers are influenced by the length and position of acetylene linkers. The effects of ethynyl groups in the diethynylanthracene units on the electronic spectra are discussed on the basis of calculated and experimental data.

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Because dibenzopentalenes as a 4npai-electron system exhibit highly electron donating and accepting properties, they would be promising for applications of functional dyes. Recently we found a novel reaction yielding dibenzopentalenes using a Ni(0) catalyst. In the course of the study, we synthesized corresponding dinaphthopentalene derivatives from 1-bromo-2-ethynyl and 2-bromo-3-ethynyl- naphthalenes by this reaction. We will discuss some physical properties and structures of newly obtained pentalene derivatives.

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9,9,10,10-tetraanisyl-9,10-dihydrophenanthrene exhibits unique electrochromic behavior with drastic change in color and structure accompanied by C-C bond fission to biphenyl-2,2'-diylbis(dianisylmethylium). By replacing the binaphthyl unit for the biphenyl skeleton, the configurationally stable chiral electron donors become available. Since only the neutral donors 1 exhibit strong fluorescence, the electrochemical input can further modify the fluorescent properties of the pair. Due to the configurational stability of helicity in 1 and axial chirality in 2²⁺, the redox reaction of optically pure material undergoes stereospecifically, thus inducing chiroptical change such as circular dichroism (CD) as an additional output. Not only the UV-Vis but also the CD spectra of dications 2²⁺ exhibit solvent dependency ("solvatochromism"), which endows the present system with a function of multi-input response system.

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To establish the light-color modulation mechanism of the firefly bioluminescence, we investigated the spectroscopic properties of the phenolate anion (1-O⁻) generated from 5,5-dimethyloxyluciferin (1-OH) under various base/solvent combinations. Observed fluorescent behavior of 1-O⁻ verifies that the light emitter of firefly bioluminescence is the excited singlet state of keto-form of oxyluciferin phenolate anion (OL⁻) in the mechanism. Especially, a bonding interaction between OL⁻ and a protonated basic moiety in the active site of a luciferase plays an important role in modulation of the pi-electronic property of the singlet-excited state of OL⁻ for multicolor bioluminescence.

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While it is known that fluorescence is often quenched in the solid state due to intermolecular interaction, there is a growing interest in organic compounds that display enhanced luminescence in the solid state. Several derivatives of 2-(2'-hydroxyphenyl)imidazo[1,2-a]pyridine (1) have been synthesized and properties of the solid-state ESIPT luminescence are studied. Though they show only a weak ESIPT fluorescence in solution, they exhibit an efficient, blue-shifted luminescence in the solid state. The luminescence quantum yield is 10 times larger compared to those observed in solution. Compounds 1, 4 and 5 are found to show two different solid-state luminescence according to different molecular packing. It is confirmed that those solid-state luminescence is controllable by thermal phase transition upon heating of powdered crystal.

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We present here a new and efficient method for generation of cationic spices of benzoannulenes by embedding platinum catecholate complex units. Synthesized triplatinum catecholate type dehydorbenzo[12]annulene was readily oxidized, generating mono-, di-, and tri-cations. Based on energetic, structural, magnetic criteria, the dication is deduced to be aromatic. This is the first experimental clue for an aromatic 10pi electron [12]annulene system.

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Recently we succeeded in the isolation of delocalized singlet biradicals utilizing the spin-delocalizing character of the phenalenyl radical. We demonstrated that the singlet biradical 2a has strong spin-spin interactions between molecules through the overlap of phenalenyl rings in the onedimensional (1D) chain even though the closed-shell Kekule structure can be drawn as a resonance contributor. To demonstrate that delocalized singlet biradicals actually have open-shell character and the electrons coupled within a molecule are involved in covalent bonding between molecules, we designed and synthesized 2b, a dimethyl derivative of 2a. 2b formed the p-p 1D chain with slightly larger p-p separation distance compared to that of 2a. Strong correlation between the p-p separation distance and the length of bond a indicates intra- and intermolecular covalent bondings interact each other and the electronic structure of the 1D chain is best represented by the RVB model.

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We synthesized a 2,2'-bipyridine-bridged t-butyl nitroxide biradical (bpybNO) as a paramagnetic host. The solution ESR spectra indicated the presence of two nitroxide groups in a molecule. The crystal structures of bpybNO and [La(hfac)3(bpybNO)] were determined by the X- ray diffraction study. The magnetic susceptibility study revealed that the presence of antiferromagnetic coupling for both compounds and the magnitude of the coupling became larger after the lanthanum (III) complexation than before. Furthermore, we also prepared t-butyl nitroxide biradicals bridged by polyether groups (phnbNO; n= 2,3). Their host-guest-complexation ability was proved; 1/1 ph2bNO-Ca(hfac) 2 and ph3bNO-Ba(hfac)2 compounds were prepared and isolated. The crystal structure analysis was successful for ph3bNO and [Ba(hfac)2 (ph3bNO)]. The magnetic coupling of ph3bNO was larger than that of [Ba (hfac)2(ph3bNO)], because the intramolecular coupling is buried by a strong intermolecular coupling.

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In connection with our previous study of (nitronyl nitroxide)-substituted dihydrophenazine radical cation tetrabromoferrate, we report preparation and magnetic property of (nitronyl nitroxide)-substituted trioxytriphenylamine radical cation tetrachloroferrate (NNTOT+FeCl4-) and tetrachlorogallate (NNTOT+GaCl4-). NNTOT+FeCl4- exhibitted a successive phase transition at 2.9 K and 0.8 K. The higher temperture transition is due to the organic NNTOT+ magnets, whereas the lower one involves Fe(III) spins.

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Multiple-resonance NMR is a technique to detect particular nucleus in a particular sequence such as 1H-13C-15N or 1H-13C-13C, where magnetic coherence is successively transferred in such a way as 1H R 13C R 15N R 13C R 1H or 1H R 13C R 13C R 13C R 1H. In this lecture are shown two examples of its application. One is selective detection of choline taken in HeLa cells using doubly 13C- and 15N-labeled choline. The other is selective detection of lactic acid as a glycolysis product of doubly 13C- and 2H-labeled glucose in cancer carrying mouse. It is important that these probes which are labeled by stable isotopes are otherwise nothing other than unmodified or natural materials. Multiple-resonance NMR thus opens the door to NMR-based monitoring of organic reactions in multi-component systems as is.

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Structural specificity including dynamic behavior and stable conformations in the bulk phase of diethylmethylammonium trifluoromethanesulfonate [dema][TfOH], which is assumed to be a prominent ionic liquid electrolyte for non-humidified intermediate temperature fuel cell, have been investigated by 1H-NMR, IR spectroscopic analyses, and molecular dynamics (MD) simulation.

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Polar coordinate (R, θ) representation is proposed for the plot of H_b(r_c) versus H_b(r_c) - V_b(r_c)/2 (= (h/2π) ²/8mΔρ_b (r_c)) in AIM analysis, to classify and evaluate weak to strong interactions in a unified way: H_b(r_c) and Δρ_b(r_c) are total electron energy densities and Laplacian of ρ_b(r_c) at bond critical points (BCPs: r_c), respectively. Any distances on the (x, y) plane of the plot are given in the energy unit, therefore, R corresponds to the energy for the interaction at BCP relative to that without interaction and θ measured from the y-axis controls the helical figure of the plot. Each plot shows a specific curve, if data at BCP for a full-optimized structure and those near it are plotted. The curve is expressed by θ_p and κ_p: θ_p corresponds to the tangent line measured from the y-direction and κ_p is the curvature of the plot.

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Mono- and diprotonation of the tri-, tetra-, and penta-bridged cyclophanes, [33](1,3,5)-, [34](1,2,3,5)-, and [35](1,2,3,4,5)-cyclophanes (2, 3, and 4), have been realized and NMR studies of the resulting carbocations are reported. Unlike [2.2]paracyclophane and its fluorinated analogs that are protonated at a position ipso to the ethano-bridge, the monocations derived from 2, 3, and 4 are protonated at the unsubstituted ring positions. Protonation regioselectivity in the dications is pseudo-meta for 2 and 3 (at unsubstituted ring positions), but for the more crowded 4 the second protonation occurs at a pseudo-meta position, which is ipso to the trimethylene bridge. Transannular pi-pi interactions in the monocations are manifested in the observed proton deshielding in the unprotonated pi-deck. DFT and GIAO-DFT were employed to study the mono- and dications for comparison with the solution studies in superacids. GIAO-derived delta NICS(1)zz data for the [3n]cyclophane monocations imply decreased aromaticity in the cofacial uprotonated arene, consistent with transannular donor-acceptor interactions.

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We were succeeded in obtaining an optically pure pyridinophane derivatives by chiral HPLC for the first time, which exhibits interesting chiroptical properties based on their planar chirality. We observed the dramatic change of their CD spectra upon their protonation. These changes were investigated by the X-ray structure analysis and by quantum chemical calculation. Details will be discussed in presentation.

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The tuning of the structure and properties of propeller-shaped triarylboranes would be easily achieved by controlling steric repulsion between the propeller moieties. In this work, we synthesized a novel triarylborane with alkynyl groups on the propeller moieties and analyzed the structure in the crystalline state and in a solution. Furthermore, we attempted to control the dynamic structural change of the propeller structure by photo-irradiation on the aryl-boron moiety.

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Diels-Alder reactions of naphthalene need harsh conditions because of its high resonance stability. In this study, we achieved the Diels-Alder reactions of naphthalene derivatives with N-cyclohexylmaleimide in the cavity of a self-assembled hollow cage. The reactions depended on the cavity size and proceeded regio- and stereoselectively.

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Gear-shaped amphiphilic molecules aggregate to form a discrete box-shaped hexameric capsule in water due to the hydrophobic effect. This capsule can encapsulate two or three substituted benzene molecules in a face-to-face geometry. In this study, we found that one hexamethylbenzene molecule and one or two hexafluorobenzene molecule(s) are simultaneously encapsulated into the capsule driven by multipole interactions. We present details of the heterogeneous and selective inclusion phenomena.

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Here we report one-dimensional self-assembly of septet stacking structures (1) of large aromatic molecules. When tridentate panel ligands, bidentate pillar ligands with hydrophilic groups, cis-protected Pd complexes, and large aromatic molecules were combined in a 6:4:12:3 ratio in water at 40 ºC, NMR analysis of the solution indicated the formation of 1 as a single compound. X-ray crystallographic analysis revealed that the product consists of two interlocked coordination cages and three intercalated aromatic molecules between the cages. It is noteworthy that the concentration-dependent 1H-NMR and DOSY-NMR analyses of the solution suggested the aggregation of 1 into a columnar structure via intermolecular aromatic stacking at higher concentration. The columnar aggregate showed lyotropic liquid crystalline nature.

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Triphenylene derivatives having long alkoxy chains were synthesized and their self-assembling behavior was investigated. These triphenylenes showed gelling ability and constructed a wide variety of supramolecular structures. The inner structures of the self-assembled supramolecular nanostructures were analyzed using XRD measurements, electronic spectra, cross-polarization microscopy, and polarized fluorescence imaging. Interestingly, the self-assembled structures which showed optical waveguide behavior reflecting the stacking manner of triphenylene core were obtained.

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In this study, we have achieved selective formation of two diastereomeric cage-like boronic esters with recognition of substitution pattern of disubstituted benzenes. When a tetrol 1 and 1,3,5-benzenetri(boronic acid) 2 were mixed in methanol, a [3+2] complex of tetrol 1 and tri(boronic acid) 2 was formed selectively. The most remarkable is the fact that the three tetrol units in [3+2] are derived from the same enantiomer of the starting material, which suggested that the diastereoselective self-assembly occurred during the formation of this [3+2] structure. Furthermore, when o- or m-xylene was employed as a guest molecule, a different boronic ester was obtained as a major product which was confirmed to be hetero-[3+2], the diastereomer of homo-[3+2]. These results suggested that the selective formation of each diastereomer of [3+2] is accomplished depending on the substitution pattern of added xylenes. Furthermore, it was found that the selective formation of hetero-[3+2] in the presence of o- or m-xylene was induced during the precipitation process.

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As our ongoing program to develop dynamically controllable self-organization, boron-contained molecular capsules triggered by amines have been reported for the first time. When Et₃N was employed as a chemical stimulus, the Lewis acid Et₃NH⁺ was produced by solvolysis reaction on the boron, and then it was encapsulated in the internal cavity. In addition, we have found that the use of n-Bu₃N led to the related dynamic capsule capable of accommodating several guest species including Cs⁺.

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We have reported that tripodands bearing a bipyridine moiety at each terminal react with a transition metal to give the corresponding pseudocryptands as a host. We report here synthesis of a novel tripodand bearing six and nine amide groups to achieve a new binding mode. ¹H NMR, ESI-MS, and UV-vis spectra suggest that the tripodand was converted to the corresponding C₃ symmetric pseudocryptand by the complexation with Fe(II). Association constants with cations in the presence and absence of Cl^– were determined by ¹H NMR titrations, which showed that the cation binding affinity was enhanced by the addition of Cl^–. This result indicates that the metallohost recognizes Cl^– and the cations cooperatively. The association constants of [L2•Fe]²⁺ are much larger than those of [L1•Fe]²⁺.

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π-Conjugated acyclic oligopyrroles as anion receptors have been found to form "planar anions" by complexation with anion to give the alternatively stacking structures with combination of counter cations in the solid state. On the other hand, in contrast to the transition from supramolecular gels comprising anion receptors to solution state by the addition of anions as tetraalkylammonium salts, the combination of the appropriate receptors and planar cation salts of anions form the nanoscale fibrous structures derived from stable charge-by-charge structures.

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Recent sophisticated supramolecular and macromolecular architectures strongly require viable means of powerful, highly reliable, and selective reactions. For this purpose, click chemistry based on Huisgen dipolar cycloaddition of azides with alkynes has generated large interests. The click reactions have been actually utilized in a variety of synthetic processes for these architectures. However, problems of safety with the azide moiety concerning toxicity and explosiveness lead to several limitations to the use. Recognizing these issues, we became intrigued by the potential usefulness of nitrile N-oxide as the substitute of 1,3-dipolar, which allows efficient [2+3]cycloaddition reaction with not only alkynes but also alkenes and nitriles to selectively give isoxazoles, isoxazolines, and oxadiazoles, respectively. These hetero-rings are versatile scaffolds for various systems and materials, because they enable simple conversion to useful functional groups; aldol, diketone, aminoalcohol, and so on. Nitrile N-oxides, however, have not been extensively employed to click chemistry yet, because the species are extremely reactive, often undergoing spontaneous dimerization to furoxanes. Recognizing these issues, we planned the click reaction exploiting kinetically stabilized nitrile N-oxides, which could provide a promising method to elaborations of highly sophisticated architectures. Herein, we wish to describe the utility and productivity of new click chemistry exploiting kinetically stabilized aromatic nitrile N-oxides, as demonstrated by syntheses and modifications of supramolecules without any catalysts.

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Upon mixing in non-polar solvent such as chloroform and toluene, an optically-active amidine and an achiral carboxylic acid bearing two oligo(ethylene oxide) chains with a vinyl group at both ends quantitatively formed the corresponding precatenane, of which the formation was supported by ¹H NMR. The precatenane was subjected to ring-closing metathesis using Grubbs' 1st generation catalyst, and the [2]catenane was obtained in 67% yield after chromatographic purification. The structure of the [2]catenane was characterized by 1D and 2D ¹H NMR measurements along with ESI-mass spectrometry.

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We have investigated whether preferential enrichment, an enantiomeric resolution phenomenon that is regarded as an event of complexity, can be applied to amino acids which are classified into a racmic compound crystal.Here we report that the amino acids such as leucine and alanine show a quite similar phenomenon to that of preferential enrichment, whenever slightly D- or L-enriched amino acids of 5 % ee are recrystallized from the mixed solvent of water and ethanol.We report the details of these experiments, together with the results of other amino acids.

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Herein, we designed oligo(o-phenylene) derivatives (OOPs) as a new helical motif. In the crystallization of a certain OOP derivative, a spontaneous symmetry breaking takes place, leading to the selective formation of either right-handed or left-handed crystal. While the OOP adopts ultimately tight helical conformation, its optically activity disappeared immediately in solution due to an unexpectedly fast racemization activated by a repulsive force operative between the condensed π-clouds. We demonstrated that removal of one electron from OOP gives rise to significant lowering of its dynamic nature, as a consequence of extensive delocalization of the resulting electronic hole over the helical structure.

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We have developed Pd-catalyzed domino homo-coupling reaction of 1. The domino coupling reaction of 1, including successive C-C (a-a) and C-N (b-c) bond formations proceeded smoothly to afford corresponding coupling product, amidoazahelicene 2. Furthermore, we have achieved transformation of 2 to axially chiral amino acid 3 and its' optical resolution. The stereostructures and optical behavior of amidoazahelicene and 3 will also be presented.

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We synthesized water-soluble ethynylpyridine polymers bearing chiral ethyleneglycol side chains. The chiral chains were introduced at 4-positions of each pyridine ring which is linked at 2,6-position with acetylene bonds. Higher-order structures and molecular recognition abilities of the polymers were investigated on the basis of CD in water. The CD band around 335 nm changed its shape with increase of polymer lengths, and its sign was finally inverted. When glycogen was added into an aqueous solution of the polymers, the CD spectrum also changed its shape, suggesting the association between the polymers and glycogen. When sodium perchlorate was added into an aqueous polymer solution, CD band around 335 nm changed its shape as well.

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Flavin is an important class of redox compounds involved in a variety of biological processes including electron transfer, fluorescence characteristics and catalytic activities for oxidative transformations. Supramolecular organogels including flavin units would provide novel functions of organocatalysis and fluorescent properties. We synthesized a new type of bisflavin, bearing a potential galator unit of 1,2-bis(alkylamido)cyclohexane. Bisflavin were found to gelate polar solvents such as DMSO and DMF. The ¹H NMR, IR, and UV-vis analyses of sol-gel-transition revealed that the molecular aggregates are formed through intermolecular hydrogen bonding of amide unit and intermolecular π-stacking of flavin rings. Induced CD peaks corresponding to the absorption peaks for the flavin moiety were observed in DMSO gel. The catalytic activities of these gels as well as mixed gel of bisflavin and 1,2-bis(dodecylamido)cyclohexane were also examined using aerobic hydrogenation of olefins with hydrazine.

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Quantum computers and quantum information processing systems (QCs/QIPSs) have been the focus of emerging science and technology. Efforts to build up true QCs face seemingly intractable difficulties in preparing well-defined scalable quantum bits (qubits). In order to circumvent this problem, Lloyd proposed from the theoretical side "coupled spin arrays with an (ABC)_n type of 1D periodicity". Realization of Lloyd's model has been materials challenge for chemists and material scientists. We have focused on the physical realization of Lloyd's model based on molecular electron spin-qubits. Here, we show our recent studies on oligo(imidazole)s-based triple-helicates relevant to Lloyd's model. We have determined their molecular structures and spin structures by X-ray analysis and single-crystal ESR spectroscopy, respectively, illustrating that they can afford suitable models for the Lloyd's approach to the implementation of QCs/QIPSs.

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Recently, nanostructured materials such as carbon nanotubes, polymer nanotubes, and metal nanotubes have received a great deal of attention due to their unique physical and chemical properties. Among them, polymer nanotubes have not been studied sufficiently though various functions can be comparatively easily introduced into them by introduction of the functional groups. Consequently, we succeeded in the synthesis of the various polymer nanotubes from polythiophene and then, have studied their functionalization. In this symposium, we present the synthesis and the properties of the new chiral polythiophene nanotubes with introduced asymmetric functional groups, and the synthesis of the new nanocomposites in the inclusion nanospace of the polymer nanotubes.

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The synthetic research of aromatic macrocycles has attracted considerable attention since they are promising candidates for the building components in the study of supramolecular chemistry. These compounds are capable of arranging themselves into one-dimensional (1D) columnar structures, which are useful for conducting carriers and forming molecular tubes and wires for nanotechnological applications. We synthesized the macrocyclic tetramer of 2-phenyl-1,3,4-oxadiazole and investigated its self-assembly. The macrocycle was stacked to form a 1D columnar structure containing water molecules. This self-assembling property facilitates the arrangement of water molecules into 1D chain structures, and these water molecules are expected to possess unique properties. Furthermore, the nanotube self-assembled into a bundle, which grew into a molecular wire. The association of the water molecules in the tubular cavity resulted in shielding of the 1D chain of water molecules by the nanotube; these macrocyclic nanotube channels are promising candidates for nanotechnological applications such as optical nanofibers.

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In this study, the C₃ symmetrical framework of benzene-1,3,5-trisurea derivatives having alkyl (C_m) and oligo(ethylene glycol) (Eg_n) chains were prepared. They showed LCST behavior upon heating. Especially, Eg₄C₈U formed a gel in 0.05 wt% aqueous solution as increasing temperature. This reverse thermal gelation behavior can be explained by the dehydration of oligo(ethylene glycol) chains in the high temperature region. For the construction of new type organic MRI contrast agents, in addition, organic stable radicals were introduced into these trisurea derivatives. Obtained trisurea-radical derivatives also showed LCST behavior and their water-proton relaxivities drastically decreased above the temperatures for their LCSTs. The preparations of the trisurea derivatives and the relation between the molecular structure and the assembling behavior will be discussed in this presentation.

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We present the unique crystal structure of the complexes between pyromellitic diimide-based macrocycle and aniline or N-ethylaniline and gelation behavior of 2. In the crystal structure, tetrameric structure of aniline and trimeric structure of N-ethylaniline were observed in the cavity of the macrocycle. Furthermore, we found the gelation of N,N-dimethylaniline when the macrocycle was added to N,N-dimethylaniline. The gelation behavior was observed only for N,N-diemthylaniline, and no other solvent, even in structurally similar solvent such as N,N-methylethylaniline, showed the gelation.

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We constructed an anionic giant vesicular system using a phosphoric membrane molecule (V). Since the reactive precursor (V*) of V contains a hydrolysable diphenylazomethine unit, V* is expected to produce V and an electrolyte (E+). The hydrolysis of V* proceeded efficiently in an aqueous phosphate-buffered solution in the presence of Vvesicles. The rate of hydrolysis increases as the pH of the vesicular suspension decreases. And we measured z-potential of V vesicles. The resulting z-potential of V vesicles was -76 mV in deionized water (pH 6.7) and -120 mV in phosphate buffer (pH 6.5). It means that the local proton-concentration must be higher in the solvent layer surrounding the anionic vesicle than that in the bulk. The time course of the conversion of V* in a buffered solution in the absence of V shows a sigmoidal curve. This behavior strongly suggests that the hydrolysis of V* is catalyzed on the surface of pre-formed V vesicles. Another intriguing feature of this dynamic system is that the number of giant vesicles increases as a result of the self-reproducing dynamics.

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Silicon nanosheet, which has the two-dimensional silicon backbone structure, is one of the most interest nanomaterials because of their nanoscale thickness and macroscale area. Here we report the soft synthesis of two-dimension silicon nanosheet terminated with phenyl groups. From the photoluminescence measurement, the band gap of the silicon nanosheet is determined about 3.0 eV, which is agreement with the theoretical direct band gap for Si6H6. It means that the silicon nanosheet indicate the nature of a monolayer sheet, reflecting completely fabrication of silicon monolayer sheet in organic solvents. The Atomic Force Microscopy (AFM) afforded strongly evidence of phenyl-capped silicon monolayer sheet. The thickness of the silicon nanosheet was measured at intervals between the sheets and the substrate surface, and yielded an average value of 1.67 nm. Furthermore, the observation of an atomically resolved AFM image of an individual sheet was succeeded, indicating that the sheet maintained the two-dimensional Si(111) backbone.

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Recently, much attention has been focused on organic semiconducting pai-conjugated molecules due to their potential applications as large-area, low-cost and flexible materials. Benzoporphyrin and phthalocyanine derivatives have the advantage of easy optimization of molecular structure; low HOMO-LUMO energy gap; and thermal and chemical stability. We will report a preparation of soluble bicyclo[2.2.2]octadiene-fused precursors of phthalocyanine, tetrabenzoporphyrin and diazatetrabenzoporphyrin derivatives and the thermal conversion of the precursors.

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From the early stage of the phthalocyanine chemistry, their core-modified analogues have been of interest with the expectation that their optical and coordination properties can be modified. Recently we succeeded in synthesizing novel analogues bearing aza-phenalene units instead of isoindole units. From the absorption spectra, these compounds can be judged to possess similar pi-conjugation systems to that of phthalocyanine, exhibiting intense Q band absorption in the vis/NIR region. We further extend this research to analogues bearing seven-membered rings in the core, which was synthesized by using biphenyl-2,2'-dicarbonitrile. In this presentation, syntheses and properties will be reported.

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Recently we reported isolation of doubly oxidized octaalkyltetraphenylporphyrins (OETPP or OiBTPP) with a 16 π-electron core. The X-ray analysis revealed that the 16 π porphyrins 2 and 4 were more distorted than the corresponding 18 π analogs 1 and 3, respectively. The bond lengths of the porphyrin skeletons in 2 and 4 clearly showed the bond alternation. Another distinct difference between the 16 π and 18 π electron state was observed in the UV-vis spectra. The UV-vis peaks for 18 π OETPPH2 (1) appeared at 446, 548 and 588 nm, whereas those for 16 π OETPP (2) were highly blue-shifted to 275 and 339 nm with no peaks in Q bands. These results presented that 2 and 4 were the first fully characterized 16 π non-aromatic porphyrins. Here, we discuss synthesis and properties of a series of alkylporphyrins (9) and benzofused 16 π porphyrins (10).

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We have elucidated the peculiar photo- and electro-properties of meso-diarylamino porphyrin: Enhancement of absorptivities at long wavelengths of the visible region, and electronic communication between the arylamine sites in the mixed-valence state through the porphyrin moiety. We have also created a new class of "Special Pair" models based on meso-diarylamino porphyrin, clarifying that it has properties suitable as a functional model.

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Electron-transfer properties of a novel porphyrin tripod (TPZn3) were investigated. When TPZn3 is oxidized by tris(2,2'-bipyridyl)ruthenium(III) complex ([Ru(bpy)3]3+), the oxidized species (TPZn3)ⁿ⁺ (n = 0-3) exhibit the characteristic NIR absorption due to the pi-bond formation among the porphyrin rings. The similar electronic interactions are observed by Vis-NIR and ESR measurements at various temperatures. The porphyrin tripod can form complex with electron acceptors bearing with pyridyl group by axial coordination. The binding constant of TPZn3 and pyridyl fullerene (PyC⁶⁰) is determined to be 1.1 x 10⁵ M^-1 in o-dichlorobenzene, while the reference monomer does not exhibit complex formation. The dynamics of photoinduced electron transfer from the excited state of TPZn3 to PyC⁶⁰ are investigated in comparison of the corresponding monomer porphyrin by using laser flash photolysis measurements. The electron-transfer from ¹TPZn3* to electron acceptors are prominently accelerated as compared to the reference monomer because of the pi-pi interactions between TPZn3 and PyC⁶⁰ as well as the axial coordination.

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Diphenylbutadiyne-connected cyclic and linear porphyrin oligomers (Cyn and Ln) were synthesized aiming at the construction of artificial light-harvesting antenna system by the homocoupling of terminal acetylene units. The chemical structures of Cyn and Ln were characterized by ¹H NMR spectroscopy and MALDI-TOF mass spectrometry. The electronic structures were discussed based on the absorption and fluorescence spectra. The Stokes shifts of Cyn were smaller than those of Ln. The observed differences are attributable to a difference in the flexibility of the dihedral angles between the neighboring porphyrin units.

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We have reported that bis-porphyrin connected by aromatic linker assembles via subtle forces to form the unique dimer in organic media, whereas the complexation of an electron-deficient flat aromatic guest into the cleft of the bisporphyrin leads to the simultaneous dissociation of the dimer. We set out to utilize these unique host-guest association for the construction of supramolecular polymers. Heteroditopic momoer and S-shaped ditopic one were prepared. The formation of supramolecular polymers of these monomers was confirmed by ¹H NMR spectroscopy, electronic absorption spectroscopy and atomic force microscopy.

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X-ray crystallography reveals a self-assembled nanotube of cyclic porphyrin dimers bearing 4-pyridyl group and its inclusion complex with C₆₀. The C₆₀ molecules are linearly arranged to form a supramolecular peapod. The photoelectric properties of this complex will be also discussed.

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Construction of functional molecular assemblies with well-defined shapes and structures are of great interest because of a variety of applications such as optoelectronics. In particular, unidirectionally bar-shaped nanostructures of porphyrins also have potentials for fabrication of nanoscale materials. In this presentation, we report preparation and photophysical property of supramolecular porphyrin nanorods structurally controlled by encapsulated-fullerene derivatives. Scanning electron microscopy (SEM), steady-state and time-resolved spectroscopy, and photovoltaic measurement are systematically performed.

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Organosilicon compounds such as alkoxysilanes (R_4-nSi(OR')_n) and silanols (R_4-nSi(OH)_n) are known to show high bonding ability to metal oxides by forming strong Si-O-metal bond on the metal oxide surface. This characteristic property is useful to develop inorganic-organic hybrid functional materials. In this work, the applicability of alkoxysilanes was examined to sensitizing dyes for dye-sensitized solar cells and the adsorptive properties of nano-porous alumina membrane with chemically modified surface by di(1-naphthyl)silanediol were investigated for aromatic compounds.

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The author tried to prepare silicon carbide-based nanoporous materials using the replica method. The polycarbosilane (PCS) as the SiC precursor filled the mesopores of mesoporous silica as the template, and then calcination and subsequent removal of the silica matrix led to the mesoporous product with a BET specific surface area of 780m²g^-1. The product had the SiC_1.9O_0.9 composition and very low crystallinity, indicating a good resistivity to oxidative conditions.

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Transition metal complexes bearing tripodal tetradentate ligands have attracted considerable interest due to their ability for the activation of small molecules, the stabilization of reactive species with unusual electric and geometric structures, catalytic activities, and so on. Although there are many reports on tripodal tetradentate ligands containing amine or phosphine moieties as donors, tripodal tetradentate ligands tethered with three thioether moieties are very rare. In this paper, we present the synthesis of phosphine and silyl ligands tethered with three thioether moieties, P(2-C₆H₄SR)₃ (R = i-Pr, t-Bu) and ^–Si(2-C₆H₄CH₂SR)₃ (R = i-Pr, t-Bu), respectively, and their complexation with transition metals.

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