矢貝 史樹

Light on: Photocontrol of J-type exciton interactions by using chromophores is reported (see picture). Hydrogen-bonded merocyanine dyes could be switched reversibly through photoinduced ring-closure/ring-opening reactions of diarylethene receptors. Addition of H-aggregation-inducing bismelamine receptors enabled the partial interconversion between J- and H-type exciton coupling. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Regioisomers of self-assembling molecules resulted in the evolution of distinct 0D and 1D nanostructures, namely nanorings and nanorods (see picture). J- and H-type excitonic coupling of naphthalene chromophores was found in the nanostructures. The bulk liquid-crystalline states contain hydrogen-bonded rosettes, which explains how the observed regioisomers generate distinct nanostructures with characteristic excitonic interactions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ditopic melamines possessing one (1) or two (2) perylene bisimide (PBI) chromophores were synthesized and their self-aggregation and coaggregation with dodecyl cyanurate (dCA) or barbital (Bar) were investigated. Optically transparent organogels were formed through self-aggregation of 1 and coaggregation of 1 or 2 with dCA or Bar in nonpolar solvents. X-ray diffraction of the xerogels exhibited typical diffraction patterns assignable to lamellar structures, suggesting the formation of tapelike hydrogen-bonded motifs. Remarkably low critical gelation concentrations (cgc) of 8.0 × 10 4 M were revealed for all organogels, thus they can be classified as supergelators. Comparison of the thermal stabilities of the gels revealed that the gels containing 2 have higher melting temperatures (T m) than those containing 1. Scanning electron microscopy and atomic force microscopy showed that the gels containing 1 are composed of sheetlike microstructures, whereas those containing 2 are composed of fibrous nanostructures, consistent with the difference in their thermal stabilities. The different self-assembled structures of our PBI aggregates can be related to whether extended stacks of PBI dyes along the hydrogen-bonded strands are possible or not. © 2012 The Society of Polymer Science, Japan (SPSJ) All rights reserved.

Perylene 3,4:9,10-tetracarboxylic acid bisimide (PBI) was functionalized with ditopic cyanuric acid to organize it into complex columnar architectures through the formation of hydrogen-bonded supermacrocycles (rosette) by complexing with ditopic melamines possessing solubilizing alkoxyphenyl substituents. The aggregation study in solution using UV-vis and NMR spectroscopies showed the formation of extended aggregates through hydrogen-bonding and π-π stacking interactions. The cylindrical fibrillar nanostructures were visualized by microscopic techniques (AFM, TEM), and the formation of lyotropic mesophase was confirmed by polarized optical microscopy and SEM. X-ray diffraction study revealed that a well-defined hexagonal columnar (Col ) structure was formed by solution-casting of fibrillar assemblies. All of these results are consistent with the formation of hydrogen-bonded PBI rosettes that spontaneously organize into the Col structure. Upon heating the Col structure in the bulk state, a structural transition to a highly ordered lamellar (Lam) structure was observed by variable-temperature X-ray diffraction, differential scanning calorimetry, and AFM studies. IR study showed that the rearrangement of the hydrogen-bonding motifs occurs during the structural transition. These results suggest that such a striking structural transition is aided by the reorganization in the lowest level of self-organization, i.e., the rearrangement of hydrogen-bonded motifs from rosette to linear tape. A remarkable increase in the transient photoconductivity was observed by the flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements upon converting the Col structure to the Lam structure. Transient absorption spectroscopy revealed that electron transfer from electron-donating alkoxyphenyl groups of melamine components to electron-deficient PBI moieties takes place, resulting in a higher probability of charge carrier generation in the Lam structure compared to the Col structure. © 2012 American Chemical Society. h h h h h

Two soluble phosphorescent host materials, 1,4-bis(3,6-di([1,1′: 3′,1″:3″,1‴:3‴,1-quinquephenyl]-5″-yl) -9H-carbazol-9-yl)benzene (P-mPCCP) and 1,4-bis(3,6-bis(4,4″-di-tert- butyl-[1,1′:3′,1″-terphenyl]-5′-yl)-9H-carbazol-9-yl) benzene (T-mPCCP) derived form carbazole and m-terphenyl derivatives were designed and synthesized. These two hosts exhibit good solubility in common organic solvents and possess high glass transition temperature (T > 160 °C) and thermal stability. P-mPCCP and T-mPCCP as the host materials doped with the guest of fac-Ir(ppy) , we fabricated phosphorescent organic light emitting diodes (PHOLED) by spin coating process. The turn-on voltage of P-mPCCP and T-mPCCP composing device was 4.0 and 7.0 eV and showed a maximum luminance of 21,100 and 3290 cd/m and a maximum luminance efficiency of 15.0 and 7.6 cd/A, respectively. © 2011 Elsevier B.V. g 3 2

Diarylethene 1 equipped with two monotopic melamine hydrogen-bonding sites and oligothiophene-functionalized ditopic cyanurate (OTCA) were mixed in a nonpolar solvent to form AA-BB-type supramolecular co-polymers (SCPs) bearing photoswitchable moieties in their main chains and extended π systems as side chains. UV/Vis, fluorescence, dynamic light scattering (DLS), TEM, and AFM studies revealed that the two functional co-monomers formed flexible quasi-one-dimensional SCPs in solution that hierarchically self-organized into helical nanofibers through H-aggregation of the oligothiophene side chains. Upon irradiating the SCPs with UV light, a transition occurred from the H-aggregated state to non-aggregated monomeric oligothiophene side chains, as shown by spectroscopic studies, which indicates the formation of small oligomeric species held together only by hydrogen-bonding interactions. TEM and AFM visualized unfolded fibrils corresponding to elongated single SCP chains formed upon removal of solvent. The helical nanofibers were regenerated upon irradiating the UVirradiated solution with visible light. These results demonstrated that the supramolecular polymerisation followed by hierarchical organization can be effectively controlled by proper supramolecular designs using diarylethenes and π-conjugated oligomers. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Till death do us part: Catenation of toroidal nanostructures (nanorings), self-assembled from more than 1000 small molecular building blocks in solution, occurs when aggregation takes place under high solution concentrations. The formation of interlocked circular nanostructures is prima facie visual evidence for the existence of self-assembled nanorings in solution (see AFM image). © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aryldisilanes composed of one or two anthryl groups and tetra- or pentamethyldisilane chain units were prepared. The substitution of disilanes on the two anthryl groups was isomeric at positions 1, 2, and 9 for 1A2S2, 2A2S2, and 9A2S2, respectively. The photochemical properties of these compounds, such as absorption and fluorescence, were studied in solution. The dependence of the intramolecular π-π and σ-π interactions on the substitution position of the anthryl group were examined. The dianthryldisilanes displayed excimer emission as well as monomer emission. The emission characteristics of the dianthryldisilanes were compared with those of the corresponding anthrylpentamethyldisilanes (1AS2Me, 2AS2Me, and 9AS2Me). We also examined the time dependence of the fluorescence in view of the calculated potential energy surface of conformers in the ground state. The time constants correspond to the relaxation from the Franck-Condon structures those are most stable in the ground state to the relaxed excimer structures in the S excited state. © 2011 Elsevier B.V. 1

We report the novel oligomer host material derived from 3,6-carbazole and diphenylsilane. Through the σ-Si structure, tetraphenylsilane moieties effectively interrupt the extending of φ-conjugation, triplet energy level of the host material increased to 2.95 eV successfully in oligomer chain. In addition, this oligomer host material exhibited high glass transition temperature (T = 119 °C) and matching HOMO (-5.57 eV) and LUMO (-2.12 eV) level with both electrodes. Employing the host material doped with green and blue-emitters as the emissive layer, we fabricated light-emitting diodes by solution processing, the maximum luminance for blue device was 454 cd/m . © 2011 CPST. g 2

Three series of cyclohexyl methacrylate based copolymers having photo-reactive side chains (C=C double bond) were synthesized and examined their performances as photopolymer in the presence of suitable oxime ester or triazine type radical photo-initiators for 365 nm light. As a result, those polymers gave negative patterns with micrometer resolution. Correlation between photochemical reactivity and chain length of the side chain/density of reactive side chain in the cyclohexyl methacrylate main chain was observed. Sterically stacked nonpolar cyclohexyl groups may push out the polar reactive side chain, and length and density of the side chain controls cross linking between two reactive sites in the single main chain or two different main chains. The image on a printing plate has enough strength for practical times of run off the print. These polymers were white or transparent powder having enough stability to preserve. Over all, three copolymers have promising features as photopolymer for printing.

A ditopic melamine bearing perylene bisimides with swallow-tail alkyl chains can be dissolved in organic solvents by mixing with complementary hydrogen-bonding barbiturate or cyanurate, forming solution processable supramolecular assemblies. Upon spin-coating the assemblies, highly organized lamellar architectures are formed with thermal annealing, which act as electron transporting layers in organic field effect transistors. © 2011 The Royal Society of Chemistry.

It's all in the packing: Self-assembly of the title system through hydrogen bonding and then aggregation led to vesicle formation, and capping of the hydrogen-bonding moieties with subsequent aggregation led to ribbons. The resulting self-assembled architectures exhibit distinct optical and electronic properties. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Extremely long nanofibers, whose lengths reach the millimeter regime, are generated via co-aggregation of a melamine-appended perylene bisimide semiconductor and a substituted cyanurate, both of which are ditopic triple-hydrogen-bonding building blocks; they co-aggregate in an unexpected stoichiometrically mismatched 1:2 ratio. Various microscopic and X-ray diffraction studies suggest that hydrogen-bonded polymeric chains are formed along the long axis of the nanofibers by the 1:2 complexation of the two components, which further stack along the short axis of the nanofibers. The photocarrier generation mechanism in the nanofibers is investigated by time-of-flight (TOF) experiments under electric and magnetic fields, revealing the birth and efficient recombination of singlet geminate electron-hole pairs. Flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements revealed intrinsic 1D electron mobilities up to 0.6 cm V s within nanofibers. Extremely long nanofibers, whose lengths reach the millimeter regime, are generated via co-aggregation of a melamine-appended perylene bisimide semiconductor and a substituted cyanurate, both of which are ditopic triple-hydrogen-bonding building blocks. Microscopy and X-ray diffraction studies suggest that hydrogen-bonded polymeric chains are formed along the long axis of the nanofibers by the 1:2 complexation of the two components, which further stack along the short axis of the nanofibers. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. 2 -1 -1

Scanning tunneling microscopy (STM) of mono- and bisurea-functionalized oligo(p-phenylenevinylene)s at solid/liquid interface visualized two-dimensionally-ordered double columnar structures of π-conjugated segments scaffolded by one-dimensional supramolecular polymerization of urea hydrogen-bonding units. In contrast to a persistent alignment of the bisurea compound supported by twofold intermolecular urea-urea hydrogen-bonding, the building blocks in the monourea double columns shows dynamic fluctuation and defects because of their rotational motion around urea-urea hydrogen-bonding axis and/or adsorption-desorption of the individual molecules from the surface. Self-assembled structures of mono- and bisurea compounds at solid/liquid interface revealed by STM can be related to their gelation abilities in organic solvents. Copyright © 2010 American Scientific Publishers All rights reserved.

Substitution effects on the photoluminescence and electrochemical properties and the photochemical stability of tris-(phenylbenzimidazolinato) Ir complexes were investigated. Facial and meridional isomers of a series of complexes having the general structure of Ir(CC) , where (CC) is (4-R-phenyl)benzimidazolinato (R = H, CF , CN, OCH ), were prepared. They are abbreviated to Ir(pmb) (1), Ir-(CF pmb) (2), Ir(CNpmb) (3), and Ir(Opmb) (4), respectively. Electron-donating or -withdrawing groups on the phenyl ring lead to both higher emission quantum, yields and longer emission lifetimes compared to those of 1 in each mer and fac series. Particularly, the emission quantum yields were high in the cases of 2a, 3a, 3b, and 4a. No photochemical isomerization was observed, in both fac- (a) and mer (b) isomers of Ir(pmb) ,Ir(CF3pmb) , and Ir(CNpmb) on irradiation with a 313-nm wavelength light from a 400 W mercury lamp for more than 20 h. All complexes excluding fac-Ir(pmb) (1a) show excellent photochemical stability in degassed anhydrous the solution. The locations of the HOMO and LUMO and the lowest excitation energy of these complexes were investigated by DFT and TD-DFT calculations on fac- and mer-Ir(Opmb) (4a and 4b). The HOMO is mainly localized over the Ir metal center and the phenyl moiety, and the LUMO mainly localized over the benzimidazole moiety. The calculated lowest: excitation energies agree with the experimental values. The X-ray single crystal structures obtained for fac-Ir(CF pmb) (2a) and mer-Ir(Opmb) (4b) are also discussed. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA. III 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3

An oligo(p-phenylenevinylene) (OPV) dimer, whose OPV units are capped on their end by monotopic melamine hydrogen-bonding units, self-assembles in methylcyclohexane to form flexible fibrous nanostructures, which are transformed into rigid nanostrips upon adding ditopic cyanurates and reconverted to nanofibers upon adding a m-xylylene-linked bismelamine. © 2010 The Royal Society of Chemistry.

Photochemical isomerization of 3-piperidino-1,2-benzisothiazole (BIT)-benzothiazole (BT) was investigated. In particular, the effect of nitro-substitution on the benzene ring was selectively examined for the parent, 5-nitro-, and 7-nitro-derivatives. 3-Piperidino-BIT and nitro-3-piperidino-BIT isomerized irreversibly to the corresponding 2-piperidino-BT, and this reaction mechanism was investigated using density-functional theory (DFT) and time-dependent (TD)-DFT calculations. These calculations showed that this isomerization goes through an azirine intermediate. In addition, excitation wavelength effect demonstrates that isomerization occurs from the upper excited state of nitro-derivatives. The HOMO-LUMO transition has charge-transfer and photoinactive characters. © 2010 The Japan Institute of Heterocyclic Chemistry.

Dianthrylsilanes composed of two 9-anthryl groups and permethyloligosilane (n = 1, 2 or 3) chain units were prepared (A2S1, A2S2, and A2S3). Photochemical intram01ecular cyclization reactions Of these compounds were studied in solution and in PMMA spln COated film. In cyclohexane solution, the A2Sn molecules gave one of three cycloadducts, depending on the chain length of the A2S/n molecules. We also demonstrate the fabrication of fluorescent images uslng CyCloaddition reactions in PMMA film. © 2010 CPST.

In this review article, we introduce our recent studies based on the self-assembly of functional dyes through multiple hydrogen bonding interactions. Functional dyes have received a great deal of attention owing to their diverse optical and electronic properties that are appreciably favorable for application as functional materials. Combination of their pi-stacking propensity with other noncovalent interactions enables the creation of diverse functional supramolecular assemblies. Multiple hydrogen bonds are highly directional noncovalent interactions, allowing a creation of oligomeric functional dye assemblies with well-defined supramolecular architectures. Such supramolecular species exhibit unique stimuli-responsive hierarchical organization processes. Furthermore, diversification of materials morphologies and local chromophore packing are possible by changing one of the supramolecular building blocks.

An experiment was conducted to show that a barbituric acid (BA)-functionalized oligothiophene undergoes self-aggregation and co-aggregation with a bismelamine receptor, affording nanorods and nanotapes with remarkable charge-carrier mobilities in their condensed states. Quaterthiophene (1a) was prepared, functionalized on one end by a barbituric acid (BA) headgroups and the other end by a tridodecyloxyphenyl (TDP) tail. Compound 1a was synthesized according to Scheme S1 and fully characterized. The UV/Vis spectra of 1a in methylcyclohexane (MCH) showed the absorption maximum at λ = 439 nm, which was strongly blue-shifted from that in dichloromethane. Furthermore, a significant drop in the fluorescence intensity was observed. Dynamic light scattering of 1 a in MCH showed the presence of large aggregates with hydrodynamic diameters around 400 nm. Atomic force microscopy (AFM) of H-aggregated 1a exhibited uniform rodlike nanostructures with hundreds of nanometers in length, which are arranged in monolayered fashion.

Several proteins, such as tobacco mosaic virus coat protein and the 4 protein of the bacteriophage 5, are known to exhibit unique dynamic self-organization processes involving ring-shaped and extended helical nanostructures triggered by chemical stimuli. However, transformation of rings into coils as observed in biological assemblies has never been realized with synthetic molecular building blocks. Oligo(p-phenylenevinylene) functionalized on one end with barbituric acid and on the other end with aliphatic tails self-organizes in aliphatic solvents to form nanorings through hydrogen-bonding and π-stacking interactions. Upon an increase in concentration, the nanorings transform into rodlike nanostructures, which are considered to be formed through helically coiled objects consisting of quasi-one-dimensional fibers. © 2009 American Chemical Society.

Co-assembly of ditopic perylene bisimide and azobenzene-functionalized melamine occurs with an unconventional stoichiometric ratio, providing well-defined nanostructures with a helically-coiled architecture where perylene chromophores are packed in desirable J-type arrangements. © 2009 The Royal Society of Chemistry.

Miniaturization of nanofibers formed from melamine-appended perylene bisimides and cyanurates are achieved by elongating the linker moieties between perylene bisimide core and melamine moieties. The resulting nanofibers gelate aliphatic solvents with low concentrations and the resulting gels are optically transparent, which are advantageous for photonic devices because no scattering of visible light takes place. Copyright © 2008 The Chemical Society of Japan.

Bis- and monoureas hybridized with the oligo(p-phenylene vinylene) (OPV) pi-electronic segment and 3,4,5-tridodecyloxyphenyl wedge were synthesized and their supramolecular polymerization in diluted solution, gel formation in concentrated solution, and liquid crystallinity in bulk state were investigated. Bisurea 1a featuring a hexamethylene linker showed the highest supramolecular polymerization ability and formed tapelike nanofibers that can gelate various organic solvents. On the other hand, bisurea 1b featuring a dodecamethylene linker and monourea 2 showed a lower degree of supramolecular polymerization, resulting in gel formations in a smaller variety of solvents. These results clearly reflect a high level of cooperativity between the two urea sites and the two OPV segments of 1a upon hydrogen-bonding and pi-pi stacking interactions, respectively. When the gels of 1a, 1b, and 2 were dried, all the compounds self-organized into multilamellar superstructures. Thermal treatment of these lamellae at high temperatures induces columnar liquid-crystalline mesophases as a result of microsegregation between the rigid OPV parts and the molten aliphatic wedges. These results demonstrate that the present molecular constituent is very useful for fabricating dye-based functional assemblies providing nanoscale pi-electronic fibers, and solvent-incorporated and bulk soft materials.

(Figure Presented) Nanodonuts! A hydrogen-bonded cyclic assembly (rosette, left) of a melamine featuring π-conjugated oligo(p-phenyleneethynylene) hierarchically self-organizes with a cyanurate in decane under dilute conditions to form toroidal nanostructures (right) with a diameter of 40 nm. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.

(Chemical Equation Presented) Melamine-linked perylene bisimide dyes (MPBIs) bearing an ethylene or trimethylene group as linker moieties were synthesized, and their self-aggregation and coaggregation with cyanurates through complementary triple hydrogen bonds have been investigated. UV/vis studies revealed that both the MPBIs self-assemble in nonpolar organic solvent through π-π stacking interaction between perylene cores, giving self-aggregates with nearly identical thermal stabilities. Upon addition of 1 equiv of cyanurate components, however, the stabilities of the resulting aggregates were dramatically changed between the two systems, suggesting the formation of different types of hydrogen-bonded supramolecular species. Dynamic light scattering and atomic force microscopic studies revealed that the system featuring ethylene linker moieties generates a discrete dimer of MPBI supported by two cyanurate molecules, whereas the system featuring trimethylene linker moieties affords extended supramolecular polymers hierarchically organizing into nanoscopic fibers. These results demonstrate that it is possible to obtain distinct supramolecular species by just changing the number of carbon atoms at the linker moieties of MPBI components. The present strategy for the fabrication of discrete or polymeric supramolecular assemblies should be applicable to other functional π-conjugated molecules. © 2008 American Chemical Society.

3-R-5-Nitro-1,2-benzisothiazole derivatives (1, R = substituents) in solution, undergo photochemical isomerization to produce 2-R-5-nitro-1,2-benzothiazole derivatives. Here, generalizations and limitations by the substituent, solvent, and excitation wavelength for the photoisomerization reaction of 5-nitro-1,2-benzisothiazoles are reported. © 2008 Elsevier Ltd. All rights reserved.

(Figure Presented) Me, myself, and dye: Core-unsubstituted perylene bisimide dyes bearing a melamine hydrogen-bonding unit link with cyanurates giving H- (red, see picture) and J-aggregates (green). In solution the aggregates can interconvert on thermal treatment or by changing the stoichiometry. In solid films the green to red color change occurs upon scratching the surface. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.

(Figure Presented) Gelling together: Merocyanine dyes possessing a cholesterol group as a gelforming auxiliary self-assemble into nanoscopic fibers in apolar cyclohexane and polar acetone to form organogels, showing dramatically distinct optical properties through exciton coupling. This dramatic change is a result of different chromophore packing arrangements within the nanoscopic fibers (see fluorescence microscopy images with photographs of the gels as insets). © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.

Upon complexation with bismelamine receptors (BMn) featuring different alkyl linker lengths (number of methylene groups (n) = 5-12), a barbituric acid merocyanine dye (1) can be loaded into diverse self-organized superstructures through multiple hydrogen-bonding interactions. UV/vis, dynamic light scattering, and NMR studies in cyclohexane demonstrate that the diversification of the primarily formed hydrogen-bonded species in solution occurs by varying the linker length of BMn. Hierarchical organization of the hydrogen-bonded species is achieved by slow evaporation of the solvent (forming solvent-free films), and the resulting superstructures are evaluated by polarized optical microscopy, X-ray diffraction, SEM, and AFM techniques. The formation of columnar structures with and without two-dimensional ordering are revealed for shorter (n = 5-7) and longer (n = 11, 12) linker bis(melamines), respectively. On the contrary, in the cases of n = 8-10, the formation of lamellar structures is unveiled. Several assemblies (n = 5, 7, 11) indicate the formation of a liquid crystalline mesophase in POM and DSC analyses. Hierarchical organization is also achieved in solution by prolonged aging, affording phase-separated crystalline nanofibers (n = 5, 7) and soft nanofibrils agglomerating into wormlike objects (n = 8), gel-forming continuous globular networks (n = 10), and nanofibers (n = 11, 12). These superstructural and morphological diversifications are an outcome of the variation in the primarily formed hydrogen-bonded supramolecular architectures. Using this strategy, diverse self-assembled materials will be obtained from a single dye component. © 2007 American Chemical Society.

The substitution of the bulky substituents, such as the triphenylsilyl groups, on the 9,10-positions of anthracene produced a remarkable increase in Of, and the substituents controlled the intermolecular stacking by diminishing the electroplex formation and inter- and intra-molecular photochemical reactions. Organic light-emitting diode (OLED) devices composed of these anthracene derivatives showed highly pure blue electroluminescence (EL). (c) 2007 Elsevier B.V. All rights reserved.

(Chemical Equation Presented) A perylene bisimide anchored with melamine hydrogen-bonding units has been prepared, and its supramolecular polymerization upon binding with N-dodecylcyanurate (CA) was examined. The resulting flexible supramolecular polymers self-organized via a π-π stacking interaction between perylene chromophores, affording ribbonlike aggregates in cyclic alkanes and ropelike aggregates in acyclic alkanes to form gels. © 2007 American Chemical Society.