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Abstract: A new dendritic dispersant of carbon nanotubes (CNTs) was synthesized and applied for the noncovalent functionalization of single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). The 1,10-bis(decyloxy)decane core [...]

Dye-encapsulated single-walled carbon nanotubes (dye@SWCNTs) were physically modified to fabricate a water-dispersible dye@SWCNT/dendrimer hybrid. A photocatalytic H2 evolution reaction that uses this dye@SWCNT hybrid as a particulate photocatalyst was conducted in the presence of an electron-relay molecule [methyl viologen (MV2+)], a co-catalyst [PVP–Pt; poly(vinylpyrrolidone)], and a sacrificial donor [1-benzyl-1,4-dihydronicotinamide]. Photoinduced electron transfer occurs between the encapsulated dye molecule inside the SWCNT and the MV2+ ion outside the SWCNT. This is followed by the relay of the electron to the co-catalyst, which reduces H+ to generate H2. The external quantum yield of the H2 evolution reached a maximum of 8.5% under irradiation with light at 510 nm. Notably, the photoinduced electron transfer between the molecules on the inside and the outside of the SWCNT proceeded smoothly despite the possibility of energy migration from the encapsulated dye to the SWCNT or the possibility of charge recombination. [ABSTRACT FROM AUTHOR]

Single-walled carbon nanotube (SWCNT)/TiO2 hybrids were synthesized using 1,10-bis(decyloxy)decane-core PAMAM dendrimer as a molecular glue. Upon photoirradiation of a water dispersion of SWCNT/TiO2 hybrids with visible light (λ > 422 nm), the hydrogen evolution reaction proceeded at a rate of 0.95 mmol/h·g in the presence of a sacrificial agent (1-benzyl-1,4-dihydronicotinamide, BNAH). External quantum yields (EQYs) of the hydrogen production reaction photosensitized by (6,5), (7,5), and (8,3) tubes were estimated to be 5.5%, 3.6%, and 2.2%, respectively, using monochromatic lights corresponding to their E22 absorptions (570 nm, 650 nm, and 680 nm). This order of EQYs (i.e., (6,5) > (7,5) > (8,3)SWCNTs) exhibited the dependence on the C2 energy level of SWCNT for EQY and proved the hot electron extraction pathway. [ABSTRACT FROM AUTHOR]

The preparation and structural characterization, optical and electrochemical properties of unsymmetrically substituted mono and bistrithiolophthalocyanines is described. The ultraviolet-visible and/or NMR spectroscopy studies of the generation of cationic species upon treatment of phthalocyanines with TFA (trifluoroacetyl) are also described.

The compounds 5,6-dibromo-4,7-diethylbenzo[1,2,3]trichalcogenoles with two adjacent bromine atoms were first prepared by the reaction of 2,3,5,6-tetrabromo-1,4-diethylbenzene (TBDEB) with elemental sulfur or selenium in DBU. The electrochemical properties of phthalocyanines and benzotrichalocogenoles are determined by cyclic voltammetry with Ag/AgNO3 used as a reference electrode.

Research has been conducted on phosphonate carbanions. The authors describe the autoxidation of these carbanions which have been derived from 9-phosphono-10-hydroacridanes, and report that their autoxidation leads to chemiluminescence of the excited acridone anion.

A donor–acceptor–donor (D–A–D) dye consisting of ferrocene units (donors) and a benzothiadiazole unit (acceptor) was synthesized to use the photosensitizer for hydrogen evolution reaction (HER) from water within semiconducting single-walled carbon nanotube (s-SWCNT). The dye was easily encapsulated into s-SWCNT by a solution method to form dye-encapsulated s-SWCNTs (dye@SWCNTs). Subsequently, physical modification of dye@SWCNTs by a fullerodendron gave dye@SWCNT/fullerodendron nanohybrids having dye/s-SWCNT/C60 coaxial heterojunction. Interestingly, dye@SWCNT/fullerodendron nanohybrids act as the photosensitizer for HER in the presence of sacrificial donor, electron relay, and co-catalyst due to the mobile carrier generation upon photoexcitation of the dye molecules. [ABSTRACT FROM AUTHOR]

To observe a clear-cut example of the formation of mobile carriers from excitons on semiconducting single-walled carbon nanotubes (s-SWCNTs) surrounded by a medium with a high dielectric constant, water-dispersible s-SWCNT nanocomposites were fabricated by physical modifications using poly(amidoamine) dendrimers that contain an aliphatic core. The evolution of H2 from water using these s-SWCNT/dendrimer nanocomposites as photosensitizers under irradiation with visible light demonstrated a photo-induced electron transfer from the s-SWCNTs to the co-catalysts. [ABSTRACT FROM AUTHOR]

Hydrogen gas, which can be used in fuel cells to generate electricity, is considered the ultimate clean energy source. Recently, it was reported that a photo-induced electron transfer system consisting of single-walled carbon nanotubes (SWCNTs) and fullerodendrons shows photo-catalytic activity with a very high quantum yield for splitting water under visible light irradiation. However, the mechanism of high efficiency hydrogen generation is not yet clearly understood. We report here the spectroscopic characterizations of the SWCNT-fullerodendron composites. The results indicate two important fundamental properties of the composite system. First, fullerodendrons preferentially interact with the semiconducting SWCNTs instead of with their metallic counterparts. Second, the photo-induced electron transfer process from the C60moiety of fullerodendrons to SWCNTs occurs more efficiently with an increasing tube diameter. [ABSTRACT FROM AUTHOR]

Direct incorporation of a Pt(ii) complex into the shell of SWCNT/fullerodendron coaxial nanohybrids produces a new coaxial nanowire, SWCNT/fullerodendron/Pt(ii), that shows efficient photocatalytic activity for hydrogen evolution from water (Φ = 0.16 upon irradiation at 450 ± 5 nm) without any aid of electron relay such as methyl viologen. [ABSTRACT FROM AUTHOR]

Tetrathiafluvalene (TTF)-annulated symmetrical and unsymmetrical phthalocyanines (4), (5), and (6) were prepared from 3,6-dioctylphthalonitrile (1) with a TTF unit, 4,5-dioctyloxyphthalonitrile (2), and 3,6-dioctyloxyphthalonitrile (3). Tetra-TTF-annulated phthalocyanine (4) and iodine produced an electron transfer complex which showed a radical cationic character. [ABSTRACT FROM AUTHOR]

We succeeded in the synthesis of a novel poly(amidoamine) dendrimer having diphenyl diselenide at the core. Modification of the dendrimer diselenide by the reaction with glucono-δ-lactone in methanol gave a water-soluble dendrimer diselenide having chiral terminal groups. The structures of dendrimers were satisfactorily confirmed by MAIDI-TOF MS spectrometry, elemental analysis, and NMR spectroscopy. Interestingly, induced circular dichroism (ICD) of the interaction between the diphenyl diselenide core and D-gluconamide periphery of the dendrimer was observed at 300 nm. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT[image omitted] [ABSTRACT FROM AUTHOR]

A new poly(amidoamine) dendron having 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) at the focal point was synthesized. Interestingly, formation of zwitterionic fullerodendrons (λmax = 930 nm for C60 and 795 nm for C70) were observed by Vis-NIR spectroscopy upon the reaction of C60 or C70 with the DBN-focal dendron. In particular, the C70 anion was effectively stabilized by the site isolation effect of the dendritic wedge. The half-life of fullerodendron 12b having C70 anion at the focal point reaches 7,345 min, which is 20 times longer than that of complex between C60 and pristine DBN. Furthermore, in order to confirm the structure of the zwitterionic complex, fullerodendron 12a was reprecipitated from benzonitrile/1,2,4-trimethylbenzene, and was observed using IR spectroscopy and APPI-MS. [ABSTRACT FROM AUTHOR]

The methanol solution of 04.5 COONa-terminated PAMAM dendrimer displayed strong blue luminescence (λmax = 445 nm) under UV irradiation at 370 nm and fluorescence intensity increased with fluoride ions. On the other hand, the remarkable changes of fluorescence spectra of the dendrimer solutions were not observed in the presence of other halogen anions (CI-, Br-, and I-). This result suggested that the PAMAM dendrimer is useful as fluoride ion selective sensor in methanol. [ABSTRACT FROM AUTHOR]

The base-catalyzed Diels-Alder reactions of 4-arylthio-3-hydroxy-2-pyrones are reported. Treatment of 4-arylthio-3-hydroxy-2-pyrones and dienophiles with triethylamine gave 2-arylthio-2-cyclohexenone derivatives by the Diels-Alder reaction involving a decarboxylation in excellent to reasonable yields. [ABSTRACT FROM AUTHOR]

Treatment of 4-arylthio-3-hydroxy-2-pyrones with acetylenedicarboxylates gave 4-arylthio-3-hydroxyphthalates by the base-catalyzed Diels–Alder reaction via a decarboxylation in good yields. [ABSTRACT FROM AUTHOR]

Novel surface-block dendrimer was synthesized via a divergent/convergent approach using [4+4] photocycloaddition of two different anthracenes bearing a newly designed dendritic substituent, of which terminal groups are long alkyl chains for one hemisphere and oligo(ethylene oxide) chains for the other hemisphere. A solution of the two different anthryl dendrons was irradiated with a high-pressure mercury lamp to afford a hetero-dimer, which consists of the two different dendrons. The surface-block dendrimer was isolated by the use of size exclusion chromatography (SEC) and well characterized by NMR spectrum, SEC, and MALDI-TOF-Mass spectrum. Furthermore, this paper describes a ratio of the photoproducts (the hetero-dimer and two homo-dimers) that were obtained from the photocycloaddition reactions carried out in neat and an emulsion condition, along with the solution. [ABSTRACT FROM AUTHOR]

A convenient rearrangement reaction of 2‐chloroglycidic esters is reported. Treatment of 2‐chloroglycidic esters with PPh 3 under refluxing condition results in the formation of 3‐chloro‐2‐keto esters in good to reasonable yields. [ABSTRACT FROM AUTHOR]

A newly designed fullerodendron was synthesized in good yield (84%) by the use of a Diels-Alder reaction of C60 with an anthryl dendron. Interestingly, the fullerodendron acts as a new catalyst that uses oxygen and light to generate singlet oxygen (1O2). The dendron facilitates various types of singlet oxygenation reactions including ene reaction, Diels-Alder reaction, and oxidation of phenol and sulfide. [ABSTRACT FROM AUTHOR]

The one-pot substitution-rearrangement reaction of 2-chloroglycidic ester is reported. Treatment of 2-chloroglycidic ester with sodium arylthiolate at room temperature results in the formation of 3-arylsulfenyl-2-keto ester in excellent to good yields. [ABSTRACT FROM AUTHOR]

Silver nanoparticles protected by first to third generation poly(amido amine) dendrons with an anthracenyl-focal point were fabricated by photo-promotion of silver ions in aqueous dendron solutions. The reaction solutions colored from light to deep brown and displayed a broad plasmon band at 450nm, indicating the formation of silver nanoparticles. The formation of particles progressed with time, although it slowed down at the light-shielding (dark) condition. The light-promoted electron transfer from amine groups of dendron to silver ions through anthracenyl moiety might concern to the formation of silver nanoparticles. According to the images of transmission electron microscopy, the shape of nanoparticles was not only spherical (15-20 nm in size) but also polygonal (20-35 nm in size). It was confirmed from the crystallographic analysis of electron diffraction patterns that the polygon was a hexagonal-close-packing (hcp) single crystal, whereas the crystal structure of spherical nanoparticles was face-centered-cubic (fcc). The reaction was fastest when the second generation dendron was used, indicating the competition of increasing number of amine groups and reducing efficiency of photo-promoted electron transfer with generation. [ABSTRACT FROM AUTHOR]

Results of oxidation of thiols to disulfides with 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) are described. A simple addition of 0.20–0.25 mol equivalent of solid DBDMH to thiol in chloroform at room temperature yielded the disulfides in excellent yield. The reaction is extremely fast and gave no other oxidized side products. [ABSTRACT FROM AUTHOR]

Field-effect transistor (FET) device has been fabricated with Langmuir-Blodgett films of C60 dendrimer. The device showed n-channel normally off characteristics with the field-effect mobility of 2.7×10-3 cm2 V-1 s-1 at 300 K, whose value is twice as high as that (1.4×10-3 cm2 V-1 s-1) for the FET with spin-coated films of C60 dendrimer. This originates from the formation of ordered π-conduction network of C60 moieties. From the temperature dependence of field-effect mobility, a structural phase transition has been observed at around 300 K. Furthermore, the density of states for impurity levels was estimated in the Langmuir-Blodgett films. [ABSTRACT FROM AUTHOR]

n-channel field-effect transistor (FET) devices have been fabricated with thin films of fullerodendron on SiO2/Si, polyimide/Au/poly(ethylene terephthalate), and polyvinyl alcohol/Au/poly(ethylene terephthalate) substrates by using solution processes. The value of field-effect mobility μ of the fullerodendron FET reaches 1.7×10-3 cm2 V-1 s-1 at 300 K. The mobility gap and optical gap have been estimated to be 0.15 and 1.4 eV, respectively. The channel conduction in the FET device follows thermally activated hopping-transport mechanism below 300 K. [ABSTRACT FROM AUTHOR]