Enhanced Photosensitized Hydrogen Production by Encapsulation of Ferrocenyl Dyes into Single-Walled Carbon Nanotubes.

Dye-encapsulated single-walled carbon nanotubes (SWCNTs) were employed for the construction of a coaxial three-component dye/SWCNT/C60 heterojunction. Despite the larger diameter (∼1.4 nm) of the SWCNTs relative to that set by Flavel's rule (0.95 nm), the photoinduced electron transfer from dye-encapsulated SWCNTs to C60 proceeded smoothly, resulting in the photosensitized evolution of H2 from H2O using a ferrocenyl-based photosensitizer, which was confirmed by the action spectra.

BNCT pancreatic cancer treatment strategy with glucose-conjugated boron drug.

Multidisciplinary therapy centered on radical surgery for resectable pancreatic cancer is expected to prolong prognosis, but relies on CA19-9 biomarker levels to determine treatment strategy. Boron neutron capture therapy (BNCT) is a chemoradiotherapy using tumor hyperaccumulator boron drugs and neutron irradiation. The purpose of this study is to investigate novel boron drug agents for BNCT for pancreatic cancer. Bioinformatics was used to evaluate the uptake of current boron amino acid (BPA) drugs for BNCT into pancreatic cancer. The expression of the amino acid transporter LAT1, a BPA uptake transporter, was low in pancreatic cancer and even lower in high CA19-9 pancreatic cancer. In contrast, the glucose transporter was high in high CA19-9 pancreatic cancers and inversely correlated with LAT1 expression. Considering the low EPR effect in pancreatic cancer, we synthesized a small molecule Glucose-BSH, which is boron BSH bound to glucose, and confirmed its specific uptake in pancreatic cancer. uptake of Glucose-BSH was confirmed in an environment compatible with the tumor microenvironment. The therapeutic efficacy and safety of Glucose-BSH by therapeutic neutron irradiation were confirmed with BNCT. We report Glucose-BSH boron drug discovery study of a Precision Medicine BNCT with application to high CA19-9 pancreatic cancer.

Hot Electron Extraction in SWCNT/TiO2 for Photocatalytic H2 Evolution from Water.

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.

Formation of zwitterionic fullerodendron using a new DBN-focal dendron.

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 (λ(max) = 930 nm for C(60) and 795 nm for C(70)) were observed by Vis-NIR spectroscopy upon the reaction of C(60) or C(70) with the DBN-focal dendron. In particular, the C(70) anion was effectively stabilized by the site isolation effect of the dendritic wedge. The half-life of fullerodendron 12b having C(70) anion at the focal point reaches 7,345 min, which is 20 times longer than that of complex between C(60) 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.

Disproportionation-induced solid-state fluorescence in 6,13-dihydropentacenes.

The thermally and photolytically induced disproportionation of 6,13-dihydropentacene derivatives into tetrahydropentacenes and pentacenes results in unique solid-state fluorescence. The fluorescence thereby depends on the molecular structure and the molecular arrangement in the solid state.

Preparation and photosensitizing property of novel Cd10S16 molecular cluster dendrimer.

A new Cd10S16 molecular cluster dendrimer has been prepared and characterized; photooxygenation reaction using the molecular cluster dendrimer as a photosensitizer was successful.

A photo-responsive hydrogelator having gluconamides at its peripheral branches.

A newly designed anthracene derivative having gluconamides at its peripheral branches formed a photo-responsive hydrogel. SEM observation of the xerogel showed a network structure consisting of fibrils. Upon photoirradiation (lambda >300 nm) of the hydrogel, regioselective photodimerization of the anthracene moiety occurred to give head-to-tail photodimers and the physical state changed from the gel to the sol.

Photo-induced H2 evolution from water via the dissociation of excitons in water-dispersible single-walled carbon nanotube sensitizers.

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.

SWCNT Photocatalyst for Hydrogen Production from Water upon Photoexcitation of (8, 3) SWCNT at 680-nm Light.

Single-walled carbon nanotubes (SWCNTs) are potentially strong optical absorbers with tunable absorption bands depending on their chiral indices (n, m). Their application for solar energy conversion is difficult because of the large binding energy (>100 meV) of electron-hole pairs, known as excitons, produced by optical absorption. Recent development of photovoltaic devices based on SWCNTs as light-absorbing components have shown that the creation of heterojunctions by pairing chirality-controlled SWCNTs with C60 is the key for high power conversion efficiency. In contrast to thin film devices, photocatalytic reactions in a dispersion/solution system triggered by the photoexcitation of SWCNTs have never been reported due to the difficulty of the construction of a well-ordered surface on SWCNTs. Here, we show a clear-cut example of a SWCNT photocatalyst producing H2 from water. Self-organization of a fullerodendron on the SWCNT core affords water-dispersible coaxial nanowires possessing SWCNT/C60 heterojunctions, of which a dendron shell can act as support of a co-catalyst for H2 evolution. Because the band offset between the LUMO levels of (8, 3)SWCNT and C60 satisfactorily exceeds the exciton binding energy to allow efficient exciton dissociation, the (8, 3)SWCNT/fullerodendron coaxial photocatalyst shows H2-evolving activity (QY = 0.015) upon 680-nm illumination, which is E22 absorption of (8, 3) SWCNT.

Photoinduced charge separation and charge recombination of fullerene bearing dendritic poly(amidoamine) with carboxylates at the terminal in aqueous media.

Photoinduced charge separation of fullerodendrimers with carboxylates at terminal sites (C60 approximately COO-) has been found in aqueous media. Time-resolved transient absorption and fluorescence measurements of the fullerodendrimers demonstrated that charge separation takes place from the terminal carboxylate anion to the central excited singlet state of C60, generating C60*- approximately COO* with high quantum efficiency in aqueous solution. In the presence of viologen dication and a sacrificial donor, the persistent viologen radical cation was generated.

Self-assembly and regioselective photodimerization of anthracene having a dendritic substituent.

[reaction: see text] Thermotropic liquid crystallinity can be induced for an anthracene having a dendritic substituent. The photodimerization reaction of an anthracene moiety in the smectic phase proceeded quantitatively and regioselectively.

The key intermediates that interact with the fluorophores in the peroxyoxalate chemiluminescence reaction of 2,4,6-trichlorophenyl N-aryl-N-tosyloxamates.

A kinetic study of peroxyoxalate chemiluminescence reactions employing 2,4,6-trichlorophenyl N-aryl-N-tosyloxamates supports the 1,2-dioxetanones still bearing the eliminating group as the key intermediates that interact with the fluorophores rather than 1,2-dioxetanedione.

An extended phenacene-type molecule, [8]phenacene: synthesis and transistor application.

A new phenacene-type molecule, [8]phenacene, which is an extended zigzag chain of coplanar fused benzene rings, has been synthesised for use in an organic field-effect transistor (FET). The molecule consists of a phenacene core of eight benzene rings, which has a lengthy π-conjugated system. The structure was verified by elemental analysis, solid-state NMR, X-ray diffraction (XRD) pattern, absorption spectrum and photoelectron yield spectroscopy (PYS). This type of molecule is quite interesting, not only as pure chemistry but also for its potential electronics applications. Here we report the physical properties of [8]phenacene and its FET application. An [8]phenacene thin-film FET fabricated with an SiO2 gate dielectric showed clear p-channel characteristics. The highest µ achieved in an [8]phenacene thin-film FET with an SiO2 gate dielectric is 1.74 cm(2) V(-1) s(-1), demonstrating excellent FET characteristics; the average µ was evaluated as 1.2(3) cm(2) V(-1) s(-1). The µ value in the [8]phenacene electric-double-layer FET reached 16.4 cm(2) V(-1) s(-1), which is the highest reported in EDL FETs based on phenacene-type molecules; the average µ was evaluated as 8(5) cm(2) V(-1) s(-1). The µ values recorded in this study show that [8]phenacene is a promising molecule for transistor applications.

Photosensitized hydrogen evolution from water using a single-walled carbon nanotube/fullerodendron/SiO2 coaxial nanohybrid.

A coaxial nanohybrid consisting of a single-walled carbon nanotube (SWCNT), fullerodendron, and SiO(2) shows high-efficiency light-driven hydrogen evolution from water. Upon visible light irradiation, SWCNT/fullerodendron/SiO(2) coaxial nanohybrid shows hydrogen evolution activity in the presence of methyl viologen (MV(2+)), benzyldihydronicotinamide (BNAH), and a colloidal polyvinyl alcohol(PVA)-Pt.

Preparation and electrochemical and optical properties of unsymmetrically substituted phthalocyanines with one or two trithiole rings and related symmetric derivatives.

4,5-Bis(benzylthio)-3,6-diethylphthalonitrile (1) was mixed with 4 -t-butylphthalonitrile and then treated with lithium alkoxide in n-hexanol to produce the corresponding unsymmetrically substituted phthalocyanines (2) and (3) with two or four benzylthio groups, respectively. Treatment of phthalocyanine (2) with nickel(II) acetate yielded the corresponding metal complex 2-Ni. Two benzyl groups of 2 and 2-Ni were removed with lithium/THF/ammonia at -78 degrees C under argon, and the dithiolate anions generated were then reacted with elemental sulfur to give monotrithiolophthalocyanines (5) and (5-Ni). A similar treatment of 3 produced bistrithiolophthalocyanine (6). Tetrakistrithiolophthalocyanine (7-Ni) was prepared by complexation of phthalocyanine (4) with nickel(II) acetate, followed by a Birch reduction of the resulting nickel(II) complex (4-Ni), and then sulfurization and cyclization of the octathiolate anions that were generated. The structures of the phthalocyanines were determined by (1)H NMR and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The optical and electrochemical properties of the phthalocyanines were examined by UV-vis absorption spectroscopy and cyclic voltammetry. Treatment of 5, 5-Ni, 6, 7, and 7-Ni with trifluoroacetic acid in chloroform generated positively charged species, which were characterized by UV-vis and/or NMR spectroscopy.

Fabrication and properties of fullerodendron thin films.

Thin films of fullerodendron (C(60)(Gn-COOMe) (n = 0.5, 1.5, 2.5)), which was synthesized from fullerene and anthracenyl poly(amido amine) dendron with methyl ester terminals and different generations (G), were fabricated by the Langmuir-Blodgett (LB) and adsorption techniques. It was characterized by X-ray reflectometry that the LB films possessed well-ordered structure, although the adsorption method led to random orientation of molecules. As to C(60)(G0.5-COOMe) and C(60)(G1.5-COOMe), the LB films took a four-layer structure consisting of a double layer of molecules, and fullerene moieties exist in the interior of the LB films. On the other hand, C(60)(G2.5-COOMe) led to a two-layer structure in which the fullerene moieties were at the air side and the dendron moieties were at the substrate side. With increasing generation of dendron, the monolayer formation ability at the air/water interface as amphiphilic molecule strengthens and the amphiphilic property becomes superior to the fullerene-fullerene attractive interaction that prevents the monolayer formation. Furthermore, in the case of C(60)(G0.5-COOMe) and C(60)(G1.5-COOMe), the reduction peak in cyclic voltammetry of the LB film remained even after UV light irradiation. On the contrary, the peak of the C(60)(G2.5-COOMe) LB film disappeared, indicating that molecular arrangement in the films affects electrochemical properties.

Peroxyoxalate chemiluminescence of N,N'-bistosyl-1H,4H-quinoxaline-2,3-dione and related compounds. Dependence on electronic nature of fluorophores.

The title compound N,N'-bistosyl-1H,4H-quinoxaline-2,3-dione (TsQD) provides peroxyoxalate chemiluminescence (PO-CL) when reacted with hydrogen peroxide in the presence of fluorophores. The chemiluminescence (CL) efficiency of TsQD was superior to that of other related compounds such as bis(2,4,6-trichlorophenyl) oxalate (TCPO), a typical oxalate for the peroxyoxalate PO-CL, under an aqueous condition. Factors affecting the PO-CL efficiency are discussed from the viewpoint of the structures of the substrates and the electronic nature of the fluorophores. A linear correlation of the logarithmic values evaluated from the CL quantum yields with the oxidation potentials of the aromatic fluorophores supports the involvement of the chemically initiated electron exchange luminescence (CIEEL) mechanism in both TsQD- and TCPO-CL systems. Also, an excellent Hammett relationship was derived from the correlation between the sigma(+) values and the relative singlet excitation yields in TsQD-CL enhanced by a series of fluorescent para,para'-disubstituted distyrylbenzenes.

Preparation of phthalocyanines with eight benzylchalcogeno substituents from 5,6-dibromo-4,7-diethylbenzo[1,2,3]trichalcogenoles.

Benzo[1,2,3]trichalcogenoles with two bromine atoms on the benzene ring, 5,6-dibromo-4,7-diethylbenzo[1,2,3]trichalcogenoles (1a) and (1b) (chalcogen: 1a = S; 1b = Se), were first prepared by treating 2,3,5,6-tetrabromo-1,4-diethylbenzene (TBDEB) with elemental sulfur or amorphous selenium in DBU at 140 degrees C (for 1a) and 100 degrees C (for 1b) for 24 h. The structures of 1a and 1b were verified by NMR spectroscopy, mass spectrometry, and elemental analysis. X-ray crystallographic analysis ultimately showed that the substitution reactions of TBDEB proceeded at the two adjacent bromine atoms. To apply 1a and 1b to construction of phthalocyanine derivatives with sulfur or selenium functional groups, 4,5-bis(benzylchalcogeno)-3,6-diethylphthalonitriles (5a) and (5b) as key intermediates were prepared by way of introduction of alkyl groups (2-cyanoethyl or 4-nitrophenethyl groups) on two chalcogen atoms, substitution of two bromine atoms with nitrile groups, and subsequent exchange of alkyl groups with benzyl groups. Compound 5a was treated with lithium in n-pentanol at 100 degrees C for 1 h to produce 2,3,9,10,16,17,23,24-octakis(benzylthio)-1,4,8,11,15,18,22,25-octaethylphthalocyanine (6a). A similar treatment of 5b in n-hexanol at 100 degrees C for 2 h gave phthalocyanine 6b. The structures of 6a and 6b were determined by (1)H NMR spectroscopy and MALDI-TOFMS. X-ray crystallographic analysis of 6a was also performed. The Q-band absorptions (lambda(max)) for 6a and 6b in UV-vis spectra were observed at 755 nm (log epsilon = 5.1) and 757 nm (log epsilon = 5.1), respectively, and their electrochemical properties were verified by cyclic voltammetry in dichloromethane with Ag/AgNO(3) as a reference electrode. Compounds 6a and 6b were further treated with lithium in THF/NH(3) at -78 degrees C and then with dibutyltin dichloride to produce phthalocyanine derivatives 8a and 8b with four dichalcogenastannole rings by way of octachalcogenate phthalocyanines 7a and 7b.

Chemiluminescence in autoxidation of phosphonate carbanions. Phospha-1,2-dioxetanes as the most likely high-energy intermediates.

Autoxidation of the phosphonate carbanions derived from 9-phosphono-10-hydroacridanes provided chemiluminescence ascribed to the excited acridone anion. The intramolecular CIEEL (chemically initiated electron exchange luminescence) mechanism can be applied to this chemiluminescence because of the much higher emission efficiency compared to that of 9-phosphono-10-methylacridanes. The effect of the phosphonate substituents on the emission efficiency and especially on the rates of the chemiluminescence decay can be interpreted to originate from the valence deviation of the phosphorus atoms, which is connected with the substituent effect on the geometrical selectivity in the olefination reaction of the phosphonate carbanions. The enhanced chemiluminescence in the presence of the fluorophores was also detected in autoxidation of the carbanions of diethyl diphenylmethylphosphonate and fluorenylphosphonate. Although the evidence is circumstantial, these results strongly support the belief that phospha-1,2-dioxetane is the most likely high-energy intermediate generating the excited molecules.