ABSTRACT
Herein, anatase titanium dioxide (TiO2) nanoparticles were prepared by boiling anatase TiO2 in water without using hydrothermal synthesis. This changed the particle diameter because boiling caused particle collision via convection. Substrates were then prepared by assembling anatase nanoparticles on 3-aminopropyltrimethoxysilane (APTMS)-functionalized Al surfaces. The effect of pH on the preparation of anatase nanoparticles was investigated, with results indicating that pH 3 is optimal for anatase adsorption on Al surfaces. The anatase TiO2 suspension was thus adjusted to pH 3 using dilute HCl solution, and the Al surface selectively adsorbed anatase nanoparticles. This method enabled the adsorption of anatase TiO2 nanoparticles at room temperature, without using a heat source. In addition to Al substrates, this method was also found to be applicable to glass surfaces.
ABSTRACT
Dye-sensitized photoelectrochemical cells (DSPECs) composed of a new near-infrared BODIPY dye D1 that is co-deposited with a ruthenium water oxidation catalyst C1 have been fabricated. The devices at pH 7.2 showed an excellent Faradaic efficiency of H2 production (65.8%) that was 5.4 times larger than that of a triphenylamine photosensitizer D2 and C1-coadsorbed cell.
ABSTRACT
Treatment of 3-aryl- and 3-heteroarylindoles with propargyl ethers under indium catalysis successfully provided aryl- and heteroaryl[c]carbazoles, which were found to be more efficient emitters compared with the corresponding [a]-analogs.
Subject(s)
Alkynes/chemistry , Carbazoles/chemical synthesis , Ethers/chemistry , Indium/chemistry , Indoles/chemistry , Luminescence , Carbazoles/chemistry , Catalysis , Molecular StructureABSTRACT
Treatment of 2-aryl- and 2-heteroarylindoles with propargyl ethers in the presence of a catalytic amount of indium nonafluorobutanesulfonate [In(ONf)(3)] gave aryl- and heteroaryl-annulated[a]carbazoles in good yields. The synthetically attractive feature is reflected by its applicability to a wide range of 2-aryl- and 2-heteroarylindoles. In the annulation reaction, propargyl ethers act as C3 sources (HC[triple bond]C-CH(2)OR). Among these, two carbon atoms are incorporated into the product as members of a newly constructed aromatic ring and the remaining carbon atom forms a methyl group on the aromatic ring, where the methyl group is always located next to the C3 position of the indole nucleus. The methyl group can be easily removed through SeO(2) oxidation followed by decarbonylation with RhCl(CO)(PPh(3))(2)-Ph(2)P(CH(2))(3)PPh(2) as a catalyst. The new annulation strategy is applicable also to symmetrical dimers such as bithiophene and bifuran derivatives. Mechanistic studies suggest that the first step is addition reaction initiated by regioselective nucleophilic attack of the C3 of 2-aryl- and 2-heteroarylindoles to the internal carbon atom of the C[triple bond]C bond in propargyl ethers. The next stage is ring-closing S(N)2 process kicking out the alkoxy group and then aromatization via a 1,3-hydrogen shift is the final step. The two carbon-carbon bond-forming reactions achieved in one-pot contribute largely to the reduction in the number of steps for the synthesis of aryl- and heteroaryl-annulated[a]carbazoles. Furthermore, utilization of the Fischer indole synthesis for efficient supply of the substrates, 2-aryl- and 2-heteroarylindoles, is another important factor shortening the overall process. The development of the annulation with a wide substrate scope provided a unique opportunity to evaluate photophysical properties of a series of aryl- and heteroaryl-annulated[a]carbazoles. Almost all the compounds evaluated in this study were found to emit purple to green light in the visible region. Some interesting structure-property correlations are also described.
Subject(s)
Alkynes/chemistry , Carbazoles/chemical synthesis , Ethers/chemistry , Indium/chemistry , Indoles/chemistry , Photochemical Processes , Acids/chemistry , Alkaloids/chemistry , Carbazoles/chemistry , Catalysis , Molecular Structure , SolventsSubject(s)
Carbazoles/chemical synthesis , Ethers/chemistry , Indium/chemistry , Indoles/chemistry , Alkynes/chemistry , Carbazoles/chemistry , Catalysis , Cyclization , Heterocyclic Compounds, 4 or More Rings/chemical synthesis , Heterocyclic Compounds, 4 or More Rings/chemistry , Molecular Structure , Polycyclic Compounds/chemical synthesis , Polycyclic Compounds/chemistryABSTRACT
A surface graft polymer with one or two phosphorylcholine (PC) polarheads at the terminus of the growing chain end was prepared by sequential reactions on a glass substrate. The dithiocarbamate group covalently bound to glass surfaces was derivatized with one or two PC groups and then irradiated with ultraviolet light in the presence of N,N-dimethylacrylamide (DMAAm). X-ray photoelectron spectroscopy, wettability measurements and dye staining experiment for the PC group showed that the resultant graft copolymers were produced via iniferter-based quasi-living radical polymerization, in which the polyDMAAm graft chain contains one or two PC groups at the terminal end of the graft chain. These polymer surface grafts may help provide biocompatibility.
Subject(s)
Phosphorylcholine/chemistry , Acrylamides , Glass/chemistry , Magnetic Resonance Spectroscopy , Surface Properties , Thermodynamics , ThiocarbamatesABSTRACT
The intramolecular [2 + 2] photocycloaddition of alpha,omega-bis(3,6-divinyl-N-carbazolyl)alkanes 3 afforded triply bridged syn-[2.2.n](3,6,9)carbazolophanes 4a-6a (n = 4) and 4b,5b (n = 5) composed of isomers derived from the difference in the direction of cyclobutane rings. In major isomers 4a and 4b, excimer fluorescence was observed, the maximum position remarkably depending on the tether length.
