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71.
Shen Q Ogomi Y Park BW Inoue T Pandey SS Miyamoto A Fujita S Katayama K Toyoda T Hayase S 《Physical chemistry chemical physics : PCCP》2012,14(13):4605-4613
Understanding the electron transfer dynamics at the interface between dye sensitizer and semiconductor nanoparticle is very important for both a fundamental study and development of dye-sensitized solar cells (DSCs), which are a potential candidate for next generation solar cells. In this study, we have characterized the ultrafast photoexcited electron dynamics in a newly produced linearly-linked two dye co-sensitized solar cell using both a transient absorption (TA) and an improved transient grating (TG) technique, in which tin(IV) 2,11,20,29-tetra-tert-butyl-2,3-naphthalocyanine (NcSn) and cis-diisothiocyanato-bis(2,2'-bipyridyl-4,4'-dicarboxylato)ruthenium(II) bis(tetrabutylammonium) (N719) are molecularly and linearly linked and are bonded to the surface of a nanocrystalline tin dioxide (SnO(2)) electrode by a metal-O-metal linkage (i.e. SnO(2)-NcSn-N719). By comparing the TA and TG kinetics of NcSn, N719, and hybrid NcSn-N719 molecules adsorbed onto both of the SnO(2) and zirconium dioxide (ZrO(2)) nanocrystalline films, the forward and backward electron transfer dynamics in SnO(2)-NcSn-N719 were clarified. We found that there are two pathways for electron injection from the linearly-linked two dye molecules (NcSn-N719) to SnO(2). The first is a stepwise electron injection, in which photoexcited electrons first transfer from N719 to NcSn with a transfer time of 0.95 ps and then transfer from NcSn to the conduction band (CB) of SnO(2) with two timescales of 1.6 ps and 4.2 ps. The second is direct photoexcited electron transfer from N719 to the CB of SnO(2) with a timescale of 20-30 ps. On the other hand, back electron transfer from SnO(2) to NcSn is on a timescale of about 2 ns, which is about three orders of magnitude slower compared to the forward electron transfer from NcSn to SnO(2). The back electron transfer from NcSn to N719 is on a timescale of about 40 ps, which is about one order slower compared to the forward electron transfer from N719 to NcSn. These results demonstrate that photoexcited electrons can be effectively injected into SnO(2) from both of the N719 and NcSn dyes. 相似文献
72.
73.
Tomoyuki Shibuguchi Yuhei Fukuta Yoko Akachi Akihiro Sekine Takashi Ohshima Masakatsu Shibasaki 《Tetrahedron letters》2002,43(52):9539-9543
A new asymmetric two-center phase-transfer catalyst was designed and a catalyst library containing more than 40 new two-center catalysts was constructed. The catalysts were applied in phase-transfer alkylations and Michael additions to afford the corresponding products in up to 93% ee and 82% ee, respectively. 相似文献
74.
This communication presents studies that nitroso Diels-Alder adduct has been furnished in uniformly high yield and high enantioselectivity using nitrosopyridine as a substrate and copper as a catalyst. The obtained Diels-Alder adduct was easily transformed to corresponding chiral amino alcohols without loss of enantioselectivity. 相似文献
75.
[reaction: see text] A new entry in catalytic alkynylation of carbonyl compounds was developed in which dual activation of both soft nucleophiles (terminal alkynes) and hard electrophiles (aldehydes and ketones) is achieved using an indium(III) catalyst. Preliminary mechanistic studies using in situ IR and NMR spectroscopic analysis are also discussed. 相似文献
76.
Advanced protocol for the detection of irradiated food by electron spin resonance spectroscopy 总被引:1,自引:0,他引:1
Yuhei Shimoyama Mitsuko Ukai Hideo Nakamura 《Radiation Physics and Chemistry》2007,76(11-12):1837-1839
Using ESR (electron spin resonance) spectroscopy, we found various free radicals in a pepper before and after irradiation. The representative ESR spectrum of the pepper composed of a sextet centered at g=2.0, a singlet at the same g-value and a singlet at g=4.0. This reflects the evidence of three independent radicals in the pepper before irradiation. Upon gamma ray irradiation, a new pair of signals appeared. The progressive saturation behavior (PSB) at various microwave power levels indicates quite different relaxation behaviors of those signals. For the evaluation of radiation-induced radicals and irradiation effects we propose a new protocol using the PSB method. This would call for an advanced protocol for the detection of irradiated foods. 相似文献
77.
Masayoshi Onishi Katsuma Hiraki Yushichiro Ohama Atsushi Kurosaki 《Journal of organometallic chemistry》1985,284(3):403-408
Thallium [1-(p-tolylimino)-2-methylpropyl]cyclopentadienide, Tl[C5H4C(=NC6H4CH3)CH(CH3)2], was prepared and treatment of the salt with [{PdCl2(PREt2)}2] (R = Ph and Et) yielded mononuclear palladium(II) complexes, [Pd{η5-C5H4C(=NC6H4CH3)CH(CH3)2}Cl(PREt2)], with an imidoyl-substituted η5-cyclopentadienyl group. In addition, [Pd(η5-C5H4-COY)Cl(PPhEt2)] (Y = CH3 and OCH3) complexes were obtained from the sodium salts of their substituted cyclopentadienyl groups. These new compounds were characterized by means of 1H and 13C NMR and IR spectroscopy. 相似文献
78.
Masayoshi Onishi Katsuma Hiraki Atsushi Iwamoto 《Journal of organometallic chemistry》1984,262(2):c11-c13
A 1,2-disubstituted ferrocene derivative, 2-[(dimethylamino)methyl]-1-hydroxyferrocene (I), was prepared from 2-[(dimethylamino)methyl]-1-iodoferrocene via 2-[(dimethylamino)methyl]-1-acetoxyferrocene. On complexation, compound I served as a stable monovalent chelate ligand of a 1,2-disubstituted ferrocene derivative. In addition, a dihydroxy derivative, 2-(hydroxymethyl)-1-hydroxyferrocene, was obtained from hydrolysis of the methiodide formed from I. 相似文献
79.
Hidefumi Hirai Katsuma Hiraki Isamu Noguchi Shoji Makishima 《Journal of polymer science. Part A, Polymer chemistry》1970,8(1):147-156
ESR spectra of homogeneous catalyst systems derived from n-butyl titanate and triethylaluminum at Al/Ti molar ratios of 1.0–10 were observed in toluene solution at several temperatures from ?78°C to +25°C. In the whole range of Al/Ti molar ratios, a single signal with a g value of 1.951 was observed at ?78°C and was associated with the first reaction intermediate. With increasing temperature, the intensity of the signal decreased gradually, while two series of signals appeared, depending on the Al/Ti molar ratio. At an Al/Ti molar ratio of 1.7, seven kinds of signals with g values of 1.960, 1.946, 1.950, 1.959, 1.980, 1.977, and 1.978, respectively, were observed. On the other hand, four kinds of signals with g values of 1.934, 1.966, 1.952, and 1.979, respectively, were found at Al/Ti molar ratios larger than 3. The structures of the species corresponding to the signals were discussed on the basis of the ESR spectra, the order of their growth and their hyperfine structures being considered. Two series of ESR signal were correlated to two kinds of active species for polymerization of styrene and butadiene, respectively. 相似文献
80.
Masayoshi Onishi Katsuma Hiraki Koichi Maeda Toshihiro Itoh 《Journal of organometallic chemistry》1980,188(2):245-253
The 2-picolylpalladium(II) complex [{Pd(CH2Py)Cl(PPh3)}2] (CH2Py=2-picolyl) (I), prepared from 2-picolyl chloride and [Pd(PPh3)4], was treated with lithium bromide, silver acetate, 4-picoline (pic) and silver perchlorate, thallium acetylacetonate{Tl(acac)}, sodium dimenthyldithiocarbamate-water-(1/2) {Na(dmdc). 2 H2O}, and 1,2-bis(diphenylphospino)ethane (dppe) to yield [{PdBr(CH2Py)(PPh3)}2] (II), [{Pd(CH2Py)OAc(PPh3)}2] (III), [{Pd(Ch2Py)(pic)(PPh3)}2](ClO4)2 (IV), [Pd(CH2Py)(acac)(PPh3)] (V), [Pd(CH2Py)(dmdc)(PPh3)] (VI), and [Pd(Ch2Py)Cl(dppe)] (VII), respectively. Halogen abstraction from VII using silver perchlorate afforded an ionic complex [{Pd(CH2Py)(dppe)}2](ClO4)2 (VIII). It was concluded that the 2-picolyl groups in these eight complexes are σ-bonded to palladium, and that in the dinuclear complexes I, II, III, IV, and VIII, they serve as bridging ligands. 相似文献