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101.
102.
Masayuki Hagiwara Shojiro Kimura Haruhiko Yashiro Takanari Kashiwagi Hironori Yamaguchi Koichi Kindo 《Applied magnetic resonance》2009,36(2-4):269-274
We have developed high-field and multifrequency (HFMF) electron spin resonance (ESR) apparatus for the magnetic fields up to 65 T at frequencies up to about 6 THz. In addition to this pulsed field ESR apparatus, we are making a multifrequency ESR apparatus with very high sensitivity in a static field. We report the results of ESR studies on BaCoV2O8 and NiGa2S4, followed by recent developments and future plans of our HFMF ESR apparatus. 相似文献
103.
Yiliang Wu Jun-Ichi Mamiya Osamu Tsutsumi Akihiko Kanazawa Takeshi Shiono Tomiki Ikeda 《Liquid crystals》2013,40(6):749-753
Photoinduced alignment in a polymer liquid crystal prepared from 6-{1-[4-(2-cyano-4-nitrophenylazo)phenyl]piperazino}hexyl acrylate and 4'-[6-(methacryloyloxy)hexyloxy]-4-cyanobiphenyl was investigated for the first time on irradiation with a polarized He-Ne laser beam at 633 nm. The azobenzene moieties as well as the inert cyanobiphenyl mesogenic units were aligned with the molecular long axis perpendicular to the polarization direction of the irradiation light. Alignment induced on short irradiation was reversible, while that induced under prolonged irradiation was irreversible due to the occurrence of crosslinking which might be caused by photoinduced decomposition of the azobenzene moieties during the photoirradiation process. 相似文献
104.
Makoto Uchimura Ryohei Ishige Masayuki Shigeta Yuki Arakawa Yosuke Niko Junji Watanabe Gen-Ichi Konishi 《Research on Chemical Intermediates》2013,39(1):403-414
We synthesized thermotropic liquid-crystalline polyesters in which 9,10-diphenylanthracene moieties are incorporated into the main chain type of polyester forming the chiral smectic C (Sm C*). The polymers were prepared by the isopropyltitanate-catalyzed reaction of biphenyldicarboxylic acid and the corresponding diols, with different ratios of diol of 9,10-diphenylanthracene moiety to the alkane diols (1, 5, and 10 mol %) under nitrogen atmosphere. The polymers exhibited thermotropic liquid crystals despite the presence of a bulky diphenylanthracene moiety in the main chain. The circular dichroism spectra revealed that a Sm C* phase was formed in the polymer with 1 mol % of anthracene moiety, although only an Sm A phase was formed in the other polymers. This is the first example of a Sm C* polyester containing a diphenylanthracene moiety in the main chain. Furthermore, we measured the optical properties of the polymers and found that they exhibited very high fluorescent efficiency. The fluorescence spectra of the thin film differed from that of a CH2Cl2 solution. 相似文献
105.
106.
107.
The demand for more efficient methods of establishing the undetermined stereochemistries of peptidic natural products continues unabated. A new method for microscale stereochemical determination was devised by integrating solid-phase synthesis, split-and-mix randomization, 18O/16O-encoding of d /l -configurations, tandem mass spectrometry, and biological evaluation. Here we applied gramicidin A as the molecule for a blind test. Gramicidin A and its 31 diastereomers were randomly prepared in microgram scale with 18O/16O-stereochemical encoding and subjected to MS/MS-structural determination and cytotoxicity assay. Only the parent gramicidin A was selected from among the 32 stereoisomers, validating the high reliability of the present strategy. 相似文献
108.
Dr. Masayuki Gon Junko Wakabayashi Masashi Nakamura Prof. Dr. Kazuo Tanaka Prof. Dr. Yoshiki Chujo 《化学:亚洲杂志》2021,16(6):696-703
We demonstrate that multi-fluorinated boron-fused azobenzene (BAz) complexes can work as a strong electron acceptor in electron donor-acceptor (D-A) type π-conjugated polymers. Position-dependent substitution effects were revealed, and the energy level of the lowest unoccupied molecular orbital (LUMO) was critically decreased by fluorination. As a result, the obtained polymers showed near-infrared (NIR) emission (λPL=758–847 nm) with high absolute photoluminescence quantum yield (ΦPL=7–23%) originating from low-lying LUMO energy levels of the BAz moieties (−3.94 to −4.25 eV). Owing to inherent solid-state emissive properties of the BAz units, deeper NIR emission (λPL=852980 nm) was detected in film state. Clear solvent effects prove that the NIR emission is from a charge transfer state originating from a strong D-A interaction. The effects of fluorination on the frontier orbitals are well understandable and predictable by theoretical calculation with density functional theory. This study demonstrates the effectiveness of fluorination to the BAz units for producing a strong electron-accepting unit through fine-tuning of energy gaps, which can be the promising strategy for designing NIR absorptive and emissive materials. 相似文献
109.
The title complex is a triple-stranded metallohelicate organized by the self-assembly of 5,17-difunctionalized calix[4]arenes and metal cations with octahedral coordination geometry. Due to hydrophilic triethylene glycol chains on the lower rim of the calix[4]arene, the metallohelicate can encapsulate cationic guests in water. NMR and UV-vis titration experiments reveal that the metallohelicate captures a pyridinium guest with an alanine derivative to form a host-guest complex with a host-guest ratio of 1 : 1. CD spectroscopy confirms the bias of the P- and M-helical sense of the metallohelicate by the captured guest. The metallohelicate captures two molecules of dicationic N,N’-dimethyl-DABCO and monocationic N-methyl quinuclidine, exhibiting a positive allosteric effect. 1H NMR titration experiments indicate that the bound guests are in close proximately to the aromatic rings of the ligands. Molecular mechanics calculations based on the UV-vis and NMR observations suggest that the first guest preorganizes the conformation of the metallohelicate to facilitate access of the second guest to the cavity. 相似文献
110.
Shuichi Ebisawa Takuro Tsutsumi Tetsuya Taketsugu 《Journal of computational chemistry》2021,42(1):27-39
A mathematical aspect of the anharmonic downward distortion following (ADDF) path is discussed. The ADDF method is utilized as an automated reaction path search method, which can explore transition state geometries on a potential energy surface from a potential minimum. We show that the maximum number of the ADD stationary paths intersecting the potential minimum is 2f + 1 ? 2 , where f denotes the degree of freedom of the system. We also show that the bifurcation of the ADD stationary path is essential to detect all the transition states connected from a given minimum. The ADDF computation is demonstrated for a H2O molecule in which pitchfork bifurcation is observed. 相似文献