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311.
Tomohiro Hirano Yuya Okumura Hiroko Kitajima Makiko Seno Tsuneyuki Sato 《Journal of polymer science. Part A, Polymer chemistry》2006,44(15):4450-4460
The effects of simple alkyl alcohols on the radical polymerization of N‐isopropylacrylamide in toluene at low temperatures were investigated. We succeeded in the induction of syndiotactic specificity and the acceleration of polymerization reactions at the same time by adding simple alkyl alcohols such as 3‐methyl‐3‐pentanol (3Me3PenOH) to N‐isopropylacrylamide polymerizations. The dyad syndiotacticity increased with a decrease in the temperature and an increase in the bulkiness of the added alcohol and reached up to 71% at ?60 °C in the presence of 3Me3PenOH. With the assistance of NMR analysis, it was revealed that the alcohol compounds played dual roles in this polymerization system; an alcohol compound coordinating to the N? H proton induced syndiotactic specificity, and that hydrogen‐bonded to the C?O oxygen accelerated the polymerization reaction. The effect of syndiotacticity on the properties of poly(N‐isopropylacrylamide)s was also examined in some detail. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4450–4460, 2006 相似文献
312.
Masanobu Wakasa Yuya Takamori Masayuki Orihara 《Journal of organometallic chemistry》2007,692(14):2855-2860
The photochemistry of octaisopropylcyclotetragermane was studied by laser flash photolysis and trapping experiments. Upon irradiation of the cyclotetragermane, the main reaction was a ring opening to form octaisopropyltetragermane-1,4-diyl biradical (λmax = 310 and 550 nm), but generations of diisopropylgermylene and tetraisopropyldigermene are negligible. 相似文献
313.
314.
Prof. Dr. Yuya Domoto Masahiro Abe Dr. Georgi R. Genov Zhengsu Yu Prof. Dr. Makoto Fujita 《Angewandte Chemie (International ed. in English)》2023,62(33):e202303714
Entangled (M3L2)n polyhedral complexes represent a unique class of supramolecular architectures that are stabilized by relatively weak metal–acetylene interactions in cooperation with conventional metal–pyridyl coordination. Counter-anion exchange of these complexes with a nitrate (NO3−) ion triggered formal metal insertion between the metal centers, and a heteroleptic ternary coordination mode with acetylenic, pyridyl, and nitrate donors was generated on the metal centers. As a result, the main frameworks of the polyhedral complexes M18L12 and M12L8 were formally extended into a new series of concave polyhedra having the compositions M21L12 and M13L8, respectively. This transformation also resulted in the local disconnection of the highly entangled trifurcate topology of the framework, providing clues toward the skeletal editing of extended and complex three-dimensional (3D) architectures. 相似文献
315.
Yuya Inaba Jian Yang Yu Kakibayashi Dr. Tomoki Yoneda Dr. Yuki Ide Dr. Yuh Hijikata Dr. Jenny Pirillo Dr. Ranajit Saha Prof. Dr. Jonathan L. Sessler Prof. Dr. Yasuhide Inokuma 《Angewandte Chemie (International ed. in English)》2023,62(15):e202301460
Chiral pyrrolic macrocycles continue to attract interest. However, their molecular design remains challenging. Here, we report a calixpyrrole-based chiral macrocyclic system, calix[1]furan[1]pyrrole[1]thiophene ( 1 ), synthesized from an oligoketone. Macrocycle 1 adopts a partial cone conformation in the solid state, and undergoes racemization via ring inversion. Molecular dynamics simulations revealed that inversion of the thiophene is the rate determining step. Pyrrole N-methylation suppressed racemization and permitted chiral resolution. Enantioselective N-methylation also occurred in the presence of a chiral ammonium salt, although the stereoselectivity is modest. A unique feature of 1 is that it acts as a useful synthetic precursor to yield several calix[n]furan[n]pyrrole[n]thiophene products (n=2–4), including a calix[12]pyrrole analogue that to our knowledge constitutes the largest calix[n]pyrrole-like species to be structurally characterized. 相似文献
316.
Aki Honda Shinichiro Hayashi Hiroki Hifumi Yuya Honma Noriyuki Tanji Naoko Iwasawa Yoshio Suzuki Koji Suzuki 《Analytical sciences》2007,23(1):11-15
We have designed and synthesized various mass probes, which enable us to effectively ionize various molecules to be detected with mass spectrometry. We call the ionization method using mass probes the "MPAI (mass probes aided ionization)" method. We aim at the sensitive detection of various biological molecules, and also the detection of bio-molecules by a single mass spectrometry serially without changing the mechanical settings. Here, we review mass probes for small molecules with various functional groups and mass probes for proteins. Further, we introduce newly developed mass probes for proteins for highly sensitive detection. 相似文献
317.
A new signaling technique for a fluorometric heparin assay has been developed using the self-quenching of fluoresceinisothiocyanate-labeled protamine (F-protamine). The binding between F-protamine and heparin led to a significant fluorescence quenching due to enhancing the proximity of the F-protamine molecules. The fluorescence of F-protamine (5.9 μg/mL) decreased to 13% in the presence of 2.0 μg/mL heparin. An advantage of this self-quenching system is that the detection can be carried out without using other indicators. With the present system, we could monitor the therapeutic level of heparin in bovine plasma, and the response was quick. These properties of the self-quenching system are suitable for practical use. 相似文献
318.
We have investigated the growth of Fe nanostructures on GaN(0 0 0 1) substrates at room temperature using reflection high-energy electron diffraction (RHEED), scanning tunneling microscopy (STM), and superconducting quantum interference device magnetometer. Initially, a ring RHEED pattern appears, indicating the growth of polycrystalline α-Fe. At around 0.5 nm deposition, the surface displays a transmission pattern from α-Fe films with the epitaxial relationship of Fe(1 1 0)//GaN(0 0 0 1) and Fe[1 −1 1]//GaN[1 1 −2 0] (Kurdjumov-Sachs (KS) orientational relationship). Further deposition to 1 nm results in the appearance of a new spot pattern together with the pattern from domains with the KS orientation relationship. The newly observed pattern shows that Fe layers are formed with the epitaxial relationship of Fe(1 1 0)//GaN(0 0 0 1) and Fe[0 0 1]//GaN[1 1 −2 0] (Nishiyama-Wasserman (NW) orientational relationship). From STM images for Fe layers with the KS and NW orientational relationships, it can be seen that Fe layers with the KS relationship consist of round-shaped Fe nanodots with below 7 nm in average diameter. These nanodots coalesce to form nanodots elongating along the Fe[1 0 0] direction, and they have the KS orientational relationship. Elongated Fe nanodots with the NW relationship show ferromagnetism while round-shaped Fe nanodots with the KS relationship show super-paramagnetic behavior. We will discuss their magnetic properties in connection with the change in crystalline configurations of nanodots. 相似文献
319.
Daisuke Sawada Yuya Tsukuda Hiroshi Saito Eiji Ochiai Kazuya Takenouchi 《Tetrahedron》2010,66(29):5407-5423
2α- and 2β-Substituted analogs of 14-epi-previtamin D3 were synthesized and isolated after thermal isomerization of 14-epi-vitamin D3 triene at 80 °C. The VDR binding affinity and transactivation activity of osteocalcin promoter in HOS cells were tested, and the 2α-methyl-substituted analog was found to have greater genomic activity than 14-epi-previtamin D3. We found that modification at the C2 position of the seco-steroidal skeleton afforded interesting effects for biological genomic activity for the previtamin D form as well as the natural vitamin D form. 相似文献
320.
We have evaluated the plasticizing effect of poly(butylene succinate) (PBS) and cellulose acetate butyrate (CAB). PBS and CAB were mixed with a melt-kneading machine. The tensile strength and strain at break in the case of the blend with 10% CAB in the PBS matrix were 547% and 35 MPa. It showed that CAB acted as a plasticizer for PBS. The biomass carbon ratio of the blends measured by accelerator mass spectrometry based on ASTM D6866 showed that the biomass carbon derived from a part of the CAB corresponded to the theoretical value of the polymer blend. The biodegradation of PBS with the CAB melt blend powders was evaluated by a microbial oxidative degradation analyzer under controlled compost conditions based on ISO 14855-2. PBS with 10% CAB was not degraded within 60 days due to the addition of CAB that could control the biodegradability of the PBS. 相似文献