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61.
The enzymatic degradation of typical chemically synthesized biodegradable plastics, such as poly(butylene adipate) and poly(epsilon-caprolactone), to a repolymerizable cyclic oligomer under continuous flow using an enzyme column was studied, directed towards green chemical recycling. It was confirmed that both polymers were quantitatively transformed into the corresponding cyclic oligomers by passage through the column packed with immobilized lipase from Candida antarctica (Novozym 435) at 40 degrees C using a toluene solution. Compared to the batch treatment in a flask, a short reaction time and a low reaction temperature occurred for complete transformations of the polyesters by continuous flow through the enzyme column. The degradation activity of the enzyme column was maintained for at least six months at 40 degrees C. Conceptual scheme of the continuous degradation equipment using the enzyme column. 相似文献
62.
Kazunobu Toshima Tomonori KimuraRyusuke Takano Tomohiro OzawaAkiko Ariga Yutaka ShimaKazuo Umezawa Shuichi Matsumura 《Tetrahedron》2003,59(35):7057-7066
The quinoxaline moiety in antitumor quinoxaline antibiotics cleaved double stranded DNA at the 5′ side guanine of the 5′-GG-3′ site upon irradiation with UV light with a long wavelength and without any additive. The quinoxaline-carbohydrate hybrid system was very effective for the DNA cleavage. Furthermore, the quinoxaline-carbohydrate hybrids exhibited strong and selective cytotoxicity against cancer cells with photoirradiation. 相似文献
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Sayaka Kira Takayuki Miyamae Dr. Kohei Yoshida Dr. Yuki Kanzaki Dr. Kenji Sugisaki Prof. Dr. Daisuke Shiomi Prof. Dr. Kazunobu Sato Prof. Dr. Takeji Takui Dr. Shuichi Suzuki Prof. Dr. Masatoshi Kozaki Prof. Dr. Keiji Okada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(44):11450-11457
Multinuclear AuI complexes with two or three nitronyl nitroxide-2-ide radical anion and phosphine-ligand scaffolds, (NN-Au)2-1 o , (NN-Au)2-1 m , and (NN-Au)2-1 p , have been synthesized to investigate the influence of AuI−AuI (aurophilic) interactions on the properties of multispin molecular systems. The desired complexes were successfully prepared in moderate yields in a one-pot synthesis from the corresponding phosphine ligand, AuI source, parent NN, and sodium hydroxide. Among the prepared complexes, (NN-Au)2-1 o , in which an aurophilic interaction was clearly observed by crystal structure analysis, showed characteristic spin−spin interactions, electrochemical properties, and solvatochromic behavior. The results from theoretical calculations also suggested that the differences in properties between complex (NN-Au)2-1 o and the other complexes are due to intramolecular aurophilic interactions. 相似文献
68.
Sugisaki K Toyota K Sato K Shiomi D Kitagawa M Takui T 《Physical chemistry chemical physics : PCCP》2011,13(15):6970-6980
Spin-orbit and spin-spin contributions to the zero-field splitting (ZFS) tensors (D tensors) of spin-triplet phenyl-, naphthyl-, and anthryl-nitrenes in their ground state are investigated by quantum chemical calculations, focusing on the effects of the ring size and substituted position of nitrene on the D tensor. A hybrid CASSCF/MRMP2 approach to the spin-orbit term of the D tensor (D(SO) tensor), which was recently proposed by us, has shown that the spin-orbit contribution to the entire D value, termed the ZFS parameter or fine-structure constant, is about 10% in all the arylnitrenes under study and less depends on the size and connectivity of the aryl groups. Order of the absolute values for D(SO) can be explained by the perturbation on the energy level and spatial distributions of π-SOMO through the orbital interaction between SOMO of the nitrene moiety and frontier orbitals of the aryl scaffolds. Spin-spin contribution to the D tensor (D(SS) tensor) has been calculated in terms of the McWeeny-Mizuno equation with the DFT/EPR-II spin densities. The D(SS) value calculated with the RO-B3LYP spin density agrees well with the D(Exptl) -D(SO) reference value in phenylnitrene, but agreement with the reference value gradually becomes worse as the D value decreases. Exchange-correlation functional dependence on the D(SS) tensor has been explored with standard 23 exchange-correlation functionals in both RO- and U-DFT methodologies, and the RO-HCTH/407 method gives the best agreement with the D(Exptl) -D(SO) reference value. Significant exchange-correlation functional dependence is observed in spin-delocalized systems such as 9-anthrylnitrene (6). By employing the hybrid CASSCF/MRMP2 approach and the McWeeny-Mizuno equation combined with the RO-HCTH/407/EPR-II//U-HCTH/407/6-31G* spin densities for D(SO) and D(SS), respectively, a quantitative agreement with the experiment is achieved with errors less than 10% in all the arylnitrenes under study. Guidelines to the putative approaches to D(SS) tensor calculations are given. 相似文献
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Masayuki Kirihara Aiko Harano Hiroyuki Tsukiji Ryu Takizawa Tomoyuki Uchiyama Akihiko Hatano 《Tetrahedron letters》2005,46(37):6377-6380
Dithioacetals can be deprotected to afford carbonyl groups using the tantalum(V) chloride catalyzed oxidation of iodide ion by hydrogen peroxide under mild conditions. 相似文献