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951.
Yong Li Xiao-Bing Cui Ji-Qing Xu Ke-Chang Li Guang-Hua Li Qing-Xin Yang 《Journal of solid state chemistry》2005,178(1):363-369
Both the homometal cluster [P(ph4)]2[Mo2O2(μ-S)2(S2)2] (1) and [Mo2O2(μ-S)2(Et2dtc)2] (2) (Et2dtc=diethyl-dithiocarbamate) were successfully synthesized by low-temperature solid-state reactions. X-ray single-crystal diffraction studies suggest that compound (1) is a dinuclear anion cluster, and compound (2) is a dinuclear neutral cluster. The two compounds were characterized by elemental analyses, IR spectra and UV-Vis spectra. The third-order non-linear optical (NLO) properties of the clusters were also investigated and all exhibited nice non-linear absorption and self-defocusing performance with moduli of the hyperpolarizabilities 5.145×10−30 esu for (1) and 5.428×10−30 esu for (2). 相似文献
952.
The rates of photoinduced electron transfer (ET) reactions across two oligo-norbornyl spacer groups (S), that is, structure 1 fused by two norbornadiene (NBD) units and structure 2 fused by three NBD units, are examined. Substituted naphthalene acted as an electron donor (D), whilst ethylene-1,2-dicarboxylate as an electron acceptor (A). ET rates were measured by fluorescence quenching experiments on these D-S-A dyads, and the results were correlated with reaction free energies according to the Marcus relationship. It was found that naphthalene with phenyl substituents showed relatively slower ET rates. The conformational flexibility of phenyl substituents may cause a hindrance on the electronic coupling between D and A. Another salient feature was the abnormally high quenching rates observed in nonpolar solvents such as cyclohexane, the results of which may be ascribed to a competing energy transfer process. 相似文献
953.
聚乙烯醇双胺肟螯合纤维的合成及其吸附性能 总被引:5,自引:0,他引:5
利用预辐接技法合成了聚乙烯醇双胺肟螯合纤维。研究了影响接枝率和胺肟基团含量的因素,讨论了吸附酸度、吸附时间对Cu(Ⅱ)离子吸附容量的影响。 相似文献
954.
气相色谱质谱联用仪与微机的数据传输和处理 总被引:1,自引:0,他引:1
报道了一种用于气相色谱质谱联用仪和微机之间实现数据传输和处理的方法。方法可更有效地利用质谱仪采集的数据,解决了工作站处理数据的局限性。经数据格式转换,原始数据可以在微机上实现色谱峰再现,从而为色谱条件的优化和定量数据处理创造了条件。 相似文献
955.
Hong Tao Gao Dong Mei Dai Tong Hua Li 《中国化学快报》2007,18(4):495-498
Non-negative matrix factorization(NMF)is a technique for dimensionality reduction by placing non-negativity constraints onthe matrix.Based on the PARAFAC model,NMF was extended for three-dimension data decomposition.The three-dimension non-negative matrix factorization(NMF3)algorithm,which was concise and easy to implement,was given in this paper.The NMF3algorithm implementation was based on elements but not on vectors.It could decompose a data array directly without unfolding,which was not similar to that the traditional algorithms do.It has been applied to the simulated data array decomposition andobtained reasonable results.It showed that NMF3 could be introduced for curve resolution in chemometrics. 相似文献
956.
Two new compounds from Zingiber officinale 总被引:1,自引:0,他引:1
Yu Zhao Qiao Feng Tao Rong Ping Zhang Chang Xin Zhou Hui Dou Shu Yun Shi Ye Cheng Xiao Lian Li Sun Su Zeng Ke Xin Huang Xiao Dong Zhang Xiao Kun Li 《中国化学快报》2007,18(10):1247-1249
A new cyclic diarylheptanoid,1,5-epoxy-3-hydroxy-1-(3-methoxy-4,5-dihydroxyphenyl)-7-(4-hydroxyphenyl)-heptane (1),as well as a new monoterpene,10-O-β-D-glucopyranosyl-hydroxy cineole (2) were isolated from the rhizomes of Zingiber officinale. The structures of compounds 1 and 2 were established based on their spectral data.In addition,the antioxidant activities of these compounds were also measured. 相似文献
957.
Xi‐Zhao Wang Jiong Jia Yan Zhang Wei‐Ren Xu Wei Liu Fang‐Niu Shi Jian‐Wu Wang 《中国化学会会志》2007,54(3):643-652
The synthesis of a series of new 5‐isoxazolpenicillins is described, which were obtained by coupling substituted isoxazoles with 6‐APA. Concise large‐scale synthesis of 3,5‐disubstituted isoxazoles by 1,3‐dipolar cycloaddition using copper(I) as catalyst was also investigated. Representative compounds were assayed for antimicrobial activities, showing satisfactory antimicrobial activities against Gram‐negative bacteria. 相似文献
958.
Margaret C. Gerthoffer Sikai Wu Bo Chen Tao Wang Steven Huss Shalisa M. Oburn Vincent H. Crespi John V. Badding Elizabeth Elacqua 《Chemical science》2020,11(42):11419
Limited supramolecular strategies have been utilized to synthesize sequence-defined polymers, despite the prominence of noncovalent interactions in materials design. Herein, we illustrate the utility of ‘sacrificial’ aryl-perfluoroaryl supramolecular synthons to synthesize sp3-hybridized nanothreads from sp2-enriched reactants. Our strategy features A–B reactant pairs in the form of a phenol:pentafluorophenol co-crystal that is preorganized for an electronically-biased and sequence-defined polymerization. The polymerization, initiated at 12 GPa, affords an alternating copolymer featuring exogenous –OH functionalities. The external substitution is confirmed through IR spectroscopy. Importantly, the inclusion of the functional unit provides the first experimental glimpse at reaction mechanism: keto–enol tautomerization that can only occur during cycloaddition is observed through IR spectroscopy. Our approach realizes the first example of a functionalized nanothread and attains sequence definition through sacrificial supramolecular preorganization and presents a further approach for de novo design of complex nanothreads.Supramolecular synthons are exploited to synthesize –OH functionalized sp3-rich sequence-defined nanothreads using pressure-induced polymerization of a phenol:pentafluorophenol co-crystal. 相似文献
959.
Peter G. Dormer Amude M. Kassim Johnnie L. Leazer Jr. Feng Xu Edward G. Corley Jimmy O. DaSilva David M. Tschaen 《Tetrahedron letters》2004,45(28):5429-5432
A general method for the preparation of syn-2,3-disubstituted-2,3-dihydro-1,4-benzoxathiin rings from 2-mercaptoethanols and quinone ketals is presented. This ring system is produced by Michael addition of a 2-mercaptoethanol to a quinone ketal, followed by cyclization of the initial Michael adduct, and subsequent aromatization to afford a syn-2,3-disubstituted-1,4-benzoxathiin in fair to good chemical yield. Several chiral syn-2,3-disubstituted-2,3-dihydro-1,4-benzoxathiin rings were prepared with this method from enantioenriched 2-mercaptoethanols. No loss of enantiopurity was observed. 相似文献
960.
Three new hetero‐bischelated rhodium (III) complexes of cis‐[Rh(PA)(L)Cl2]Cl (where PA = phenylpyridin‐2‐ylmethylene‐amine; L = 2,2′‐bipyridine, 2,2′‐dipyridylamine and 1,10‐phenanthroline) have been successfully prepared and characterized. Each complex shows high intensity bands in the UV region, and these are assigned to spin‐allowed π‐π* transitions. The medium‐intensity absorption band profile in the lower energy region can be explained by convolution of spin‐allowed CT and d‐d* transitions. The emission spectra at low temperature (77 K) of these complexes in EtOH/MeOH (4:1 v/v) are virtually identical. They all exhibit a broad, symmetric, and structureless red emission with a microsecond lifetime and hence are assigned as the d‐d* phosphorescence. 相似文献