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981.
A new series of MR-IPN polyacrylamide—poly(vinyl-ethylenediamine)chelatesorbents were prepared by the reaction of ethylenediamine with MR-IPN matrixes.The newchelate sorbent showed good sorption properties for auric and platinic ions. 相似文献
982.
IntroductionTriazenereagentsareinterestingbecauseoftheirstrongcomplexationabilitieswithtransitionmetals .1 6However,littledecolorationofthemcatalyzedbysilverionhasbeenstudiedinanalyticalchemistry .Manyanal ysistshavereportedtheuseofcatalyticreactionsfort… 相似文献
983.
The effects of atomic multipole moments obtained by the potential-derived method on hydrogen bonding
A potential-derived atomic multipole method called the cumulative potential-derived atomic multipole method is developed, with which electrostatic atomic multipole moments are derived by fitting the molecular electric potential in a cumulative way. It is applied to the hydrides of N , O , F , S , Cl , and methanol and the hydrogen-bonded dimers formed between them. The relationship between atomic multipole moments and molecular charge distributions is found. The structures calculated with Buckingham's electrostatic model are in good agreement with experiments. The phenomena of nonlinear structures of most H -bonded complexes—the deviations of symmetry axes of electron donors from H bonds—and correct distinguishing between two alternative structures are attributed to atomic dipole and quadrupole moments. Compared with other methods, this method has a quantitative and qualitative advantage and simple algorithm. The main conclusion is that the atomic multipole moments play a substantial role, although a potential-derived charge model was deemed sufficient previously. © 1993 John Wiley & Sons, Inc. 相似文献
984.
Adsorption of NH3 onto activated carbon prepared from palm shells impregnated with H2SO4 总被引:3,自引:0,他引:3
Adsorption of ammonia (NH3) onto activated carbons prepared from palm shells impregnated with sulfuric acid (H2SO4) was investigated. The effects of activation temperature and acid concentration on pore surface area development were studied. The relatively large micropore surface areas of the palm-shell activated carbons prepared by H2SO4 activation suggest their potential applications in gas adsorption. Adsorption experiments at a fixed temperature showed that the amounts of NH3 adsorbed onto the chemically activated carbons, unlike those prepared by CO2 thermal activation, were not solely dependent on the specific pore surface areas of the adsorbents. Further adsorption tests for a wide range of temperatures suggested combined physisorption and chemisorption of NH3. Desorption tests at the same temperature as adsorption and at an elevated temperature were carried out to confirm the occurrence of chemisorption due to the interaction between NH3 and some oxygen functional groups via hydrogen bonding. The surface functional groups on the adsorbent surface were detected by Fourier transform infrared spectroscopy. The amounts of NH3 adsorbed by chemisorption were correlated with the contents of elemental oxygen present in the adsorbents. Mechanisms for chemical activation and adsorption processes are proposed based on the observed phenomena. 相似文献
985.
A highly general, convenient, and inexpensive catalyst system was developed for the N-arylation of sulfonamides with aryl iodides or bromides by using 5-20 mol % of CuI as catalyst, 20 mol % of N-methylglycine (for aryl iodides) or N,N-dimethylglycine (for aryl bromides) as ligand, and K3PO4 as base. 相似文献
986.
Rui Yan Li Zhi Ru Li Di Wu Xi Yun Hao Ru Jiao Li Chia Chung Sun 《International journal of quantum chemistry》2005,103(2):157-166
Using four basis bets, (6‐311G(d,p), 6‐31+G(d,p), 6‐31++G(2d,2p), and 6‐311++G(3df,3pd), the optimized structures with all real frequencies were obtained at the MP2 level for the dimers CH2O? HF, CH2O? H2O, CH2O? NH3, and CH2O? CH4. The structures of CH2O? HF, CH2O? H2O, and CH2O? NH3 are cycle‐shaped, which result from the larger bend of σ‐type hydrogen bonds. The bend of σ‐type H‐bond O…H? Y (Y?F, O, N) is illustrated and interpreted by an attractive interaction of a chemically intuitive π‐type hydrogen bond. The π‐type hydrogen bond is the interaction between one of the H atoms of CH2O and lone pair(s) on the F atom in HF, the O atom in H2O, or the N atom in NH3. In contrast with the above three dimers, for CH2O? CH4, because there is not a π‐type hydrogen bond to bend its linear hydrogen bond, the structure of CH2O? CH4 is noncyclic shaped. The interaction energy of hydrogen bonds and the π‐type H‐bond are calculated and discussed at the CCSD (T)/6‐311++G(3df,3pd) level. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
987.
Four chiral polymers P-1, P-2, P-3 and P-4 were synthesized by the polymerization of (S)-2,2'-dioctoxy-1,1'- binaphthyl-6,6'-boronic acid (S-M-3) with (S)-6,6'-dibromo-1,1'-binaphthol (S-M-1), (R)-6,6'-dibromo-1,1'- binaphthol (R-M-1), (S)-3,3'-diiodo-1,1'-binaphthol (S-M-2) and (R)-3,3'-diiodo-1,1'-binaphthol (R-M-2) under Pd-catalyzed Suzuki reaction, respectively. All four polymers can show good solubility in some common solvents due to the nonplanarity of the polymers in the main chain backbone and flexible alkyl groups in the side chain. The analysis results indicate that specific rotation and circular dichroism (CD) spectral signals of the alternative S-S chiral polymers P-1 and P-3 are larger than those of S-R chiral polymers P-2 and P-4, but their UV-Vis and fluorescence spectra are almost similar. The results of asymmetric enantioselectivity of four polymers for diethylzinc addition to benzaldehyde indicate that catalytically active center is (R) or (S)-1, 1'-binaphthol moieties. 相似文献
988.
Hai‐Yang Liu Shi‐Jin Li Yi Zhao Wei Ni Xiao‐Jiang Hao Jun‐Zhu Li Yan Hua Bai‐Bo Xie Chen Qing Chang‐Xiang Chen 《Helvetica chimica acta》2007,90(10):2017-2023
Four new podocarpane‐type trinorditerpenenes, (5β,10α)‐12,13‐dihydroxypodocarpa‐8,11,13‐trien‐3‐one ( 1 ), (5β,10α)‐12‐hydroxy‐13‐methoxypodocarpa‐8,11,13‐trien‐3‐one ( 2 ), (5β,10α)‐13‐hydroxy‐12‐methoxypodocarpa‐8,11,13‐trien‐3‐one ( 3 ), and (3α,5β,10α)‐13‐methoxypodocarpa‐8,11,13‐triene‐3,12‐diol ( 4 ), together with four known diterpenes, 12‐hydroxy‐13‐methylpodocarpa‐8,11,13‐trien‐3‐one ( 5 ), spruceanol ( 6 ), ent‐3α‐hydroxypimara‐8(14),15‐dien‐12‐one ( 7 ), and ent‐3β,14α‐hydroxypimara‐7,9(11),15‐triene‐12‐one ( 8 ), were isolated from the twigs and leaves of Aleurites moluccana. Their structures were elucidated by means of comprehensive spectroscopic analyses, including NMR and MS. Except 8 , all compounds were evaluated for their cytotoxicity; compound 4 exhibited moderate inhibitory activity against Raji cells with an IC50 value of 4.24 μg/ml. 相似文献
989.
Yahan Cui Rong Deng Xiangshuai Li Xinghuo Wang Qiong Jia Emilie Bertrand Kamel Meguellati Ying-Wei Yang 《中国化学快报》1990,30(12):2291-2294
A multifunctional nanohybrid based on mesoporous silica nanoparticle and biocompatible polypeptide was fabricated for targeted and dual-responsive therapy of tumor cells. 相似文献
990.
ZHENG Yan YANG Bing ZHANG Hai-quan LU Ping SHEN Fang-zhong LIU Lin-lin XU Hai YANG Guang-di MA Yu-guang 《高等学校化学研究》2007,23(6):720-725
A soluble poly(meta-phenylene)derivative with rigid twisted biphenyl unit was synthesized by the Yamamoto coupling reaction.The polymer is soluble in common organic solvents,and the number-average molecular weight is about 6500.The UV-Vis and quantum chemical calculation indicate that the different conformation segments named "conformers" exist in the polymer backbones;it was also further confirmed by the single crystal X-ray diffraction study of the dimeric model compound.The π-π transition of biphenyl segments of twisted and planar conformations made the polymer exhibit a strong absorption around 256 nm and a weak absorption at about 300 nm.Furthermore,the polymer exhibits a strong UV photoluminescence at 372 nm when the excitation wavelengths are longer than 300 nm.The ultraviolet-emitting electroluminescence(EL)device with the single layer structure shows EL λmax of the derivative at 370 nm. 相似文献