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971.
Kyung‐Youl Baek Masami Kamigaito Mitsuo Sawamoto 《Journal of polymer science. Part A, Polymer chemistry》2002,40(12):1937-1944
A series of functionalized 2‐bromoisobutyrates and 2‐chloro‐2‐phenylacetates led to α‐end‐functionalized poly(methyl methacrylate)s in Ru(II)‐catalyzed living radical polymerization; the terminal functions included amine, hydroxyl, and amide. These initiators were effective in the presence of additives such as Al(Oi‐Pr)3 and n‐Bu3N. The chlorophenylacetate initiators especially coupled with the amine additive gave polymers with well‐controlled molecular weights (Mw/Mn = 1.2–1.3) and high end functionality (Fn ~ 1.0). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1937–1944, 2002 相似文献
972.
Xu‐Xia Sun Shu‐Lan Ma Hai‐Bo Huang Chuan‐Min Qi 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(2):o87-o88
In the crystal structure of the title compound, C21H21NO2, strong N—H⋯O and O—H⋯O hydrogen bonds exist. The keto–amine form is favoured over the enol–imine form in the tautomerism. Six‐membered chelate rings formed by intramolecular hydrogen bonds increase the stability of the whole molecule. Intermolecular hydrogen bonds link adjacent units together, forming an infinite one‐dimensional chain parallel to the a axis. 相似文献
973.
Zheng‐Yu Yue Shu‐Hui Li Po Gao Jin‐Hui Zhang Peng‐Fei Yan 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(5):o281-o282
The title compound, C30H46O9, prepared from a mixture of α‐ and β‐dihydroartemisinin, has α‐ and β‐arteether moieties linked via an –O– bridge, so that the molecule is asymmetric about the bridge. The endoperoxide bridges of the parent compounds have been retained in each half of the ether‐bridged dimer. The rings exhibit chair and twist–boat conformations. 相似文献
974.
Nickel(II) and cobalt(II) derivatives of the blue copper protein Pseudomonas aeruginosa azurin have been studied by resonance Raman (RR) spectroscopy at liquid-nitrogen temperatures. Vibrational assignments for the observed RR bands of Ni(II)-azurin have been made through a study of (62)Ni-substituted azurin. A comparison of Ni(II)-azurin RR spectra with those of the wild type (Cu-containing) protein showed Ni(II)-S(Cys) stretching vibrations, nu(Ni-S)(Cys), at substantially lower frequencies (approximately 360 versus approximately 400 cm(-1), respectively), indicating that the Ni(II)-S(Cys) bond is much weaker than the corresponding Cu(II)-S(Cys) bond. Resonance enhanced predominantly nu(Ni-N)(His) modes indicate that the metal-N(His) bond distances in the Ni(II) derivative are the same as those in native azurin. The vibrational data also confirm a tetrahedral disposition of ligands about the metal in Ni(II)-azurin found in the protein crystallographic structures. As expected, excitation profile measurements on Ni(II)-azurin show that the nu(Ni-S)(Cys) assignable modes give maxima at the 440-nm absorption band, which confirms a S(Cys) --> Ni(II) charge-transfer origin of the 440-nm electronic transition in Ni(II)-substituted azurin. 相似文献
975.
Figuerola A Ribas J Llunell M Casanova D Maestro M Alvarez S Diaz C 《Inorganic chemistry》2005,44(20):6939-6948
The reaction of Ln(NO3)3(aq) with K3[Fe(CN)6] or K3[Co(CN)6] and 2,2'-bipyridine in water/ethanol led to eight trinuclear complexes: trans-[M(CN)4(mu-CN)2{Ln(H2O)4(bpy)2}2][M(CN)6].8H2O (M = Fe3+ or Co3+, Ln = La3+, Ce3+, Pr3+, Nd3+, and Sm3+). The structures for the eight complexes [La2Fe] (1), [Ce2Fe] (2), [Pr2Fe] (3), [Nd2Fe] (4), [Ce2Co] (5), [Pr2Co] (6), [Nd2Co] (7), and [Sm2Co] (8) have been solved; they crystallize in the triclinic space group P and are isomorphous. They exhibit a supramolecular 3D architecture through hydrogen bonding and pi-pi stacking interactions. A stereochemical study of the nine-vertex polyhedra of the lanthanide ions, based on continuous shape measures, is presented. No significant magnetic interaction was found between the lanthanide(III) and the iron(III) ions. 相似文献
976.
The synthesis of some new N‐[1‐(2,5‐dichlorophenyl)‐5‐methyl‐1,2,3‐triazol‐4‐yl]‐carbamic acid ester derivatives are reported in this paper. The yielded products 6a‐l were confirmed by Elemental analyses, NMR, MS, and IR spectra. 相似文献
977.
Isamu Onishi Kyung‐Youl Baek Yuzo Kotani Masami Kamigaito Mitsuo Sawamoto 《Journal of polymer science. Part A, Polymer chemistry》2002,40(12):2033-2043
A half‐metallocene iron iodide complex [Fe(Cp)I(CO)2] induced living radical polymerization of methyl acrylate (MA) in conjunction with an iodide initiator [(CH3)2C(CO2Et)I, 1 ] and Al(Oi‐Pr)3 to give polymers of controlled molecular weights and narrow molecular weight distributions (MWDs) (Mw/Mn < 1.2). With the use of chloride and bromide initiators, the MWDs were broader, whereas the molecular weights were similarly controlled. Other acrylates such as n‐butyl acrylate (nBA) and tert‐butyl acrylate (tBA) can be polymerized with 1 /Fe(Cp)I(CO)2 in the presence of Ti(Oi‐Pr)4 and Al(Oi‐Pr)3, respectively, to give living polymers. The 1 /Fe(Cp)I(CO)2 initiating system is applicable for the synthesis of block and random copolymers of acrylates (MA, nBA, and tBA) and styrene of controlled molecular weights and narrow MWDs (Mw/Mn = 1.2–1.3). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2033–2043, 2002 相似文献
978.
Six new indole alkaloids, named kopsifolines A–F ( 1 – 6 ), with an unprecedented hexacyclic carbon skeleton, constituting a new structural group of monoterpenoid indole alkaloids, were obtained from the leaf extract of a Malayan Kopsia species, and their structures were established by spectroscopic analysis. 相似文献
979.
Zhen‐Yi Jiang Xiao‐Hong Xu Hai‐Shun Wu Fu‐Qiang Zhang Zhi‐Hao Jin 《International journal of quantum chemistry》2004,97(4):876-882
Geometric and electronic properties of CmN2 (m = 1–14) clusters have been investigated by density functional theory using the hybrid B3LYP functional and the 6‐311G(d) basis set. Harmonic frequencies for these clusters are given to aid in the characterization of the ground states. These results show that CmN2 (m = 1–14) clusters form linear structures with D∞h symmetry. Two N atoms favor to bond at ends in linear isomers. The chains with odd m have triplet ground states whereas the ones with even m have singlet ground states. The calculated HOMO–LUMO gaps and ionization potentials all show that the CmN2 (m = 1–14) clusters with even m are more stable than those with odd m, which is consistent with the observed even–odd alternation of the time‐of‐flight signal intensities. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 相似文献
980.
Hong‐Ze Gao Zhong‐Min Su Chun‐Sheng Qin Ri‐Gen Mo Yu‐He Kan 《International journal of quantum chemistry》2004,97(6):992-1001
Bis(2‐methyl‐8‐quinolinolato)aluminum(III) hydroxide complex (AlMq2OH) is used in organic light‐emitting diodes (OLEDs) as an electron transport material and emitting layer. By means of ab initio Hartree–Fock (HF) and density functional theory (DFT) B3LYP methods, the structure of AlMq2OH was optimized. The frontier molecular orbital characteristics and energy levels of AlMq2OH have been analyzed systematically to study the electronic transition mechanism in AlMq2OH. For comparison and calibration, bis(8‐quinolinolato)aluminum(III) hydroxide complex (Alq2OH) has also been examined with these methods using the same basis sets. The lowest singlet excited state (S1) of AlMq2OH has been studied by the singles configuration interaction (CIS) method and time‐dependent DFT (TD‐DFT) using a hybrid functional, B3‐LYP, and the 6‐31G* basis set. The lowest singlet electronic transition (S0 → S1) of AlMq2OH is π → π* electronic transitions and primarily localized on the different quinolate ligands. The emission of AlMq2OH is due to the electron transitions from a phenoxide donor to a pyridyl acceptor from another quinolate ligand including C → C and O → N transference. Two possible electron transfer pathways are presented, one by carbon, oxygen, and nitrogen atoms and the other via metal cation Al3+. The comparison between the CIS‐optimized excited‐state structure with the HF ground‐state structure indicates that the geometric shift is mainly confined to the one quinolate and these changes can be easily understood in terms of the nodal patterns of the highest occupied and lowest unoccupied molecular orbitals. On the basis of the CIS‐optimized structure of the excited state, TD‐B3‐LYP calculations predict an emission wavelength of 499.78 nm. An absorption wavelength at 380.79 nm on the optimized structure of B3LYP/6‐31G* was predicted. They are comparable to AlMq2OH 485 and 390 nm observed experimentally for photoluminescence and UV‐vis absorption spectra of AlMq2OH solid thin film on quartz, respectively. Lending theoretical corroboration to recent experimental observations and supposition, the reasons for the blue‐shift of AlMq2OH were revealed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 相似文献